How Much to Replace a Hot Water Cylinder?


Most homeowners have a hot water cylinder installed to take care of their hot water needs. As a whole, hot water cylinders will last for a long, long time. You will need to replace them if they leak or if you wish to upgrade to a bigger, better hot water cylinder capacity.

Replacing your hot water cylinder is fairly simple for a professional who has undergone training to do just that. However, if you’re looking to do it yourself, then beware because even though the task seems simple enough, it can become quite a nightmare fast.

If you’re looking for hot water cylinders, then HotWaterCylinders.NZ is the right place for you to go.

Hot Water Cylinder Leaking

Is your hot water cylinder leaking? The first thing to do is to locate your water meter and then turn the gate valve clockwise to isolate the leak. If you’re looking for your water meter, it is usually placed at the front section of your property – in your footpath, your shared driveway, or your garden.

What to Do?

The next step is to locate your switch board or power and look for the switch called “water heater,” “hot water,” or “cylinder.” Then, the next step is to simply switch it to the OFF direction.  This will ensure that the hot water cylinder does not run empty and burn the element out while you’re waiting for the plumber.

The important thing is don’t jump to conclusions. Ask your plumber to check your hot water cylinder. If he tells you to buy a new hot water cylinder, get a second opinion. There are instances when the anlysis might be wrong, which eventually costs you thousands when you could have had a simple fixing done. Be sure to get another plumber’s opinion and see how things go.

Why Is My Hot Water Cylinder Leaking?

There are many reasons why your hot water cylinder might be leaking. You need to ask for expert opinion to isolate the case and provide measures to fix the problem. There are many reasons why your hot water cylinder is leaking.

These faults can apply:

  • Lose connections
  • Faulty element washer
  • Faulty valve
  • Excessive pressure
  • Cracked tank (caused by over pressure, over heating or old age)

What Happens Now?

At HotWaterCylinders.NZ, we help you solve your problem in the fastest and most cost efficient way possible. We apply an extremely effective elimination process to discover the fault and provide you with the best recommendation instantly. This assessment will be done at your premises free of charge.

We deliver the best products and services at the most affordable pricing range in the market. You will surely find excellent materials and experts in the field when you choose HotWaterCylinders.NZ. We offer the safest and most reliable professionals and materials in hot water cylinder installation and other products and services. Finding a hot water cylinder that fits is crucial.

Why Hire Hot Water Cylinder Specialists

HotWaterCylinders.NZ has installed thousands of hot water cylinders aross New Zealand in the past several years. We have developed systems that have lowered our labor and materials significantly. This enables us to beat the competition as they are unable to compete with our offering with the same level of quality and compliant installation. We make educated decisions every single time. We don’t make mistakes – that’s how you save a bundle when you choose us.

We employ our own staff – we don’t subcontract any of our work to outside staff, unlike so many of the other companies who offer hot water cylinder services. We have on staff certified plumbers and gasfitters who hold electrical licenses. This allows us to provide you professional services from start to finish. We offer our own fixed warranty so you will be able to avail of our warranty without having to seek out who caused the damage when using outside tradesmen. We take full responsibility for our installations.

Master Plumbers Guarantee 

We are insured and warrantied. We offer a $10 million public liability and are registered Master Plumbers and Gasfitters, giving you peace of mind.  We have been installing hot water cylinders for years and we intend to stick around for the duration of your warranty. On request we are happy to provide testimonials from your area to reinforce your trust with the satisfaction of our existing client base. Hot Water Cylinders is who we are and what we do every day!

What if I Need a New Hot Water Cylinder?

If our specialist determines that your Hot water cylinder can no longer be utilized you have several options available:

  • Replace your existing hot water cylinder “like for like” maintaining your existing pressure and layout.
  • If your existing hot water cylinder is main pressure you have the option to upgrade to a solar/heat pump ready mains pressure hot water cylinder for only $300 more than the “like for like” option.
  • If your existing hot water cylinder is low pressure you have all the above options available or replacing your low pressure cylinder “like for like” option.

Repair vs. Replace

Your decision on whether to repair or replace a malfunctioning water heater should start with its age. A traditional tank-type water heater lasts for 8-12 years. An anode rod inside your hot water tank helps protect the water heater’s interior lining by attracting corrosive particles through electrolysis.

Over the years, the rod corrodes and is unable to perform its job. At that point, corrosion inside the tanks begins, which marks the end of your unit’s life. Signs of this include discolored or rust-colored water and a metallic odor or taste.

Tankless water heaters may last up to 20 years. However, they cost 2-3 times more than regular ones.  Tank leaks most often signal that a unit needs to be replaced, especially if it is more than 6-8 years old.

Different Types of Hot Water Cylinder

Here are a few different types of hot water cylinder that you can choose from:


Upgrade to A Mains Pressure Rheem

$1,990.00 (incl. GST)
Manufacturer: Rheem

Product Code: MPU2300


  • 1 x 180lt Rheem Mains Pressure hot water cylinder (7 year warranty)
  • RMC mains pressure valves pack.

Ask about our speacial for a cylinder wrap.

Reuse exisitng drain and strapping.

*** Available in Auckland and Waikato only ***

Special deal is for upgrading your existing low pressure how water cylinder to a new Rheem 180L Hot water cylinder.

The Cylinder included in this package is for a Rheem 1711 mm x 488 mm. Please confrim your size before placing the order.

Extra repair work or modifications may incur additional cost, this will be confirmed onsite before begin. You will not be charged a callout.

To speak to a technician requesting to confirm the above cost please call our free-phone number today – 0800 429 546 or use our installation calculator.



$1,700.00 (incl. GST)
Manufacturer: HJ Cooper

Product Code: stain180sh



Includes a 180 L HJ Coopers mains pressure, solar ready and heat pump ready hot water cylinder, all labour and materials included around the install of the cylinder (only available in Auckland)

In some cases conditions will apply but you will be advised before we proceed with any work. Price only applies on payment in advance please contact us for more details. As this is a “like for like” deal you can upgrade your old valves for an additional $525.00.

This special is for a “LIKE FOR LIKE” replacement, you must already have a mains pressure. Cylinder must be installed in same position.

For deals to upgrade to Mains Pressure please >> CLICK HERE <<


1 x 180lt Stainless Steel Mains Pressure hot water cylinders (10 year warranty)

All Plumbing and Electrical work (unless your current wiring / switch is not compliant)

All involved materials within the scope quoted



$2,449.00 (incl. GST)
Manufacturer: Rinnai

Product Code: UPGIMQO76

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Upgrade to a new Rinnai stainless steel mains pressure hot water cylinder!

Replace your worn out leaky low pressure hot water cylinder to stainless.


  • 1 x 180lt Rinnai Mains Pressure hot water cylinder (10 year warranty)
  • Heat pump and solar heating ready
  • Mains pressure Valves
  • Tempering valve
  • Limiting valve
  • Cold feed expansion valve
  • Seismic restraints

*** Available in Auckland only *** LIMITED AMOUNT!

Special deal is for upgrading your existing low pressure hot water cylinder to a new Rinnai 180L Stainless steel Hot water cylinder.

Extra repair work or modifications may incur additional cost, this will be confirmed onsite before begin. You will not be charged a callout.

To speak to a technician requesting to confirm the above cost please call our free-phone number today – 0800 429 546 or use our installation calculator.

Special available in Auckland only, please refer to our terms and conditions for more details



$3,220.00 (incl. GST)
Manufacturer: Rheem

Product Code: FREZWCHY54




Included is:

  • 1 x 160lt Rheem Stellar efficiency Mains Pressure hot water cylinders (MADE IN NZ)
  • All plumbing, electrical work and involved materials
  • All mains pressure valves as required
  • All external work and adjustments including new drain
  • All gas fitting work and certification

Rheem 160L Stellar Mains Pressure Gas Hot Water Cylinder

1900mm high x 485mm wide x 558mm deep

10 year warranty on the storage cylinder and SuperFlue
5 year labour warranty on the cylinder and SuperFlue

FREE CALL 0800 429 546

*Installation available for Auckland areas only. This deal is based on your current install meeting the buidling code, any alterations to bring it up to standard will be charged for.

Rheem 160L Stellar Mains Pressure Gas Hot Water Cylinder

10 year warranty on the storage cylinder and SuperFlue
5 year labour warranty on the cylinder and SuperFlue
12 month warranty on labour and parts
5 star energy rating
Reheats 200 litres per hour
Innovative styling blends with the external home environment
Stellar SuperFlue increases both efficiency and performance
Vitreous enamel lining protects the cylinder from the variety of water qualities found around New Zealand

The Rheem Stellar is the most efficient domestic gas water heater available in New Zealand. With high flow rate capabilities it’s ideal for homes with more than one bathroom and moderate to high hot water use. It’s ideal for massage showers or filling baths and with no electrical conections necessary continues working even if the power goes off. Stylish in design, this energy efficient water heater also carries a 10 year Rheem *Warranty.

Why Compare Prices?

If you’re looking to have your hot water cylinder installed, repaired, or replaced, then you’ve come to the right place. At HotWaterCylinders.NZ, we provide the best products and services. Choose from a vast array of products and services and compare prices to get the best deal.

Comparing prices lets you find the best products and services as lesser cost. This means you get excellent services and products at a very affordable price scheme. Find your best choice from a myriad of products and services designed to cater to your every need.


Your requirements may vary but rest assured that our master plumbers and certified electricians can give you what you need. Whether you’re seeking to repair or replace your hot water cylinder, we’re here to help. Call us today and get a free quote.

How Do I Know If My LPG Bottle Is Empty?

A shower running cold mid-bath is never a welcome change. And it’s just as frustrating when your heating appliance or gas hob stops without a hint, because you’re suddenly out of gas. You can stop this annoying thing from happening again if you know when your LPG bottle is running low.

Help is here as we’ll show you an easy way to check when the bottle is about to run empty – so you can keep your gas supply going.

How long does a LPG bottle last?
For a family of two adults and two children, a 45kg bottle used for both hot water and gas cooktops will typically last about 6-8 weeks. It’s a different thing if you add a gas-fired space heater.

Gas cylinders typically have a change-over regulator (reg) installed between them. Some cylinders have an automatic reg that switches from the empty bottle to the full one when the first runs out. Other cylinders have a manual regulator, which you will need to turn by hand to switch to the reserve bottle.

The change-over regulator usually has a viewing window or an indicator. When both bottles are full, the indicator will be Black, Green or Clear. When one bottle is empty, the indicator will be RED. The reg will have a change-over valve and a directional arrow. If your regulator is manual, do not adjust the directional arrow. Many people mistake it for the change-over valve, but the arrow simply indicates which bottle is empty.

It’s a good idea to regularly check the indicator on the change-over regulator, so you can call us when one bottle is empty.

How to test the level of LPG in the cylinder
One way is to pour warm (not boiling) water down the side of the bottle. Wait a few minutes, then run your hand down the side of the bottle. The level where it feels cool to the touch indicates how much LPG is left.

This is a fairly accurate method, but there’s an easier and faster way – using a LPG cylinder weighscale.

gas_bottle_scaleThis is an innovative sensing device that monitors bottled gas levels and automatically sends an accurate reading of the remaining gas in the cylinder. The weighscale is installed underneath your LPG cylinders. We can set them up for you, and once they’re there, checking your cylinders will be one less thing to worry about.

The device is also tied to a mobile app, which you can  access to get detailed daily usage reports or prompts when your cylinders need a refill. You never need to guess the gas level as there are easy to view visuals and graphs for the remaining LPG. As the supplier, we also have this data in the app, so we’ll also know when to deliver the next cylinder so you can keep your gas going without interruptions.

This works for both residential and commercial applications. For more information about this new technology, a chat or call is most welcome. Get in touch with Hot Water Cylinders NZ!

Gas Hot Water Vs Electric

The Hayman Thermostatic Storage Electric Heater made by L.T Hayman Ltd in Auckland you see is almost 60 years old!

gas_VS_electric_water_heatingIncorporated is a Satchwell Thermostat (made in South Africa) enabling the user to change the internal storage temperature. This was before our new laws around Legionnaires’ disease were passed a few years ago preventing manufacturers from incorporating an adjustable thermostat.

As in the case of our Hayman Thermostatic Storage Electric Heater, when an older tank gives up and it’s time replace it, the question each home owner should ask is, “Is it worth switching to gas?”.

To read up on some of the benefits when upgrading to gas, please visit our Upgrade to Gas section.

old_low_pressure_hwcThis blog is not designed to convince you to buy a gas product, rather point out the benefits gas will bring and, in some instances, the disadvantages when upgrading from an electric hot water cylinder.

When looking at gas vs electric water heating there are several things you will want to ask yourself, including why, when, and how much will it cost?

The following should play into your decision making:
Why do I want an upgrade to gas?
Is it Opportunity, because your cylinder needs replacing?
Is it Savings, because you believe gas is cheaper to run?
Is it Lifestyle, because want to enjoy unlimited time in the shower?

Whatever the reason may be, it’s important to know all the facts.

Without doubt, the best time for an upgrade to gas is when your hot water cylinder needs to be replaced. This is simply because you are about to spend $1500+ on a replacement which could go towards a gas water heating system if all variables apply.

If you have done your due diligence and are confident gas is the way to go, then by all means upgrade to instant gas water heating.

To help with your due diligence, we have compiled the following “to do list” for you.
If you can answer all the below with Yes, then you are ready to go with gas!

  1. Are you upgrading because your hot water cylinder needs to be replaced?
  2. Do you have a single level home?
  3. Are you upgrading from low pressure to gas?
  4. Can the gas unit be positioned in a compliant manner and central to most delivery points, especially the kitchen and shower?
  5. Do you already have gas on the property or intend to go with LPG at the time of upgrade?

If you are looking at gas because you believe it’s cheaper to run, then you are right and you are wrong. Savings will fully depend on your site conditions and how your current hot water cylinder system is set up.

There are ways to make savings on an electric system without upgrading to gas including:
• Flow restrictors
• Smart controllers
• Better insulation

If your home has 2 levels or more, you may want to be cautious before upgrading to gas as pipe lag and undersized units may result in more energy use, negating any desired savings. Additionally, in many cases when upgrading from mains pressure to gas you will also experience a water pressure drop. Pressure loss with instantaneous water heating systems is very common, especially when retrofitted into the existing house plumbing.

Lifestyle is one of those reasons that is hardly arguable. The home owner understands the pros and cons and is willing to make sacrifices to gain a specific desired outcome.
Some of these include:
• Longer showers
• Gas cooking
• Combination systems

Despite your motive, it is advisable to keep all the above points in mind.
Whether you are upgrading to gas or upgrading to mains pressure, one of the key factors is your property.

Before making any commitment, get a second or even third opinion. Why not speak to the hot water specialists to get advice on a solution that will not only compliment your property and desired benefits but also meet your budget!
Call Hot Water Cylinders NZ today!

Manual vs Auto-Reset Cylinder Thermostats

Cylinder thermostats are energy-saving, safety devices. They control the heating element of your hot water cylinder by measuring the temperature of the water inside and switching the heat supply on and off to ensure water temperature stays within the acceptable range.

If the water temperature falls below the required minimum temperature, the heat supply (boiler or electricity) will start up. The New Zealand Building Code requires the minimum temperature inside a hot water tank to be 65oC. This is hot enough to inhibit the growth of harmful bacteria like Legionella. Once the desired temperature is reached, the thermostat will turn off the heat supply again.

On the other hand, if the temperature exceeds the maximum setpoint, the cylinder thermostat will switch off the heat supply to avoid unnecessarily overheating your water. This saves a lot of energy and obviously money on your energy bills.

As the water in the tank sits unused, it will start to lose some heat. If the temperature drops below the low limit, the thermostat will kick in to reheat the water and maintain the temperature.

Some hot water tanks will have either a manual or an auto-reset thermostat. So what’s the difference?

Manual-reset thermostat

Standard domestic electric water heaters’ control circuit consists of a manual-reset high limit switch, a lower thermostat, an upper thermostat, two heating elements and wires.

The upper element is energized when power is initially turned on to the unit. This heats the water in the upper third of the hot water tank, where hot water is drawn when you open a tap inside the house. When the desired temperature is reached in the upper third of the tank, power is switched to the lower heating element which continues to heat the water in the lower part of the tank until the lower thermostat setting is reached.

If the temperature inside the tank reaches 85oC (170oC), the high limit switch will be tripped. To ensure the over-temperature and energy cutout is set, you need to press the ‘reset’ button on the thermostat. See samples below:


Auto-Reset Thermostat

Just as the name suggests, an auto-reset thermostat has the capability to reset itself.

This is often offered as an upgrade feature for solar and hot water heat pump applications. Generally, solar water heaters generate tons of heat and have a tendency to heat water beyond the thermostat settings. This would result in frequent tripping of the high-limit switch, hence the need for an auto-reset thermostat.

Manual-reset thermostats may be used in split solar hot water systems, but it would need replacing every few years.

Some modern hot water cylinders also provide auto-reset thermostats as an option, allowing the water to remain within the ideal temperature range without any intervention.

The ‘reset’ button

The thermostat isn’t the only part of your electric water heater that can trip the reset button. If you are finding yourself having to reset the water heater too often or if you run out of hot water frequently, one of the following might be to blame:

  • Loose wiring. A loose wire in the heating element cause excess heat that will activate the high-limit switch.
  • Faulty high limit switch. If this device starts malfunctioning and consequently overheats the water, the switch will trip.
  • A short in the heating element. The thermostat may still work if there’s a short in the heating element, but the water will continue to be heated beyond the recommended temperature and trip the high-limit switch.
  • The problem may also be the electrical setup in your home.

If you suspect any of these, you should get a professional in to inspect your water heater.

More information about thermostats

If your hot water cylinder doesn’t have a thermostat or has a faulty one, do not attempt to install or replace it yourself. This is a job for a licensed and qualified tradesperson. There are electrical wiring and plumbing regulations and standards that must be followed. Also, it can be dangerous to an untrained person. Be sure to have the minimum limit set to 65oC to disinfect your water supply of harmful bacteria.

Please remember that setting the thermostat to a higher setting does not make the water heat up faster. Your heating system is designed to heat up water at a predefined rate, and raising the setting too high will simply result in wasted energy and even risks of scalding.

Since a temperature of 65oC may be too hot for most people, it is advisable to install a thermostatic mixing valve. This device mixes hot and cold water so you will get the right temperature from your taps and showers.

For more information about hot water cylinder thermostats, call the experts at Hot Water Cylinders NZ on 0800 429 546.

Hot Water Storage Cylinders, The Facts

Simply put, a hot water storage cylinder is a tank used to store hot water required for space heating or household use. It goes by other names such as hot water tank, heat storage tank, hot water cylinder, thermal storage tank or hot water thermal storage unit.

We don’t often think about this appliance as long as we get hot water on demand. But as soon as we’re greeted with that unwelcome cold shower, the realisation hits. The good news is hot water tanks are generally reliable and operate for many years without a glitch.

When that hitch finally comes, it’s good to have a background on this household convenience. It will also reduce your energy spending. Here are all the information you need to know when choosing the right hot water cylinder.

hot_water_storage_cylinder_mains_pressureTypes of storage cylinders

The main type of new installations in New Zealand are mains pressure storage water heaters, where the operating pressure is the same as the incoming supply (120-1,400 kPa, usually 350-700 kPa).

Besides that, other heaters operate as:

  • Low pressure, open-vented system, wherein pressure is provided by a cold water storage header tank (3-12 m head/30-120 kPa). This was traditionally used in Kiwi homes.
  • Low pressure system with a pressure-reducing valve to minimise the mains pressure water (3-12m head/30-120 kPa)

Here’s how the three types of systems compare:

Heater Type Mechanism Pros Cons
Low pressure, open-vented, header tank Cold water stored in a header tank is fed via gravity into the storage water tank located below the header tank. As the water is heated, it rises to the top of the cylinder where it can be drawn for domestic use.

The heating process causes water expansion, hence the open-vent pipe for releasing excess pressure. This pipe typically feeds back into the header tank supply.

  • Cheaper to install
  • Few valves required
  • Equal pressure system
  • Quiet operation
  • Suitable for wet back connection
  • Needs wider pipes
  • Needs grading to avoid air locking
  • Low pressure supply
  • Prone to pressure fluctuations
Low pressure, pressure reducing valve system

(open-vented or unvented)

This type works similar to a header tank system, but it uses a pressure-reducing valve to reduce the pressure from the mains supply to a pressure that can be maintained within the height of the vent pipe.

Supplies low pressure hot water and high pressure cold water to fixtures, hence called unequal pressure system.

  • Inexpensive installation and maintenance
  • Few valves required
  • Suitable for wet back connection (if open-vented)
  • Difficult to achieve a balanced flow to a shower
  • Needs larger diameter pipework for hot water supply
  • Prone to pressure fluctuations
Mains pressure, unvented Supplies mains pressure hot water to all outlets. It has an expansion vessel (internal or external) that allows the heated water to expand, but a pressure relief valve is recommended in case of expansion vessel failure.

This valve must be specified for the particular system used to achieve the required pressure rating.

  • More flexibility in locating the cylinder as header tanks and vent pipes are not required.
  • Equal pressure system
  • High pressure hot water
  • Quick hot water delivery
  • Smaller diameter pipework
  • Greater flexibility of pipework


  • More water wastage due to frequent heat-up cycles
  • Increased depreciation on pipes and fittings
  • Difficult to install
  • Subject to water hammer


Hot water storage tanks can also be classified based on how they are run: electric or fuel fired. The most commonly used fuel is gas, either natural or propane. But in some areas, an oil-fired heater is popular.

Fuel-fried models have vent pipe at the top that carry off exhaust gases, while electric units simply have a power cable connecting the heater to your electric service panel.

Indirect vs. Direct systems

This refers to how the water is heated in the tank. Most cylinders are indirect systems. They are heated using an external source such as a solar thermal or gas boiler, where water is heated then fed through a copper coil in the hot water tank. The heat is then transferred from the external heat source to the water inside the cylinder. In direct systems, an internal immersion heater directly heats the water inside the tank.

Methods for storing heat

  Method Advantage
Hot water tank with closed water circuit Heat is stored in the tank using external heat exchangers (coils) that can be directly tapped or used to power other heat exchangers The tank is not continually fed with cold water, which reduces limescale deposits especially in ‘hard’ water areas

Reduced oxygen levels, which minimises requirements for materials used in the tank, water circuits and pipework

Stratified hot water tank with closed circuit/ stratified thermal storage/ thermocline tank/ water stratified tank storage Mechanisms are put into place to maintain the vertical stratification of the water column, i.e. water at the top must be kept hot (90-95oC) and water at the bottom cold (20-40oC). Best for places with wide climatic range.

Design and construction

Water heater tanks are usually made of stainless steel, copper or vitreous (porcelain) enamel-lined carbon steel.

Electric and gas types are mostly similar in construction, sharing common components such as the drain valve, TPR valve, dip tube, internal anode rod and pipes and fittings. The main difference is that electric water heaters have a separate thermostat, while gas water heaters have a built-in gas control valve. In addition, gas models have an internal flue to vent gas and circulate heat; a heat limiting device to prevent overheating; and a special sensor called a ‘thermocouple’ to shut off the gas in case of emergency.

Most modern hot water tanks are made of stainless steel, which is lined with glass to prevent corrosion. Corrosion or rusting is the main reason for tank failure. An anode rod inside the tank also prevents the steel from rusting. It corrodes in place of the steel, so this part must be checked once a year and replaced if necessary. Otherwise, the steel will start to rust. Once a hole forms, the tank will eventually have to be replaced.

At the bottom of the tank is a drain cock that will empty the heater. A valve is fitted on the supply pipe to shut down the hot-water plumbing without interrupting the cold-water supply.

Because hot water tanks both heat and store water, they need to have some sort of insulation in order to maintain warm water in between heating cycles.


Water has a high specific heat capacity, which means it can store more heat per unit of weight compared to other substances. It’s one of the best medium for heat storage. In comparison, it can store four to five times as much heat as stone and up to ten times as much as most metals, per unit of weight.

When kept in an efficiently insulated tank, hot water will retain heat for longer. Thermal insulation significantly reduces standby heat loss and speeds up the heating process, which means you use less energy for heating water.

The most common insulating material for hot water tanks is fibreglass, which is typically fixed in place with straps, tape or the outer jacket of the water heater. For outdoor tanks, sprayed-on polyurethane insulation is common.

Water heaters have different insulation ratings. If you find the rating too low, you can add extra insulation on the outside of the tank to further reduce heat loss. In places with extreme weather conditions, the hot water cylinder can be fully enclosed in a specially built insulated space.

However, there is such thing as “too much” insulation. If you live in humid locations and you add more layers of insulation to an already well-insulated tank, condensation may occur which may lead to rust, mould or other operational problems. Air flow or combustion gas outflow, either by convection or fan-assisted, must be maintained to prevent condensation.

Heater effectiveness

Both the recovery rate and capacity of the tank affect your supply of hot water at home.

The recovery rate, or the speed at which a tank heats water, indicates how many gallons of water can be heated to 100oF in an hour. When you’re using water faster than it’s heated, you’ll eventually get colder water from the tap. However, since the tank also stores hot water, its capacity will also affect the ongoing supply at the tap.

Choosing a hot water tank with a suitable capacity and recovery rate depends on your household’s hot water demands. Electric heaters typically have low recovery rate but high tank capacity, which makes them suitable for intermittent use. On the other hand, fuel-fired tanks heat water faster but don’t necessarily have a large cylinder, which is good if you need hot water ready any time of day.


As mentioned earlier, tank capacity is a major consideration in choosing a hot water cylinder. Choosing a cylinder that’s too big will unnecessarily bump up your energy bill, while a tank too small will mean bouts of hot water shortage.

The right size depends on how much hot water your household uses on average. If you’re not sure, the table below will give you an idea on which size you need:

Family Size Gas Electric
1-2 30 30
2-3 40 40
3-4 40 50
5 or more 50 80

For big households or for commercial use, a tank with a higher recovery rate and capacity is ideal to ensure uninterrupted supply of hot water.

Space requirements

f can be installed in interior spaces of a property or in auxiliary areas such as a basement, garage or crawlspace. Ideally, they should be located closest to the plumbing system. Pipes running from the tank must be installed vertically for faster delivery of hot water into the home. The pipework may be adjusted when installing a hot water cylinder in less than ideal locations.

If standard-size water heaters do not suit any of the available spaces in your property, you have two other options to choose from.

Tall tanks (also called tall boys) range from 46 to 60 inches in height and 18 to 21 inches in diameter, and are typically installed in basements or garages where the height can be accommodated easily. They can hold up to Extra height is required to allow the connecting pipe to be installed on top of the tank.

Short tanks (also called low boys) range from 30 to 49 inches in height and 20 to 26 inches in diameter, and are suitable for crawlspaces, under cabinets or areas with low headroom. These are shorter and wider than the standard water tank, allowing them to hold the same amount of water (up to 50 gallons).

If you’re looking at hybrid water heaters, you’ll need extra space for proper installation. So that’s one thing to consider.

Safety issues

Water stored below 60oC can permit the growth of harmful bacteria, such as those that cause Legionnaire’s disease which is fatal to young children and those with compromised immune systems. This is why some jurisdictions impose a limit on tank water temperature. However, water at a temperature above 49oC can cause painful scalding injuries.

In order to prevent both dangers, it is recommended to use mixing valves that would automatically mix cold water with the hot water from the tank to maintain maximum temperature below 49oC. These valves are installed at outlets for sinks, showers or baths.

Features and Modern Technology

  • ENERGY STAR rating

Modern appliances are given star ratings to indicate their energy efficiency. The ENERGY STAR is a government-backed symbol that can help you choose and support energy efficient products and practices. Check the energy factor (EF) rating as well – it speaks of a product’s water-heating efficiency.

Products with higher ratings are more efficient. While they are typically more expensive upfront, they are designed to save you money in the long run. Not to mention, they have a smaller carbon footprint.

For easy comparison, check the EnergyGuide labels of the units you’re considering. This will give you an idea on how the product is expected to perform and how much its estimated annual operating cost.

  • Smart water heaters

Modern water heaters have intuitive technology that “learns” your household’s hot water consumption patterns and automatically adjusts the temperature and other operating features accordingly. These are obviously more energy efficient, which can reduce your energy bill.

Installing a hot water cylinder

Installation is best done by a qualified professional. An experienced plumber would know well how to run pipes or where to locate the tank, and would give helpful advice in choosing a suitable hot water cylinder for your home.

Google Googled Hot Water Cylinders And Found The Right Specialist

Founder Larry Page’s luxury yacht Senses is sitting in Auckland needing two new specialized hot water cylinders. So the Google founder’s maintenance company Googles “hot water cylinder specialist” and finds Hot Water Cylinders NZ.

They found the ultimate hot water cylinder specialist right there and then, because his maintenance company went ahead and signed us up for the job. Seeing our expertise and capability, they have trusted HWC NZ to replace the existing units and manufacture the exact same models to get their superyacht ready for sail once again.


The cylinders were designed with the following specifications:

  • 250L horizontal marine style duplex stainless steel hot water cylinder
  • S/S 304 cased & insulated
  • 550dai x 1525 length
  • 3 x custom element flanges to suit existing stock elements
  • 850KPA relief valve and 20mm connection
  • Custom inlet & outlet sizes based on original
  • 20mm cylinder drain
  • No coil
  • 1x tank anode
  • Mounting angle brackets including nuts and bolts


Check out a video of these marine hot water cylinders below:

Marine Hot Water Cylinders

Designed to withstand the special demands of the marine vessels and boats, our marine hot water cylinders are built with the highest quality components to ensure optimal performance and longevity.

Our marine cylinders are made with grade 304 stainless steel, which has good resistance to oxidation even in continuous service in temperatures of up to 925oC. And when you’re out in the water 24/7, corrosion resistance is a crucial factor. In comparison to other materials used in hot water cylinders such as copper-nickel or aluminium-bronze alloys, stainless steel resists salt-water corrosion better which makes it a clear choice for marine hot water cylinders.

That being said, stainless steel is not totally immune to corrosion. It can experience localized corrosion under certain conditions, so some stainless steel cylinders will fare better than others. The difference lies in engineering and design. Needless to say, our team is confident that we can supply cylinders fit for a supercraft like Senses.

The new cylinders had to be the same design because other pre-made units would neither perform well enough for the superyacht’s hot water demands nor sit well with its Philippe Starck interior.

Google trusts its search engine to show the best and most reliable experts in their fields, so much so that they chose Hot Water Cylinders NZ when it showed on the top results.

Gaining the trust of one of Google’s executives says a lot about our team. These people mean business in whatever they do. And we know they only make strategic decisions that will provide the best outcome for them. Senses is a yacht for VIPs, celebrities and the affluent who expect nothing short of luxury, so everything in it must be built to impress.

We don’t take the word “specialists” lightly. We brand ourselves that way because we know our job extremely well. We don’t just sell the priciest cylinders in order to drive sales, we take the time to listen to our clients’ needs and specifications in order to provide the best in terms of performance, efficiency and economy. Whether it’s gas, electric or solar powered, we’ve got the expertise and experience for that!

In the case of Senses, our goal was to build reliable hot water cylinders at par with the standards and specifications of the original. That’s a huge feat, considering we need to design and supply everything from the custom element flanges to the nuts and bolts.

More about Senses

Photo credit:

Photo credit:

The 59.2 metre expedition motor yacht was engineered by Germany’s Fr. Schweers Shipyard in 1999 and was last refitted in 2015. Built to surpass the challenges of the world’s oceans, Senses is Lloyds rated and deemed perfect for the 21st century adventurer. describes Senses as “the opportunity for a truly unique lifestyle in luxury yachting” with its stylish interiors and comprehensive inventory of equipment. True enough, the yacht features an impressive arsenal of toys including six WaveRunners, two jet skis, kitesurfs, surfboards, kayaks, paddle boards, a Jetboard, a Jetlev and a helipad – plus tons of inflatable toys for endless parties!

The yacht offers lavish accommodations for up to 12 guests, with 7 spacious modern cabins and a gymnasium that can also be converted into a cabin.

Hot Water Demand on Boats

With its 15,000 km plus of coast, waterways and lakes, New Zealand is every boatie’s paradise. Boating is like a way of life, a tradition during perfect summer days for families and solo adventurers alike. Living on boats is also a growing trend amongst Kiwis who love boating and want something other than the typical lifestyle.

Whether you’re sailing for the weekend or you’re on an extended cruise with lots of water adventures in between, you can never have enough of hot water on board. A nice warm shower is the ultimate refresher, washing off the salt and sweat at the end of the day. Especially when you’re wintering someplace on a boat, hot water is something you just can’t live without.

Many boats carry a water heater that operates either from engine heat or on electricity. The problem with the former is that the engine has to be running constantly to ensure a steady supply of hot water. That’s very inefficient when you’re just mooring, and causes unnecessary wear on the engine. The fact that the water in the heater can be heated depending on the temperature of the engine’s coolant creates some serious safety risks. Nevertheless, these heaters work well for smaller boats.

For bigger vessels, a custom-fitted hot water cylinder makes a lot more sense, due to its larger capacity and efficiency.

In the case of Senses which has a private beach club complete with a Jacuzzi, sauna and steam room, having hot water on demand is essential. Now with its new high spec hot water cylinders, Senses is once again ready for charter in New Zealand and the South Pacific.

With the right type and size of hot water cylinder, you can enjoy these creature comforts and luxuries in your own boat, too!

Talk to us for a consultation on any of these numbers: 0800 4 CYLINDERS or (NZ FREE) 0800 429 546.

The District Health Board Is Warning People Against Turning Down Their Hot Water Cylinders To Save Money

Legionnaires’ disease, also called Legionellosis, is a severe and potentially fatal type of pneumonia. It is contracted by inhaling water vapour or steam containing the Legionella bacteria, which is very likely to happen when taking a hot shower.

The bacteria love warm, stagnant water. They can grow in water temperatures ranging 20 – 45oC and thrive in the range of 32 – 44oC, which commonly occur in plumbing systems, spa pools, hot water tanks and evaporative condensers of commercial AC systems. However, Legionella bacteria cannot grow at higher temperatures and are killed almost instantaneously at around 70oC.

legionnaires_disease_in_hot_water_cylindersThis is why the District Health Board is sending a warning against turning down hot water cylinders in an attempt to save money. For the same reason, the Building Code also requires hot water systems to have the storage water heater thermostat set to a minimum of 60oC.

This warning should not be taken lightly. Legionnaires’ disease can lead to respiratory failure, septic shock or complications that may result to organ failure or even amputation, which was sadly the case for two people in Hawke’s Bay in 2015.

Facts about Legionellosis

  • The illness is caused by Legionella strains, particularly pneumophila and L. longbeachae, which are ubiquitous in the New Zealand environment. They are found in both potable and non-potable water systems, and can easily find their way into engineered water reticulation systems.
  • Hot water cylinders are a breeding ground for the Legionella bacteria, as are boiler systems, water-cooling towers, garden hose-pipes, air conditioners and even mist sprayers in the grocery store produce section. Legionella can also survive in some soils or composts.
  • Legionella bacteria cannot be contracted by drinking contaminated water nor transmitted from one person to another.
  • In healthy people, the disease manifests as a very bad cold with symptoms including high fever, chills, headaches, muscle aches, loss of appetite, cough and occasionally diarrhoea. But for those with immature or impaired immune systems (i.e. children, older people, smokers, alcoholics, cancer patients, etc.), the effects can be much worse and fatal.
  • A mild form of Legionnaires’ disease, known as Pontiac fever, doesn’t affect the lungs and usually clears within two to five days without treatment.
  • Although the bacteria primarily target the lungs, it can also cause infections in wounds and other parts of the body.
  • Some infected people will suffer long-term health issues such as fatigue, neuromuscular and neurologic symptoms.
  • The legionella bacteria primarily spread through micro water droplets, but it can also be transmitted via aspiration of contaminated water or working with contaminated soil.

Are you safe from Legionellosis?

Homes and workplaces are generally safe. But as a homeowner, it is your duty to undertake regular maintenance of your water systems. Workplaces are also required under legislation to comply with building maintenance guidelines, especially those with cooling towers.

Many infections are without symptoms as healthy adults have antibodies to the bacteria, showing evidence of previous exposure. Only a small number of cases will have had an illness with symptoms.

What can you do to minimize your risk?

Prevention should always be the first course of action.

  1. Since Legionella bacteria cannot survive in water at 60oC or above, you should keep your hot water cylinder at a minimum temperature of 60o
  2. For households with a roof collected tank water supply or other non-reticulated water supply, the water tank must be maintained according to the guidelines.
  3. When working with potting mix, soil or compost, wear a mask to avoid inhaling dust. Dampen the soil to avoid stirring up the dust too much.
  4. Installing tempering/mixing valves are recommended to ensure safe water temperature at the tap. To prevent burns and scalds, water tap temperature should be no more than 45oC for children and no more than 55oC for adults.

For more information about keeping your water systems safe, contact our team at 0800 429 546.

Chlorine Can Damage Your Hot Water Cylinder

The sudden spike in hot water cylinder failure in Christchurch is said to be connected to the recent introduction of chlorine to the local water supply, according to this report. The controversial chemical is believed to have led to leaks in pipes and cylinders. Since the issue broke, more than 2000 hot water cylinders have been replaced.

Property management firms and cylinder manufacturers have reported an increase in plumbing faults and demand for new units.


Chlorination and Corrosion

New Zealand has had many years of chlorine-free water supply until recently when a deadly gastro outbreak due to water contamination happened in Havelock North. Many people argue that chlorine may not be to blame as some parts of the country with chlorinated water did not experience the same problem. So is the Christchurch dilemma an isolated case?

It turns out that Christchurch isn’t the only one. Last year, plumbers in Hastings reported a 30 per cent spike in hot water cylinder breakdown following the chlorination of the local water supply, according to a New Zealand Herald report. The same thing happened to Hastings and Napier as well.

So does chlorinated water actually cause corrosion?

Chlorination may not be directly to blame. However, the presence of chlorine in the water supply is a major contributing factor. Older cylinders may have existing cracks or pin holes, which are usually plugged up by mineral and lime scale that has built up. When chlorine is added to the water, it cleans and dissolves the sediments in the cylinder, exposing the cracks or pinholes. This explains why a hot water cylinder which has been working fine in the last 3 decades is suddenly failing.

That bChlorine_can_damage_your_hot_water_cylinder_2eing said, some cylinders that have only been running for 18 months also failed. Many units in the area were newly replaced in the aftermath of the quake. So many pointed out that chlorine may also strip off the protective oxide coating from the copper, making the cylinder more prone to corrosion and leaks.

Experts analysed a number of defective cylinders in Christchurch and found multiple corrosion pits, which they concluded to be the cause of the unit failure. Traces of chlorine were identified in all pitting sites but were not present on non-pitting surfaces, which proves that chlorinated water actually causes a chemical reaction in the pipes.

Causes of Corrosion

Copper is nearly a noble metal due to its reluctance to oxidation or corrosion. Copper in hot water cylinders also has an added layer of oxide lining that makes it practically “rust proof”.

causes_of_corrosion_hot_water_cylinderHowever, copper may actually corrode when there is galvanic action or electron movement between the copper and its surroundings. Here are several other factors that can contribute to the corrosion of pipes, fittings and fixtures. The degradation of a cylinder depends on the rate at which one or more of these factors work:

  • Chemicals – Water carries naturally occurring and added minerals and impurities which can effect corrosion in various ways. For instance, high levels of calcium (which often present in hard water) may lead to calcification in pipes and fittings. When the water is chlorinated, the chemical compounds in the added chemical can react with copper, steel and plastic pipes which will consequently accelerate the corrosive action of both plastic and metal plumbing fixtures.
  • PH levels – Copper has an oxide lining that could be stripped when the water is at a certain PH level. This leads to a more rapid rate of corrosion.
  • Oxygen – Both water and oxygen are required for rusting to occur.
  • Temperature – Chlorine in extremely hot water is particularly corrosive on copper, brass, galvanized iron and stainless steel pipes and fittings. While this fact is taken into consideration when designing hot water cylinders, corrosion is inevitable and will happen gradually.

causes_of_corrosion_hot_water_cylinder_2Oxidation can happen uniformly or non-uniformly. Uniform surface corrosion is usually caused by low PH or high PH and when the copper comes into contact with phosphates or air. This gives the copper a greenish patina. Non-uniform corrosion drills pits into the surface. If the pitting is severe enough, it can penetrate a pipe and cause pinhole leaks.

Preventive checks

For cylinders to fail in less than 10 years is unacceptable, especially since replacement can cost a bomb and a lot of trouble.  Preventing corrosion can be more challenging when the water is mass treated. But the good news is you can pre-empt future failures and extend the life of your hot water cylinder. Here’s what you can do:

  • Watch out for moisture. It’s easy to overlook a slight drip, but you’ll know it’s there when the carpet is getting a bit wet or moist.
  • Keep an eye out for discoloured water or the appearance of blue-green stains in sinks and baths. If there’s white buildup around the fittings, that’s already a sign of calcification.
  • Have your cylinder checked according to maintenance schedule to find any pitting and stop potential leaks in their track.
  • If you are installing a new unit or a replacement, check with your installer that the cylinder is fit for purpose and has proper galvanic protection. We recommend replacing alloy-coated cylinders with Titanium-coated ones, because Titanium is more resistant to corrosion.
  • Make sure to choose a reliable installer with a good record, as correct installation has a major effect on the performance and life of your cylinder.
  • Make sure the sacrificial anode is in good condition. To find out more about sacrificial anodes click here.

When it happens, corrosion won’t be your sole problem. The water damage caused by leaks can impact your flooring, cabinetry and building structure as well. So it’s imperative that the unit and pipework are checked and maintained as needed.

For more information, contact our team today on 0800 429 546.

Is Your Hot Water Cylinder Pilot Light No Longer Working?

Did your gas water heater suddenly stop working? Chances are the pilot light, which ignites the gas burner on your hot water heater, has gone out. If it has, you can try re-igniting it according to your water heater label. If the pilot light keeps going out, there are a number of potential problems to check.


  1. A bad thermocouple

The thermocouple allows gas to flow to the burner when it senses heat from the pilot. If it detects an unlit pilot, it automatically turns off the gas as a safety precaution. The thermocouple may stop operating if it is dirty, bent or damaged.

Rheem UV6379L 18 Inch Thermocouple Kit Water Heater Replacement

Dirt and grime can be cleaned off using a piece of sandpaper. If the thermocouple is bent far away from the pilot, you can simply bend it back to its original position, making sure it is close enough to the flame. The pilot light should appear blue in colour. If there is no clear sign of dirt accumulation or bending, then the device may simply be broken and needs replacing. This can be checked using a multimeter which tests the voltage coming from the device.

In theory, replacing a bad thermocouple is easy and only takes a few steps:

  1. Turn off the gas valve – do a quarter turn such that the handle is at a right angle to the pipe.
  2. Unscrew the nuts on the gas, thermocouple and pilot lines.
  3. Turn off the shutoff valve
  4. Remove the gas control and pilot light burner assembly
  5. Use a flat blade screwdriver to pry the spring clip on the thermocouple head and pull out the old thermocouple from the bracket.
  6. Install the new thermocouple (this should be the same type, size and length).
  7. Slide the burner assembly back in and reattach all three lines to the control valve.
  8. Relight the pilot, following the instructions carefully
  9. Reset gas control and refit access cover.


It is important to test for gas leaks, especially when replacing a thermocouple. When the gas burner turns on, soak a sponge in a 50-50 water/dish soap solution and wet the screw joints – air bubbles will indicate a leak.

A word of caution: before cleaning or cleaning, make sure to turn off the gas and wait for the thermocouple to cool to the touch. There will be a faint gas smell when you remove the gas lines, but this should dissipate within seconds. If the smell lingers, you should call your gas utility.

Working with gas carries a lot of safety risks, which is why we don’t recommend doing this operation yourself. It’s always best to err on the side of caution. Also, some hot water heaters also have a closed burner chamber that is difficult access, so it’s better to just call in a registered gas fitter.

Another thing is that, in some older models, the thermocouple can’t be replaced due to the unavailability or discontinuation of spare parts. Here at Hot Water Cylinders, we replace thermocouple on any brand, with the exception of Rheem.

  1. Flex tube problems

If the thermocouple checks out, you might want to check for flex tube issues. Sometimes, this tubing gets kinked in places, which disrupts the gas flow and prevents proper pilot operation. Unkinking may resolve the issue. But if it fails, you’ll likely need a new flex tube.

  1. Dirty pilot tube

If the thermocouple isn’t to blame, try checking the pilot tube. There might be dirt and grime buildup that obstructs the flow of gas. Unlike a broken thermocouple, a filthy pilot tube is much simpler to fix.

To start the process, turn off the gas and wait for the pilot to cool. Then, take a needle and clean the tube making sure to take out any blockage. After cleaning, turn the heater on and check if the pilot light will ignite. If it doesn’t repeat the process until everything works fine again.

  1. Main control valve issues

When all other issues are ruled out, the last thing you could check is the main control valve. It is rare for main control valves to go out but it is still possible. If you get a good result after testing the thermocouple using a multimeter, then a bad main control valve might be the culprit.

  1. Gas regulator issues

The gas regulator basically works by opening to let higher-pressure gas into the system and quickly shutting down when the “downstream” pressure reaches the desired level. The moving parts in this device are constantly in use and, hence, are prone to wear and tear. If the gas regulator is worn out, you’ll notice the pilot on your water heater, furnace and other gas appliances snuffing.

Other possibilities include a leak that is causing the burner to extinguish, an ignition that needs replacing or intermittent low gas pressure due to system fluctuations.

It’s a tall list of things to remember for the uninitiated, but a licensed gas fitter will have the expertise to find and fix the issue quickly and safely. They will also keep you from making errors that might make your warranty void.

If you are not able to light the pilot on your water heater, contact us on 0800 429 546 or use our advisor.

The Importance Of Seismic Restraints

Do you want this to happen to your cylinder?


If you don’t, seismic restrains are an excellent choice when installing your cylinder.

What are seismic restraints?
Seismic restraints for hot water cylinders are steel straps used to keep a hot water cylinder in place, preventing it from falling during an earthquake. They are affixed by screwes and washers of a certain standard to the wall framing around the cylinder. Hot water cylinders are heavy items, with a 135 litre cylinder weighing around 170 kg when it’s full of water. If there are no restrains, this is quite a lot of weight to be flung around in an earthquake, not to mention if you have an even bigger one. It can also damage other items such as pipes which are connected to it, and cause a flood.

Along with this, NZBC B1.3.2 standard requires building elements (including storage water heaters) to be adequately supported including support against earthquake forces. The method illustrated in Figure 14 is acceptable for water heaters up to 360 litre capacity. Where fittings and pipework are attached to the water heater through the supporting platform or floor a 50 mm minimum clearance shall be provided between the fitting and the support structure. 6.11.5 An alternative acceptable solution for securing storage water heaters against seismic forces is given in Section 203 of NZS 4603.


If you are getting a new cylinder installed, make sure that it comes with a seismic retraint kit!

Retrofitting a seismic restraint kit
If you already have your cylinder installed and are not looking to replace it anytime soon, it is possible to retrofit seismic restraints to your exisiting cylinder. However, this is more complicated than installing with a new cylinder, since access behind the cylinder is required. If this is something you would like to do, it is best to contact us to discuss the job.