Is Your Hot Water Cylinder Leaking?

Is your hot water cylinder leaking? There are few home maintenance issues that can make your heart sink and your wallet run and hide than finding out your hot water cylinder is leaking, or worse yet, has completely corroded and the leak has been undetected for a while.

The most common faults with hot water cylinders can be put down to loose connections, faults with the element washers, faults with the valve, excessive pressure or due to time, heat or pressure – having a cracked tank.

But whether you need just a repair made or you want to replace your hot water cylinder – are the company for you. Instead of simply replacing your hot water cylinder – why not talk to us about upgrading while you’re at it? are stockists of Mains Pressure, Low Pressure, Gas Water Heating, Solar Cylinders, Wetback Cylinders, Boilers and Heat Pump Water Heaters.

The traditional water heater has been stuck in a cupboard taking up precious space in many homes in New Zealand. The latest in cylinders can now be installed both inside or outside the home with the latter providing you with more usable inside space.

If you are looking to repair, replace or upgrade then will take the guess work away for you. You won’t be mucked about – what you see is what you will get – and best of all you will always get our best price upfront.

If you are unsure of what type to choose or what your upgrade options are then we are happy to give you free quotes so you can compare your options and make the best decision. can provide hot water heating options from Southland to Northland and everywhere in between. Our technicians are experienced and know what will work best in your area.

So if you are wanting to repair, replace or upgrade your hot water cylinder – call us today on 0800 4 CYLINDERS.

New Zealand’s first Hot Water Cylinder Size Finder

Will your new hot water cylinder fit in the same space as your old one?

Which hot water cylinder will fit? Find hot water cylinders by size.
Hot Water Cylinders LTD makes it possible!



Our new hot water cylinder finder is a search engine that will find any cylinder available in New Zealand that will fit within your given parameters.  Enter the available space you have in terms of height and width (diameter), then submit.

The result will deliver which cylinder will either exactly fit or is just over your given parameters.


For your convenience you can also filter by brand, pressure type and price. We are confident that this tool will help you find the right product quickly. Enjoy!

Once you have found your product, why not get an installation price? Free and best price quotes are available around the clock. Call us on 0800 429 546 for more information or use our hot water cylinder price calculator.

Hot Water Cylinder Trays Are Now Mandatory

IMPORTANT NOTICE: Safe trays are now compulsory with all new internal hot water cylinder installations, as per G12/AS1 clause 5.2.3 of the New Zealand building code.”

The above notice is what you will find on most newly sold (Image of a Rheem) hot water cylinders. Last year one of our blog posts discussed whether or not you need a cylinder tray. At the time the blog discussed a faulty product which resulted in flooding and insurance claim. In that particular instance the damage was minimal and covered by the manufacturer. Can you imagine the yearly claims when thousands of hot water cylinders are installed without hot water cylinder trays?important_notice

You can take a big guess on who would have lobbied the idea and pressed to get this incorporated into recent New Zealand building code G12 amendments. This standard sets a legal guideline on how a hot water cylinder may and may not be installed.


Looking across the ditch, our Australian friends have had this requirement (regulation) as part of their compliance documents (e.g standard AS/NZS 3500) since 1996 but for some reason it never made it into the New Zealand building code, until now.

AS/NZS 3500 is also an acceptable standard in NZ which begs the question, why bother with two sets of standards in the first place?

Previously, accidental discharge control was optional unless a potential risk of water damage to another property existed, which in most cases only really applied to multi-story situations. Although control was considered “good practice” the homeowner could “opt out” to achieve savings on the installation. Or the plumber would keep it on the quite “to be competitive” and win a job against more expensive quotes that included the installation of a hot water cylinder tray.

Before the change, manufacturers such as Rheem have stated in installation instructions that a safe tray must be fitted, meaning plumbers should have already been recommending, quoting and installing hot water cylinder trays.

Now that this law has come into effect, ignorance is no longer bliss and benefits are relative to:

> The manufacturer knowing that installers can made responsible for water damage if the standard is not followed.

> The homeowner, knowing that any potential leaks are controlled while they are sleeping.

> The insurance, knowing they can legally peruse compensation on behalf of the homeowner.

Additional benefits also include:

  • Level playing field when plumbers are pricing jobs.
  • Prevention being the best protection.

NOTE: Plumbers and homeowners should ensure the installation complies with the updated standard to avoid any costs associated with non-compliance or resultant damage from water discharging from a hot water cylinder. 


Progress is always accompanied with challenges and challenges are accompanied with questions.

Some legalities are still undefined and It is not clear on whether a cylinder try must be installed on replacement hot water cylinders as well as newly installed hot water cylinders. When a “repair” or “like for like replacement” takes place, the building act allows one to maintain the current state of affairs. For example, although tempering valves are required by law, a plumber does not have to install a new one when replacing an existing old or damaged hot water cylinder that never had a tempering valve to begin with. Its good practice but not a legal requirement. He can just go ahead and maintain the existing setup treating the installation as a “like for like” situation.

But then this principal does not apply to seismic restrains. The DHB is yet to comment on this and we will update the blog once we know more.

Because compliance is relative and no job is like another, you want to be safe and ask the right questions before committing to any installation. Its always best to make an educated decision rather than deal with the unwanted consequences of ignorance.

ALTERNATIVES WHEN IT GETS TO EXPEN$IVE!rheem_27_instant_gas_water_heater

A cylinder tray needs to be connected to an approved point of discharge via a 32mm – 40mm drain. In many cases, for example double story homes the route of this drain becomes a major challenge. Especially when you are talking about cutting walls open or having surface mounted pipework to get the drain out.

If the cost or convenience of having a cylinder tray is not attractive, there are alternatives within the same ballpark in terms of $$$.




For example Instant water heating. For about the same price of new hot water cylinder + tray you can convert to gas and enjoy the many benefits. We offer LPG and natural gas solutions. Future-proof or expand, your possibilities are limitless.


Relocate your hot water cylinder to the outside and free up that cupboard space. In external situations, no cylinder tray is required and the costs are about the same as a new internal hot water cylinder + tray.

Most of our customers tend to go for this option when the installation of a cylinder tray becomes too difficult or expensive. Talk to us for more information.


Lets have a look at G12 a bit closer.

You can view the old and newer version (third edition) of G12 by following this link VIEW G12 AMENDMENTS.

Its very interesting to see that they have removed the wording from 6.11.3

a) Safe trays complying with Paragraph 5.2.3 where water could penetrate another household unit within the same building.

Which now reads:

6.11.3 Storage water heaters shall have: a) Safe trays complying with Paragraph 5.2.3

tray insallation

The above relevant paragraphs read as follows:

5.2.3 now reads..

Safe trays Performance E3.3.2: states that; Free water from accidental overflow from sanitary fixtures or sanitary appliances must be disposed of in a way that avoids loss of amenity or damage to household units or other property. An acceptable method of preventing water damage is to locate a safe tray below the water tank (see Figure 4). The safe tray shall incorporate a drain with a minimum diameter of 40 mm. Where the tank overflow discharges into the safe tray, the diameter of the safe tray drain shall be greater than the overflow pipe from the tank and comply with Paragraph 5.2.2.


5.2.2 Overflow pipes Water tanks shall have an overflow pipe to discharge any overflow to a visible place within the same property that does not create a nuisance or damage to building elements. The overflow pipe shall be sized so that the discharge capacity is no less than the maximum inlet flow. The outlet of the overflow pipe shall not permit the entry of birds or vermin. Overflow from a WC cistern may discharge internally into a WC pan.

COMMENT: Manufacturers’ literature must be referenced for pressure and flow information on tempering valves and tapware. Outlets (e.g. shower mixers and showerheads) must be appropriate for the available flow and pressure. Note the limitations on lengths and pipe sizes given

6.11 Water heater installation

6.11.1 Water heaters shall be installed in accordance with the manufacturer’s instructions.

6.11.2 Where heating units, sacrificial anodes, thermostats, pipework connections, valves, or other accessories being components of a storage water heater are installed, they shall be accessible for inspection, maintenance and removal.

6.11.3 Storage water heaters shall have: a) Safe trays complying with Paragraph 5.2.3 b) Connections compatible with the pipe material used, and c) Drain pipes (for every storage water heater of more than 45 litres capacity) which: i) have a conveniently located isolating valve, and terminate with a cap or plug suitably located to easily empty the vessel for maintenance, or ii) terminate outside the building with a cap only.
cyl;inder setup

The installation below shows the safety valves discharging into the cylinder plug and waste, which does not comply as one could argue that these pipes are blocking the passageway designed for the control of accidental water which is managed by the safe tray only. NZ Regulations define acceptable methods of discharge which includes safety valve drains.




What Is A Water Heater?

When selecting a new water heater for your home, choose a water heating system that will not only provide enough hot water but also that will do so energy efficiently, saving you money. This includes considering the different types of water heaters available and determining the right size and fuel source for your home.

Every home has a water heater and most of us are familiar with the big metal cylinders that can be found tucked away in our laundry room, basement or special “hot water cupboard”. Like all technology though, water heaters are constantly evolving with new design, new fuel systems and new sizing.

Storage Hot Water Heaters:

  • Inexpensive and widely available in a variety of sizes.
  • Waste 10%-15% of energy through radiant heat loss.
  • Can run out of hot water during extended use.
  • Life expectancy 10-15 years.
  • Average EF rating 0.67.

Tankless Hot Water Heaters:

  • Take up little space and can be mounted inside or on an outside wall.
  • Little or no standby energy loss.
  • Use 20% to 30% less energy than comparable storage tank models.
  • Hot water flow rate is limited by the size of the unit.
  • Can be expensive and costly to install.
  • Life expectancy 20 or more years
  • Average EF rating 0.75

Solar Hot Water Heaters:

  • Low to no energy cost.
  • Savings can pay for the unit in 8-12 years.
  • Requires the collector to be in full sun throughout the year.
  • Expensive and costly to install.
  • Usually use a conventional water heater for backup.
  • Life expectancy 20 or more years

Heat Pump Hot Water Heaters:

  • Low operating costs.
  • Can only be installed in locations that stay between 4°-32° C.
  • Do not operate efficiently in a cold space.
  • Can install an air-source heat pump that combines heating, cooling, and water heating; or a standalone heat pump just for heating water.
  • Can be two to three times more energy efficient than electric water heaters.
  • Higher initial cost than storage water heaters.
  • Colder climates using a heat pump water heater may add to heating and cooling loads.

The newer styles have generally lost the big bulky tank completely in favour of hot water-on-demand. What makes a water heater (no matter which type you have) interesting is that they exploit the heat rising principle to deliver hot water right to your tap with a minimum of fuss.
To create hot water, a scientific process called thermodynamics is required. This process uses an energy source to heat water above the initial temperature it arrives into your home at. In a typical home, we use hot water in cooking, cleaning, bathing, and space heating.
There are various types of water heaters available and the type you choose will inherently depend on where you are based, how many people are going to be using hot water and the kind of energy sources you’ll be using (electric, gas, solar or wood).

Your water heater is a cleverly designed system that heats cold water to an ambient temperature. They are generally reliable and can operate for years without any issues. When water comes into your home, depending on the time of the year, it makes a journey through a system of pipes, and it’s usually cold or cool. If you are not a fan of bathing in cold water or washing your dishes or clothes in cold water, then you need a water heater.

When choosing a water heater, you should keep an eye out for a technical term – “recovery rate”. The Recovery Rate is the speed at which a water heater heats your water to 37.7C in an hour. Once you draw water faster than it’s heated, the temperature drops. Choosing a water heater that has an appropriate capacity and recovery rate depends on how much water your home demands and how your unit heats the water. Typically, heaters with low recovery rates have a high tank capacity. Although it takes longer to heat the water, there’s more of it for intermittent use. Electric heaters fall into this category. On the other hand, a fuel-fired heater (gas or oil) with a high recovery rate needn’t have a large tank, because it can heat the water faster. In general, electric models have the lowest recovery rate, and oil-fired units have the highest.
If you’re considering replacing or simply installing a new water heater, looking at the various advantages and disadvantages is always wise. Some of the general pros and cons we can share with you are:

We know that purchasing a water heater requires a lot of thought. Call us on 0800 429 546 today and we can help you select the best water heater for your needs.

Explaining electric hot water heaters

What is an electric hot water heater?

How do electric hot water heaters work?

What are the differences between hot water heaters available?

Most of us don’t give a passing thought to how our water is heated as long as it is hot when we turn on the hot water tap or get in the shower. There are various ways our water can be heated and these generally are by Gas, Heat Pump, Solar, Wetback or Power (Electricity).

An electric powered water heater can be referred to by many names – a hot water storage tank, a hot water tank, thermal storage tank, hot water thermal storage unit, heat storage tank or a hot water cylinder.


Electric hot water cylinders are the most common form of water heating in New Zealand.

The cylinders use an electric element in an insulated tank to heat the water to a temperature set by a thermostat.

It acts a bit like a hot water jug or kettle. It has an immersion element inside the cylinder (which looks like a metal loop or coil) and it heats the surrounding water.

The cylinder is an insulated water tank with a cold tube to carry water in, and a hot tube to send the water where it’s needed inside the home. The heating is controlled by a thermostat that turns on the heating element when the water goes beneath the pre-set temperature.

When the heating element is on, electric power runs through it, creating heat. Unlike a gas water heater, the heat does not go through a heat exchanger. Instead, it flows directly into the tank’s water supply.

Electric water heaters (with an immersion element) are more energy efficient than gas water heaters. A conventional electric model averages a 90 percent efficiency rating, while a conventional gas water heater averages a 60 percent rating. Electric power is generally more expensive than natural gas.

Gas does outperform the electric model in water heating speed and recovery time. A gas heater can heat around 190 litres in roughly an hour, while an electric heater takes several hours to heat the same volume.

Some other benefits to electric hot water heaters are that out of all the various types of water heating products available, they have the lowest upfront cost.

They also have a certain amount of flexibility. You can buy cylinders with additional connections suitable for having a solar water heater, heat pump water heater or wetback added in the future. This allows you to change the way you use your hot water, and for adaptation should your family size grow or the demands you require on hot water change.

You can purchase an electric hot water heater that has a thermostatic control. This means that it will automatically turn off when it reaches the temperature you set on the thermostat. This will save you money over time.

If you have a boiler system in your home, an electric water heater will not be connected to your boiler. This means that if your boiler breaks down, you can still generate hot water for your home.

If you well insulate your electric water heater, it can keep water hot for several hours after it switches off. You can set a timer on your heater so that it only switches on during cheaper off-peak electricity hours.

You can usually turn your electric water heater on or off by simply flicking the switch on the wall socket. This is a great power savings ability especially useful if you are going away on holiday and you will have no need for hot water in the house while you are away.

And what kind of things should you be aware of regarding an electric hot water heater?

  • Heating water using electricity is more expensive than heating water with say, gas. A typical electric water heater uses 3 kilowatts of electricity an hour, so it will cost the average house about 78c an hour to run. Most households will need to run an electric water heater for at least a couple of hours a day to get the water hot enough – costing at least $560 a year.
  • An electric water heater needs a thermostatic control, otherwise it can heat the water to far too high a temperature.
  • Some heating engineers may recommend you leave your electric water heater on 24/7 – however, this can be very expensive unless it has a thermostatic control.
  • Be aware that you need to heat the water in your electric water heater to above 50°C to kill off bacteria.Above all consider all of your options. What works for one household might not be the best option for yours. Getting the sizing, the placement and the installation right is important for obtaining your long term enjoyment from your new water heater.

Rinnai is getting greener in 2017

Rinnai have been busy with some exciting changes to products making sure they remain one of New Zealand’s preferred suppliers of electric hot water cylinders. The next 12 months will see some exciting changes to their range starting with changes to some of the Mains Pressure Enamel products.

Always striving to be at the forefront of future-proof technology, Rinnai, as part of our commitment to the environment has made changes to our manufacturing process. Innovations to the materials that we use to assemble our finished products will enable our cylinders to be kinder to the environment while still allowing us to meet the same exacting standards you have come to expect.

These changes will mean that the height of some of our Mains Pressure Enamel Electric cylinders will be changing over the coming months.

The first of these changes will be reflected with the production of our Mains Pressure Enamel 180L 488 product (ME18048830/ME18048820). This means that all orders from now on will be fulfilled with the new height.

The full schedule of changes to affected Mains Pressure Enamel cylinders can be found below:

ME18048830 180 488 1660 1695 3 NOW
ME18048820 180 488 1660 1695 2 NOW
ME25059030 250 590 1580 1595 3 MID NOV 2016
ME25059020 250 590 1580 1595 2 MID NOV 2016
ME250590D30 250 590 1580 1595 2X3 MID NOV 2016
ME250590D20 250 590 1580 1595 2X2 MID NOV 2016
ME18059030 180 590 1190 1205 3 END NOV 2016
ME18059020 180 590 1190 1205 2 END NOV 2016
ME09048830 90 488 955 1030 3 EST MAR 2017
ME09048820 90 488 995 1030 2 EST MAR 2017
ME13548830 135 488 1295 1328 3 EST JAN 2017
ME13548820 135 488 1295 1328 2 EST JAN 2017
ME30059030 300 590 1790 1805 3 JUN 2017
ME30059020 300 590 1790 1805 2 JUN 2017
ME300590D30 300 590 1790 1805 2X2 JUN 2017
ME300590D20 300 590 1790 1805 2X3 JUN 2017

From November 2016 we will be phasing out the dual element 2kW and 3 kW 180L Mains Pressure Enamel products (ME180590D30 and ME180590D20) from our range. Stocks of this product will not be replenished and orders for these products will continue to be fulfilled while stocks last.

As always, Rinnai is committed to the environment and to our customers. For more information on any of the products discussed above please contact us 0800 4 CYLINDERS


Blowing up a hot water cylinder

I made this GIF from an experiment done by Myth Busters to show the extent of damage a hot water cylinder can do when there is no pressure relief. blowing-up-hwc

The image above reinforces the importance of using individuals that understand the physics of hot water and the effects an installation can have on its surroundings.

So at what point will a cylinder explode?

In principal it’s simple to understand. Heating a substance causes molecules to speed up and spread slightly further apart, occupying a larger volume that results in a decrease in density. So “larger volume” means “more space” which is limited to the size of the hot water cylinder.

If hot water is not used and your thermostat fails, your immersion element will continue heating your water (to boiling point) until such time one of the pressure relief valves activates and relieves the pressure. Every installation should include two relief valves, one on the cold water side and one on the hot water side.

This regulation was put in place around 1997 meaning that any cylinders installed prior to that may only have one source of pressure relief. Hence the low pressure vent copper pipe going through the roof.

This is where it gets tricky. Many installers dont bother replacing older valves when replacing an old hot water cylinder with a new one. Others have managed to install a tempering valve on a low pressure system right into the overflow pipe, blocking the only means of pressure relief. The hot water system then becomes a time bomb which may result in something pictured above.

Sometimes its not the plumbers’ fault but rather the homeowner who sees a pipe dripping on the outside of a house and thinks.. “Oh, this should not be leaking” and decides to “blank” it off by any means available, creating the perfect conditions for a catastrophe. My recommendation on this is, see a dripping pipe? Please call the plumber.

If you are unsure about what valves you need or already have, send us an email or give us a call for help.



Gas Water Cylinders and Saftey

dux_hot_water_cylinderThis 1996 Dux Hardie (a james Hardie product) Vitreous Enamel gas hot water cylinder has had several repairs done over the years. Whether it was a failed gas thermocouple, replacing of a down-draft diverter or Piezo ignition device, we always pride ourselves in the ability of troubleshooting by following a simple process of elimination, identifying and fixing gas water heaters.

After a “smell of gas” was noticed, Hot Water Cylinders NZ were called to the scene to investigate and hopefully fix yet another possible fault. After only a few minutes onsite, our installers identified that an overheating issue had caused a “split in the seams” resulting in a drip onto the flame which evaporated, mimicking the smell of gas. This Natural Gas hot water cylinder was naturally redundant!

After a life span of 20 years the owners agreed it was time for a new and more efficient solution.

The first thing I noticed with these image was the quality and safety awareness of the installation itself. Unlike many older gas jobs we come across, no short cuts were taken and no safety measures were avoided which contributed to long life span and safe operation of this appliance on a property that has been purchased and sold over 8 times in the last 20 years.


A quick look on the labels and manual show how important it is for the gas fitter to read and apply manufacturers instructions, these include:

  • For safe operation this water heater must be fitted with…1) Thermostatnatural_gas_cylinder
    2) Over-temperature control
    3) Combination pressure and temperature relief valve

Additional important points include how important it is to get your hot water cylinder serviced, ensuring valves are operating safely giving your hot water cylinder the best chance to provide you with hot water for many years to come.  Relief valves should be checked for adequate performance or replaced at intervals not exceeding 5 years or less in areas where local regulations apply.

With an appliance that includes an open flame (pilot light), safety must be recognized and followed to prevent harm to person and property. For instance, a gas hot water cylinder must be installed on a fire-proof base. The appliance should not be enclosed unless otherwise recommended by the manufacturer and sufficient ventilation has been provided. Operation should never take place with panels or covers removed and anything flammable should not be stored (prevented) in the vicinity of the appliance. It almost sounds like so much can go wrong, which could be true unless the installation company has enough experience to apply a “prevention” mentality which would eliminate all risks by simply following a code of standard.


In this instance the owner of the property decided to switch to a tankless hot water solution. This meant reclaiming of their garage space and all the benefits that come with tankless water heating.

Being able to reuse the existing gas pipe meant savings on the installation. the only thing left was to remove the gas flue and repair the hole left in the roof. After 6 years of history with this appliance, it think deserves a special spot on our blog!


10 Mistakes to avoid when buying a new Hot Water Cylinder

  1. Price Price Price
    Compare the price you have for one brand with another quality brand. Don’t be shy to ask for an alternate brand quote. Look at the differences and select the product that will most likely meet all your expectations now and in the future. This will also filter out those who are ‘partial to one brand’. They will always give you reasons as to why ‘their’ brand is better than the others.10_Mistakes_to_avoid_when_buying_a_new_Hot_Water_Cylinder
  2. Don’t Settle for Less.
    If you have to replace your existing hot water cylinder, make sure you get the most recent technology and quality. Many installers will try to flog off outdated stock and make it look like the deal of a lifetime. You will be surprised what modern specifications you are able to get for the same price without having to compromise on quality or warranty.
  3. Low VS Mains Pressure
    Let’s face it, with today’s technology, the world is going mains pressure. If you are replacing your low pressure cylinder, don’t let anyone tell you that you can’t replace it with a mains, because you have low pressure tapware. You can in fact upgrade to mains pressure and set your mains pressure system to accommodate your low pressure tapware. That way you have already future proofed for your upcoming new and amazing mains pressure tapware.
  4. Future Proofing
    This ties in nicely with point #1. Believe it or not a cylinder that is future proofed for solar, heat pumps and alternative energy will cost you the same as a cylinder that is not. With climate change and the costs of energy on the rise, you want to be ready for the next energy revolution which will involve having a cylinder that is also ready.
  5. Warranty
    Read the fine print! They say you get a 20 year warranty when in fact it’s conditional to a yearly service and expense, this should not be required at all, especially in the first 5 years. Seven to 10 years is a good indication of where a warranty needs to be here in New Zealand. Please note that parts subject to wear and tear are in most cases only covered by a one year warranty.
  6. Power Supply
    The trouble with cheap quotes is that they tend to leave out what They believe ‘you don’t need’ but will in-fact only benefit you in the long run. For example, this is the case with the power supply to your new hot water cylinder. If you are replacing an older hot water cylinder, your power switch will be of the same age and wont comply. If it’s round and in most cases black (Baker Light Power Switch), it must be replaced. These switches are deemed as unsafe (electrical hazard) by the electrical board of New Zealand because they can only support 10 AMPS (just below 2KW) and most cylinders now require 16 AMPS the same goes for the wiring from and to your hot water cylinder and electrical board. The last thing you want is for an older component to cause damage to your new shiny hot water cylinder or home and voiding the warranty in the process.
  7. Compliant Installation And Certification
    No one expects you to be a plumber but it is always good to know a bit more about your installation. Do the research and find out what the minimum requirements are. The best place to start is by looking at the New Zealand Building Code G12 which can be downloaded for free >> G12 HERE. It will only take 15 minutes to get your head around the basics. You will then be able to ask the right questions and the installer will be very careful not to cut any corners. Make sure your installation complies and that you have received a producer statement on completion. This will be very important when you come to sell the property as it becomes part of your LIM report.
  8. Maximise The Size Of Your Storage
    if you have the space, USE IT. The more water you can store the more efficient you become. They all come with 2KW or 3KW elements so you are not ‘using more energy’ you are only heating more water that is stored and ready to be used. The insulation values are the same so minimal heat loss. Considering point #4, another advantage is, should you decide to add an alternative cheaper form of energy later, you will be able to store more water that has been heated efficiently. Because most forms of alternative efficient energy are dependent on having sunlight or the right temperatures, you want to heat as much water as possible during that time and use your storage outside that time. Hence it’s best to store as much hot water as possible. As a small example, the price difference from going from a 180 Litre to a 300 Litre hot water cylinder is about $300.
  9. Licensed Installers
    We cannot voice the importance of this enough. Make sure the installer is registered! Regardless of whether the installation complies or not, the technician must be licensed and registered by the plumbing board of New Zealand. If not and something happens, your insurance will bail. ASK TO SEE THE LICENSE and on completion ask for a producer statement. Selecting an installer that is a Master Plumber will ensure you have someone that is experienced and insured to do the job.
  10. Drain Discharge Size And Location
    Some guys just looooove cutting corners and the discharge pipe is the most likely place. It takes more materials and more time to run the drain to an approved and less annoying position. On most installations, the drain must be 20mm to comply (refer to G12 above). All pressure relief valves from your hot water cylinder discharge water every now and then. This happens as water is heated and expansion takes place. The last thing you want is for a pipe to be sticking out your front door or constantly discharging water onto your footpath. All drains must discharge into an approved point of discharge. What is considered an approved point of discharge? Give us a ring to find out or stay tuned for my next blog.

What are the pro’s and con’s of a tankless water heater?

Rheem_24_tankless_hot_waterIts not a great thing when your hot water cylinder is leaking and has to be replaced. The only real benefit under such circumstances is that you suddenly get an opportunity to look at a more modern and efficient hot water system for your home.

In New Zealand we are certainly spoiled with unlimited access to gas supply, whether it’s natural gas in metropolitan areas or LPG in more rural areas. With this in mind, the circumstance begs the question whether it is worth looking at tankless hot water heating.

Let’s look at some situations, site conditions and costs to evaluate the pro’s and con’s of tankless water heating.


Lets list some of the benefits tankless gas water heating offers.

Here are the top 5

  1. The cost of natural gas per KW (Which gas to select? see below) is on average 8 cents/KWh + $30/monthly fixed line fee, in comparison electricity is on average 28 cents/KWh offering a significant difference and savings. LPG will cost slightly more but has a much higher burning value. Most tankless water heaters are available in LPG and NG
  2. Continuous flow water heaters deliver an endless supply of hot water that will never run out, as they heat water when you need it, for as long as you need it.
  3. They heat on demand, rather than keeping water hot and stored ready for use, they use less gas than traditional storage water heaters, which is good news for the environment and you. Another important point is that when converting to tankless water heating, you are by default converting to mains pressure.
  4. Tankless water heaters mount conveniently to the wall, taking up less space, which is good news if you have a compact home site or apartment or are just short of space. You can finally convert that hot water cylinder cupboard into whatever your heart desires.
  5. Take advantage of condensing technology which makes some of these gas units 90% efficient saving you even more on your power bill.


What are some the disadvantages of tankless gas water heating?

  • The installation cost is approximately 30% – 40% more expensive than your conventional hot water cylinder installation. Unless you are using a Hydro unit, in most cases an external power point is also required which adds on average another $300 + GST to the installation.
  • Most tankless hot water units incorporate an electronic ignition system replying on 240 Volts. Unlike hot water cylinder storage, If you have a power outage, you wont have hot water.
  • Because cold water has to run through a heat exchanger first, it takes time, this time is translated into a flow rate. Flow rates on Continuous flow water heaters will always be lower than on hot water cylinders which means if you are already on mains pressure, you may notice a drop in pressure. To compensate for this pressure drop, you may have upgrade to the next size Continuous flow water heater. Sizing values are given in Liters per minute for example the Rheem VT 26  will supply 26 Liters per minute.
  • You must always ensure the water heater size you are buying is suitable for your home. If the unit is undersized, you may not achieve the temperatures and pressure you are used to or expect. Continuous flow water heaters are sized by total plumbing points and occupants. for more information please speak to our sales team.


Liquid Petroleum Gas (LPG): Is ideal when you dont have access to natural gas or the getting a supply of natural gas is expensive. LPG has a heating value of 102 (MJ/m3), so much more grunt than natural gas achieving high temperatures with less effort using less gas.

How much LPG gas will you need? A 45 KG LPG Bottle will on average evolve 21 m3 of gas at a cost of circa $90 per bottle. A tankless heater of 26L/ minute will use 200MJ, therefore you multiply the heat value by the amount of energy stored (21m3 stored per bottle x 102 = 2142MJ heat available ) The total is then divided by the demand, 2142 ÷ 200MJ = 10.71 hours. Thats 10.71 hours of showering on one bottle, or 64 x 10 minute showers. Great heating value giving you a long supply of gas.

Natural Gas (NG): If you already have NG on your property, no installation line fess will apply and tankless water heating would be very desirable. Natural gas has a heating value of 40 (MJ/m3) meaning you will use more to achieve a desirable heat. This something to consider when comparing costs with LPG. If available on your street and the cost to get a permanent gas line with meter onto the property is free or at low cost, then this option would be an advantage as there is no handling of bottles onsite and you cannot run out.

Our technicians have developed further methods to save you even more on gas by using smart controllers and specialist appliance commissioning processes.

With variations of readily available gases in New Zealand, tankless hot water heating has certainly become the way of the future. Technology and efficiency is improving daily making this a desirable option for kiwi homes. Maybe It’s time you joined the gas revolution!

Hot Water Cylinders NZ are currently running a special to convert to a mains pressure tankless hot water heater for only $2800! Checkout our special deal here. Questions? Give us a quick call.