Category Archives: Low Pressure

How Does a Pressure Reducing Valve Work?

It’s quite rare for people to worry about high water pressure. However, when it does happen, it could cause a lot of problems. If you fail to address the issue or protect your system using the right piece of equipment, you could end up spending thousands of dollars on repairs or replacement. It could also result in damaged appliances such as laundry machine and dishwashers. 

Several things can cause high water pressure. For example, supplying companies have to ensure that all of their customers get enough water supply. Hence, they sometimes have to use high pressure to pump the water, especially in areas dotted with high-rise buildings. Another factor that could cause your problem is thermal expansion, a common issue triggered by water heater use. 

It’s not possible for the supplying company to reduce the water pressure, so your only option is to have it adjusted using a pressure reducing valve. 

What is a pressure reducing valve?

Essentially, a plumber installs a water pressure reducing valve near your water meter to control the hydraulic pressure coming from the main line. It’s crucial to double check the type of pressure reducing valve you will install to ensure that they work well with your system.Here are the main three types you can find in the market: 

  • Direct-acting – It’s the simplest and most economical type which works well with both convoluted bellows and a flat diaphragm. This type of PRV works best for low to moderate water flow. 
  • Externally piloted – This type of PRV comes with double diaphragms, which allows for higher capacity and increased sensitivity to water flow and pressure changes. It also offers you the flexibility to make use of different pilot valve types such as soleniod, air-loaded, pressure, temperature or combinations. 
  • Internally piloted – It incorporates a main and pilot valve and uses inlet pressure to open the valves. Compared to the direct-acting type, it has a higher capacity and accuracy. It also senses pressure internally, so you don’t need to add an externally installed sensing line. 

To know which among the three would best fit your system, you should consult with a professional plumber. They can provide you with the necessary details to help you decide.

How does a PRV work?

Now that you’re acquainted with what a pressure reducing valve is plus its three main types, let’s take a closer look at how it works. 

A typical PRV is designed to work even in the harshest environment. Regardless of pressure or upstream flow fluctuations, a PRV ensures a steady downstream pressure. It does this with the help of its major components such as the valve body, pilot regulator, and control filter. Here’s how each part works: 

  • Valve body – It stabilises the returning water flow while regulating the pressure.
  • Pilot regulator – Think of it as the “brain” of the valve body. Basically, it determines the water flow coming in and out of the chamber.
  • Control filter – Located inside the valve system, this filter helps you minimise damage because of accumulated debris coming in from the main line.

The system works by opening or closing the valves depending on the available upstream flow. So, for example, if the pressure in the upstream line is high, the pilot regulator drops the plunger, triggering the valve to gradually open. Consequently, if the upstream flow is low, the pilot slightly lifts the plunger, causing the valve to slightly close.

This all happens continuously, even if you don’t use water. It’s a straightforward process that happens quite fast. With the right pressure reducing valve in place, you can ensure that your household or commercial space gets enough water and protect your system from all kinds of pressure-induced mishaps. 

Shop for a Pressure Reducing Valve Today!

You’d be surprised by the usefulness of a tiny piece of item like a pressure reducing valve. With it in place, you can avoid nightmarish situations such as burst pipes, damaged water consumer lines and defective appliances. The best part is that they don’t cost a lot of money.     

If you live in an area here in New Zealand where the water pressure is too high such as Christchurch, you will definitely need a PRV installed. If you’re not certain about the water pressure of the supply line, you may find it useful to check it yourself using a water pressure gauge. You can also stay on the look out for common signs of high water pressure such as:

  • Banging noise in the pipes
  • Low water supply in your hot water cylinder
  • Unreasonably high water bill
  • Unexplained noise coming from your dishwashers or washing machine

Looking for a water pressure reducing valve for your plumbing system? Find the perfect one here at Hotwater Cylinders. You can choose from more than hundreds of items in our product catalogue. If you need more information about a product, don’t hesitate to get in touch with us.

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.

WHO BENEFITS?

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. 

SOME CHALLENGES AND CONSIDERATIONSunderbench_cylinder_on tray

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 $$$.

 

 

external_hot_water_cylinder

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.

Alternatively…

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.

AMENDMENTS IN G12, 

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.

RELATED PARAGRAPHS

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.

cylinder_drains_into_tray

 

 

Low pressure after installing mains pressure?

cylinder_blockageHow would you feel if you just had your low pressure hot water cylinder upgraded with a mains pressure to only get the same low pressure you had before? Not happy, right?!

I thought this story was interesting because it tends to happen very often and we from Hot water cylinders ltd end up getting the phone calls to investigate and repair. In this scenario some cylinder guy replaced the hot water cylinder and forgot to remove the transport thread protection, completing the installation with this inserted into the pipe. After the installation was complete this “bung” found its way to the valve blocking any flow of water. the poor home owner was not sure what to think of it for over 4 weeks and put up with the low pressure thinking it may have been normal until he picked up the phone and made the call.. “Uhm.. excuse me.. if I have a mains pressure cylinder should it be dribbling out of my shower head?”  Well.. NO of course not.

Mistakes made by Noobs are fixed by professionals. Want to learn more bout LP cylinders? Click here for information about low pressure hot water cylinders.

OTHER REASONS YOU MAY HAVE LOW PRESSURE AFTER A MAINS PRESSURE INSTALLATION INCLUDE:

  • The non return valve was installed incorrectly (opposite way in reverse)
  • Debris from the installation found its way to the strainer in the tempering valve blocking flow
  • Transport bungs are not removed
  • The incoming diffuser has accidentally been pushed into the tank causing a blockage
  • Pipework is kinked restricting flow
  • Pipework badly brazed restricting flow
  • Pipework badly crimped restricting flow

Not sure what the issue is? Please give us a ring and we will help you get to the bottom of it!

 

How many hot water cylinder types is there?

Have you ever wondered about how many types of hot water cylinders there actually is?

We have complied a list of hot water cylinders for you, showing application, benefit and disadvantages helping you make an educated decision before purchasing your next hot water cylinder.

First of all we need to separate the PRESSURE TYPES from the MATERIAL TYPES. In New Zealand one can purchase almost any material type at three different pressures.

Most common pressure types available in New Zealand (Domestic Applications) 

    • Low Pressure, open vented systems where the pressure is provided by a cold water storage tank, open vent or rely on a pressure-reducing valve to reduce the pressure below mains pressure supply.
      Typical Pressure: 30 – 75 KPA, typically 3 – 7.5 metrets Head
    • Medium Pressure, open vented systems where the pressure is provided by a cold water storage tank, open vent or rely on a pressure-reducing valve to reduce the pressure below mains pressure supply.
      Typical Pressure: 75 – 120 KPA typically 7.5 – 12 meters Head
  • Mains Pressure, with a working pressure equal to incoming supply. Pressure can be limited to any requirement but using the appropriate valve work.
    Typical Pressure: Ranging from 120 – 1400 KPA (Domestic Supply is typically 350 – 750 KPA depending on requirement)

Mains pressure water heaters are the predominant type of new installation in Australia and New Zealand.

COMPARISON TABLE OF HOT WATER STORAGE TYPES AT DIFFERING PRESSURES. 

hot_water_cylinders_types

The following hot water cylinder material types are available in New Zealand

   CYLINDER MATERIAL PRESSURE ADVANTAGES DISADVANTAGES
Enamel Lined Low Pressure
Mains Pressure
– Supply of mains pressure
– Low cost supply Installation
– Very common in NZ
Requires sacrificial anode
8 – 20 year life expectancy
Copper Low Pressure
Medium Pressure
15 – 40 year life expectancy
– Large Storage at low cost
– Can be used for high temperature power
sources such as wetbacks and solar.
 

– Not suitable for most  modern tap ware
– Requires sacrificial anode
– Low pressure

Stainless Steel Low Pressure
Mains Pressure
– 15 – 50 year life expectancy
No sacrificial anode required
– Can be used for high temperature power
sources such as wetbacks and solar.
– Large storage at high cost
– Higher supply cost
– Come with the longest warranties

Upgrading your sacrificial anode when replacing a hot water cylinder.

hot_water_cylinder_anodeHow would you like to increase the life span of your current or new hot water cylinder by at least 10 years?

Sounds too good to be true? Every hot water cylinder contains a sacrificial anode which prevents the breaking down of the tank and components. As the name suggests “sacrificial” would mean that at some point it would have to be replaced to maintain this form of protection. In the image to the right you can clearly see the difference within 10 years of operation. Most house holders are not made aware of this fact and unknowingly allow the continuation and breakdown of their relatively young or new hot water cylinder.  By replacing this sacrificial rode you can easily add another 10 years to its operation saving significant cash by preventing the breakdown of metals.

The sacrificial anode (also called an anti-corrosion rod) is typically made of magnesium. It it used to attract corrosive elements so that the tank itself will not corrode as quickly. It can be replaced when it is badly corroded.

But when your hot water cylinder is installed in a tight spot with limited height which is the case in most scenarios, how can you replace this rode (typically over 1 meter length) without actually removing / disconnecting (which would cost you more than its worth) the hot water cylinder to fit it in?

Making it easy to change a cylinder anode when clearance is tight.

When is time to replace your sacrificial anodes you might be faced with several challenges. Either HWC_Anodeyou will have to drain and remove the hot water cylinders or you may have to put a hole through the ceiling above for access. So what is the solution? A flexible Anode! this specialized anode requires less than 250mm clearance and can be installed within 1 hour. So whether you have an existing cylinder or getting a new one, why not ask to be upgraded to one of these allowing you to make the replacement when its due? Saving you cash long term!

Please ask our team about this upgrade which can be purchased for under $200 with a new installation.

You can purchase our flexible sacrificial anode here: Flexible Hot Water Cylinder Anode

Rheem Alpha low pressure made in 1967

Rheem_AlphaHard to believe but we got called to this 48 year old Rheem Alpha hot water cylinder because a mains pressure upgrade was requested and not because it was leaking!

A typical low pressure installation with a vacuum relief valve and 15mm hot water feed to the house. No Seismic restraint or tray despite there being another property underneath. Safe-trays are a required by law in Australia but not in New Zealand if the property affected is not a separate title. We from Hot Water Cylinder NZ still believe this is good practice, ensuring that if and when a leak occurs the water can be managed and drained preventing damage to your own and others property. We are currently offering a FREE CYLINDER TRAY with every mains pressure upgrade! Call us for more info.

The danger of cheap hot water cylinder quotes.

wrongly_installed_hot_water_cylinderThis home owner would have been stoked to get this cylinder installed at $500 below going market price! There is a good reason why…

Often we lose out on installations because of price, home owners don’t know any better employing plumbers that happily install hot water cylinders in manner that is dangerous and inefficient to home owners.

We were called to this job which was just done recently by a local plumber, failing to follow basic building code requirements this installation resulted in overheating and damage of tap ware.

What were the requirements?

The installation was a replacing a faulty low pressure with a new low pressure hot water cylinder. the legal recommendations are very clear in this situation clearly stating that the plumber SHOULD bring this installation up to the current standard. which includes:

 

  1. Installing a tempering valve.
  2. Installing a cold water expansion valve.
  3. Installing earthquake restraints.

Non of which were done on this installation, putting this family at risk and increasing their power bill unnecessarily. Do you have a cheap quote? Before you commit, its a good idea to compare apples with apples!  Not sure? Give us a ring on 0800 4 CYLINDERS.

HUNSON RT AKA “THE ELEPHANT”

Hunson_brandManufactured in Glen Innes Auckland on January 1978 by W. Hunt & Son Ltd this HUNSON RT revolutionized mains pressure water heating in New Zealand!

Due to high manufacturing costs and technology limitations, in the 1970’s hot water cylinders were primarily manufactured from copper.                                                         hunson_RT

Copper hot cylinders are made to suit low to medium pressures (75KPA – 120KPA), with medium pressure cylinders being made from thicker copper. The week spot on a cylinder is not the actual copper material but rather the machine manufactured welding seams. Anything above 120KPA depending on weld quality and the seam will crack resulting in a burst hot water cylinder!

So how do you get around this problem and achieve mains pressure using low pressure technology? W. Hunt & Son Ltd certainly acknowledged the demand for mains pressure and their reply was the advanced Hunson RT Direct mains pressure hot water system. Great engineering and ahead of its time.

What makes the Hunson RT so special?

hunson_diagram

 

The basic principal was to use the heat exchanger to supply mains pressure ONLY to one shower making it a semi “instantaneous water heater” (in the 70’s showers started becoming more popular) whilst using the large low pressure body of water to supply the exchange heat to the mains pressure coil and direct supply to all other low pressure fixtures such as a bath or laundry.

On request Hunson could manufacture these cylinders with multiple elements up to a total of 8KW! This would certainly make the supply more reliable and showers longer but expensive to run (not sure about power rates VS income in the 70’s). Modern cylinders use the same technology in reverse because water can now be stored in a mains pressure environment (stainless steel or enamel) and of course also because of a few other reasons such as efficiency and reliability.

What challenges did this “new style” mains pressure cylinder present to home owners?

hunson_rt_instructions

 

 

To start with, it was important the plumber got the installation right. If you have a look at the image you will see the instruction says: “At all times, the flow from the cylinder should be strong and steady, but not excessive”. Mains pressure can be anywhere from 120KPA to 500KPA and the term “not excessive” is too broad. If the pressure was set too high the heat exchanger would not have enough time to keep up with the demand. Plumbers also started using the mains pressure supply (which was originally only intended for one shower) to deliver mains pressure to the whole house and all plumbing fixtures! This immediately presented a problem because the standard supplied element of 3KW could not keep up with the demand and showering usually was over after 5 minutes! This was also the case with Hunson RT you see in this image. the only reason this cylinder survived over 30 years was because the hot water from the low pressure supply side was never used. The sludge build-up on the inside would reach all the way up to the element. Despite a sludge relief point which was most likely never ever used.

Another common issue this technology presented was random cold patches during a warm shower. Have a look at the diagram and see whether you can identify expansion, cold water inlet, hot water supply, overflow and sludge outlet. This date_230178cylinder also provides bottom entry connections for wetbacks.

Why did this hot water cylinder receive the nickname “The Elephant”? 

It turns out there used to be an engineering company in New Zealand call Elephant NZ. Elephant NZ originally came with this technology and design which was purchased by W. Hunt & Son Ltd. Why that actually engineering company was called Elephant, we don’t know but if you do, please send me an email so we can add this info to our article.

Over 30 years! Starkie HWC supplied by Henry & Co LTD

henry_and_co_ltd_hot_water_cylinder

Every now and then we come across goodies like this! This hot water cylinder has been supplying hot water for over 30 years! Originally supplied by Henry & co Ltd. A quick Google search reveled the company is still around as a tool supplier. The bottom clearly show the state the cylinder is in, we are confident the cylinder rusted through years ago but its own weight created a natural seal preventing water to lea out. Eventually the holes got bigger and bigger leading to what it is today. I would love to know how many showers this tank accommodated!

What a great find..rusty_low_pressure_water_cylinder.

30 year old Simplex hot water cylinder

simplex_hot_water_cylindersIt’s amazing how many of these Simplex hot water cylinders we come across in the Auckland area. This year we ripped out more than 100 Simplex hot water cylinders! In most cases the hot water system was converted to a main pressure system which required an installation of an additional drain and mains pressure valves. In this picture you can clearly see that only means of safety available is the open vent which deals with any expansion (sometimes caused by over heating). There is no tempering valve, no expansion valve and no drip try. Its amazing that these copper cylinders can last up to 35 years without bursting. Usually the only reason they do end up bursting or rusting away is because the thermostat fails which results in the element overheating the water to 99 degrees and this puts more stress onto the tank resulting high level expansion and contraction cracking the weld. Quality of water is also a big contributor to rust and life expectancy of a copper hot water cylinder.

Has your cylinder burst before the recommended expectancy? Maybe its a good idea to investigate the cause before installing your new one to ensure your new hot water cylinder lasts much longer.