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.
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
If your hot water cylinder suddenly stops working (producing hot water) it’s a good Idea to go through a checklist of elimination to determine what the fault is before getting any quotes to repair or even replace your hot water cylinder. Initial understanding of what the problem is can save you lot of cash!!
WHY DON’T I HAVE HOT WATER?
If your hot water cylinder is not producing hot water, one of the reasons could be:
You are setup on ripple control through your current power provider. If so, your current power provider has the ability to disconnect your Hot water cylinder from the grid during peak times. Give them a ring and find out whether you are. (This is common in the Auckland area)
Have you checked your switchboard to see if the fuse has blown? You should be able to confirm this visually.
With all electrical fault scenarios, if you are unsure how to investigate / rectify, we strongly recommend asking a professional for assistance. This could be a registered electrician or registered plumber holding a current limited electrical certificate.
WHY HAS THE FUSE BLOWN?
If you have determined that your fuse has blown , there will be a good reason why that has happened in the first place.
This could include the following:
With tear and wear an immersion element will break down over time eventually causing an electrical short due to a broken circuit. This will lead to an RCD tripping (RCD’s are not common with hot water cylinder) or fuse blowing. Sometimes a new hot water cylinder element can also be faulty as shown in the image here. Within 2 hours this brand new element failed majorly causing a fuse to blow and leaving the homeowners with no hot water.
Every hot water cylinder incorporates a thermostat that controls the element. Thermostats are designed to ensure the immersion element switches on when the water temperature is below 60 degrees. Unlike older style thermostats, modern versions cannot be set below 60 degrees. Stipulated by law to prevent the growth of legionnaires bacteria. (for alternative systems to manage legionnaires bacteria please follow our blog for upcoming information) Thermostats may fail, turning off the element permanently. Some models incorporate an integrated trip device which can be reset. Caution is advised though because also in this case, there is a reason why the thermostat has tripped in the first place.
CAN MECHANICAL FAULTS RESULT IN “NO HOT WATER”?
Alternative to electrical faults mechanical faults may also result in your hot water cylinder not delivering hot water. The reason we say “delivering” is because your cylinder may still be “producing” hot water but delivery prevented by a different component in the system. One of these components is your tempering valve. (assuming the installation is a compliant one, for more information please visit our blog post Cheap cylinder quotes)
A tempering valve is installed to protect your household from scolding hot water. For a more legal description please download NZBC G12. Most tempering valves incorporate a non-return valve on the hot, cold or both sides (Tempering valves shall comply with NZS 4617 or AS 1357.2) which prevents the hot water from siphoning back into the cold water line. Additionally on both the hot and cold sides the tempering valve includes a miniature style strainer which catches any debris before entering the valve. This is designed to protect the valve from damage and prevent maintain clean delivery. Keeping the above in mind two things can happen with this valve that will prevent your hot water cylinder from delivering hot water to your taps.
If your cylinder thermostat recently failed then your immersion element would have continued to heat your water to boiling point which can put a lot of strain onto the integral HDPE parts of the tempering valve. Standard tempering valves (not rated for high temperatures such as solar above 99 degrees) incorporate High density Polyethylene parts which are rated to about 99 degrees Celsius. At 99 degrees, depending on age these will start liquefying or breaking down. Once these parts start cooling down again they will fusion preventing further mechanical operation. In this instance we are talking about the non-return valve which will no longer open allowing hot water to travel to its destination.
2. The integral miniature style strainers mentioned above have an approximate straining value of 20 microns. If you are getting a new tempering valve installed on an older system you will most likely get some of the existing lime/sludge/debris caught in the strainer which may initially look like the “pressure” has been reduced but will eventually fully clog to point of blockage.
A new installation involves new pipes, new valves and a new hot water cylinder, all of which can contain debris from the installation, transport or product itself. If the system is not flushed properly at time of the installation this will guaranteed lead to valves blocking preventing hot water delivery.
WHY IS MY HOT WATER CYLINDER OVERFLOW PIPE DRIPPING?
Every hot water cylinder, regardless, whether its mains or low pressure must have a method of expansion relief. As water is heated its density will decrease requiring more space and creating more pressure. If this pressure is not managed properly your hot water cylinder could/will explode or “burst” once it reaches its maximum rated manufacturing pressure limit. Some additional factors such as incoming pressure will also affect your system pressure as a whole.
I will cover all the valves in different blog posts, for now what you need to know is that.. If the valve is “dripping” (Especially when the cytlinder then its doing what its supposed to. This includes water exiting your relief vent through the roof.
A “drip” is normal whereas as a regular stream or gush may not be. If you are experiencing a stream, gush or heavy drip some of the following reasons may apply:
A recent increase of pressure may have happened due to utility repairs or improvements.
Your hot water cylinder is over heating because the thermostat has failed.
On low pressure systems your incoming pressure is reduced with a pressure reducing valve. This valve may wear down over time eventually allowing more pressure through than the vacuum relief valve (the vacuum relief may also be the cause) or open vent height may be allowed for. In this case maintenance or replacement will be required.
On mains pressure systems, cold water expansion or temperature relief valves may be faulty, worn out or simply requiring a clean. Both valves have a lever which allows you to open and discharge hot water. Often, doing this may solve the issue as grit may be the offending cause or your excessive drip.
We have listed the most common faults above to ensure you can make an educated decision before taking any action. If you cant find information about the fault you are experiencing on our website, please don’t hesitate to call our friendly technical team at no charge.
Us Kiwis just love to get free quotes for any size job, this includes hot water cylinders of course.
Whether we need a quick fix or a complete replacement, its a good idea to shop around and see what the market has to offer.
Once you have all of your quotes its very important to consider some of the following things.
WHO IS THE INSTALLER?
The plumbing industry has made some considerable progress over the last few years by introducing a licensing scheme and compliance based requirements to ensure standards are maintained and to reduce the amount of unqualified individuals operating within the industry.
First check to see if they are authorised to undertake the work by asking to see their card. All authorised tradespeople must carry their authorisation card issued by the Board. The card also details what a person’s supervision requirements are, if any (on the reverse).
You can also check to see if a trades person is authorised phoning the Board on 0800 743 262.
It’s simple, If they DONT carry a licence DONT employ them!
IS THE INSTALLER EMPLOYED OR SUBCONTRACTED?
Many Auckland based product supply companies use marketing tricks such as promoting a service which enables them to sell their product. Such companies will in most cases subcontract out their work which presents several issues and challenges that can effect you.
Some of these are:
Who is responsible when something goes wrong? Ultimately the person billing you has the final responsibility but a dispute between the supplier and contractor will only lead to your inconvenience.
Subcontractors are on a limited “budget” meaning targets need to be met or they don’t make any money. If anything goes wrong it will either cost you more or shortcuts will be taken.
Insurance and warranty are always a big factor in a licensed industry. When something goes wrong no one is ever to blame and no one ever wants responsibility. the more middlemen the more complicated it becomes with a claim.
Bias attitude towards their own product will always disadvantage you with a high risk of getting what they want to sell and not really what you need.
WHAT IS INCLUDED IN YOUR QUOTE?
We all understand bottom line $$$ but is it really cheaper when we look closer??
The main problem every consumer has, is by not being a specialist they don’t know what is required, what they really need and how to finally compare apples with apples.
This might be the case with many other industries but thankfully with hot water cylinders its almost black and white and very easy to make a comparison. This is mainly because the supply and installation is broken down into two main sections:
LEGAL REQUIREMENTS. THE LAW STIPULATES WHAT THE MINIMUM STANDARDS ARE AND WHAT YOUR INSTALLER MUST INCLUDE AND INSTALL WITH NO EXCEPTIONS.
INSTALLATION QUALITY AND GOOD PRACTICE. THIS INCLUDES ASPECTS OF THE SYSTEM WHICH ARE NOT A LEGAL REQUIREMENT BUT ARE RECOMMENDED.
WHAT ARE THE LEGAL REQUIREMENTS?
For a full overview of legal requirements for hot water cylinders,
please download the following document clause-g12.
REPLACING LIKE FOR LIKE LOW PRESSURE
Hot water cylinders systems installed 10+ years ago DO NOT comply with today’s legal requirements. When a plumber replaces your hot water cylinder, even if he is only replacing like for like HE SHOULD inspect and ensure the remaining parts of the system are up to standard.
If the existing system does not have a tempering valve and he is replacing the hot water cylinder he must include a tempering valve.
If the existing system does not have seismic restraint and he is replacing the hot water cylinder he must include seismic restraint.
If the existing hot water cylinder is not open vented, he must include a low pressure cold water expansion valve.
ELECTRICAL COMPONENT: If you have an existing round (typically black in colour) electrical switch from Bakelite, this must be replaced.
REPLACING LOW WITH MAINS PRESSURE
System that are being upgrading from low to mains pressure are more complex and have even more compliance requirements. Some things to look out for are:
Have all the correct valve been installed? these include a tempering valve, cold water expansion valve, correctly sized TPR and isolation valves.
Has the installer allowed for a 20mm drain minimum? In most cases your existing drain will only be 15mm. Some installers tend to reuse this drain and discharge two valves into it, which is absolutely not allowed (CWE and TPR valve).
Whether the installer is saving materials by not upgrading the drain, not installing a tempering valve as required by law, not upgrading your electrical switch or not ensuring your seismic restraint is installed correctly the motive is always the same..They want to reduce their spend to increase their income leaving you with a non compliant, potentially unsafe and inefficient hot water system.
Every hot water cylinder installation must legally include:
Tempering valve (low pressure systems have low pressure tempering valves which are more expensive)
Seismic restraint must applied on all hot water cylinder installations, including external models.
Energy saving valves such as a cold water expansion valve.
Correctly sized Temperature relief valves.
ELECTRICAL COMPONENT: If you have an existing round (typically black in colour) electrical switch from bakelite, this must be replaced.
WHAT IS A GOOD STANDARD INSTALLATION?
As specialists we look at future proofing your installation and ensure your system runs as efficient and safe as possible despite some aspects not being a legal requirement. Some examples include:
Installing a drain point at the lowest point possible will ensure the next person servicing or repairing your hot water cylinder will not charge you for an hour because he has to wait for it to drain.
Maintaining a compact installation within the hot water cupboard will ensure you have space for storage.
Ensuring all pipework is secured correctly will prevent leaks in future when a pipe is accidentally hit by storage items. This will also prevent rattling and noise when hot water taps are opened and closed.
Separation of materials is important to prevent rusting (electrolysis), in many cases a cylinder tray is recommended as a base.
Using the inlet diffuser correctly is important to prevent cold water patches during showers.
As you can see the list of things you need to be aware of is closely linked to price! We from Hot Water Cylinders NZ have the best price and service policy, always endeavoring to give you the best price possible! Speak to us today and we will give you a quote tailored to your needs. You can be confident that all our installations fully comply to the standards and that no corners will be cut ensuring you get the best money for value! Speak to us today on 0800 4 CYLINDERS
expansion relief. As water is heated its density will decrease requiring more space and creating more pressure. If this pressure is not managed properly your hot water cylinder could/will explode or “burst” once it reaches its maximum rated manufacturing pressure limit. Some additional factors such as incoming pressure will also affect your system pressure as a whole.
