Everything you need to know about low pressure hot water cylinders

Low Pressure Hot Water Cylinder – NZ

You probably don’t spend a lot of time thinking about your hot water cylinder – that is, until something goes wrong or it’s time to replace it. And then when you do start looking into it, you quickly realise that there are a lot of options and details to research.

If you suspect you have an issue with your hot water cylinder, or think it may need replacing, have a read of our article “How do I know if my hot water cylinder needs replacing?” – or give us a call for a free initial diagnosis over the phone.

In the meantime, here is some useful information about low pressure hot water cylinders that will help with some concerns or queries you have.

What is a low pressure hot water cylinder?

Quite simply, it’s a hot water cylinder that delivers low pressure water to your property. What do we mean by low pressure water?

Pressure is the force that pushes water through the pipes, so your water pressure will be different depending on whether you’re on low or mains pressure water. Generally, a low pressure system provides water pressure at around 75 kpa. In contrast, main pressure will provide water to your house at up to 500 kpa.

Initially, all houses in New Zealand were on low pressure water. However, most new homes nowadays are built with mains pressure water systems.

How do you know if you’re on a low pressure system or mains pressure?

There are a few ways to figure this out:

  • It usually says so on your hot water cylinder – look for the big white sticker on your cylinder that says “low” or “high”.
  • How old is your house? If it’s pre-1990s, you’re probably on low pressure.
  • Is there a copper pipe sticking out of your roof, probably above the cylinder? If so, you’re probably on low pressure (this usually gets removed if once you switch to mains pressure).
  • Turn your hot water on for few seconds, then turn it off. Turn your cold water on for a few seconds, then turn it off. If your cold water has more pressure than the hot, then you’re on a low pressure water system.

What makes a low pressure water cylinder different from any other types?

A low pressure water cylinder has a few distinct differences. The biggest difference is the size. Low pressure water cylinders are available in quite small sizes (15 to 40 litre underbench models) and mainly go up to 250 litres; while you can get high pressure cylinders that hold up to 350 litres. The newer high pressure cylinders are actually more compact that old cylinders, so they hold more water, but take up less room. Low pressure cylinders also take up more room because the pipes associated with them are larger than newer mains pressure pipework.

Because most low pressure cylinders are lined with either copper or enamel, they’re suitable only for inside storage. A stainless steel mains pressure cylinder, on the other hand, can be located outside, as is becoming more and more common as people would rather use the space inside the house for other uses.

A low pressure cylinder doesn’t have a temperature/pressure relief (TPR) valve – a valve that relieves excess temperature and pressure if either reaches a critical point.

Should we stay on low pressure?

For some properties, staying on low pressure might make sense – if the property is a rental or a bach, or if you think staying on low pressure might help you (or your tenants) save on water or power bills (by encouraging less water use). Cylinder Direct can replace an older low pressure hot water cylinder with a new one from our trusted brands Rheem and Rinnai. Read more here on our Electric Low to Low Pressure Swap page.

Should we switch over to mains pressure?

If it’s time to replace your hot water cylinder, it’s a great opportunity to talk to us about upgrading your water heating system. This is a great way to add some value to your property and possibly cut down on your water and power bills.

Upgrading to mains make sense if you want stronger hot water pressure in your home. You’ll immediately notice the difference, increasing your hot water pressure from around 75kpa to up to 500kpa of pressure.

Your showers will feel better – and you’ll probably be able to shorten shower times (great if you have teenagers in the house!).

If you’re renovating a bathroom or kitchen, it’s almost essential that you swap over from low pressure to mains. Modern tapware and mixers won’t work properly on a low pressure system, and it’s becoming harder to find specific lower pressure mixers (using mains pressure mixers on a lower pressure system actually makes the flow worse).

We have a range of mains pressure cylinders, varying in size and features, from our trusted brands Rheem and Rinnai.

Read more about Electric Low to Mains Pressure Upgrade pricing here.