Low pressure vs mains pressure hot water cylinder

Hot Water Cylinders NZ

If you need to replace or upgrade the water heating system in your home, you will likely hear or read about low pressure and mains pressure hot water cylinders.

It’s also beneficial to know the difference between a low pressure hot water system and a mains pressure system if you’re buying a new home in New Zealand. As you’ll also want to understand which system the property has.

What exactly do we mean by water pressure?

Water pressure is more than just how the shower pressure feels to you. Pressure is the force that pushes water through the pipes (measured in kilopascals or kpa). So your water pressure will be different depending on whether you’re on low or mains pressure water. Generally, a low pressure hot water cylinder will provide water pressure at around 75 kpa. In contrast, mains pressure will provide water to your house at up to 500 kpa.

It’s more than just how the water feels – it can actually make a difference to your water bills.

What is a low pressure hot water cylinder NZ?

A low pressure hot water cylinder delivers low pressure water to your property.

Initially, all houses in New Zealand were on low pressure water.  There are a few ways to determine whether your property is still on low pressure:

  • Have a look for a sticker on your hot water cylinder – there should be one that says either “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, 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 is a mains pressure hot water cylinder NZ?

Most homes in New Zealand built from the 1990s onward have mains pressure water systems. They provide a better flow of hot water, faster water heating, and more even flow when you have multiple showers or taps on at once.

A mains pressure system will deliver water pressure of up to 500 kpa, much greater than a low pressure system that will sit at around 75 kpa. You’ll definitely notice the difference in your showers.

What are the main differences?

Other than the water pressure delivered, there are other differences worth noting between a low pressure and a mains pressure hot water cylinder NZ:

  • Low pressure water cylinders NZ are available in quite small sizes (15 to 40 litre under-bench 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 than 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 NZ 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 (more about that here). 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 makes 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 (which is 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.

Get in touch with the knowledgeable team at Cylinder Direct for a no-obligation initial chat and we’ll help you determine what’s best for your home and your budget. Have a look at our Hot Water Cylinders page – then give us a call.