Water pressure

In New Zealand there are basically three types of hot water pressure – Mains pressure, Unequal low pressure, or Equal low pressure.  Mains pressure is when the hot water pressure is strong and is about the same as the mains cold water pressure.  Low pressure is when the hot water pressure is lower than the mains cold water pressure.  The main reason there is low pressure hot water is that the older hot water cylinders were not built strong enough to handle strong hot water pressure.  You will need to know what kind of hot water pressure you have so that you buy appropriate tap ware.

How to determine what pressure you have:

Mains Pressure:  If you have mains pressure then it will most likely say “Mains Pressure” on your hot water cylinder.  Mains pressure does not require a copper water pipe vent to stick up through your roof.  When you turn on the taps or mixer, the flow will be strong and about the same for the hot and cold pressure.  If you put your thumb over the hot water tap and turn the hot water on slowly it is unlikely that you could stop the water.  To avoid getting burnt by the hot water it is good to use a hot tap that hasn’t been used for an hour or so, so that the water in the pipe has cooled down.  Please be very careful with hot water.

Low Pressure:  If you have a low pressure hot water system there will be a copper vent pipe sticking up through your roof.   If you put your thumb firmly over the hot water tap and turn the hot water on you should be able to stop the water.  When you turn on the hot water tap or mixer, the flow will be slow from the hot tap and the cold tap may have a higher pressure or the same.  Please read the next paragraph to determine what kind of Low pressure system you have.

Equal or Unequal Low Pressure:  If your hot water pressure is low then sometimes the cold water pressure for your shower will have been intentionally restricted with a pressure reducing valve or a flow restrictor to make the hot and cold water pressure equal.  This has been done to help your shower water mix more evenly.  If this has been done then both your cold and hot water pressure will both be low and your water pressure is what we call “Equal Low”.

If the cold water pressure is definitely stronger than the hot water pressure, then your cold water pressure hasn’t been restricted you then you have “Unequal Low” water pressure.

Converting to Mains Pressure:

If you would like to convert to mains pressure you can get a plumber to install a mains pressure hot water cylinder or you can get a continuous gas water heating system.   The price to upgrade to mains pressure including the supply of the fittings and the full installation ranges from about $2,200 to $3500 depending on how much work is required and what type of system you choose.