Monthly Archives: November 2014

Cold Water Expansion Valves

Very often we get clients calling us saying there is a pipe that is constantly dripping outside their house and they want it fixed so that it stops. The first thing that we do Is try to educate the clients on what the role of this valve is along with the rest of the valves on the hot water cylinder. So what does a Cold Water Expansion valve do??

When your cylinder is filled with cooler water at high pressure after you, let’s say have used it for a shower or filling the sink with hot water, the element comes on to heat the water back up to it maximum temperature.  The water being heated up causes the water molecules expand and increases the already high pressure in your hot water cylinder to even higher. The Cold Water Expansion has 2 roles in this situation,

  1. it’s a safety mechanism that releases excess water pressure  from your hot water cylinder as it heats up to avoid over pressurizing,
  2. it’s a energy saving device, because it is installed where the cold water comes into your cylinder, it drips out cold water instead of other valves at the top of your cylinder wasting and dripping hot water.

So this valve is made to drip while the cylinder is heating, however if yours is dripping all day and all night constantly this may indicate it is time get us in to replace the valve or investigate other issues that may be forcing the valve to drip.

How do I know my cold water expansion valve is working?

Check that the valves on-top of your cylinder are not discharging any water because if they are then the cold water expansion valve isn’t doing its job, also when you do manually turn your cold water expansion valve on, look for discoloration of the water as this indicates the valve is rusted internally or the rubber seal has perished and is no longer effective. If you are still concerned, getting a hot water cylinder service by us includes checking this valve and others thoroughly.

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