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Help. Water Worries

February 2016


We have just had a power shower fitted – by an Irish company. The bathroom and hot press are on the top floor, the pump is in the hot press. The problem is we were told we needed to open a pipe to let cold water into the cylinder or else it would burst if it got too hot. I have never heard anyone having to do this. We are now afraid to put our heating on for long in case it bursts and floods the house. As we are both over 76 years I would be most grateful to you for any help. 


This sounds unusual to me, as the advice is contrary to the usual set- up of the water heating system in a residential property. The hot water supply in a house is normally provided via a hot water copper cylinder generally located in a hot press. There are two principal means of heating the water within the copper cylinder: via an immersion or directly off the heating system in the house.

Cold water is directly fed into a copper cylinder from the cold water storage tank (usually in your attic). As hot water is used it is automatically replaced with cold water, which is subsequently heated.

The installation of a pump on the hot water circuit is simply to increase pressure on the downstream supply and has no relationship to physically heating the water.

With regard to your concerns about excessively hot water and bursting or flooding, an overflow pipe installed at the top of your cylinder as standard discharges excess hot water into the water tank in the attic space. In turn, the tank in the attic will have its own overflow pipe exiting the building at roof level, discharging any excess water externally so as not to flood your house.

If you have specific concerns that the copper tank is too hot, you can alleviate this by running the hot water taps (therefore allowing cold water to enter the system) or by adjusting the heating controls /regulator, eg immersion and or boiler.

In addition, your copper cylinder should have a thermostatic control valve that can be set to limit the heat output of the heating elements within the copper cylinder. This can also be adjusted, but should be completed by a qualified professional.

On the basis that there appears to be a level of uncertainty over the installation of this system, it is my recommendation that a registered plumber inspects the heating system and confirms that everything is installed correctly.

Andrew Ramsey is a registered Building Surveyor and a member of the Society of Chartered Surveyors Ireland.