Selgas
Perhaps this will enlighten you some – the purpose of the TPR valve is to allow expansion of the water when it is being heated to take place. Under normal conditions when the element is not heating the water will not be discharging from the relief valve. When the thermostat calles for heat and the elements heat up – the expansion of the water passes through the TPR valve to waste.
If you fit a cold water relief valve on the cold line to the cylinder it should have a rating of no more than 70% of the maximum setting of the hot water relief valve and this will allow cooler water to be run to waste in times of heating up.
Fitting a pressure limiting valve to the inlet supply to the cylinder will ensure that no excessive pressure is applied to the system and cause problems with the valves.
Hope this clarifies some of your concerns and explains the purpose of the valves in simple enuff terms for you.
Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians
