i am about to change all the radiators in a house on a 8mm micro bore system. they are on the old twin entry pipe valves so i am going to replace all to a valve on each side. all but 1 will have trv's fitted. what i need to know is do i need to put a differential bypass valve in or will it not need one as the radiator without the trv will allow enough flow. if it does need one where would be the best place to put one bearing in mind the manifolds on the flow and return
Boiler type ??? if it is a pressurised system, some need a bypass depending on whether the boiler has an integral one fitted. If you fit 2 x lockshiled valves to one radiator - this will act and is suitable as a bypass.
This is only a precaution, as the boiler thermostat will cut the boiler off when it reaches temperature or if it overheats, all the bypass is for is incase all radiators valves are closed it protects the boiler as the heat can still get away from the boiler. If all valves were closed the pump would be pumping against them and the heat that'll build up could damage the boiler.
If the thermostat failed the boiler will be fitted with an overheat stat, this will cut the boiler off. If the overheat stat failed the pressure would build up in the system, but the boiler will have a pressure relief valve, once the pressure reaches 3.5 bar the valve will open and the pressure will be discharged to outside.
Not very likely the thermostat, overheat stat and pressure relief valve will all fail at the same time. The one radiator will be fine.
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