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We have just had an extention built with wet under floor heating in screed, but still have radiators in the old part of the house. The system has a zone valve that controls the radiators and the wiring harness seems to mean it doesnt need a second zone valve for the ufh part. Both the radiators and underfloor use a common boiler return.
The problem is this - if I use the underfloor heating at a high temp (45c) the radiators heat up even when the thermostat on that zone valve is closed. What seems to be happening is that the outlet from the ufh manifold is backing up into the radiators via the common return. Has the plumber forgot to fit a non return valve or something?
I can minimise the problem by using the lowest temperature on the manifold mixer valve because then the return is 24c and hardly noticeable, but I would like to run the ufh at 45c to heat the room quicker.
The problem is this - if I use the underfloor heating at a high temp (45c) the radiators heat up even when the thermostat on that zone valve is closed. What seems to be happening is that the outlet from the ufh manifold is backing up into the radiators via the common return. Has the plumber forgot to fit a non return valve or something?
I can minimise the problem by using the lowest temperature on the manifold mixer valve because then the return is 24c and hardly noticeable, but I would like to run the ufh at 45c to heat the room quicker.