TRV Configuration

[Edward W. Thompson]

The house of a friend is fully centrally heated but none of the radiators are fitted with thermostatic control valves. The system was fitted about 15 years ago, possibly longer.

The house has three bedrooms and a bathroom upstairs and the downstairs comprises a hallway, large lounge, dining room and kitchen. All spaces are fitted with radiators including the hallway. The system is controlled by a simple thermostat in the lounge. Hot water is by an indirect cylinder.

I was thinking the most appropriate plan is to install TRVs to all the radiators except those in the lounge, where the thermostat is sited, and to change the thermostat to a programmable type.

I will appreciate guidance whether this plan is sensible or whether all radiators should be fitted with TRVs.

[Andy Hall]

Completely reasonable. You don't want a TRV in the space where the thermostat is sited.

[Dave Fawthrop]

|The house of a friend is fully centrally heated but none of the |radiators are fitted with thermostatic control valves. The system was |fitted about 15 years ago, possibly longer.

Look at the feeder fittings on the radiators. Old ones are sort of semi hemispherical. New ones are an imitation 15mm pipe. If old, you may have to remove the radiator to get the fitting out and replace it with a new one.

|The house has three bedrooms and a bathroom upstairs and the |downstairs comprises a hallway, large lounge, dining room and kitchen. |All spaces are fitted with radiators including the hallway. The |system is controlled by a simple thermostat in the lounge. Hot water |is by an indirect cylinder. | |I was thinking the most appropriate plan is to install TRVs to all the |radiators except those in the lounge, where the thermostat is sited, |and to change the thermostat to a programmable type.

Some would argue that the best place for the thermostat and non TRVd = valve is in the hall, and some not.=20

|I will appreciate guidance whether this plan is sensible or whether |all radiators should be fitted with TRVs.

--=20 Dave Fawthrop

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[Set Square]

You don't say whether the system is fully pumped, or whether it is gravity hot water and pumped central heating. If gravity, you should either convert it to fully pumped or - at least - fit a zone valve and tank stat in the HW circuit in order to provide independent control of HW and CH as well as providing a boiler interlock. [Come back if this needs more explanation].

Fitting TRVs to all but one radiator is entirely reasonable. The rad nearest the room stat should have two lockshield valves (and no TRV) so that it can't be turned off without using tools.

Assuming it's a vented system, you *could* have a problem with pumping over when most of the TRVs are closed, depending on how the fill and vent pipes are connected. If this *is* a problem, it will need to be addressed. You could also consider swapping the pump for one with automatically variable output - such as a Grundfos Alpha - which will reduce the noise when most of the TRVs are closed.

[sponix]

FWIW, I found them surprisingly easy to remove with the appropriate tool.

The best place for the non TRV radiator is the room with the room stat. Ideally this would also be the hall.

sponix