The Efficient Home Forum

I am looking at the Evohome system and would just like to check what I want to do is possible.

I have a combi-boiler and 7 radiators. All but one have a TRV - the one in the bathroom.

I want to be able to do the following:

Have the heating come on for 2h in the morning (separate times weekday/weekend) so the bathroom radiator always comes on (to warm towels up), and the remaining radiators come on only if they are below a programmed temperature threshold.
Then for the rest of the day the heating only comes on if one of the 6 radiators with a HR92 drop below a temperature threshold (I know by definition the bathroom will come on at these times as well).
To be able to vary the temperature threshold per radiator and per day.

Is this possible??

The bathroom radiator would also therefore be serving as a bypass and a bypass valve would not be necessary I believe??

Thanks
Andy

Yes what you want to do is possible.

Depending on the flow rate through the bathroom radiator it may be sufficient for a bypass, but bear in mind most boiler manufacturers will state what they define as a bypass circuit and if an open circuit radiator is an acceptable method...

This is interesting. The only radiator in my setup without the Evohome TRV is the towel radiator in the bathroom. My plumber has actually just called to say he'll come and fit a new valve to it on Friday.

My understanding is that without an Evohome TRV fitted it would cause the temp in other rooms to overshoot? However, my plumber just mentioned something about one radiator shouldn't have a TRV but didn't go into too much detail about it. Can someone explain in a bit more detail whether my towel radiator should or shouldn't have a TRV fitted?

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danmoz98 wrote:This is interesting. The only radiator in my setup without the Evohome TRV is the towel radiator in the bathroom. My plumber has actually just called to say he'll come and fit a new valve to it on Friday.

My understanding is that without an Evohome TRV fitted it would cause the temp in other rooms to overshoot? However, my plumber just mentioned something about one radiator shouldn't have a TRV but didn't go into too much detail about it. Can someone explain in a bit more detail whether my towel radiator should or shouldn't have a TRV fitted?

There is nothing anywhere that say's one radiator should be 'open circuit'... but bear in mind that pre-evohome this was how we did things, hence boiler manufacturer instructions will normally state 'the room with the room thermostat needs the radiator left without a TRV fitted'.... but we don't do this with evohome.

As the evohome system uses the HR92 Radiator Controllers as the room thermostats then there isn't a room with a room thermostat, however there is still a requirement to ensure the minimum flow rate of central heating water through the boiler otherwise it will short cycle or overheat hence why we fit automatic bypass valves to heating systems (https://theintergasshop.co.uk/60-automa ... ass-valves) rather than leave radiators open circuit.