Escape radiator

[alanem]

Will it affect my combi boiler performance if I have a TRV on every radiator? At the moment I have a Wifi room stat in the lounge and the only radiator without a TRV is in the hall. It races away and all I can do is have it open or closed. Can I put a TRV on this one as well? Thanks.

 

[Mottie]

You shouldn’t have a TRV in the same room as the room stat.

 

[Madrab]

Yup, the TRV and room stat in the lounge will fight against each other. Take the TRV in the lounge and swap it with the one in the hall.

 

[ericmark]

Will it affect my combi boiler performance if I have a TRV on every radiator? At the moment I have a Wifi room stat in the lounge and the only radiator without a TRV is in the hall. It races away and all I can do is have it open or closed. Can I put a TRV on this one as well? Thanks.

It was the adding of a TRV in the hall which finally got my mothers house working well. However with a TRV and wall thermostat in the same room they must be set to complement each other, so I used a programmable TRV head so I could easy set same temperature, having a TRV showing *123456 is not going to help setting them to work together, although it can be done.

So the idea with a modulating boiler is the TRV's set the room temperature, as they close they force more water through those still open until the by-pass valve starts to lift which means unless the boilers algorithms are designed otherwise (some are very clever) as the TRV's close the return water temperature will increase and the boiler will modulate more and more until it can't modulate any more at which point it starts to switch off/on using a mark/space ratio to further reduce output.

However there is a problem, unless a wall thermostat is added, it would continue to cycle all summer, so a wall thermostat is added to the room kept coolest on the ground floor, with not alternative heating, and not outside door, in most homes that room does not exist so hall is the next best, however in the hall we want a large radiator to re-heat hall when outside door is opened, so the TRV is set so it will close when it detects the sudden drop in temperature as door is opened, called window open feature, and we set a time for this, then it opens to reheat the room rapidly, but before it reaches the wall thermostat setting it closes again so it only just will switch wall thermostat when its been running some time.

If I look at mine now, it is in over night mode so TRV target 17°C current 18°C the wall thermostat target 18°C current 20°C so my wall thermostat is showing the hall is 2°C warmer at wall thermostat level to TRV level, in the day time I allow for this by setting the TRV cooler than the wall thermostat, since I don't use front door, the TRV in the hall has not got the window open option, it is the kitchen TRV which has that.

But can't have a wall thermostat programmed for different temperatures through the day, unless the TRV is also programmed for same changes. So you set the TRV like shown

or with more expensive version

So you match with wall thermostat, depending on make of wall thermostat some can be set to link with the TRV, mine was claimed to link, but to be frank since I need at set 2°C lower than wall thermostat it does not work, I have Nest wall thermostat.

From what I read the Hive wall thermostat has a feature called "call for heat" so the Hive TRV can tell the Hive wall thermostat to switch on for 30 minutes, and with EvoHome the wall thermostat is more like a hub where you set temperature of each room.

However this cost £15 with bluetooth, can get them for £10 without bluetooth and I have them in 5 of my rooms and they work well, except they only show target temperature they don't show current temperature. Called a eQ-3 there is also the terrier i30 which does the same being a stand alone unit, the bluetooth version of eQ-3 can be paired with other units as well when you have more than one radiator in a room.

Of course using a system with OpenTherm will or should at least work a lot better, as by time it is ready to start the mark/space ratio the boiler temperature is reduced so less heat lost up the flue, however last house was Bosch that does not support opentherm, and this house oil so boiler does not modulate anyway.

First house has a Myson fan assisted radiator by entrance, now that was a lovely unit, very fast rewarming the room, but expensive, looked at the new Myson iVector but costs too much, and design of kitchen where my radiator is it does not reduce cupboard space, if it did then would go for kick space fan assisted, first house was open plan, two normal radiators in main twin rooms not TRV on them, wall thermostat half way between the two, but Myson by the door, which was set on thermostat so really only kicked in after front door opened. Speed set around 1/2 way.