Smart thermostatic radiator valves - need smart thermostat? Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[TraceySmith]

I'm considering putting in smart/wireless thermostatic radiator valves and I'm wondering whether I also need a smart thermostat. I've read that the drawback of putting in the valves and not replacing my current (Honeywell) standard thermostat is that the radiators can't call for heat and turn the boiler on and off. However, I've also been told that I don't need a smart thermostat as I can simply keep the existing thermostat up (to say 25 degrees) and adjust the individual radiators. I'm a bit confused and would be grateful for any info re the pros and cons of each option. Thanks in advance.

[stoneyboy]

Hi traceysmith,
The first question is what would a wireless thermostatic valve (WTV) do for you that a standard capsule one would not. Both will control room temperature but the wireless one will allow you to do this from your armchair.
Linking the wireless ones to a thermostat will only enable the boiler to be turned on if your programmer allows it.
If you have money burning a hole in your pocket then fitting WTVs is an option but don’t expect major savings on your energy bill.
Regards S

[ericmark]

With a modulating boiler the TRV can do most the control required and setting it up is the problem as wall thermostat needs to be slightly higher than the TRV so it only turns off on warm days.

But this has not really worked with non modulating boilers.

So mothers house it worked fine, this house not really worked.

The main advantage of the electronic head was it shows target and current, so if current exceeds target the lock shield needs closing a little until it does not over shoot.

The problem with the electronic TRV was over the top anti hysteresis software, so set at 7 am to 20 deg and it is 10 am before at 20, so had to set to 22 then down to 20 at 8 am, but this means the geofencing does not work.

So looking at more expensive models like Drayton Wiser, which works out how long it takes to heat the room.

But the eQ-3 which were only £15 each in 2019 when I fitted them, with bluetooth worked if anything better than the Energenie which was 3 times the price.

How the Terrier i30 work I don't know.

What are your aims?

[TraceySmith]

Thanks for your replies.

To answer the questions: for reasons too long-winded to go into here, I need to be able to adjust heating in different rooms at different times without going round and manually turning the TRVs. This is why I've been looking at smart/wireless TRVs.

I've had conflicting advice about the need to have a smart thermostat as well and am just trying to get my head around this and decide. I'll be getting a plumber/electrician in so am not thinking about the complex boiler issues mentioned.

Obviously putting in a smart thermostat will cost more but this is ok if I'm getting useful benefits from it. Keeping the existing standard thermostat would be cheaper in the short term but keeping it on at a high level (as suggested by an electrician) so that the radiators can call for heat feels weird to me. Am I being stupid? Would it be completely fine? Or would I be better getting a smart thermostat to enable the smart TRVs to turn the boiler on and off?

Hope this makes sense.

[ericmark]

I am uncertain why with linked TRV heads we have a wall thermostat, a hub yes, but why does it need to measure temperature? Only reason I can think of is so if the TRV heads go wrong, it will over ride and turn off the heating.

The Honeywell Evohome seems to act as a simple hub, rest seem to have a thermostat built into hub.

I will guess the idea is you can gradually built the system? In fact I got the electronic TRV heads first, then added the Nest Gen 3 thermostat later only to find it did not work any longer with Energenie TRV heads, so spent £45 each on heads no better than the eQ-3 heads which cost £15 each.

Two have failed so need to replace them, (smashed by carpet fitters) trying to find what does what is like getting hens teeth.