Any recommendations for a good brand of traditional TRV?

  • 22 February 2021
  • 17 replies
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I’ve found that a couple of Salus ones are rubbish at controlling room temperature. They turn off too late (after the room is warm) and don’t turn on enough when the room is heating from cold. Not sure if it’s way too much hysteresis or too wide a proportional band. Or maybe it’s just all mechanical TRVs are intrinsically rubbish having experienced Honeywell Evohome (HR92) ones.

The radiators are quite generously sized for the room and can certainly warm it well with manual intervention.

 


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@25 quid They all rely on similar technology, wax and a piston = hysteresis.

I found Drayton to be mehh...OK (within the confines that none are really OK, You can’t expect them to be anything like as reactive as sensor operated ones where hysteresis has to be deliberately built in

a question for you, can you tweak the hysteresis of the electronic ones or is it preset?

I have a couple of other makes, I can’t for the life of me figure out why they all including the Drayton behave so differently, especially in respect of knob number vs room temp. I’d sort of expect if it goes from 1 to 5 that 19/20 would be somewhere in the middle…

Another thing is how much stiction there is in the valve below, I think wear greatly affects how well the trv works, as it changes the proportionality of the operation.

Thanks @woz I think it’s amazing that expanding wax can push against the strong springy resistance of the valve itself. Drayton is certainly a brand I know that has been in temperature control for decades. Thanks for the tip!

The Honeywell electronic ones aim to maintain a stable temperature within an unadjustable amount; it seems to be 0.5°C. You can enable optimised stop, which turns off up to an hour early if the room will still be within 1°C by the actual off time.

I might try one of these. Cheap as chips! 

https://www.screwfix.com/p/cassellie-eq-3-smart-thermostat/886gv

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I might try one of these. Cheap as chips! 

https://www.screwfix.com/p/cassellie-eq-3-smart-thermostat/886gv

@25 quid

interesting, I might try these, seems too cheap to be true cf the competition

but I note the following (as they say, go figure...)

late edit: be prepared for long periods crouching on the floor attempting to program said valve, no app and setup is complicated and not a quick job to change times etc. 

Might be ok for one position where you’re unlikely to want to change it seasonally.

 

Yeah, I spotted it was just a dumb device, but that’s ok for me as there is a smart device elsewhere that will modulate the boiler. This ought to stop a room from overheating whilst allowing it to warm up quickly.

I enjoyed the paradox highlighted above! 🤣

There an even more crazily cheap one which is documented as only doing on/off control. This is a shame as the room will annoyingly cycle 1°C above and below the set point.

I can’t confirm if the EQ3 one finds the sweet spot of partial opening — someone did run a test for 70 hours and reported control to within 0.1°C, which seems implausibly good.

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There an even more crazily cheap one which is documented as only doing on/off control. This is a shame as the room will annoyingly cycle 1°C above and below the set point.

I can’t confirm if the EQ3 one finds the sweet spot of partial opening — someone did run a test for 70 hours and reported control to within 0.1°C, which seems implausibly good.

@25 quid highly implausible, I would have thought the thermal inertia of the radiator would cause way more than 0.1°C variation

My current setup is rubbish, it overshoots by way more than a degree, and there’s no way to reduce the hysterics (both mine and the temperature). Don’t buy a Salus wireless thermostat, it’s rubbish, regularly fails to communicate or respond from the app. The physical thermostat is also very un-user-friendly  

I wasn’t clear on the differences between the first two shown on that link?(the 3rd was bluetoothed)

Yes, the crazy cheap one comes in other flavours including Bluetooth.

The reason the Salus wireless thermostats overshoot is that they don’t modulate the boiler as the room gets near the set point. That’s what I was banging on about in a previous thread once upon a time. The Honeywell stuff does that very cleverly to avoid overshoot and accurately maintains a comfortable constant room temperature.

After a little more research, I see people have hacked the EQ3 for separate control, but they didn’t offer (hadn’t discovered) anything other than on/off control. So I suspect it only heats until it’s too hot, turns off, overshoots, waits til it’s too cold, turns on. The only clue was that the manufacturer documents a boost function that sets the valve to 80% for 5 minutes. So it seems maybe it does do progressive opening control? 

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@25 quid That’s partly the reason, but the biggest offender is the hysteresis, it’s set to 1 degree and can’t be changed, it needs to be half that. Set to 20 it goes off at 21, and doesn’t come back on until 19- awful...(stat not trv)

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Yes, the crazy cheap one comes in other flavours including Bluetooth.

“Flavours” 🤣🤣🤣🤣🤣🤣🤣Love it 👏👍👍👍👍👍👍👍👍👍👍😂😂😂😂😂

Hey @25 quid 

We’ve just had traditional TRVs installed on all our radiators, as they didn’t have any when we moved in… we went with Draytons. 4 days in and all seems good. The ones we went for range from 0-5 + ‘max’ with halfway intervals too, which has actually been really handy so far to get things just right. :thumbsup:

 

Hey @Nataly, thanks for the tip! You don’t want to get too hot doing all that DIY! 😉  

The nice shiny chrome one was out of stock at my local Toolstation, so I went cheap, but still Drayton. I checked the detailed specs from the manufacturer and yours is slightly better control, but I have got some instant gratification! 😉 

Fingers crossed. I’ll report back on performance… 🤓

No news yet, but I had another DuckDuckGo and found an interesting set of opinions from a while back that still seem relevant.

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Hey @25 quid 

We’ve just had traditional TRVs installed on all our radiators, as they didn’t have any when we moved in… we went with Draytons. 4 days in and all seems good. The ones we went for range from 0-5 + ‘max’ with halfway intervals too, which has actually been really handy so far to get things just right. :thumbsup:

 


We have these same ones, all set to Max. Just having these increases the points on your EPC! It’s a bit silly given how they don’t last (i.e. the wax + piston design).

 

I’d like to get these smart ones : https://www.netatmo.com/en-eu/energy/valves

but maybe once they get cheaper

Owww, they look good, but quite expensive (HomeKit too)! I assume @Ohit, they don’t coordinate/control the boiler, they are just isolated TRVs one per radiator?

My new Drayton was working very well this morning, night and day compared to that Salus Cr$π. Off to Toolstation for another later… Thanks for those tips @Nataly & @woz.

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Owww, they look good, but quite expensive (HomeKit too)! I assume @Ohit, they don’t coordinate/control the boiler, they are just isolated TRVs one per radiator?

They will work with Netatmo’s thermostat, which would be connected to the boiler.

 

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