Tuya Thermostat Installation

[Taylortwocities]

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[Taylortwocities]

If only you had shown us that before!
The red and yellow/green go on the volt free contacts. live and neutral as on the old one.

Edit, make sure the fuse in the supply to the boiler etc is 3amp. It should be.

 

[ericmark]

The Tuya as with the Moes comes in different versions which all look very similar

Modbus is not really used in the UK, and NTC is the type of temperature probe.

And yet another where the Instructions come with many options and one needs to be very careful to select the correct version. It does seem the ME81H.31 does have volt free contacts.

 

[Mr_C]

Marvellous! cheers guys works a treat

 

[ericmark]

Out of interest what improvement is the new thermostat? I have been considering Tuya or Moes for my flat under main house, so I can see what temperature it is, rarely turn heating on in the flat, in main no more than store rooms, but would be interested in a report on how they work.

 

[Dazie]

Beware- your new controller may not be suitable for your setup.
At the moment you have L and N powering the thermostat and volt-free contacts connecting 1 and 3 when heat is required. Lines 1 and 3 might not be 240 volt, some boilers use an extra low voltage for that function.
Your new toy uses the L supply to the stat for signalling as well as power. More info needed- pics of the terminations at the boiler or wiring centre would be useful, as would make/model of boiler, are there motorised valves, that sort of stuff

Sorry for the 2 years late message, but had to ask...

By this do you mean that the new thermostat switches between connecting L to 2 (NC) when no call for heat, and connecting L to 1 (NO) when heat is called for? I ask because it looks like N is being connected rather than L in the link to the manual you posted: Moes Thermostat

I have an old non-condensing, non combi, open vented system which supplies switched 230V live from the timer to the thermostat which then switches that same live out to the motorised valve and ultimately the boiler switched live input. My current old thermostat only has 3 wires (2 in use for the live in, live out) and I was hoping I could use them as L input, N input (both to power the thermostat), and switched L output to send to the motorised valve.

Do you think this would work, noting that it would require L to be switched to 1 to call for heat (and not N as discussed above)? I would probably replace the switched live from the timer with a permanent live and use the timer built into the new thermostat - otherwise its supply would be cut every time the timer switched the heating off! (EDIT: or I suppose I could just leave the timer set to permanently on so the live input to the thermostat would remain permanently on?)

 

[Stuckinarut]

Post a photo of your existing thermostat wiring

 

[ericmark]

I would question today why fit any wall thermostat which does not link to TRV heads with most central heating systems? I know in theroy you could have a thermostat in every room to ensure the boiler does fire when required, but it is so much simpler to have a thermostat/heat link/hub what ever name the manufacturers use, that is linked to the critical TRV heads.

The Moes instructions don't really say why one would want the GA version, I would assume for heat pump as can be used heating or cooling, for a gas boiler it would be the GC version, and electric underfloor heating the GB version which has a 16 amp rather than 3 amp rating.

This

is showing the heat pump, there is a M which I would assume means motor. I am not really into heat pumps. But unless a very basic system and very small property I would not today fit a thermostat which will not link to TRV heads.

 

[RandomGrinch]

The Moes instructions don't really say why one would want the GA version, I would assume for heat pump as can be used heating or cooling, for a gas boiler it would be the GC version, and electric underfloor heating the GB version which has a 16 amp rather than 3 amp rating.

This

is showing the heat pump, there is a M which I would assume means motor.

It is the symbol for a motorised valve.

For use with mains powered actuators that are driven open, or closed - usually with wet underfloor heating systems.

 

[Dazie]

Post a photo of your existing thermostat wiring

Its a UK non-condensing, non combi, open vented system, with Y Plan wiring like:

As you can see, when the the programmer turns on the radiator heating, it feeds 230V live/line to the L terminal on the room stat, which then feeds to the 3 port valve when calling for heat. Once the valve has switched, it feeds the 230V to the boiler SL and the boiler fires and controls the pump as required. Note the N on the room stat is for stats that have a thermal control to finely control the stat triggering and mine does not use that.

I want to replace it with a cheap digital/wifi stat but, other than the battery ones which I prefer not to use but will if mains powered is not possible, I am not sure which makes/models will work with 3 wires one of which is a L out. So the new stat needs L plus N to power itself and would need to give a switched L out (I would simply change the current L which is switched from the programmer to a permanent L and use the new stat to set the programmes for radiator heating).

(Note that I am keeping costs to an absolute minimum as this is all going to be ripped out next year to be replaced, probably for a heat pump).

Thanks for all advice given.

 

[Dazie]

It is the symbol for a motorised valve.

View attachment 363277
For use with mains powered actuators that are driven open, or closed - usually with wet underfloor heating systems.

Yes that is what I assumed (I would just use one of the terminals), which leads back to my original question... is this output switching N only or can it somehow switch L instead?

I am trying to avoid the GC version as I only have 3 wires to play with so was hoping that the GA version could simply output a switched L. Or maybe I could use GC and connect one of the "dry contacts" to the incoming L, but would it be ok with 230V?

(Note that no underflow heating is involved, the common UK y-plan solution used the 3 port motorised valve to divert water between radiators, hot water or both).

 

[RandomGrinch]

I am trying to avoid the GC version as I only have 3 wires to play with

If you must have the Tuya, get the GC version, and do this..

I could use GC and connect one of the "dry contacts" to the incoming L,

It will be fine taking 230V.

I suppose I could just leave the timer set to permanently on so the live input to the thermostat would remain permanently on

Yes, and I know you are going for minimal cost - but most smart thermostat installs would probably replace the programmer with a two channel receiver - have a look out for some Black Friday deals.

But as asked earlier...

Post a photo of your existing thermostat wiring

 

[ericmark]

For a battery powered cheap programmable thermostat like this batteries last around 2 years, I replaced every year to be sure they did not fail. Non programmable like this

actually lasted around 4 years, caught me out with mothers house had not realised battery powered. To have a wifi connected thermostat not sure on battery life, mine not old enough to have even used one set of batteries. Even the TRV's the cheap eQ-3 last a year, the Energenie over 2 years on a pair of AA batteries.

I would agree I don't like battery, so I fitted Nest Gen 3 which only has a back-up battery, which is recharged from the 12 volt supply. However that is now only a back-up thermostat, as it will not connect to TRV heads, so main one is now a Wiser.

I would not entertain idea of a heat pump as remember the winter of discontent when we lost power every other day, and how cold it got, so my boiler is battery backed, so will continue to work with a power cut, the size of solar array and battery pack to work a heat pump is a non starter, so even if they were made so would cost less than oil or gas, I would still not have one.

As to why fit a new thermostat for only a year, this thread is confusing, as shows pictures of modern boiler and wiring to a thermostat posted by @mr C and then we have @Dazie so answering two people on the same thread, I did consider the Moes thermostat, but with the lack of any linking to TRV heads it seemed not to be the way to go.