Smart thermostat fitting - check my working ?

With the days getting nippier, the siting of our programmable 'stat continues to be a pain (it's up high and she now can't stand).

Going back to 2002, our CH was fitted by a professional (because it was paid for by the in-laws). The plumber sub hired an electrician to wire everthing in, including the original stat, which was as cheap as they come without actually being made of cardboard.

Come sometime later, I upgraded it (prompted by the failure of the mechanical timer on the boiler. That too could not have been more cheap ...) to a Horstmann DTR2. And then forgot all about it.

Now I am looking to some sort of smart stat, so SWMBO can just dial it in via her phone (or even ask Alexa :) ?!).

have come across this:

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MOES Smart Thermostat WiFi Temperature Controller Smart Life APP Remote Control for Electric Heating Works with Alexa Google

Which seems just the ticket.

Now the wiring ...

removing the existing stat, I see there is a red wire and a sleeved wire into it, from the 2002-fitted wiring by the expert. However there is also a blue wire that's just terminated and shows as having a current.

So is my guess and hope that this is the 3-wire setup needed for that state correct ? And there is L+N+load ? Which is what an expert should have left behind ?

Thought I'd check here, as it would be a 1 in 100 times of things not being shit. And I'm old enough to be wary of such luck :)

Thanks in advance.

Reply to
Jethro_uk
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Oh dear. That's Chinesium based on a platform called Tuya. The hardware is probably fine, but expect it to stop working when they can't be bothered to update the app or withdraw the servers. I give it 3 years...

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Are you keeping the existing timer/controller and setting it to call for heat 24/7? Or removing that as well?

Basic mechanical thermostats don't need a neutral, but AIUI electronic ones do (unless battery powered). But I think they're normallly a pair of (relay) contacts to interrupt the output of the controller, rather than a live input?

If the input is a switched live from the controller, rather than a permanent live, I'm not sure how this one stays powered when the heat is off?

Theo

Reply to
Theo

We'll cross that bridge when we come to it.

Exitsing timer is f***ed and has been since about 2004 (which was one reason for getting the programmable timer stat). So the boilers heating switch is set to permanently "on" and the stat does the work.

The current stat is a Horstmann DTR2 and battery powered (the batteries seem to conk out every autumn ...)

Presumably the boiler setting of permanent heating makes it permanent live - and then the stat simply switches that back to the boiler to fire up ?

Anyway, a bit of googling revealed this:

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Which seems to suggest that "GC" (Water/Gas boiler) is my situation ?

I hope the ordered unit has better details than MOES website ....

I guess I could pull apart the boiler and see where the wires end up ....

(SWMBO swears she can remember the electrician commenting that he had wired the stat up to be easily upgraded in future ....)

Reply to
Jethro_uk

That would be a reasonable assumption, presumably "old colours" triple and earth - red, yellow, blue? The L being switched by the timer.

er they do for the heater to increase their sensitivity and reduce the hysterisis.

Aye, without batteries would need the L to be permenant live.

I'd expect an electronic stat to have "volt free" contacts, as you say contacts that make (or change over) on demand for heat.

Batteries... or provision of permenant live. With a programmable stat or a "smart" one the time switch is redundant for the heating and can be removed and what was it's output to the old stat connected to permenant live. Or just set its heating to always on.

Reply to
Dave Liquorice

surely you want the version for boiler heating, not for electric UFH?

the latter quite likely requires a floorstat ...

Reply to
Andy Burns

Yes, I managed to select the wrong one for the link :(

Although I was pleasantly surprised the boiler version is £2 cheaper :)

Reply to
Jethro_uk

Theo explained :

Yes they do, to improve the response of the thermostat/ reduce the hysterisis. When they turn on, it also turns on a small heater (resistor), which warms up the bi-metal making it switch off soner than it naturally would.

Reply to
Harry Bloomfield, Esq.

So, following on from this, I decided to sneak a peek at what's going on at the boiler end ...

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seems to show the other end of what I saw in the thermostat housing.

4 wires + earth in a single cable.

Brown-Live Blue-Neutral Earth

and then the more interesting wires - 3&4 black and grey respectively, with red tape markings.

So referring back to "GC" on

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presumably L&N are obvious and the 3+4 from boiler go to 1+2 "dry contact" on the 'stat ?

Can life really be that simple ?

Reply to
Jethro_uk

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