Replace Sunvic TLM 2253 thermostat with digital

[Wordle Champ]

Hi,

I'd like to replace the below with something new and digital. The dial is so insensitive it is impossible to set a temperature, you can tap it (not moving the dial) and it will come on/go off depending on the state it was in. If I set it to 20 degrees I think it actually ranges from 18 to 25 so I'm forever moving it 1/1000th of a mm in either direction.

We knocked down a wall that it was on and it had to be repositioned somewhere less than ideal, kind of now stuck up in a corner.

Ideally I want a remote sensor I can put in the middle of the room and it feed back the actual room temperature to the thermostat. Failing that, just something that is more sensitive/accurate on the dial (or digital).

All this does is turn on ceiling heating. It is not connected to a boiler or anything else. I believe it is 240V so perhaps that limits my choice.

Many thanks in advance!

 

[stem]

All this does is turn on ceiling heating. It is not connected to a boiler or anything else.

"Ceiling heating" I assume that is electric? If so you may need a thermostat that has a higher current rating that the usual thermostats associated with central heating systems that are connected to a boiler, they tend to only be a few amps.

The voltage isn't a problem most thermostats will work with 230V. But the current rating is. Unless the thermostat is switching a relay instead of the heating directly.

So a bit more information is required, particularly about the 'load' that the thermostat will be switching before we can recommend anything.

 

[Wordle Champ]

Yep, electric heating in the ceiling. It's like being under a grill!

The spec sheet here https://www.wolseley.co.uk/product/sunvic-tlm2253-room-thermostat/ says it is used for 20A.

Checked consumer unit and looks like it has a 16A rating. (B16?)

 

[stem]

B16 is indeed 16A, [B relates to its sensitivity] and as the thermostat is rated at 20A it would seem likely that it is switching the full load; in which case you would need to find a similarly rated thermostat as a direct replacement. [Most of the thermostats that are usually recommended on here are for systems with boilers and so only need to be rated at a few amps.] Although it might be worth seeing if you can find out the actual current draw of the heater.

In the past I have used Salus (RT500RF no longer in production) and Horstmann (HRFS1) wireless thermostats for resistive electric heating purely because they were among the few that had a 16A rating. Neither seem to be top rated choices though. But they are cheap and you tend to get what you pay for. Having said that, I've had a Salus controlling the electric heating in my conservatory for over 10 years and it still works fine. Albeit rather user unfriendly to program.

You may see figures quoted that show two values such as '16(8) A Max.' for example. The first higher figure relates to resistive loads (eg electric heating elements), and the second for inductive loads (eg motors).

Maybe someone else could offer a personal recommendation.

As an alternative, it should be possible to wire a separate relay into your heating control circuit to switch the heating load, and then the relay could be controlled by a thermostat having a low current rating. So you could then take your pick of the mainstream thermostats.

 

[ericmark]

It is hard to regulate inferred heating, as not really measuring air temperature, the normal is to combine air and inferred heating so the air temperature is kept lower to allow for the inferred, and the inferred heater is not switched on/off with a thermostat it is the air heater which is controlled.

The problem is as soon as inferred turns on/off you feel the heat, or loss of heat, so only method is to switch more or less units on/off to control it, hence the 4 bar electric fire.

Colour is important, and the thermostat you link to seems to have a reflective panel which seems wrong. However it seems common to measure air temperature so may be that's the whole idea to stop the direct inferred from working the thermostat, some thermostats use a mark/space ratio to stop over shoot, this one for example, which was good with old gas and oil, but messed up new modulating gas boilers, so they have gone out of favour, the problem is you have to carefully read the spec to see if it uses that method, and if it can take the load.

Rapid switching wears out contracts, so likely needs a solid state relay so it does not wear out quickly, I like most people had inferred heating years ago, in the form of tungsten bulbs, so air temperature was set to 18°C but with lights on felt like 20°C, today LED lights and programmable thermostats have replaced it.

At one time every garage and church had heaters like this

they were effective because with a garage doors were being opened and closed all the time, and with a church the time it was heated for was short. There was normally only manual control.

Today most central heating systems are moving to analogue control, digital (on/off) is used to turn off whole system, but most TRV's are analogue, opentherm is analogue, and the boilers modulate i.e. switch up/down so most systems have moved to analogue.

It seems there is very little available for digital which will likely change if gas is phased out, and we are forced to use electric, but inferred control is complex, even to the getting of Q glass windows the right way around. Inferred can pass through normal glass.

So being so complex, I would have thought it would need a site visit to work out control method. But with some luck maybe some one on here has worked with inferred panels and can advise.

 

[Wordle Champ]

It is hard to regulate inferred heating,

Hi - It is not infrared heating. It's basically underfloor heating but in the ceiling, I imagine there is a mat of thin filaments just above the plasterboard.

 

[ericmark]

Heat raises, so how does that work?

 

[RandomGrinch]

Hi - It is not infrared heating. It's basically underfloor heating but in the ceiling, I imagine there is a mat of thin filaments just above the plasterboard.

If it's not convective, or conductive, it's probably infrared

 

[BlueLoo]

Hi - It is not infrared heating. It's basically underfloor heating but in the ceiling, I imagine there is a mat of thin filaments just above the plasterboard.

That's a new one for me.

 

[ericmark]

Seen fan heaters in ceiling, in the main air conditioning units which can also heat, or door curtain heaters, and inferred heaters, seems different types of inferred so do not glow red, but can't see how conduction or convection will work in the ceiling, when I was at school some 60 odd years ago heat transfers with one or more of three methods, conduction, convection and radiation.

I know energy can be transferred by microwaves and induction but this does not seem a valid method for heating the home.

 

[RandomGrinch]

and inferred heaters, seems different types of inferred so do not glow red

If an infrared heater is glowing red, then it's wasting energy with all this useless 'visible light' stuff!

 

[oldbutnotdead]

You do get radiated heat from any object that is hotter than its surroundings but convection is a more powerful mechanism- so the ceiling panel wastes a lot of energy getting the ceiling up to temperature- once it has done that then radiation becomes the primary heat transmission mech. Of course it helps if the ceiling is heavily insulated above the panel.......
OP, best bet is a relay to do the power switching of the panels, once you've fitted that you can experiment with a wide range of thermostats (many suppliers offer 30 day returns no questions so you can buy,try & return if it doesn't do a decent job).

 

[Wordle Champ]

Maybe someone else could offer a personal recommendation.

I've done more digging and it is an ESWA system and I suppose the ceiling has these (attached) somewhere above the plasterboard.

A neighbour has the EFK-20 thermostat (attached), but I can't find one anywhere. And ideally I'd like a smart version or a dumb version with a remote sensor I can place in the room

Stem - I see your comment on this other thread - https://www.diynot.com/diy/threads/eswa-ceiling-heating-thermostat-and-controls.564427/ - those 1/2/3/4/5 thermostats are in my other rooms.

 

[BlueLoo]

https://www.diynot.com/diy/threads/eswa-celing-heating-thermostats.162910/

 

[Wordle Champ]

https://www.diynot.com/diy/threads/eswa-celing-heating-thermostats.162910/

Yeah thanks, I'd found that but nobody actually recommended a replacement that I can see.