Wiring a smart thermostat to my combo boiler - not working

[Chris7197]

Hey guys, so I’ve got an (admittedly cheap) smart thermostat that i want to wire to my Glowworm Easicom 28c. However, after following some installation guides I’m not having any luck.

In the first pic (which was taken before I wired the thermostat in) - I’ve wired the thermostat to the circled yellow area on the left, with obviously thermostat live going to boiler live, and same for neutral. I’ve then wired another wire (I have a 4 + earth cable) to the RT terminal on the boiler, and I’ve tried connecting the other end to 4 on my thermostat and had no luck. Also tried to 5 instead.

I’ve also removed a small red wire linking RT to 24V on the right of the boiler (circled in yellow on the right)

The thermostat powers on as does the boiler, but I don’t think it’s communicating with the boiler properly - I.e it’s not managing to turn the heating on.

Have I missed any obvious steps? Thanks in advance!

 

[Chris7197]

Just tried putting the dry contacts to RT/24V on the right, no luck

 

[CountryFan]

It looks like your new thermostat doesn't support 24v so that won't work. You need a link wire between L and 3. 4 to RT on mains voltage side on green block.

 

[ericmark]

It looks like your new thermostat doesn't support 24v so that won't work.

I thought dry contact means the same as non volt contact so it can be any voltage, as long and the low voltage (230 VAC) and extra low voltage (under 50 volts AC) are not run in the same cables, or use special cables with built-in screen?

To my mind, the start point is to download the installation manual. There is often multi methods, and it will explain what bridge wires are required etc. Each boiler is slightly different, and some for some unknown reason put the terminals inside gas tight enclosures, so with that type you need to be gas safe to wire them up.

 

[jackthom]

From the picture, 4 and 5 on the thermostat do the switching so connect one of them across to Live with a short wire and connect the other to RT on the boiler plug where you have tapped off the mains power.
That’s the turquoise plug, NOT the 24V one.

 

[CountryFan]

View attachment 395230 I thought dry contact means the same as non volt contact so it can be any voltage, as long and the low voltage (230 VAC) and extra low voltage (under 50 volts AC) are not run in the same cables, or use special cables with built-in screen?

Yeah I thought that too, but might have been getting confused with the input 100-230vac. I would have thought it would work with the 24v and perhaps there's a switch not selected on the boiler. @Chris7197 hasn't responded to messages, so maybe it's fixed.

 

[ericmark]

@Chris7197 hasn't responded to messages, so maybe it's fixed.

Hopefully. I did consider one of those cheap thermostats myself, but to get the wires to it to hard-wire was not going to be easy. So went for a wireless version.

 

[Chris7197]

Thanks guys - in work atm so can’t try, but I’ll try bridging the L to 3 (or 4? Is that ok as it’s a ‘dry contact’?)

 

[CountryFan]

Thanks guys - in work atm so can’t try, but I’ll try bridging the L to 3 (or 4? Is that ok as it’s a ‘dry contact’?)

Thanks for replying. Yes it's fine to link the L to 3, 4 to RT on turquoise block. Dry contact basically means it doesn't supply voltage, voltage is supplied to and from it.

 

[ericmark]

Since not sure which connections you are using in boiler, low voltage or extra low voltage I would keep the two sets of terminals circled in red and blue apart. If you connect the wires in 4 and 5 together, the boiler should run.

 

[Chris7197]

Cheers guys, trying later. I do have this from the boiler manual and also some diagrams from the manual for the thermostat..I’ve just noticed that it actually says RT for 6/7 on the right of the thermostat (for gas boiler), which I somehow didn’t notice. Maybe that changes things l?

 

[Chris7197]

Just tried putting the dry contacts to RT/24V on the right, no luck

Ok so some progress lol - in this configuration is is getting closer…when the thermostat requests heating, the radiator icon on the boiler starts flashing, but it doesn’t actually turn the burner on. After a few minutes the radiator icon stops flashing. If I get to to request heat again - the radiator icon doesn’t flash again until I turn the boiler off and on again

Going to recheck all my connections later to make sure they’re tight etc

 

[CountryFan]

Does the boiler have an i button to press?

 

[scw24489]

The photos arent terribly clear but it looks like a cable wired into the Ebus port on the white ELV connector, this together with the fact the 24V link was in suugests you already have a manufacturers Ebus based control installed, It needs to be one or the other not both.

 

[Chris7197]

The photos arent terribly clear but it looks like a cable wired into the Ebus port on the white ELV connector, this together with the fact the 24V link was in suugests you already have a manufacturers Ebus based control installed, It needs to be one or the other not both.

I was actually about to come on here to post again, I remembered earlier we were given a slightly rubbish remote control which we haven’t used and that was what was stopping it working. Doh! Thanks for your help