Problem with thermostat

[Harry Thomas]

So I have a combi, my thermostat is Honeywell dt90e. Wanted to change thermostat to a programmable so bought a 2 wire programmable stat when wired In. The stat is calling for heat but boiler won't fire. I took stat off and connected a wago to both wires and the boiler fires straight away. Has anyone had this before or anyone know what's wrong. Thanks

 

[Aquarius]

Good evening Harry, it could be a faulty thermostat. What thermostat have you replaced it with?

 

[Harry Thomas]

Good evening Harry, it could be a faulty thermostat. What thermostat have you replaced it with?

I've got x2 brand new thermostats one is danfoss and other is flowmasta so surely can't be X2 faulty stats

 

[snowhead]

How many terminals on the Thermostat connector and any numbers on them?

 

[Aquarius]

Could be that you’ve wired it up wrong?

 

[Harry Thomas]

How many terminals on the Thermostat connector and any numbers on them?

There is 2 terminals . A common and a on. So it's pretty basic when the thermostat is calling literally sends a live back down and boiler will fire. I have wired to the manufacturers diagram , also tried the other way around and still getting nothing.

 

[Aquarius]

Do you hear the relays clicking?

 

[Murdoch]

Yup. Make and model of new units would be handy

 

[Harry Thomas]

Do you hear the relays

Do you hear the relays clicking?

I think so can't remember from memory

 

[Harry Thomas]

Yup. Make and model of new units would be handy

The new models thermostat s are danfoss tp5000si and flowmasta td230w if that helps

 

[Murdoch]

The new models thermostat s are danfoss tp5000si and flowmasta td230w if that helps

doesn’t the Danfoss model need live and neutral too?

think the Flowmasta unit also needs live and neutral

what made you think you could use these?

 

[Aquarius]

Danfoss has a battery, mains and rf version of this. Can’t seem to find flowmasta version. Are you able to provide photos of wiring?

 

[Harry Thomas]

doesn’t the Danfoss model need live and neutral too?

think the Flowmasta unit also needs live and neutral

what made you think you could use these?

The existing thermostat was 2 wire which is live and neutral. So that's why I went for the danfoss and flowmasta as they're the same. The only difference is, is programmable.

 

[Harry Thomas]

Danfoss has a battery, mains and rf version of this. Can’t seem to find flowmasta version. Are you able to provide photos of wiring?

All I've done is put the live to port 1 and neutral to port 2. Have tried swapping them but nothing happens. The cable has two which is 1.5mm live and neutral

 

[Aquarius]

Ok it’s like pulling teeth, and there’s no neutral unless a live and neutral, in which case it won’t work, as you need switched lives.

 

[Murdoch]

All I've done is put the live to port 1 and neutral to port 2. Have tried swapping them but nothing happens. The cable has two which is 1.5mm live and neutral

BUT your 2 core cable, despite it being red/black or brown/blue is NOT live and neutral.

 

[Harry Thomas]

BUT your 2 core cable, despite it being red/black or brown/blue is NOT live and neutral.

Okay I'm assuming as followed the wiring backs and goes to a junction box and it's linked to boiler live and neutral

 

[Harry Thomas]

Ok it’s like pulling teeth, and there’s no neutral unless a live and neutral, in which case it won’t work, as you need switched lives.

Okay but how comes the existing room stat works without a switch live or am I getting the terms confused so have I got a live and switch live ( no neutral)

 

[Aquarius]

Okay but how comes the existing room stat works without a switch live or am I getting the terms confused so have I got a live and switch live ( no neutral)

Sounds more likely

 

[Murdoch]

Okay but how comes the existing room stat works without a switch live or am I getting the terms confused so have I got a live and switch live ( no neutral)

because all it is , is a switch so live and switched live ...............

Best you get somebody with knowledge involved .