Replacing Room Thermostat 3 wires to 2 wires??

[Ric2013]

I always agree with you Harvest, except when I don't.

I was going to bed, but I thought the OP might do it wrong and have heating that only runs in the summer if Shaun is mistaken. Shaun is probably now checking and will be back soon?

Shaun and mine and your posts crossed, because I need to write an essay instead of 5 words

 

[BlockABoots]

A heating off terminal

Red to a
Yellow to c

Blue in choc block

This is is what i mean the the manual and the diagram on the inside of the shell are completely misleading as they clearly show that Neutral is to be wired up which i thought was wrong in the first place but then had second thoughts when i read the manual.....

https://i.*********/laFpKnN.jpg

Not to worry guys im not going this right now just want to be sure before i replace the thermostat

 

[Ric2013]

I think you should get an electrician in.

 

[Harvest Fields]

I always agree with you Harvest, except when I don't.

I was going to bed, but I thought the OP might do it wrong and have heating that only runs in the summer if Shaun is mistaken. Shaun is probably now checking and will be back soon?

Shaun and mine and your posts crossed, because I need to write an essay instead of 5 words

I have he same problem mate. Sometimes I am midpost, then I get distracted by the kids or the missus and by the time I actually post someone has beaten me to it.

 

[Harvest Fields]

I think you should get an electrician in.

Me too mate

 

[Harvest Fields]

This is is what i mean the the manual and the diagram on the inside of the shell are completely misleading as they clearly show that Neutral is to be wired up which i thought was wrong in the first place but then had second thoughts when i read the manual...

https://i.*********/laFpKnN.jpg

Not to worry guys im not going this right now just want to be sure before i replace the thermostat

They are not mis leading mate. They are perfectly clear and do not take this the wrong way but you are not understanding them at all. The new timer unit and the instructions say nothing about a neutral. Do yourself a massive favour and get a heating engineer or Sparks In to fit it for you. It’s a 30 minute job max with coffee, biscuits and a chat for a pro.

 

[ShaunCorbs]

This is is what i mean the the manual and the diagram on the inside of the shell are completely misleading as they clearly show that Neutral is to be wired up which i thought was wrong in the first place but then had second thoughts when i read the manual...

https://i.*********/laFpKnN.jpg

Not to worry guys im not going this right now just want to be sure before i replace the thermostat

Yep your right, it's the neutral writing on it that through me

Red to a
Yellow to b
Blue in a choc block

Sorry for any confusion

 

[Harvest Fields]

Yep your right, it's the neutral writing on it that through me

Red to a
Yellow to b
Blue in a choc block

Sorry for any confusion

What chance do we have if even the pro’s are making these kind of mistakes shaun?

 

[ShaunCorbs]

What chance do we have if even the pro’s are making these kind of mistakes shaun?

be fine, just would only turn the heat on what ever the stat is set at eg desirable temp

 

[oz-plumber]

Re: The old thermostat, did that have a light come on when the heating was on?
If so, that's what the neutral is for.

As for the DT90, all that thermostat does is switch the active.
When the thermostat calls for heat, it sends the 240v supply back to the boiler to switch the boiler on.
Connections in the DT90 - A & B ( C is used for cooling )

All you have to do is find is the wiring connections in the boiler thermostat terminals and use those wires. If there's a neural there, cap the neutral.

 

[BlockABoots]

Ok, chocolate blocked off the blue wire, connected red to terminal A and yellow to terminal B, turned the power back on and nothing blew up!. The boiler fires up when i set the temp higher than the current displayed temp and goes off when i set it a few degrees below and pump stops running when i turn the heating off completely.

Only thing i have noticed is even if i turn the heating off the little flame icon on the LCD display of the thermostat stays on so the thermostat is still calling for heat, it only disappears if i set the temp higher than what the current room temp is. Im guess it is normal for the flame icon to still be displayed even though the heating is turned off as it is a battery operated thermostat??

 

[Harvest Fields]

The flame should go off but the display should still be on

 

[Ric2013]

Hmm. I would think it is normal, as the room stat is not intelligent enough to know if the programmer has switched off the heating.

 

[BlockABoots]

Hmm. I would think it is normal, as the room stat is not intelligent enough to know if the programmer has switched off the heating.

Yeah that what i though what with it being battery operated. The main thing is the flame disappears as soon as the target temp is reached, i just didnt know if it communicated with the programmer via the 2 wires so it knew that it wasnt on and thus stop calling for heat....but then i guess if the programmer is switched off then it doesn't matter if its calling for heat

 

[Ric2013]

Well, when the set temperature is reached, the room thermostat itself is the item that is switching off the live to the boiler (pump etc), so in that circumstance it knows what is going on.
Glad you got it going. I was concerned you were going to persist in connecting neutral to terminal C

 

[Harvest Fields]

If you turn the temp down low enough it should still go off?

 

[BlockABoots]

Well, when the set temperature is reached, the room thermostat itself is the item that is switching off the live to the boiler (pump etc), so in that circumstance it knows what is going on.
Glad you got it going. I was concerned you were going to persist in connecting neutral to terminal C

Nah, i came across a few other threads on different forms who had the same colour wires as mine and every replied said to connected red to A, yellow to B and terminate the blue

 

[BlockABoots]

If you turn the temp down low enough it should still go off?

Yeah if i lower the target temp below the room temp the flame disappears and the boiler goes off

 

[Harvest Fields]

Yeah if i lower the target temp below the room temp the flame disappears and the boiler goes off

Then what’s the issue?

 

[BlockABoots]

Then what’s the issue?

I was questioning if the digital thermostat should still be displaying the 'calling for heat' icon (flame) when i had turned the heating off or if it should disappear

 

[Harvest Fields]

I’m getting confused! so if you turn the thermostat up it comes on? But if you turn it to 5 degrees the flame stays on?

 

[BlockABoots]

If you turn the temp down low enough it should still go off?

I’m getting confused! so if you turn the thermostat up it comes on? But if you turn it to 5 degrees the flame stays on?

Yeah if i lower the target temp below the room temp the flame disappears and the boiler goes off

 

[Ric2013]

Harvest: it's all good.

 

[Harvest Fields]

So you have stated above that the flame symbol. Which is the symbol that shows the stat is calling for heat or not goes off then there is no issue. Unless you are talking about something else?

 

[BlockABoots]

Thanks for the help guys!

Now i just need to calibrate the target temp so the heat level is just right.....why do they insist on putting room thermostats in hall ways where is probably one of the more coldest areas of a house!??