NEST gen 3 fitting on Honeywell programmer and room stat

[JC-DIYman]

 

[JC-DIYman]

seems like rads are getting to hot and calling for heat almost constantly

 

[stem]

Was expecting to find a link between 13 and 14 link the HWC to the pump but that connection must be made.

There are two ways of powering the pump. It can be wired directly to the same connections as the boiler, so that the pump operates whenever the boiler does. Or, some boilers have an overrun facility that keeps the pump running for a short time after the boiler has gone off to dissipate residual heat. In this instance, there will be a special set of terminals provided inside the boiler to connect the pump to, and then the boiler will control the pump.

The boiler (& pump) gets its power via the cylinder thermostat when hot water is required, and via the orange wire from the motorised valve when heating is required.

Looking at your wiring centre, I believe that the removed three core cable would have been for the original thermostat, that the yellow and red wires were connected to terminals 4 and 9 and when you removed them you added the red link between these two terminals.

If so, the white wire in terminal 4 will go to the motorised valve, and the yellow wire in terminal 9 should be connected to the Nest Heatlink terminal 3 'heating call for heat'.

If the above is correct and that is all that you have changed at the wiring centre and it worked OK before, then everything should work OK now. Assuming of course that the connections at the Heatlink are correct.

 

[Taylortwocities]

Sounds like the boiler is getting a call for heat all the time. Maybe the thermostat permanently enabled, or there is a wiring fault.
Do you have a multimeter, or a two-probe voltage tester? You are going to have to trace back why there heating is constantly on, or get a heating engineer to sort it out.

PS Can you explain why you chose this particular time to mess around with your (otherwise working) heating system?
If you hadn't noticed, much of the country is covered in snow and people have died from cold.

 

[JC-DIYman]

Sounds like the boiler is getting a call for heat all the time. Maybe the thermostat permanently enabled, or there is a wiring fault.
Do you have a multimeter, or a two-probe voltage tester? You are going to have to trace back why there heating is constantly on, or get a heating engineer to sort it out.

PS Can you explain why you chose this particular time to mess around with your (otherwise working) heating system?
If you hadn't noticed, much of the country is covered in snow and people have died from cold.

I have multimeter. Chose this time as we have builders in from next week changing around our bathrooms!

 

[JC-DIYman]

There are two ways of powering the pump. It can be wired directly to the same connections as the boiler, so that the pump operates whenever the boiler does. Or, some boilers have an overrun facility that keeps the pump running for a short time after the boiler has gone off to dissipate residual heat. In this instance, there will be a special set of terminals provided inside the boiler to connect the pump to, and then the boiler will control the pump.

The boiler (& pump) gets its power via the cylinder thermostat when hot water is required, and via the orange wire from the motorised valve when heating is required.

Looking at your wiring centre, I believe that the removed three core cable would have been for the original thermostat, that the yellow and red wires were connected to terminals 4 and 9 and when you removed them you added the red link between these two terminals.

If so, the white wire in terminal 4 will go to the motorised valve, and the yellow wire in terminal 9 should be connected to the Nest Heatlink terminal 3 'heating call for heat'.

If the above is correct and that is all that you have changed at the wiring centre and it worked OK before, then everything should work OK now. Assuming of course that the connections at the Heatlink are correct.

The yellow and red from the thermostat were connected to 2 and 3 which I removed and then removed link between 2 and 4. I then re-routed link from 9 to go to 4 instead of 3. I have photo of original layout if it helps.

 

[EFLImpudence]

Just find a diagram of the system and start again.

 

[JC-DIYman]

Nest Wiring

 

[JC-DIYman]

 

[JC-DIYman]

and before installing NEST

 

[EFLImpudence]

Isn't '6' on the Nest call for hot water?

 

[Johnmdc]

Nest is wired wrong brown in 1 should be in 4 black in 3 should be in 6 and grey in 4 should be in 3.
And bring the wires into the nest through the knock outs in the back of it.

 

[JC-DIYman]

Nest is wired wrong brown in 1 should be in 4 black in 3 should be in 6 and grey in 4 should be in 3.
And bring the wires into the nest through the knock outs in the back of it.

Are you sure?

 

[Johnmdc]

Yes.
On your old clock 1 is hot water off which is 4 on the nest
3 is hot water on which is 6 on the nest
And 4 is heating on which is 3 on the nest.

 

[JC-DIYman]

I really appreciate the help. I have re-wired and looks like attached. Note there was no brown in 1, I think that's just the photo. I have yet to reset the boiler, so can you say if this now looks right, thanks.