Help wiring 3rd gen nest heat link

markh1 said:
Yes, it’s on Combi on/off on stat, just to update I used the test heat function on the stat and the boiler started (had to go through the boiler pre start up as power had been off) but worked fine I stopped the test waited for the boiler over run to stop and the tried the dial on the stat, turned it up and it worked so I turned it off. Then I tested the manual override button on the heat link, the lights came on but boiler did nothing, I turned it off and no noise from boiler heat link manual flame icon gone out and back to just connected light but now the stat doesnt work, turned stat up and boiler doesn’t start, it’s like the manual heat button on the heat link has stopped it working - could it be a faulty heat link?
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There could be a delay on your boiler to prevent it firing up and then switching off too often, sounds strange as you obviously have everything wired as it should be or it wouldnt fire up at all. have you got it working through the app?
 
Just to be sure of your connections in your heat link , you have a perm feed L into the L terminal you also have a perm feed into term 2 A neutral into Neutral term, your call for heat to your boiler in term 3, then obviously your 12v to your stat in T1 and T2.
 
The app is connected to the device, I turn the dial on the app and a short delay later the stat changes, but I’ve turned the heating up on the app and boiler still hasn’t started up. I turned off the power and did a continuity test between the lr on the boiler and the 3 on the heatlink and it beeped so connection is there. Hot water working fine on the boiler but somehow pressing the manual heat button on the heatlink has stopped it working I’ve switched off the power after trying the 10 second hold of the heatlink button to reset and still not working.
 
markh1 said:
The app is connected to the device, I turn the dial on the app and a short delay later the stat changes, but I’ve turned the heating up on the app and boiler still hasn’t started up. I turned off the power and did a continuity test between the lr on the boiler and the 3 on the heatlink and it beeped so connection is there. Hot water working fine on the boiler but somehow pressing the manual heat button on the heatlink has stopped it working I’ve switched off the power after trying the 10 second hold of the heatlink button to reset and still not working.
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OK can you confirm the heat link wiring is connected as I stated above?
 
bright_Spark said:
Just to be sure of your connections in your heat link , you have a perm feed L into the L terminal you also have a perm feed into term 2 A neutral into Neutral term, your call for heat to your boiler in term 3, then obviously your 12v to your stat in T1 and T2.
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Yes exactly as you say I grouped the lives into a choc and took two from this to the live and 2, got the call for heat connected to 3, grouped the neutrals all but N4 on my plan as this is used for the stat now and got connection to neutral. Using a fuse light pen on the connections the live lights the screwdriver as does 2 and 3 neutral doesn’t as normal, the tf1 and 2 don’t but guessing as only 12v
 
markh1 said:
Yes exactly as you say I grouped the lives into a choc and took two from this to the live and 2, got the call for heat connected to 3, grouped the neutrals all but N4 on my plan as this is used for the stat now and got connection to neutral. Using a fuse light pen on the connections the live lights the screwdriver as does 2 and 3 neutral doesn’t as normal, the tf1 and 2 don’t but guessing as only 12
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OK so far so good, it does actually sound like a missing neutral but in your boiler you should have a perm feed and neutral, have you confirmed this?
 
Yes the boiler has live neutral and lr plus earth connection, the neutral from the boiler is n1 in the plan and this goes into the choc block with n2 and n3 the only neutral I’ve removed is the N4 which went to the stat anyway
 
markh1 said:
Yes the boiler has live neutral and lr plus earth connection, the neutral from the boiler is n1 in the plan and this goes into the choc block with n2 and n3 the only neutral I’ve removed is the N4 which went to the stat anyway
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OK well it sounds like you have wired this correctly. the neutral to your stat was not needed as you say. The only thing niggling at me at the moment is to verify that the neutral that went to your stat did not go via the wiring centre upstairs then onto your boiler for its neutral and by disconecting it to check the neutral still goes to the boiler
 
The continuity test showed it went straight to the clock, and the cable with the earth and other stat wire can be seen coming into the clock, so the same 2core and earth cable, No other wires in the wiring centre which haven’t been located
 
I assume I don’t need any connection to ls on the boiler, it didn’t have one before?
 

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markh1 said:
The continuity test showed it went straight to the clock, and the cable with the earth and other stat wire can be seen coming into the clock, so the same 2core and earth cable, No other wires in the wiring centre which haven’t been located
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It is rather odd as it would be unusual to have a faulty nest. I have installed litraly hundreds of the things and have never had a bad one, the other thing i suggest is to check the terminals, these heatlinks are very easy to actually not get the wires into the terminals properly and they make a weak connection. Sometimes work and sometimes dont, worth re doing these
 
I will double check the connections, they all look connected, screws tight, I agree they feel a little flimsy as is the stupid space they have given to install them. As for the call for heat it goes from 3 on the heatlink upto the wiring centre (D) I have connected this to A in the wiring centre which goes to lr on the boiler. I connected the multimeter to lr on the boiler and the connection 3 on the heat.ink and it beeped so assume this means a loop exists.
 
Boiler must be wired correctly if the hot water still works.
Ls hasn’t been used in your install and this usually takes the power to the common on your heating controls.
If lr fired that boiler before it should now.
You can also just wire terminal 3 wire into the common and bypass the heatlink and see if the boiler comes on.
 
markh1 said:
I will double check the connections, they all look connected, screws tight, I agree they feel a little flimsy as is the stupid space they have given to install them. As for the call for heat it goes from 3 on the heatlink upto the wiring centre (D) I have connected this to A in the wiring centre which goes to lr on the boiler. I connected the multimeter to lr on the boiler and the connection 3 on the heat.ink and it beeped so assume this means a loop exists.
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OK I think the neutral from your stat was needed at the boiler. you may have to put a link in the boiler from the neutral term into the neutral of the stat where it went to, I was trying to read your manual but it stops at the critical part of the wiring, just check the manual and look for the neutral as I think you are sending the signal from your heat link but it looks like there is no return
 
Mike83 said:
Boiler must be wired correctly if the hot water still works.
Ls hasn’t been used in your install and this usually takes the power to the common on your heating controls.
If lr fired that boiler before it should now.
You can also just wire terminal 3 wire into the common and bypass the heatlink and see if the boiler comes on.
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Mike I think he has the boiler wired correct for the hot water which is his perm feed and neutral but I believe the neutral is missing from the call for heat in the boiler
 
You hit the nail on the head bright spark, I checked all the connections and the call for heat wire came out even through screw was in and the screw was giving a live signal when tested, guessing it was in contact with the screw but not what it needed to be connected to inside. After some faff got it in (doesn’t help I have the wires coming in from made holes in the back so they have to to be bent at quite an angle in the very narrow space and the screw connections feel cheap. Tested the stat, the manual override and app and all now working.

All that stress from just a poor connection ! Lesson learnt, I really appreciate your time in helping me with this. Thanks
 
markh1 said:
You hit the nail on the head bright spark, I checked all the connections and the call for heat wire came out even through screw was in and the screw was giving a live signal when tested, guessing it was in contact with the screw but not what it needed to be connected to inside. After some faff got it in (doesn’t help I have the wires coming in from made holes in the back so they have to to be bent at quite an angle in the very narrow space and the screw connections feel cheap. Tested the stat, the manual override and app and all now working.

All that stress from just a poor connection ! Lesson learnt, I really appreciate your time in helping me with this. Thanks
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ha ha easy done mate those terminals are awful.
 
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