Nest Thermostat fitting on Easicom 28, Glow Worm

25 Nov 2014
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United Kingdom
Hi there,

I have recently purchased a Nest thermostat and am trying to connect the Heat Link to my boiler (Glow Worm Easicom 28). I have so far successfully completed everything as per the guidelines and even followed some further instructions on the Nest Forum website for my specific boiler. (see below).

At this point I’d like to point out the boiler did not have a thermostat attached previously.

The boiler will generate hot water but will not fire up the heat for the radiators. When the nest thermostat is turned up I can hear and audible click from the Heat Link so I know they are setup and working together.

My main thinking at the moment is the in built clock on my thermostat is the reason things aren't working, as when I switch on the heat at this point (how the heating normally worked) the heating comes on (even is Nest is ‘calling for heat’ or not. So basically this is over riding anything that the nest is requesting and doing it’s own thing.

I have 3 cables running from the boiler front right panel.

1) L ---> L in heatlink

2) N ---> N in heatlink

3) RT ---> T3 in Heatlink


L ---> T2

Hope this helps,

Any help would be greatly appreciated.

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If the Nest (or any other device) has timing options then, yes, you will have to set the boiler timer to permanently on.
If the Nest (or any other device) has timing options then, yes, you will have to set the boiler timer to permanently on.

Thanks for your reply.

If I set the boiler timer to permanently on then regardless of what the Nest Thermostat is 'requesting' from the boiler, the boiler is always on and the Nest cannot control this.

Is there a link in the room stat terminals within the boiler. If so it is permanently switched live. This must be removed then the timer switched to permanently on and this will basically hand over the control to the Nest.
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Yes there's a good chance there's a link on the X17 terminal block, between the 24V and RT terminals, which should be removed.

BTW I nearly had a heart attack when you said Live was connected to T2 but I guess you weren't referring to the heatlink 12V terminals T1/T2. :)
My advice is power the heat link directly from plug socket or mains don't use glow worm connections, 2 wires will not fit.Add the link to 1 and 3 (on the heat link) as described in the nest install then send 1 wire to empty slot on glow worm call for heat connection. It's easy if you spend 2 days before installing. And yes if you have no room stat previously installed you need to remove the loop on boiler.
Did you ever get the Nest Thermostat working? I have just bought one and my boiler is also a Glow worm Easicom 28. Any tips?
Success! I have just installed my 3rd generation Nest learning thermostat to a Glow worm Easicom 28 boiler without any real difficulty. For someone who doesn't do much electrical work it was quite daunting but if you are careful, you can get the job done in under 2 hours. What I found was that there were no videos explaining how to install it as the first thermostat in a property - only videos showing how to replace a thermostat with a Nest one.

Key things you need to know:
  1. Your boiler brand and model so you can get the wiring diagram for it off the net.
  2. Are you replacing a thermostat in your property or installing one for the very first time.
Best help guide video so far:

Things you will need to install the Heatlink:
  • Screwdrivers, Some electrical cable (if replacing a thermostat 5-core, if installing a new thermostat 3 core), wire strippers.

Top tip is to watch the video above (at least the first 4 parts) and read the manual.

The steps to installing the nest as a first thermostat are:
  1. Start by wiring up the heat link as shown in the wiring diagram and picture below. Remove the cover with a small phillips screwdriver. Strip the wires.
  2. Put Blue in N, Brown in L, and black in "3". (If it is a first install, you do not need to worry about T1 & T2 that are mentioned in other videos.)
  3. Using a small length of wire, create a link between L and "2". Make sure these wires are securely held in.

  1. **** Turn off the power to your boiler at the main breaker switch or fuse box. ****
  2. Find the wiring box or junction box for your boiler - you may have to take the front cover off your boiler. The rest of this explanation will be aimed at the Glow worm Easicom 28 for which you will need to un-do the two screws underneath that hold on the front cover. You will then find two plastic covers - one for a 24V circuit and one for a 230V circuit. Before touching these ensure your power is switched off!
  3. Open the right hand plastic box and gently pull the blue X1 box from the circuit board.
  4. Connect the wires from the heatlink to the box. Blue wire goes from N to N. Brown wire goes from L to L. Black wire goes from 3 to RT. Again ensure these are secure before moving on.
  5. Replace the blue X1 box to the circuit board.

  1. Install the heatlink device approximately 30cm away from your boiler with the screws provided. Replace the cover to the heatlink device, you should not need to go in there again.

  1. Before moving on there are two more things you need to do to get this to work which I found on this thread above. You will need to open the left hand 24V box on the front of the boiler. In that area you will find an X17 chip on the circuit board. Remove it and then take out the wire link and replace the chip back to the circuit board. This will hand over control from the timer to the Nest device.
  2. The second thing you need to do it to turn the boiler to timer mode and activate it for the entire time (click all the of switches to the on position).

Thats it - done! Now just set up your Nest control module. I suggest if its a new install - buy the Nest stand. If you want it on a wall - you can plug in the USB and then run the cable up into the wall but it seems like a waste of time to me. Mine is on a stand next to my TV and works perfectly. Hope this helped! Let me know if you have any questions or queries and I will see if I can help although, I doubt I will be much use unless its a Glow-Worm Easicom 28! Good luck!
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i hope you tested the integrity of the case seal of the boiler using an approved method after removing it to fit that, an effective case seal is what prevents fumes from the boiler potentially entering your living space.
No I didn't actually! I don't have a sniffer. I did however replace the cover exactly as I removed it. Do you have any suggestions?
Yeah ok. Thanks for ALL your help. You have just reminded me why I don't hang out in forums like this. Bye.
the only proper way is to get a gas safe engineer out who is qualified to test the appliance for safety, unfortunately you are not, may not be the answer you was hoping for but it is the correct one.
Any answer would have been better than your sarcastic puzzle-type response. Thank you for your (eventual) honest answer.
Yeah ok. Thanks for ALL your help. You have just reminded me why I don't hang out in forums like this. Bye.
glad you don't hang out here, manners don't cost nothing , its about yours and others safety at the end of the day, you say you don't hang out here, but your still here

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