How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Andrew Smith Your Own Question
Andrew Smith
Andrew Smith, Engineer
Category: UK Plumbing
Satisfied Customers: 3629
Experience:  Domestic Gas, Commercial Gas, LPG, Unvented Hot Water, Part P Electrical, Commercial Catering
Type Your UK Plumbing Question Here...
Andrew Smith is online now
A new question is answered every 9 seconds

I'm trying to fit a Nest Heat link (second gen Nest) to a

Customer Question

Customer: Hi ***** *****, I'm trying to fit a Nest Heat link (second gen Nest) to a Vaillant Ecotec plus 831 boiler (2nd gen)
JA: Thanks. Can you give me any more details about your issue?
Customer: The Ecotec plus 831 has two PCB revisions - and most guides pertain to the first one. I've posted this on the Nest community ( but I don't quite understand the (French) person's response. I'm clear that I have to remove the 24V RT loop (as the Nest Heatlink isn't 24V) But the boiler won't fire when I do that, even though I believe I've wired Live and Neutral etc up correctly. But the fact that it won't work (the heatlink will click just like a thermostat - but the boiler won't respond) suggests otherwise.
JA: OK got it. Last thing — JustAnswer charges a fee (generally around $18) to post your type of question to UK Plumbing Experts (you only pay if satisfied). There are a couple customers ahead of you. Are you willing to wait a bit?
Customer: You'll bill me in GBP, though (or Paypal?)
JA: OK. Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 1 year ago.
Category: UK Plumbing
Expert:  Andrew Smith replied 1 year ago.

did you get an answer?

The nest receiver will make and break a contact just like a standard 0v thermostat.

You just need a pair from the 24v contacts you have removed the loop from and take them to the stat.