Nest heating terminals 5 & 6 permanently closed

[Marcpd]

Good afternoon,

My nest system was installed a few years back and has been working fine.

recently I have had a combination of a rewire with a new boiler installed by professional electricians and plumbers. During these works incorrect wiring caused the local fuse to blow 6 times before the cause was identified and corrected. Since this occurrence terminals 5&6 and permanently closed meaning hot water is always requested.

is it possible to carry out a repair to the heat link? 

[Frustratedddd]

Oh dear that sounds a little worrying if the Pro's got it wrong 6 times!

I assume you are talking about the Heat Link terminations?

To save the water being on 24hrs, just disconnect terminal 6 and make safe for now.

You say terminals 5-6 are closed, does it switch at all from 4-5?

[Marcpd]

ok.

Yes sorry, the terminal connections.

No the 4 & 5 terminals (which should be nornaly closed) remain open circuit whilst 5 & 6 terminals (normally open ) remain closed even when power is removed.

[Frustratedddd]

You are saying in that case the terminals are welded together.

Yes the relay can be repaired if you are good with an iron/hot air, or know someone who could do the repair for you. Getting hold of the relay should be easy enough, but personally I would just buy a new Heat Link if you want things working quick!

Where are you located?

[Jeremyg]

Hi @Marcpd!

Thanks for reaching out to the community, and thank you for your support @Frustratedddd. I am sorry to hear that the Nest heating terminals 5 and 6 are permanently closed, but no need to worry; help is here. Thank you for your previous troubleshooting steps. I need to know a few things about your thermostat in order to provide you with a better resolution.

• What Nest thermostat model do you have? For your reference, you can check out this article on how to tell which Nest thermostat you have.
• Does the thermostat display show any error codes or messages?
• When did the issue first occur?
• What is the make and model of your HVAC equipment?

I'll be waiting for your response; any additional details you can provide will be helpful.

Best regards,
Jeremy.