Worcester 37CDi Greenstar and Nest 3rd Gen

9 Feb 2018
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United Kingdom
I recently had a Nest 3rd Gen installed by a Nest Pro to my Greenstar 37CDi Combi gas boiler.
The Nest itself is working perfectly but the pump is constantly running 24 hours a day.

Worcester have not been able to make any suggestions and the Nest Pro Installer & Nest have also drawn a blank. We know it's the pump because the noise stops if you disconnect the pump power.

Fairly frustrating because of the constant noise combined with I'm using electriciy and wearing the pump out faster for no reason!

Has anyone had any experience of Nest and Greenstar boilers? Not sure where to turn now!
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The pump is part of and is controlled by the boiler.

Unrelated to the Nest or any other external device.
I thought that but if we disconnect the heat link and reattach the integrated controls (with RF thermostat) the pump stops running
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Really struggling to see how though. I'll get some photos. The Nest Pro, Nest and Worcester have signed off on it...
Bit of a long shot but don't suppose your boiler is a zwbr combi with the built in digital programmer?
Is that the model? Sticker says Greenstar 37CDi Combi 155 W IPX4D

It does have the built in digital programmer - why?
If it was the zwbr it would explain the pump running, as its a cdi it not the fault I was thinking of.

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