Honeywell Evohome Problems

24 Nov 2019
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United Kingdom

yesterday I attempted to replaced my existing LightwaveRF thermostat and boiler switch with a new Honeywell Evohome system, but I'm having problems with it. The boiler is a Vaillant ecotec plus 831 Combi Boiler.

I believe the boiler switch is wired up correctly (though I may be wrong!), if I press the switch on it to turn it on manually then the green light comes on and the boiler seems to fire up and run OK but it only stays on for a few minutes (the actual length of time seems a bit random but don't think it's run for longer than ten minutes) and then it switches off, green light goes off and the boiler shuts down (though the pump keeps on running for a few minutes I think). This behaviour is the same whether the thermostat itself is powered or not.

The thermostat seems to be connected to the switch OK and testing reports a good signal, but it never seems to turn the boiler on, even though the current temperature is below the target, not currently using any TRVs (that's another issue!) just relying on the main thermostat as the temperature sensor.

So, any suggestions for what the problem might be? Could something wrong in the wiring cause that behaviour? That seems unlikely as the switch seems to correctly run the boiler, it's just that the switch itself doesn't come on and stay on like it should but I'm certainly no expert.

edit - Oh, and hot water from the boiler seems to be working OK.
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When the green light is on solid, it means your preheat is turned for the hot water, and the burner (orange light) will stay on until satisfied. Does your heating actually come on?
The heating was coming on just not staying on and not being controlled by the thermostat. However, seems to be sorted now, I re-ran the guided setup and it now seems to be working as it should, did the manual setup before so maybe there was something wrong there.

Still having problems with the TRVs though, I bought 1 a week or so back which works fine and then a further 8 recently, none of which seem to want to bind with either the Honeywell thermostat or my LightwaveRF controller (which is compatible with them). Looking at them though I realise that they are different to the one I bought previously, the screen and the printing of the Honeywell logo are the other way up (the wrong way for my radiators in fact), so I'm wondering if they are non-UK versions and therefore are being prevented from binding. The model number on the box for each 4 pack seems to list them as HR924WE whereas the other one is an HR92UK (obviously missing the 4 because it was a single one not a 4 pack), so thinking I may have been sold non-UK stock. They were bought through Amazon Marketplace from a UK retailer and there certainly wasn't any suggestion they were non-standard so hopefully won't be an issue getting them returned and refunded.

Does anyone know if the screen orientation etc. means they are non-UK and would that be the reason they don't bind?

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