Thermostat won't turn heating on unless hot water is also on

[NeilFann]

I've got a 3rd gen learning thermostat. Recently, the thermostat won't turn the central heating on unless the hot water is also on by schedule or boost. So:

Thermostat below ambient temp: central heating off 

Thermostat above ambient temp and hot water off: central heating off 

Thermostat above ambient temp and hot water on: central heating on 

I don't think this was always the case and it might have conicided with other boiler work. I now have a brand new boiler that is functioning properly. Any ideas how what this could be and how I might fix it?

[Houptee]

If you just had a new boiler installed they must have wired it wrong or if it is a combi boiler that also makes your hot water then they programmed something wrong in the setup.

What brand boiler and model number is it?

Can you take pics of the thermostat wires connected to the boiler showing the terminal screw labels and post them here?

[DragosC]

Hi there, @NeilFann

Could you tell us please what type of boiler do you have? Also, what type of wiring plan do you have? System boiler with S plan (2 separate valves) or Y plan ( one single 3 port valve)? 

[NeilFann]

Hi there, firstly I didn't make clear in the original post that this problem also existed with the previous boiler, it didn't start with the new installation. Apologies for that. This makes me think the issue is with the nest or the boiler connector that the nest connects to, which then passes the signal to the boiler. Does that sound plausible? The boiler is a Vikera easy heat plus and I think we have a Y valve that's been recently replaced. I'm not remotely knowledgeable about heating systems so I'm looking if there's something simple to try it to direct a repair person better. Any ideas?

[DragosC]

Understood. Thanks for letting us know. We do have a line of Nest engineers that can come to take a look, but they come at the customer's own cost. Their visit is not covered by the company. 

[AlexD]

Hi, I wanted to check in. How has it been going with your device? Let me know if you need any further assistance. 

[AlexD]

Hey there, I haven't heard from you in a while so I'll be locking this thread. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community. Thanks, AlexD.