Nest To Hive

[Doc_Jam]

Hi Everyone

I am hopeful someone smart on here can help me out....

I had a Nest 3rd gen learning thermostat connected to my Ideal Heat 12 System Boiler. It was flakey the entire time we had it. Google replaced the heat link once and the thermostat once in the first 12 months.

This year it seems worse. The heating just came on for the first time and the burner stayed on indefinitely. house got very hot and I had to turn the boiler off at the mains. At this point we'd had enough so at the recommendation of a friend, went out and bought "Hive Active V3 Wireless Heating & Hot Water Smart Thermostat".

I tried to install it myself as I have thermostats in previous houses, just not Hive's.

The problem is the boiler turns on but seems to not respond to the Hive, most of the time the burner just stays on but will periodically turn off for no apparent reason.

My Ideal Logic Heat 12 only has 2 cables, Heating on (NO) and Hot Water on (NO) but neither of the diagrams on the Hive installation manual seem to match my situation. I don't appear to have Heating off (NC) or Hot Water off(NC)

My Nest, which did work for a while was wired in as follows:

And although it was flakey it did work for a year pretty well.

The Hive is currently wired in as follows:

But the burner comes on as soon as the boiler turns on, and it stays on almost all the time.

I have no idea what I need to do to sort it out. I don't even know if I need to call a plumber or an electrician.

Does anyone have any ideas or knowledge that might help me here?


Thanks in advance

 

[ianmcd]

you have an S plan and it sounds like one of the micro switches on the zone valves is sticking

 

[Doc_Jam]

Thanks Ian. I'll give my plumber a call then. Thanks for the quick response.

 

[CBW]

What did you do with the Nest thermostat wires, T1 and T2?

 

[Doc_Jam]

Chris

What did you do with the Nest thermostat wires, T1 and T2?

I taped them off and left them in the wall

 

[Doc_Jam]

you have an S plan and it sounds like one of the micro switches on the zone valves is sticking

Just confirmed this, the central heating valve is busted and needs replacing. Thanks for again for getting back to me.

 

[ianmcd]

Just confirmed this, the central heating valve is busted and needs replacing. Thanks for again for getting back to me.

No problem, post a pic of it and you might be able to just change the actuator head without draining anything down , most modern ones you can

 

[Doc_Jam]

No problem, post a pic of it and you might be able to just change the actuator head without draining anything down , most modern ones you can

Yeah it's a Danfoss HPA2 and the actuator has gone.

 

[Doc_Jam]

Yeah it's a Danfoss HPA2 and the actuator has gone, new one from plumbase is about 55 quid. It does look like the valve itself may have leaked a tiny bit as there was corrosion around the copper valve under the actuator. I might get somone in the change the whole valve at some point but I'll test with just the head replacement.

 

[Doc_Jam]

This is what it looked like under the head. I've cleaned it right up but every time I twist the valve the tiniest bit of liquid appears around the valve

 

[CBW]

This is what it looked like under the head. I've cleaned it right up but every time I twist the valve the tiniest bit of liquid appears around the valve
View attachment 284839

Based on that I’d change the lot

 

[Doc_Jam]

Based on that I’d change the lot

That's the plan, just need to wait until payday before I can get a plumber round to do it. Changing the valve is a little beyond my skill set. I wouldn't know how to get the water out the system to do the work

 

[DP]

Perhaps nothing wrong with nest unit then?

the programmer ( for heat) opens the heating valve, valve once fully open will operate a switch within the enclosure, switch then runs the boiler. The state of that valve would seem to suggest issue lay there not in Nest which you changed for its ‘malfunction’

 

[Doc_Jam]

Perhaps nothing wrong with nest unit then?

the programmer ( for heat) opens the heating valve, valve once fully open will operate a switch within the enclosure, switch then runs the boiler. The state of that valve would seem to suggest issue lay there not in Nest which you changed for its ‘malfunction’

We kept the Hive in the end as we had not had a good experience with the Nest overall, with 2 part replacements in less than 12 months being needed.

But yes you are likely correct, this time I don't think the Nest was actually at fault.

The calls for heat and hot water were going through ok , just the heating valve wasn't shutting off afterwards.