Hive - Heating won't turn off!

[fabioclm]

Hi everyone - I’m hoping I can get some insight into why my central heating won’t turn off when told to by the Hive receiver.

Boiler: Procombi Exclusive 24
Hive: Single channel receiver
No previous thermostat had been installed

I’ve got a cable going from the Hive receiver to the same fused spur that powers the boiler connecting N and L, delivering power to the receiver. Then I’ve got a second cable connecting Pin 1 (common) and Pin 3 (Heating On) to the Room Stat terminals on the boiler where a short red link cable used to be (which I removed as per instructions)

After installation I powered everything up, I manually set the boiler to Hot Water + Central Heating and set the mechanical timer to ON. Nothing happened, GREAT! Then I turned up the heat on the Hive thermostat, Hive receiver lights up, boiler fires up, central heating is On, perfect. I turn down the heat on the thermostat, receiver light goes off, boiler stops, central heating is off. So far so good.

THEN I turn heat up again on the thermostat, central heating goes on, BUT when I turn the thermostat down this time, the central heating stays on. Now the only way to turn it off is by setting the dial on the boiler to Hot Water only. The light on the Hive receiver went offline, so it got the command from the thermostat… just no change in the boiler. If I turn the dial to Hot Water + Central Heating now the boiler will just fire up and central heating will come on, even if Hive receiver is off so Hive isn't controlling anything.. Should also say that changing the mechanical timer between Off, Timer and On settings doesn't do anything, only the main dial controls the heating now.

I've also removed the grey and black cables, re-installed the link between the Room Stat terminals as it was originally and the boiler was operating as expected, with central heating controlled by the mechanical timer...

I tried swapping the grey and black cables (1 & 3) to see if it changed but nothing. I’ve also cut off power to the boiler and back on again to see if I could replicate the Hive firing up the boiler like it did the first time I wired it up… no success.

Not really sure what to do now short of getting someone to come and have a look at it but thought I’d ask to see if anyone has any clues.

Apologies for the essay, appreciate any help

 

[RandomGrinch]

THEN I turn heat up again on the thermostat, central heating goes on, BUT when I turn the thermostat down this time, the central heating stays on.

How long did you leave the boiler running, before manual intervention?
Is pre-heat mode active?

 

[fabioclm]

Between Hive turning it on and off the very first time only a couple of minutes. Then the second time when Hive turned it on but not off I left it for a while, maybe half an hour in the hopes that the boiler had to run for x amount of time no matter the command from Hive. After maybe 30 mins I turned it off manually.

No pre-heat mode available as far as I know, except for the Hot Water which it was not active anyway.

 

[ianmcd]

diconnect the blue connector wire in the 2nd terminal of your pic (frost stat ) and see if it behaves with that disconnected.

 

[fabioclm]

@ianmcd Thanks - I did that. There are 2 cables in that terminal actually, one with the blue cap and a black one.
I removed the blue one only, no change. Boiler fires up and heating comes on as soon as I turn the dial on the boiler to HW +CH
I then re-installed the blue cap wire and disconnected the other one - same as above
I removed both completely - same as above
I even switched the black and grey cables from the receiver and tried all of the above. As soon as the dial on the boiler is turned to HW + CH the boiler will just fire up and the heating will come on even though hive receiver is not calling for heat

 

[ianmcd]

disconnect either wire 1 or wire 3 in the hive , if the boiler still comes on the problem is at the boiler end , if it doesnt it is at the Hive end

 

[RandomGrinch]

I guess you don't happen to have a multimeter?
I'm not an expert as Ian is, but I would want to rule out the hive having a sticky relay.
...aah beaten to it!

 

[fabioclm]

Thanks guys for the replies. So I disconnected wire 3 on the Hive and the central heating still came on so I guess the problem is with the boiler? I just don't get why it worked the first time around and then it just stopped... Just seems so erratic.

What could've happened to the boiler when I first connected Hive that would fault it?

I assume this won't be fixed with just switching a couple of wires and will involve replacing parts on the boiler?...

 

[ianmcd]

I would be looking at where the on-board timer is wired in, it sounds like it is over riding the Hive , it will have a L&N and usually 2 x blacks , remove one of the black wires and see what happens