Hive dual controller - hot water permanently on.

[YorkColin]

Hive dual controller fitted to replace Honeywell ST9400C programmer and BDR91 wireless thermostat. We have a Worcester Bosch boiler with separate hot water tank (not a Combi). Central heating seems to work perfectly in so far as can be boosted and programmed to come on and turn off via the Hive. The issue is with hot water - it's always on and kicks the boiler in when temperature drops below thermostat temperature. A plumber has looked at it and says that it might be the Honeywell valve motorhead.

Could it be this? Could it be something else? Seems strange that all was working fine with the old controller and the valve motorhead has failed at same time as when changed. Any advice appreciated.

 

[cross thread]

If only started since changing it’s probably a wiring issue or you have it on permanent on the app.

 

[YorkColin]

If only started since changing it’s probably a wiring issue or you have it on permanent on the app.

Definitely not on permanent on the app. We got an electrician to do the installation and he says it was essentially a straight swap.

 

[RandomGrinch]

Definitely not on permanent on the app. We got an electrician to do the installation and he says it was essentially a straight swap.

It should have been a straight swap, the Hive could even have sat on the existing backplate and worked - although some modification would have been required to link out the BDR91.
Could you send us a pic of the wiring behind the Hive so we could double check?