do i need this honeywell control unit?

[scfc151]

ive had a hive thermostat installed getting rid of the old honeywell timer. the wiring was a straight swap. there is one cable coming from the unit on the top left to another honeywell unit. is this one required?

the plumber left it in. but now and again i have to reset it if the heating stops working and then its fine again.

cheers

 

[stem]

If the Honeywell R660D unit is connected to an original room thermostat then it needs to have been decommissioned. This can be done in several ways. Although it looks to be still operational, it is possible that the installer has modified its internal wiring to take this into account.

However, it should not still be controlling the heating, if it is it will interfere with the operation of the Hive.

You should ask the installer.