Electric UFH mat into Evohome

[Johninuk]

Hi
I have an existing Evohome system and wish to add a new zone/room which contains an electric UFH mat , my thoughts are to use a BRD91 and single zone thermostat T87RF2033 . The electric mat is rated at 3amps and the maximum load I understand that can be switched on the BRD91 is 5 amps so should be no problem there .
My questions are
1. Can someone help me with a wiring diagram for the BRD91 ?
2. Do I only bind the thermostat to the Evohome controller or do I need to bind the BRD91 as well ?
3. If the stat calls for heat and the relay switches on the E-UH , will the boiler also fire as clearly this would not be required .

Many thanks

John

[Richard]

Is the existing evohome system controlling a wet heating system? If so I do not recommend this as the E-UFH will call the boiler for demand, which is not good as all HR92's (if you have them) could all be shut.

[Johninuk]

Yes that is the case , I was hoping that there would be a setting in EVOHOME that isolated a zone ( E-UFH) from the relay that would fire the boiler , it would appear not.

OK in that case could I simply buy another EVOHome controller and have them on a separate "system" not connected in any way to a heating boiler ? How would I go about setting this up ?

[Richard]

The issue here is that the Honeywell heating products are just not designed or rated for E-UFH. They don't have floor probes, the relay boxes are only 5A rated and they have to work in tandem with other control systems to operate.

If you are hell bent on doing this then a second connected thermostat could be used, but this is not a straight 'out the box' solution.