Results 1 to 2 of 2

Thread: Heating not coming when it should

  1. #1
    Automated Home Lurker
    Join Date
    Feb 2020

    Question Heating not coming when it should

    EDIT: Subject should clearly have been 'Heating not coming ON when it should'


    I've got a Honeywell Evohome system which I've had for about 6 months, on the whole it's been working brilliantly. However, with this snap of cold weather we've had I've noticed the heating in one of the rooms isn't coming on when it should be. The rest of the zones appear fine.

    Here's my setup:
    - Evohome controller (being used as a thermostat for the zone it's in)
    - BDR91 relay
    - Infrared (electric) heating panel
    - T87 thermostat

    So what's happening is the temp is set to 21c at the thermostat, and if I look at the System Summary on the Evohome I can see that the zone in particular is requesting heat (it's set to 100%). The thermostat knows the desired temp is 21c, and the current temp is 18.5c (for example). But the BDR91 relay isn't as on as frequently as it should be. It's not that the heating never works, it's just not heating up enough.

    I've done an RF comm check and the comms to that zone checkout ok.

    At the moment I've not reset anything, as I said, it works OK for the other zones and this zone does work, it's just not as warm as it should be.

    Any advice / extra info I can provide?

    Thanks, Matt

  2. #2
    Automated Home Legend
    Join Date
    Sep 2014


    You've left your overall system configuration a bit vague - more info about the overall system setup would be helpful.

    It sounds like the zone in question is the electric heating panel ? So presumably this zone is configured as "electric heating" in the zone config, and has this BDR91 bound to the zone to switch the power to the panel ? (Although hopefully through another bigger relay, as the BDR91 is only rated for 5 amps...)

    Is the T87 the thermostat in the room with the panel or is it the controller ?

    So what does the rest of your system look like ? Are other zones also electric heating or are they radiator valves ? And if so how many other BDR91's do you have controlling the rest of the system ? Combi boiler or S-Plan ?

    In any zone controlled by TPI (this includes electric radiator zones) the proportional band is +/- 1.5C, so in your example 18.5C is more than 1.5C below the set point so the relay should stay on continously until it gets to at least 19.5C - then it will start to switch proportionally.
    Last edited by DBMandrake; 7th February 2020 at 12:26 PM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts