This guide is for evohome owners and installers with a Honeywell Home BDR91 wireless relay box. The steps follow the BDR91 guide and evohome installation guides from Resideo, which makes Honeywell Home products.

What This Problem Means

The BDR91 is a wireless relay box that switches valves, pumps, boilers or other heat sources when its controller tells it to. Resideo says that if RF communication is lost, the red LED lights and the relay box operates in failsafe mode, as set in Installer Mode.

Common Symptoms

• The red LED on the relay box is lit
• The green LED stays off when the heating should be on
• The boiler, pump or zone valve doesn’t switch
• The relay box LED doesn’t flash during a signal test

Safe Checks You Can Try

1. Read the relay box lights

Green LED on means the relay is on; green LED off means it is off. A red LED that stays lit means radio contact has been lost and the relay box is in failsafe mode. Resideo says devices connected to the mains should be installed by a competent person, with the power isolated before wiring, so look at the lights only and never open it.

2. Check the controller

The relay box takes its commands by radio from the controller it is bound to, such as the evohome controller. Check that controller is on and within range: Resideo gives evohome an RF communication range of 30 m in a residential building environment.

3. Run a signal test

Resideo’s evohome installation guide includes a signal test started from the evohome controller. During the test, the relay box LED flashes from 1 flash (poor) to 5 flashes (excellent), and no flashing means the relay box has not received a test signal from the evohome controller.

4. Know what the button does

Resideo’s guide says pressing the button temporarily overrides the current relay position. Holding it for 15 seconds clears the binding data, so don’t hold it unless you mean to rebind.

5. Ask your installer to rebind it

If radio contact can’t be restored, your installer can rebind the relay box. Resideo’s guide says to press and hold the button for 15 seconds, until the red LED blinks rapidly, to clear any previous binding data, then press and hold it again for 5 seconds, until the red LED blinks slowly. After binding from the evohome controller, you should see a SUCCESS message on the controller, and the LED on the relay box should stop blinking.

6. Check the siting

Resideo says to leave at least 30 cm between the relay box and any metal objects, including wall boxes and boiler housing, and not to mount it on a metal wall box. Moving a mains-wired relay box is a job for a competent installer or electrician.

BDR91 lights explained

Resideo’s two evohome installation guides give different colours for the signal-test flashes: the newer guide says red and an older one says green. Count the flashes, whichever colour they are.

Resideo’s guide for its newer evohome R3 controller, published for EMEA, says “this Evotouch will not work with the older BDR91”.

The LED meanings come from Resideo’s BDR91 guide and the binding steps from Resideo’s evohome installation guide.

When To Contact Support

If none of these steps fix it, contact Resideo, which makes Honeywell Home products, through Resideo’s UK site.