Honeywell Evohome Install & Review

Honeywell Evohome Install & Review

Our house had a manual thermostat in the hallway and a very simple timer for heating and hot water. This has been a bugbare for me since we moved in, we’d turn the temperature up in the evening to keep the living room warm but forget to turn it down before bed, if we set the heating to turn off the bedrooms get cold and our daughter wakes up at 4am, if we leave it on we get hot and wake up. So finally I took the plunge and ordered the Honeywell Evohome system from The Evohome Shop not only were they one of the cheapest but they have a support forum and from reviews etc online seem to be quick to help.

The Honeywell Evohome system is a wireless smart home thermostat, but for me its greatest feature is that it can control individual radiator thermostats which each act as sensor and actuator, so rather than making the fairly random guess between 1 and 6 for how hot a room is and then hoping that the heating is on when you want it to be, each room can demand heat as required and be closed off to save energy when not. The latest version of the controller also has built-in Wifi so can connect to your router and then the internet so the system can be controlled remotely via an iPhone or Android app. 

The installation was relatively painless, our system doesn’t have a proper 10way junction box as Honeywell suggest but rather a box full of screw connector blocks. When I installed a new pump last year I upgraded these to Wago connectors to tidy it up and give better connections but they are still a jumble of wires in a box. Once I’d identified which cables were which and disconnected the unused cables for the room stat and spares leading to the old timer it was easy to wire in the BDR91 relay devices as per the instructions.

Setting up the Evohome controller was straight forward, it was a step by step guide and binding (pairing) the various room thermostats was a simple procedure. The greater problem came when setting up the relays, the controller comes with one of the BDR91 relays as a kit, this is pre-bound as the boiler control. Then with the Hot Water Kit, a second BDR91 is supplied. The obvious assumption is that the relay for turning the heating on and off would be the one pre-bound and labeled boiler control, then the 2nd BDR91 from the hot water kit would be bound for turning on hot water.

The problem occurs when you try to setup the hot water, it asks if you have “2 two way or 3 way valves” or “Hot water only valve”, I have a 3 way so selected to first option, the controller asks to bind the Hot Water relay, this is fine, but then it asks to bind the Heating relay, so I bind the one that came with the controller. All seems well so hopefully it all works. I start testing it, turn the room temperature up and wait, and wait, and wait. Nothing happens, well, I’d gone downstairs maybe its a signal issue, so I head into the hallway, centre of the house so should reach everything, lets try that again. Nothing still, OK maybe I screwed up the bindings, so lets do a factory reset and try that again. Followed the instructions again and all looks good, I begin testing and the heating comes on, happy days, but within a few seconds it went off, and the hot water wouldn’t do anything.

OK so I take to the internet, read the FAQ’s, and the Evohome Shop Forum. The main issue I found seemed to be that the BDR91 relays must be minimum 30cm from any other devices and from any large metal objects, boilers & water tanks particularly. (The manual just shows 30cm from the boiler). So I moved the relays, and separated them and managed to get them over 30cm from the HW tank. I tried the system again and unbound and rebound the devices. Still no luck or HW and heating.

After more googling & reading the forum posts I find one that discusses the same Y-Plan system I have, this one suggested that because the heating and HW relays control the 3-way valve and then this controls the boiler this setup doesn’t require a separate boiler relay. So the boiler relay that came pre-bound should be unbound and the boiler relay set to None. Then the Heating and Hot Water relays would both be bound through the Hot Water setup.

Success, after a 4th unbinding and rebinding exercise it finally began working in some way as expected, heating worked, it would come on as expected and go off again but still no joy on hot water. I gave up on it and went to bed figuring that it would be a case of fault finding in the morning.

The following morning I get up wondering where to start, do I reset it all and go from scratch, do I check the wiring again for a 3rd time, should I switch the relays around and see if its a faulty relay, etc, etc. First things first though have a wash and get dressed, who’d have thought, hot water. Maybe its left over from last night, lets worry about it after breakfast. Some deeper testing and once again the heating is working, but the hot water is at temperature too. OK so the easiest test is to take the thermostat of the tank and let the temperature drop, sure enough after about 2 minutes the temp on the controller updates and the relay clicks, the valve turns and the boiler fires, put the thermostat back on the tank and after another couple of minutes the temp goes back up and the relay clicks off. I’m not sure what happened overnight, maybe I didn’t test properly after the final reset but it’s now working so I’m not going to question it.

Conclusion: It’s only been 24hours since I installed so we’ll see how it functions long term but as a review of the installation process I have to say that the physical installation is much easier than configuring the settings on the device, I don’t know whether the installer training that Honeywell provides covers this in more depth but the different configurations and the fact that although the relay comes pre-bound it is likely wrong for the majority of installations all seems counterintuitive. In the end I figured it out without contacting Evohome Shop for assistance but I did find the important information on their forum so must give them credit for that.

I did today check the heating while we were out and although it was an unseasonably warm day I did consider boosting the heating ready for when we got home. I’ll try and remember to update this again once we’ve had the system running for a few weeks with a better review of performance.

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