Spurious Heat Demand - Comms issues?

[Ozomatli]

We are having issues with a recently installed Evohome system where the boiler continues to fire when there should be no demand.

For example at 9pm the temperature for all rooms changes to 5C as an overnight setting. Occasionally the boiler comes on for a cycle or two after the set point change. Sometimes is has been as many as four cycles.

The HR92s all reflect the 9pm set point temp (5C) and the rooms are all way warmer so there should be no demand for heat.

When experiencing the issue I’ve looked in the System Summary in the Installer menu and it shows a zone or two calling for heat even though the room is above temp. It seems that if I override the temp for a zone and cancel it then the zone realised there is no actual demand, the summary shows 0% for that zone and once all zones show 0% the boiler shuts down.

I have the hot water kit installed and both BDR91s and the CS92 are 30cm apart.

When testing I saw the issue occur when the controller, boiler relays and HR92 calling for heat were all within 5 metres of each other. Signal strength is reported good for all components. The zones reporting the heat demand change each time so it doesn’t appear to be a single HR92 causing the problem.

My heating engineer has installed a number of these systems and has not seen this issue. He spoke to Honeywell’s support line but they weren’t useful.

Not sure what to try next. I like the system but something is not right..

It is worth moving the relays further apart?

Thanks,

James

[Richard]

Hi James,

What i think you may need to do is re-calibrate the radiator valves. If you unlock the head below the screen of the HR92 and lift just the unit off the base plate, leaving the white/black base plate attached to the radiator.
On the base plate, you need to spin the black hand wheel fully anti-clockwise to ensure the radiator valve is fully open, and then sit the head back on and lock in place. Within about 60 seconds of locking the HR92 back on the base plate, you should see a message displaying 'CYCL Valve'. Let this go through its calibration and hopefully will solve the issue.

If the HR92 has not been cycling fully to open/close the valve it would not be sending the signal back to the Evohome controller to tell the BDR to switch off.
Let me know if this helps at all

Kind Regards,
Kieran

[Ozomatli]

Hello Kieran,

Thanks for your reply.

I have found the removing the master HR92 from a zone calling for heat, adding back and then letting it sync has solved the issue before. However the problem comes back. In fact I'd unbound the two HR92s in the kitchen earlier this week so I could change which one is the master. I'd made sure the everything is tight and the hand wheel was fully open before putting the HR92 back on, locking it on and that syncing. The next morning that zone was the one that had a spurious heat demand!

All of the rads are brand new with Honeywell Valencia valves so that shouldn't be an issue.

I think I'll look at moving one of the relays in the airing cupboard this weekend to ensure they are as far apart as possible.

James

[Ozomatli]

For info all of the wireless components in the airing cupboard (2x BDR91, 1 x CS92A) are now all at least 1 meter apart and everything has been behaving itself. So far anyway!

[Ozomatli]

I spoke too soon. Woke up this morning to a cold hall as there was a random override of 5C set for that zone.

At 7am all zones are set to 5C as we are out of the house at work. However despite all zones in the System Summary showing 0% demand the boiler carried on for two cycles.

I'm going to get a Evohome installer in to take a look. If that doesn't work then it's all coming out!

[Richard]

I spoke too soon. Woke up this morning to a cold hall as there was a random override of 5C set for that zone.

At 7am all zones are set to 5C as we are out of the house at work. However despite all zones in the System Summary showing 0% demand the boiler carried on for two cycles.

I'm going to get a Evohome installer in to take a look. If that doesn't work then it's all coming out!

Well, its either bound incorrectly or you have RF comms issues. If you haven't read this (https://theevohomeshop.co.uk/content/11-evo-help) might be worth a read.

[Ozomatli]

That page is very useful.

This weekend I'm going to move the boiler relay further from the hot water cylinder. It's around 40cm away at the moment.

Last night I had a situation where the kitchen zone was still calling for heat even though the setpoint had changed to 5C and the room was around 20C. The kitchen TRV and controller were about 1.5m away from each other and the airing cupboard is pretty much directly above both of them. I removed the TRV from the rad and then put it back on and the sync caused the system to turn the boiler off...

It probably is comms issues but there must be some major interference to disrupt the RF enough to cause issues at those distances.

[Ozomatli]

I've now done a full reset of each component of the system following the guides in the Customer Support area. Then carefully worked though each component pairing BDRs, waiting 5 mins etc as well as waiting for the sync message after adding each HR92 etc. The HR92s and CS92 are all at least 50cm from each other and 50 cm from the boiler.

I'm still getting odd overrides set. In all cases the override is set to the previous set point temp. So for instance where a set point for the Living Room changed the temp from 20C to 15C an override was created keeping the room at 20C. The controller was within 10m of the HR92 (on the same floor) in each case.

So at this point I'm throwing in the towel. I have a Google Nest sat ready to be installed once the lockdown comes to an end. I know I lose functionality (and money!) by changing but Evohome is just not reliable for me.

The Evohome kit will go on eBay and hopefully I can get some money back.