The Efficient Home Forum

I am also having this problem. I have just purchased a control unit having previously bought a Y87RF. I'm gradually building up the system before I install it and I will be getting the HR92's when I have fitted some TRV heads to my radiators. Both the controller and the Y87RF came with a BDR91. At the moment I have the Controller, BDR91 and Y87RF setup on the test bench so I can get used to the workings and the settings in the Controller before I fit the system. I have noticed that the BD91 switches on even after the temperature on the Y87RF has reached its target temperature. This happens about every 10 minutes and stays on for between 30secs and a couple of minutes. This sequence goes on for about 30 minutes or so. I have the Y87RF setup as the representative temperature sensor for the Controller. This should not happen and I am a bit concerned about replacing this system with my old one. Plus I don't find Honeywells tech support answer to this as being "normal" very reassuring! Is this problem being looked into as it seems as Pompy suggested, down to bad progamming. I have a spare BDR91 so I will try that out and report back on my findings.

craylad wrote:At the moment I have the Controller, BDR91 and Y87RF setup on the test bench so I can get used to the workings and the settings in the Controller before I fit the system. I have noticed that the BD91 switches on even after the temperature on the Y87RF has reached its target temperature.

When you say a test bench what do you mean? If the devices are too close to each other they will not respond properly and if the thermostat is within 1.5 degrees either side of set point the thermostat will be in TPI mode and still very much 'on'.

I see. They are all in the same room so that probably explains my problem. I have had the three devices about 8 feet apart from each other and still had the problem. Do they need to be further apart? It kind of goes against what would be expected of wireless devices, where generally the closer the better for signal strength. You mentioned "TPI". I've looked it up there is a Honeywell pdf explaining it very well and I understand it now. I was a bit worried about installing this but now I'm reassured. Many thanks for your reply.

I am also seeing this behaviour. Heating is set to off, all zones are showing around 20 degrees so there is absolutely no need for the boiler to be fired, yet for some reason the system is starting it up for a short time every ten minutes (I am sat here watching it!). I only have one BDR91 so no issues with dodgy interaction between them. I have seen the behaviour reported elsewhere but not a fix, anyone got any ideas?

Any pics of the BDR91 installation George? It is an installation or binding error...

I have the same issue with mine, its a fundamental flaw with the Evohome system itself, nothing to do with Signals that Honeywell would like you to think, I have three BDR 91 relays controlling my system all 300mm apart, two control the water and heating valves the third controls the boiler, the boiler one is setup as a boiler control relay, this fires on randomly when it suits itself although it has been cleared several times and retaught, after logging and when I look at the system behavior any HR radiator valves that are not fully closed and show any demand whatsoever will fire the relay even when the system is set to off, yes set to "off"

It appears that the valves calling for heat override the system and fire the boiler, I found this out when one of the kids turned the valve in the bedroom and the boiler fired up, I then started logging behavior and found the boiler was firing randomly, this morning I took some pictures where all valves appeared to be closed and at 0% but the boiler relay was showing 2%, the boiler then fired up although neither the heating nor hot water BDR's were on at the same time, just the boiler relay and the system was set to off. As a Automation and controls specialist never have I come across a system that when it is off it still operates !! off means OFF not maybe off or can be overridden from another device when set to off.

This is Honeywells response

https://ensupport.getconnected.honeywel ... es-to-fire

As far as I am concerned regardless of what the HR92's are doing or requesting,off should override all heat requests from the valves, if you have one valve that doesn't fully close this will call for heat from the boiler until the HR92 re calibrates itself, if your boiler is out of the way you will know nothing about the on/off cycling even tough you deem the system to be off on the controller which intern wastes energy and gas, not bad for a system which is supposed to save you Energy !!

John Vincent wrote:if you have one valve that doesn't fully close this will call for heat from the boiler until the HR92 re calibrates itself

Just to confirm a HR92 cannot calibrate itself... This is a manual process done by the user where you remove the HR92 from the valve base plate, rotate the black hand-wheel fully anti clockwise and then put the HR92 back on and lock the locking catch.

The symptoms that are displayed above by Honeywell is one of the very reasons we recommend TRV valve bodies are replaced if they have any age about them.

I would still be interested in having a picture of your installation John, as RF comms issues are normally the main culprit for the evohome Controller not ending heat demand.

Mine's doing the same. I work from home, so hear the bathroom radiator (it's the bypass, no 92 on it, seems to spend a lot of time on!). Just checked all the zones - the only one that is likely to turn the system on is set to 16 and its at 16. The boiler's fired up but that is the only zone on the threshold and the valve is open 7%. It turns off before any hot water gets to the rad! Quite bizarre. I'd just like to be able to get to the logic so I can see what's firing the system & why. Feels like I'm fighting with it!

SLALS02 wrote:Mine's doing the same. I work from home, so hear the bathroom radiator (it's the bypass, no 92 on it, seems to spend a lot of time on!). Just checked all the zones - the only one that is likely to turn the system on is set to 16 and its at 16. The boiler's fired up but that is the only zone on the threshold and the valve is open 7%. It turns off before any hot water gets to the rad! Quite bizarre. I'd just like to be able to get to the logic so I can see what's firing the system & why. Feels like I'm fighting with it!

If its set at 16 and the room is 16, then you need to keep putting energy into that room for it to stay at 16? If no energy was put into the room it would go to 15.5 or 15? That is the logic...

I've found same. In my case the heating relay is miles from anything as I attached it to where the room thermostat was. The hot water is the opposite andstuck between pipes - but has no issues.

I've found with the heating relay it has had two mad moments when it turns itself on every few minutes (even when heating is turned off on the panel. I've 'cured it' by popping the relay of the base and resetting it.

Given the heating is set 'off' anyone any idea why a wireless relay can do this?