Honeywell Evohome and UFH Controller HCE80/HCC80
Hi,
I have an issue on the following setup:
- Air source heat pump (without buffer tank)
- Honeywell Evohome controller ATC928G3000
- Honeywell BDR91T relay (paired to Evohome controller)
- Honeywell UFH controller HCE80 (paired to Evohome controller)
As expected, the Evo home controller calls for heat via the BDR91T relay once every hour, for a minimum of 10 minutes. However, the HCE80 UFH controller (which is paired to the Evohome controller), opens the UFH heating circuits multiple times an hour, and is not synced with the replay heat call in any way. This raises two issues:
- When the heat demand is off and the UFH is on, the UFH controller is circulating unheated water around the circuit.
- When the heat demand is on and the UFH is off, the heat pump will shut down due to insufficient flow rate around the heating circuit.
I would've expected the UFH controller on/off cycles to sync with the heat demand on/off cycles, is this not the expected behaviour?
Can anyone who has a HCC80/HCE80 in an Evohome setup confirm whether it syncs with heat calls?
I've been bouncing emails back and forth with Honeywell support, but only seem to be getting canned responses that don't address my questions!
Many thanks!
What you are experiencing is not unusual but I agrees super frustrating. It's all to do with stupid TPI and it not being synced. Also the boiler is cycling to the total system demand and the UFH is cycling to the zone's demand. Its more luck than design if those two cycle together. This was my sole reason for moving to OpenTherm and now more recently an HM80 for the UFH.
As I have a heat pump I had to use a BDR91T relay to unlock the 'heat pump' specific setting on the Evohome controller. The relay only calls for heat once an hour and (as far as I understand) doesn't use TPI. Trouble is, the UFH controller does not match this and cycles 3-4 times an hour. I have only one zone setup as the moment so the total system and UFH demand are the same.
The HCE80 UFH controller in an Evohome setup is sold as being heat pump compatible, but I'm not finding that.
Curious how it worked in your setup, did you find that the UFH would run when there was no call for heat at the relay?
I see this same behaviour with my setup OpenTherm + 4xHCE80.
Nothing you can do about it I’m afraid. At low zone demands < 10% (24C) I observe the HCE80s TPI the UFH pump even though the boiler will not fire.
It does seem to work though, my zone temperatures are very stable.
Unfortunately not for me. If the UFH heating loops are closed when the Evohome calls for heat, the heat pump stalls and then won't start again for 10-15 minutes.Originally Posted by kevinsmart
I get the feeling Honeywell support know about the issue, but won't directly say.
Looks like I will need to find another solution for heat control.
really interested to hear what you find out. would like to move for heat pump in my home also , but the lack of evohome documentation on the subject of exactly how you set it up for heat pump (both the system physical layout and the control side) is making me very wary.
Seeing the same. Many times a day a see just UFH pump started and floor zone actuators opened but no boiler running, BDR91 relay LED is off..
Gas boiler here.
I am going to try lower MINIMUM ON TIME rate..at the 20 minutes cycle I have it set to 5 minutes.
Could this be the reason? Ie boiler running time would be less than 5 minutes due to too low heat demand.
Still, I would expect HCE80 controller to know that boiler is not going to run now due to too low demand and do not start pump this time and only when boiler starts.
UFH is when OT really shows its strength over any TPI device. Infact the TPI that is built into the BDR91 was frustrating enough for me to switch it with an ancient HM80.
It looks like the HCE80 works fairly autonomously apparently calculating and responding to zone demands itself.
For instance you will see it opening actuators for zones even when the Evotouch controller reports 0% demand.
Which explains why the HCE80 controlled pump runs even when there is no boiler demand.
There wasn't anything more to find out, the HCE80 doesn't sync it's cycle rate with the evohome heat calls and (because heat pumps require a good flow rate) this causes the heat pump to shut down if the UFH vales are not open.
One way around this issue would be a buffer tank, however, this is not stated as a requirement anywhere in any of the honeywell literature that I can find.
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