EvoHome H/W Heating Issues Some Observations and Questions

[M J]

Hi, So I was finally able to find someone to install the H/W kit and and BDR91 to control a single zone for some UFH we have.

This was installed on Thursday and the Sparky had some problems getting the binding set up, I pointed him to the need to unbind the existing CH BDR and then start with H/W and then C/H which seemed to have worked and we tested making calls for each BDR before he left.

Then that night at 6:40pm I had a comms Error followed shortly by another error at 6:51

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In the morning the H/W did not fire up and I cleared the faults and it did heat the water up to 55%

Then Friday night at 6:38pm another comms error

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This morning the H/W did not fire up and I have had time to do some digging. I did get the Override button on the BDR to turn on for 5 mins but then it turned off. It did heat the H/W up a bit.

The other two BDRs for UFH and Rads are working fine. There is good spacing between the C/H and H/W BDR's

2022-01-29 09.18.33.jpg

the CS92 might be a bit of an issue so might try and move that. The CS92 is in the photo of the two BDRS behind the brick wall on the lower right of the BDRS.

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I did do comms check and the less than helpful screen said the following:-

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Not sure why it says there are 2 Acuators? Maybe just sloppy wording?

So after some further digging in the main controls I might have found a culprit that would be stopping the H/W from firing up..

The Hot Water Differential was set at 10% so if I understand this correctly if the tank was showing 45% + it would not call for heat and only if it was less than 45%? So maybe everything worked OK and it got to slightly above 45% and then turned off?

So I have changed that setting to 5% Diff and kept the target at 55%

The H/W Overrun was set to zero minutes so I changed that to 10 minutes as that is suggested default on EvoHome site.

I will monitor to ensure that this now works Sunday morning to get the Water up to right Temp for the day.

So some questions

1. Comms Fault - What is the Boiler Relay? Is that the BDR?

2. Comms Fault - Heating Valve Actuator? Is that the CS92?

3. Any guess on what might be breaking the comms at 6:40 ish? I am wracking brain as to what might be kicking off at that time to cause the fault...

4. What do people have setup for the Heating Diff? - Recommendations?

5. Same question for Heating Overrun time?

[bruce_miranda]

You might have a double bound BDR91. You need to clear all previous bindings and bind each BDR91 again to unique functions.
Boiler Relay is normally the BDR91 Relay that actually fires the Boiler. But it depends if you have this set up or not.
Heat Valve Actuator is the BDR91 thar opens the HW zone valve.
Heat diff just stops the boiler from firing to heat HW if the temp has just dropped a little from what you had set it.

[M J]

Thanks for the response Bruce.

So looks like it is reporting a comms fault to the two BDR91 not the CS92.

I will monitor further to see what happens. We did clear all bindings when we set up and rebound in sequence so not sure how we managed to double bind? Anyway Central heating and UFH heating working fine, and I think the H/W might be solved by the change I made to the Heat differential which was perhaps set too high at 10% difference.

Cheers

[bruce_miranda]

The Heat diff makes no difference, if this solved your issue then its merely coincidental