Odd behaviour from HR92s

[Eniodi]

I don't think the install - ie, the pairing of devices, and sticking the heads on valves - is the issue here. I think there are considerable issues at the software level. For a "mature" system Evohome is looking pretty dated to me. There is no logging of temperatures or heat demand. No historic data analysis. Every other system on the market has some degree of historic data for the user to see.

I almost went with the JohnGuest system, but decided against it because I wasn't sure about the long term software support. They also require separate thermostats to the valve controllers, which adds cost - though in hindsight I'm finding that the temperature reporting by the HR92s even with tweaking the offset settings is crap, and will probably have to add additional thermostats to give more accurate room temperature control for certain problematic rooms. I have a JG UFH manifold and pump, and am using the Evohome HCC80r controller and actuators on it. I needed a system that could combine UFH and rads - and only Evohome and JohnGuest seemed to cover that correctly. The Evohome HCC80R also doesn't have wiring for a zone valve to isolate the UFH pipe circuit, which the ATAG boiler engineer thought was ludicrous. Water is always flowing through the UFH mixer and shorting the heating system to the radiators. According to Honeywell/Evohome this is the way to do it - according to literally everyone else, there should be a zone valve to shut off the underfloor circuit.

[g6ejd]

I've had my Evohome system for 4-years now and throughout that time I have observed so-called 'phantom' demands, in-fact right now at 23:23 I can hear the pump running, but the system was programmed to switch off at 23:00, it's a system 'feature' that has never been solved.

[Eniodi]

I wondered if it was an issue specific to using the OpenTherm bridge. I see it very often - usually an hour or so after all my set points reduce at night. I can hear the pump going upstairs, and all the room temperatures reporting at or slightly above set point. Then, if I check the % demand at the Evohome controller it's reporting 0% across the board, including on the boiler.

But I've also noticed that the % figures change at random. If you have more than 6 zones, you can flick between pages - flick back and the % figures are sometimes wildly different, such as even going from 0% to 100% for a given zone.

It also seems odd that sometimes a room that is further below its set point than another can report a lower % demand.

Another odd one - I have a T87 thermostat in two rooms - they often report a room temperature 0.5 degree out from the Evohome controller. So, it can read 19.5 while the controller says 20.0.

[Eniodi]

Have you been in contact with Honeywell/Evohome support? I've now logged a long list of issues, and they are supposed to be escalating it (beyond the guy reading off the simpleton flow chart) - that was supposed to happen by yesterday, still waiting to hear back.

[Richard]

There is a firmware update coming shortly that will deal with these low demand issues.

I noted something a while ago which may help. If your installer has used Honeywell Home Valencia valves with the 'balancing insert' and they have 'balanced' the heating system with them, this will reduce the amount of pin movement or stroke the TRV will have which isn't good. I would recommend with evohome that the balancing insert is not used and you balance on the lockshield valve. Certainly if the black balancing insert has been wound in, personally I would wind it out (until it goes loose) and recalibrate the HR91/HR92.

valencia valve callibration.JPG (46.55 KiB) Viewed 566 times

[Richard]

I wondered if it was an issue specific to using the OpenTherm bridge. I see it very often - usually an hour or so after all my set points reduce at night. I can hear the pump going upstairs, and all the room temperatures reporting at or slightly above set point. Then, if I check the % demand at the Evohome controller it's reporting 0% across the board, including on the boiler.

But I've also noticed that the % figures change at random. If you have more than 6 zones, you can flick between pages - flick back and the % figures are sometimes wildly different, such as even going from 0% to 100% for a given zone.

It also seems odd that sometimes a room that is further below its set point than another can report a lower % demand.

Another odd one - I have a T87 thermostat in two rooms - they often report a room temperature 0.5 degree out from the Evohome controller. So, it can read 19.5 while the controller says 20.0.

The OpenTherm Bridge will carry on doing what it was last told to do until it is told to do something else. Errors with the OpenTherm Bridge are often actually RF issues between the evohome Controller and the OpenTherm Bridge.

[Eniodi]

There is a firmware update coming shortly that will deal with these low demand issues.

I noted something a while ago which may help. If your installer has used Honeywell Home Valencia valves with the 'balancing insert' and they have 'balanced' the heating system with them, this will reduce the amount of pin movement or stroke the TRV will have which isn't good. I would recommend with evohome that the balancing insert is not used and you balance on the lockshield valve. Certainly if the black balancing insert has been wound in, personally I would wind it out (until it goes loose) and recalibrate the HR91/HR92.

valencia valve callibration.JPG

I'm using Pegler Terriers, and they don't have balancing calibration. I've balanced on the lock shield side only.

The low demand/minimum throw issue better be sorted with the next firmware (can't come soon enough). It is clearly a software/instruction issue since the valve throw calibration only deals with the fully open position. The system needs to instruct a minimum opening amount to account for the compression in the valve internals and give in the HR92 seat when the HR92 determines it fully closed (the point at which it measures resistance when closing). This issue would appear to affect both Terriers and Valencia valves.

[Richard]

Some TRV's just aren't fully compatible by design. They need to be exactly like this one for near perfect operation - https://theevohomeshop.co.uk/content/9- ... patibility

[Eniodi]

I wondered if it was an issue specific to using the OpenTherm bridge. I see it very often - usually an hour or so after all my set points reduce at night. I can hear the pump going upstairs, and all the room temperatures reporting at or slightly above set point. Then, if I check the % demand at the Evohome controller it's reporting 0% across the board, including on the boiler.

But I've also noticed that the % figures change at random. If you have more than 6 zones, you can flick between pages - flick back and the % figures are sometimes wildly different, such as even going from 0% to 100% for a given zone.

It also seems odd that sometimes a room that is further below its set point than another can report a lower % demand.

Another odd one - I have a T87 thermostat in two rooms - they often report a room temperature 0.5 degree out from the Evohome controller. So, it can read 19.5 while the controller says 20.0.

The OpenTherm Bridge will carry on doing what it was last told to do until it is told to do something else. Errors with the OpenTherm Bridge are often actually RF issues between the evohome Controller and the OpenTherm Bridge.

Can't be just that - my Evohome controller and OpenTherm bridge are only a short distance apart, and signal tests always come back good.

Got any explanations for the other stuff? T87s showing a temperature 0.5 out from the controller? Room temperatures magically jumping up 1.5 degrees when adjusting set point on the controller? % usage figures changing when changing pages in the system menu?

[Eniodi]

Some TRV's just aren't fully compatible by design. They need to be exactly like this one for near perfect operation - https://theevohomeshop.co.uk/content/9- ... patibility

Pegler Yorkshire Terrier 3 - it's on the list!!! Are they not compatible really?

I've been requested by Evohome support to swap out problem valves for Valencias (valves which are otherwise in perfect working order), but a user on this thread has detailed the same low demand issues with the Valencias.

Having watched your video, the Terriers measure up fine. The valve height is correct, thread detail correct. The issue is not with the fully open position (or the pin being depressed when screwing down the HR92 seat) - the issue is with the over-compression when the closed position is determined.

I think the real question is, what is the change in the firmware that will address the low demand issue (and is that an admission that there is a low demand issue, as I've detailed at the start of this thread)?