The Efficient Home Forum

Update
After further investigations it would appear the Evohome is never telling the boiler to switch off!!! The Evohome system parameters show 0% demand, but the boiler CH is effectively circulating water around the pipework and bypass radiator slowly getting cooler and cooler with the burner never coming on. The pump and fan never switch off! It will stay like this for hours until there is a genuine demand for heat. If I cycle power to the boiler it powers back up with the CH off. However, with a few minutes (probably because of 4 minute refresh rate on Evohome RF comms) the CH is back on (pump and fan but no burner). I presume this is the Evohome telling the boiler to switch on even though its system parameters still show 0% demand.
Selecting the Evohome quick action ‘Heating Off’, which I believe is switch all radiators to 5 degrees turns the boiler CH off!!! I don’t understand how Opentherm commands work. Please anyone with ideas or have I just been sold a system with both Honewell controls and Ideal Opentherm members that doesn’t work?
Thanks for your time.

Original Post

Ideal Logic Max Combi2 boiler
Evohome with R8810A Opentherm bridge
HR92 radiator controllers
We had Evohome working with a 30-year-old standard boiler for about 7 years. We decided to upgrade to a modern combi boiler to be more efficient. We specifically chose the Ideal boiler so we could use the Opentherm control to maximise that efficiency.
The problem is as follows. The boilers seems to work for awhile correctly. The CH switching on when there is a demand from the Evohome then the CH switching off a short while after that demand has been met. Then at some point the CH on the boiler doesn’t switch off. The pump and or fan will run continuously for hours with the burner not coming on. The Evohome shows no requirement for CH in the system parameters. The only way to stop this is to switch the boiler off and then on again. Please anyone ideas on how to proceed as I’m caught between not knowing if it’s the boiler or Evohome system at fault. The boiler installer is very helpful but knows nothing about Evohome or Opentherm.
It would also be very helpful if someone has installed a system like this with no problems.
Thank you so much.

jon.harris661 wrote:Update
After further investigations it would appear the Evohome is never telling the boiler to switch off!!! The Evohome system parameters show 0% demand, but the boiler CH is effectively circulating water around the pipework and bypass radiator slowly getting cooler and cooler with the burner never coming on. The pump and fan never switch off! It will stay like this for hours until there is a genuine demand for heat. If I cycle power to the boiler it powers back up with the CH off. However, with a few minutes (probably because of 4 minute refresh rate on Evohome RF comms) the CH is back on (pump and fan but no burner). I presume this is the Evohome telling the boiler to switch on even though its system parameters still show 0% demand.
Selecting the Evohome quick action ‘Heating Off’, which I believe is switch all radiators to 5 degrees turns the boiler CH off!!! I don’t understand how Opentherm commands work. Please anyone with ideas or have I just been sold a system with both Honewell controls and Ideal Opentherm members that doesn’t work?
Thanks for your time.

Original Post

Ideal Logic Max Combi2 boiler
Evohome with R8810A Opentherm bridge
HR92 radiator controllers
We had Evohome working with a 30-year-old standard boiler for about 7 years. We decided to upgrade to a modern combi boiler to be more efficient. We specifically chose the Ideal boiler so we could use the Opentherm control to maximise that efficiency.
The problem is as follows. The boilers seems to work for awhile correctly. The CH switching on when there is a demand from the Evohome then the CH switching off a short while after that demand has been met. Then at some point the CH on the boiler doesn’t switch off. The pump and or fan will run continuously for hours with the burner not coming on. The Evohome shows no requirement for CH in the system parameters. The only way to stop this is to switch the boiler off and then on again. Please anyone ideas on how to proceed as I’m caught between not knowing if it’s the boiler or Evohome system at fault. The boiler installer is very helpful but knows nothing about Evohome or Opentherm.
It would also be very helpful if someone has installed a system like this with no problems.
Thank you so much.

I think you will find Ideal have a long history of issues with any other 3rd party OpenTherm product. Why did you choose an Ideal Logic? Worst boiler on the planet.

Because it seemed to get good reviews and seemed to be one of the few British boilers to have the Opentherm badge. Im no expert just a member of the public. Do you have any useful advice other than replace the boiler?

Hi,

What kind of temperature setpoint changes do you currently use across your Evohome zones (assuming you have multiple zones)? I'm wondering if you might only have small changes in the setpoints which might cause the boiler to run for most of the time rather than switching off when the zone temperatures are all well above their setpoints. You could try reducing their minimum setpoints and see if this has a similar effect to the 'heating off' quick action.

I have an Evohome setup with my new boiler (Worcester Greenstar 30i compact) connected via the opentherm bridge + opentherm converter and it seems to work OK with the boiler switching off for a while when each zone's setpoint reduces to 15deg from their max setpoints of between 18-22deg. I previously had a Glow Worm Ultracom2 boiler which also used an opentherm connection to Evohome and this worked OK too. It's a long time since I last looked into the exact details of the opentherm messages sent to the boiler, but I can see on my system that the requested flow temperature (from the Evohome controller via the opentherm bridge) is eventually reduced to 10deg when all zones are at or above their setpoints and the boiler eventually shuts down and its pump stops for an extended time. FYI: I use Domoticz & a HGI80 device to monitor my Evohome system. However, if I look at the heat demand via the settings page on the Evohome controller it may sometimes show 0% demand from all zones, but the boiler might still be active (it's a system boiler so is active when the pump is still running even if the burner is off).

Dan

jon.harris661 wrote:Because it seemed to get good reviews and seemed to be one of the few British boilers to have the Opentherm badge. Im no expert just a member of the public. Do you have any useful advice other than replace the boiler?

Ideal are owned by Groupe Atlantic who are a French company. Nothing is UK owned anymore I'm afraid. The Dutch (and Dutch boilers) are much better with OpenTherm than the UK in any case.

As for advice, the OpenTherm Bridge is too close to the boiler and the switched fused spur. Try moving it away from them first (1m clearance to everything if you can) so it is completely on its own and it might work a bit better. Apart from that, unless you can see the OpenTherm data/messages I cannot really be of more assistance.

Have you seen this video? I made this a few years ago, but shows the complexities of what you are dealing with when it comes to diagnosis - https://youtu.be/icLf5-G0lTs?si=tiypwynVqTECi1YE

Hi Thanks for the info. Great video. I do wish i had got another boiler but all does seem to be working now. I spoke to Honeywell technical support who were very helpful. They updated their firmware for me and the system has been working great since.

Thanks Dan for your help. Ironicaly i didnt go for the Worcester boiler because of the extra interface needed and i thought that might cause problems with even less support. However, Honeywell kindly updated the firmware on Evohome for me which seems to have sorted the problem. Also as a bonus i seem to have some new weather features on it.
Cheers Jon

That's great to hear that it's all now working OK after the update to your Evohome controller's firmware and that Resideo support were able to help. I haven't previously heard of examples where the newer firmware has fixed Opentherm related boiler issues so it's great to know. I assume that the new controller firmware is showing the Application Software version as 02.00.19.33?

Yes thank goodness. Im still waiting nervously for it to go wrong! Previously i was on 02.00.17.03.

Interesting thread as also have an Ideal boiler, which was already in the house, and I too am using Opentherm.

With no heating demand scheduled, the boiler will randomly run both the pump and fan for exactly 4 minutes, sometimes consecutively, often multiple times an hour or as infrequently as once every 5 or 6 hours, and I too have always wondered if this was an Ideal quirk or an Evohome opentherm quirk. The boiler doesn't fire during these 4 minute runs.

Other than the odd behaviour mentioned above, for an old combi it runs reasonably well with Opentherm, with just an infrequent reluctance to add that last 0.5°c to reach setpoint from time to time, which might last a few days. I do like the ability to set the maximum flow on the boiler, which is an option missing from many other brands.

Ideal customer service were next to useless and Resideo not much better, so with no heating scheduled for a reasonably lengthy time, such as overnight, I switch the boiler to summer (hot water only) mode, which prevents these 4 minute runs. Not ideal (pun intended) but not sure what else to do.

Thanks for mentioning firmware, which I am off to check.