Given the recent spate of posts about boiler/opentherm issues, you might be interested in the following (then again you might not).
For the past year, I have looked at (my wife says ‘procrastinated over') options for a replacement boiler which has involved me taking many soundings from tech support teams, installers, experts and forums. Each time that I thought that I had reached a decision, reports of a potential compatibility issue would arise. This resulted in me dropping Ideal, Intergas and Veissmann boilers from my short list. The decision-making process was not helped by a lack of knowledgeable installers: most just wanted to fit a new boiler on to my existing system. Thanks to some excellent advice from Top Brake (I hope that your ankle is getting better) and Atag Tech Support, I was able to find an installer that was happy to work with my existing Evohome system.
As of yesterday, I have a replacement Atag IS boiler connected to my 3 year old Evohome system via Opentherm. Use of the latter was conditional on me being able to switch back to a BDR if any Opentherm issues should arise.
Configuration Changes: A conventional ’S’ plan configuration has been modified with the replacement of the heating zone valve with an inline open/motorised closed valve connected in series to the existing HW BDR. The existing HW BDR has been disabled and unbound from the controller. When the HW BDR demands heat, the HW zone valve opens and the CH inline valves closes giving HW priority. A boiler relay has been established using an Opentherm bridge - a 5 minute job.
Boiler Changes: The boiler has been configured to P1 - max boiler temperature 70C.
First Impressions. Opentherm just works - no ‘if or buts’ as far as I can tell but it is still early days. When HW is demanded, the boiler seems to set a target temperature of about 10C above the existing cylinder temperature - no mad rush to 92C or max boiler temperature. Boiler temperature increases as the cylinder water temperature rises to the maximum P1 setting of 70C. Given our life style, I do not foresee any issues setting HW heating periods outwith the times when we want heating. That said, in Winter, I suspect that we will need to change the boiler target temperature to P0 - 80C to get a quicker cylinder re-heating time.
This morning when I got up at 7am to make a cup of tea, HW was heating (about 2C below the Evohome set temperature) and the boiler temperature was 65C. About 40 minutes later, the selected zones were all at set temperature and the boiler was running on pump only at 45C flow/41C return.
Summary: Noting all the other posts about boiler/Opentherm issues, I am pleased that, with an Atag boiler, Opentherm appears to work (as it is designed to do?). I appreciate that I am tempting fate by writing this!!
Sorry that there are no fancy graphs etc. I would be very interested in monitoring my system (other than by popping into the garage to look at the boiler) but I confess that without something that is just 'plug and play', I am out of my depth (its an age thing). I will update this post when the system has been running for a few more days.
For the past year, I have looked at (my wife says ‘procrastinated over') options for a replacement boiler which has involved me taking many soundings from tech support teams, installers, experts and forums. Each time that I thought that I had reached a decision, reports of a potential compatibility issue would arise. This resulted in me dropping Ideal, Intergas and Veissmann boilers from my short list. The decision-making process was not helped by a lack of knowledgeable installers: most just wanted to fit a new boiler on to my existing system. Thanks to some excellent advice from Top Brake (I hope that your ankle is getting better) and Atag Tech Support, I was able to find an installer that was happy to work with my existing Evohome system.
As of yesterday, I have a replacement Atag IS boiler connected to my 3 year old Evohome system via Opentherm. Use of the latter was conditional on me being able to switch back to a BDR if any Opentherm issues should arise.
Configuration Changes: A conventional ’S’ plan configuration has been modified with the replacement of the heating zone valve with an inline open/motorised closed valve connected in series to the existing HW BDR. The existing HW BDR has been disabled and unbound from the controller. When the HW BDR demands heat, the HW zone valve opens and the CH inline valves closes giving HW priority. A boiler relay has been established using an Opentherm bridge - a 5 minute job.
Boiler Changes: The boiler has been configured to P1 - max boiler temperature 70C.
First Impressions. Opentherm just works - no ‘if or buts’ as far as I can tell but it is still early days. When HW is demanded, the boiler seems to set a target temperature of about 10C above the existing cylinder temperature - no mad rush to 92C or max boiler temperature. Boiler temperature increases as the cylinder water temperature rises to the maximum P1 setting of 70C. Given our life style, I do not foresee any issues setting HW heating periods outwith the times when we want heating. That said, in Winter, I suspect that we will need to change the boiler target temperature to P0 - 80C to get a quicker cylinder re-heating time.
This morning when I got up at 7am to make a cup of tea, HW was heating (about 2C below the Evohome set temperature) and the boiler temperature was 65C. About 40 minutes later, the selected zones were all at set temperature and the boiler was running on pump only at 45C flow/41C return.
Summary: Noting all the other posts about boiler/Opentherm issues, I am pleased that, with an Atag boiler, Opentherm appears to work (as it is designed to do?). I appreciate that I am tempting fate by writing this!!
Sorry that there are no fancy graphs etc. I would be very interested in monitoring my system (other than by popping into the garage to look at the boiler) but I confess that without something that is just 'plug and play', I am out of my depth (its an age thing). I will update this post when the system has been running for a few more days.
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