It ultimately comes down to how much you want to use OT or whether you are happy for the boiler to do everything itself?
For me I was adamant I wanted OT so I specced the boiler to match. Ideally I would have gone for the Intergas as well, but eventually they admitted all the issues that have been mentioned before. My understanding is the only solution would be for intergas to change the pcb.
I went for an Atag iS32 and the difference in fully installed price was £500 more than the equivalent intergas eco RF. That was also with a more expensive fitter, but he definitely knew his stuff and did include 10y warranty.
Slightly off topic - sorry. If you are really lucky and your Atag installer needs a missing part, then the man from Atag pitches up in his van with the built in Atag boiler. Apparently, he is a very keen mountain biker and has connected the boiler to a portable shower which he uses in the car park before driving home.
I did it for you.
I sent this to Intergas on 26 June:
Hello
I am considering the purchase or the ECO RF 36 combi boiler.
Will you please confirm that this will operate as intended with Honeywell Evohome in particular the Honeywell R8810A1018 Wireless OpenTherm Bridge R8810.
Thank you.
Tony
Guess what reply I received?
I suspect that they may have given you a reply along the lines that last year they had met with Honeywell and tested Evohome with Opentherm on the RF Eco. It was only went I spoke to their Opentherm expert - armed with information from one of their installers - that Intergas UK admitted that it was aware of the multi-zoning demand issue and this had been referred back to Intergas Netherlands for advice/resolution. That, I think is where matters stand. As many have posted on this forum, Evohome can talk to many boilers via Opentherm: sadly, not all of them respond to that discussion as they should. My concern about choosing a boiler that might or might not work with Opentherm is liability if Evohome over-rides the built in the boiler's max flow temperature protection.Originally Posted by the crooner
I understand what you are saying thank you. Its pretty poor design though if an external electronic control overrides a safety protection in a boiler.
I wont buy Intergas because they wont talk to me. I emailed Vaiilant in Germany asking whether opentherm will be supported in the UK after the UK helpfully told me that its not supported end of. I guess that rules out Vaillant.
So I am left with Atag, or bin opentherm altogether and go with Worcester Bosch. There's a well respected installer in the next village.
But thoughts have also turned to keeping the existing boiler and S plan and buying a vented mains pressure thermal store like the Advance or Boilermate.
If anyone has any feedback on this I'd be grateful. Its clearly the cheapest option now, and if the boiler dies in a few years, again relatively cheap to replace it.
Tony
I wouldn't give up all together. This is the reply that I got from Intergas in December:
Quote: There is no resolution date for the issue with the Eco PCB at present, we are still awaiting any news on that sorry.
We have no release date for the Extreme boilers but I have been assured that they will be opentherm compatible. As soon as we have a release date for these boilers we will let everyone know.
Regards
Steve Merry
Technical Support Engineer
Unquote
The release of the new intergas boilers keeps going further and further back. I was in exactly the same position and ended up going for the Atag as it simply works as it should with multizone OT.
Valiant may be slightly cheaper, but I didn't fancy the hassle of needing extra buses and the risk I've got no formal support if it goes wrong.
Thanks for this.
Do the Atag controls for setting boiler temperature still work with OT, or does OT override everything on the front panel?
When HW or CH is demanded (with a large zone temperature variation) the boiler flow maximum temperature is controlled by the boiler. For example, I have a profile set with a max boiler flow temperature of 70C. I have seen a slight over-run of 2 or 3 degrees but I have never seen the any exceedance of the TSet 70C target which is part of the 70C profile. When all the zones are close to their target temperatures, the boiler flow temperature starts to fall towards the condensing range. In sum, the front panel works as it should on the Atag Is24 boiler. That said, as I haven't run the boiler through a Winter period, I have yet to see the boiler in full condensing mode for a protracted period. The Evohome logic is based on getting all zones up to heat. It follows that max condensing efficiency may well be achieved by not having zones chop and change temperatures too often. For example, if a child goes up to their bedroom, say, mid afternoon and cranks up the HR92 by 5C, then the boiler will immediately crank up to 70C in my case until the new temperature is achieved. That said, it will not be at 70C for long.
I also have my HW and CH separate from each other. Opening the HW valve closes the CH valve.
How many boilers are properly compatible with Evohome when used in its OpenTherm configuration?
From what I've seen here, none are truly working correctly and that includes Atag as well as Ideal, Vaillant, Intergas & Veissmann.
Dan Robinson (an Intergas specialist installer), has said on another forum that multi-zone Intergas/Evohome doesn't modulate. Now does that mean the boiler only operates at one flame setting, or does it mean it doesn't modulate in the way he would expect it to? This begs the question of how Intergas/Evohome/OpenTherm performs when set up as a single zone?
Evohome is a kind of hybrid TPI/Modulating setup where OpenTherm is used and I think it shows in the higher (non-condensing) flow temperatures over long periods of time - this being the very thing OpenTherm was designed to prevent. We know the idea of OpenTherm is to keep flow temperatures as low as possible for as long as possible and I've yet to see an instance reported of this actually happening with Evohome.
Martin.
Last edited by blowlamp; 2nd July 2017 at 05:57 PM.
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