Evening chaps
Gus, I can't see that this is anything to do with the Atag, the boiler is a slave to the Evo OT module which in turn is a slave to the Evo Controller - the system is a CH system primarily as per the Honeywell OT instructions, when HW is requested, power shuts the CH valve and opens the HW valve in tandem (which sounds exactly as yours was). The fact that the system is now working without issue, because it's programmed for the HW to not coincide with a high CH demand, suggests Evohome gives priority I would have thought, possibly delaying the HW triggering. Unless I'm misunderstanding what you are suggesting?
Upon thinking further, the additional UFH system under a further normally closed valve would work independent of both the HW and CH, as this would run off the main 22mm branch from the boiler and not after the CH/HW valves - initially powering the pump/valve via a BDR91 (single zone for now) given that it has it's own blending valve it would meter down the hot water when the HW is on, and request what it needs as per a normal zone. This does beg the same question though, would the Evohome treat this effective BDR zone valve like it does the HR92's when requesting heat or delay the opening of the UFH valve when the normal CH circuit is drawing a high demand .
Gus, I can't see that this is anything to do with the Atag, the boiler is a slave to the Evo OT module which in turn is a slave to the Evo Controller - the system is a CH system primarily as per the Honeywell OT instructions, when HW is requested, power shuts the CH valve and opens the HW valve in tandem (which sounds exactly as yours was). The fact that the system is now working without issue, because it's programmed for the HW to not coincide with a high CH demand, suggests Evohome gives priority I would have thought, possibly delaying the HW triggering. Unless I'm misunderstanding what you are suggesting?
Upon thinking further, the additional UFH system under a further normally closed valve would work independent of both the HW and CH, as this would run off the main 22mm branch from the boiler and not after the CH/HW valves - initially powering the pump/valve via a BDR91 (single zone for now) given that it has it's own blending valve it would meter down the hot water when the HW is on, and request what it needs as per a normal zone. This does beg the same question though, would the Evohome treat this effective BDR zone valve like it does the HR92's when requesting heat or delay the opening of the UFH valve when the normal CH circuit is drawing a high demand .
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