Getting information on how a condensing boiler should respond under Opentherm control is still something of a challenge.
1. Atag has confirmed that the boiler is responding as they would expect if it was being controlled by their Atag One controller.
2. My hot water is limited to max boiler set temperature.
3. Initially, when the boiler comes on, with just heating selected, the boiler flow temperature will rise to the max boiler set temperature and stay there until all the zones are near their set temperatures. During this process, the boiler audibly modulates downwards, and gas usage reduces.
4. Some time after, the boiler temperature flow/return temperatures start to fall. I have seen a return temperature of 45C.
5. The piece of the jigsaw that has me slightly baffled, is how Evohome copes with optimum start when there is no heat; i.e.; when the motorised valves have switched to hot water priority? On simple observation alone, it copes - presumably by upping the boiler flow temperature when heat to the CH is available. I am not sure how it learns from this situation, but I suspect the same applies with the old 'S' plan when a hot water demand kicks in.
6. Zone temperature overshoots have not been a problem. I did see one zone at 1C higher than the set temperature this morning, but that was shortly after the system switched from hot water to heating.
1. Atag has confirmed that the boiler is responding as they would expect if it was being controlled by their Atag One controller.
2. My hot water is limited to max boiler set temperature.
3. Initially, when the boiler comes on, with just heating selected, the boiler flow temperature will rise to the max boiler set temperature and stay there until all the zones are near their set temperatures. During this process, the boiler audibly modulates downwards, and gas usage reduces.
4. Some time after, the boiler temperature flow/return temperatures start to fall. I have seen a return temperature of 45C.
5. The piece of the jigsaw that has me slightly baffled, is how Evohome copes with optimum start when there is no heat; i.e.; when the motorised valves have switched to hot water priority? On simple observation alone, it copes - presumably by upping the boiler flow temperature when heat to the CH is available. I am not sure how it learns from this situation, but I suspect the same applies with the old 'S' plan when a hot water demand kicks in.
6. Zone temperature overshoots have not been a problem. I did see one zone at 1C higher than the set temperature this morning, but that was shortly after the system switched from hot water to heating.
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