What Is Weather Compensation?

[@NickAskew]

Thanks for this brief explanation. Firstly I'm in the Netherlands and ASHP is beginning to catch on and we have a number of neighbours who have taken the leap. I still have to make that jump but I'm trying to get my head around certain aspects of ASHPs and weather compensation is one of them. Currently I have a gas boiler with a smart thermostat in the living room with an OpenTherm connection to the boiler. The thermostat has no knowledge of the outside temperature but obviously it does know the current room temperature and the target temperature. So (going solely by the gas usage) it appears to regulate the flow temperature based on the distance between the the room temperature and the target temperature. Now I was also under the impression that the thermostat can "learn" how long it takes to reach the target temperature. So this means that if I want the room to be at 19C at 7AM then it knows that the boiler might need to be fired up at 6:32AM so that the room is comfortable in time. It would seem preferable to me to run the water from an ASHP at a lower flow rate for longer rather than demanding a higher temperature. Are there systems that can regulate in this way?

[@MentalLentil-ev9jr]

That's how most heat pump systems work. For example, my heat pump will try to run 24 hours a day (it's set up for 24 hour heating) without turning off, it will select the correct water temperature based upon the outside temperature - it doesn't consider the room temperatures. When it cannot modulate low enough for the heat pump, it will run on and off with cycles around an hour to give the right amount of heat into the room. In the Netherlands, with your spark gap, the heat pump should be far cheaper to run than a gas boiler, even if it isn't optimised.