Hmm. I wonder if adding an air-to-water pump to the existing loop, before the boiler, can be made to work? Perhaps with a microcontroller intermediating the thermostats on both to turn each on at the ideal time?
There are products that exist for that, though as always: maybe not in your market.
Over here they're called hybrid heat pumps and are quite popular. (At least with those that offer to sell them.) They're used in improving existing gas powered solutions. The heat pump takes most (or usually all) of the heating, while the existing gas heater provides hot water and can add peak heat if needed.
Can you point to some of those. I am curious at other options for my own heating operations but the landscape is difficult to navigate as a consumer and then you need to find people capable of helping out.
- Remeha, with the types Elga Ace, Mercuria, and Mercuria Ace
- Nefit/Bosch with Nefit EnviLine hybrid and Bosch Compress 7400i AW
- Vaillant aroTHERM plus/pro/split
There's also the Quatt Hybrid, which I haven't heard of before, but it looks nice. And according to their website it has a large market share.
