heat exhange

Hi All. I have an air to water heating pump and wondering what settings should I choose on the flow control device. The options are: - Variable differential pressure - Constant differential pressure - Constant I have a mixed heating system with underfloor heating downstairs and radiators...

I have a Pulsacoil 3. The pump was pulsing for prolonged periods even when not running the hot tap so I changed both the DHW wet sensor and the PHE dry sensor. Now when I run a hot tap the pump starts for approx. 5 seconds then switches off. If I close then reopen the tap the same happens. If...