Two circuits for cooling?

[joth]

On 10/08/2025 at 08:56, -rick- said:

 

Oh now I'm confused. Am I thinking of someone else?

 

I thought you had a heat gain problem in the bedrooms even during heating season so wanted the ability to cool the bedroom while the downstairs wanted heat. After I read that I looked back at some old threads and thought I read about how to do that you had to install a second zone with a big buffer tank to give the zone enough volume to avoid cycling. Have I misunderstood something?

Haha well remembered - yes that is a problem we have in our house, but not one I've tried to solve through simultaneous ASHP heating and cooling. (Although a w2w heatpump would indeed allow pumping excess heat from the FCUs upstairs back down to the UFH downstairs)

My solution is during the heating season, the ASHP is in heating mode only (for the UFH) and the bedrooms have additional fan bringing in cool air from outdoors as needed (essentially an MVHR mega-boost mode). This air intake fan shares duct work and electronic dampers with the FCU network.