I am an experienced self builder, however this ifs the first time I’ve decided to use a heat recovery system and the first time I’ve had to use air source heating so I’m asking which systems you’d recommend, the house I’m building is approximately 3500sq/ft with underfloor heating both upstairs and  downstairs with both floors being block and beam.

 

thanks Nigel

I'm going for  Zehnder Q600 for our 300m² build. At 350m² you're well in to 2x MVHR territory.

 

ASHP will depend on your heat demand. Try and get as much insulation and air tightness in the fabric and you'll end up getting away with a small monoblock rather than a larger (more expensive) split system. I'm going for an 8.5kw mitsubishi ecodan.

 

I've no practical experience of either systems yet, so don't be taking my recommendations too seriously!