mono-stereo Just got a heat exchange unit on the roof. Its very quiet. It does resonate through the flat roof so there is a bit of a hum (like a distant harley davidson) in the spare room, which has the flat roof. No planning permission needed. gets problematic if you have multiple units.
Chose to put it on the flat roof as it was a bit easier than on the ground round the back. You can’t see it from the road. I love it. Currently got it on full blast and bedroom door open and it is cooling the rest of the house (albeit slowly). My smart electricity meter tells me it is costing me 10pence per hour.
