Yes, I will chime on the solar and floor heat. I would rather see the whole floor on one zone with two inputs near the manifolds. The reason is pretty simple....often the solar will produce temps that will be too hot for the floor and it will be both uncomfortable to stand on and it may crack at a spot where the heated and unheated concrete meet.
If an antiscald thermostatic valve was used (simplest way), or a motorized 3-way valve (could be run off an arduino and outdoor sensor) then the floor could get the right temp at all times of the year and still be direct from the solar without a HX.
A buffer tank could be put in if you want but it may not be necessary OR you might want to do some DHW as well in which a HX will be necessary.
Lots to figure out. I'm not keen on LPG unless it is way cheaper than it is here. Otherwise I would just go electric as a backup (or a heat pump). Any combustion product has a lot of drawbacks.
|