@Wifiwits
In a previous house, laid underfloor in an extenstion I built. It had a high vaulted ceiling so u/floor was practical option.
The room had its own stat & the boiler (oil) was fired thru an ‘OR’ circuit sharing supply to water tank & rads in rest of house. Underfloor circuit was tee’d off’with circulation valves plus had a temp mix valve in the circuit. Set back temp at 16°. Helped by James at Commercial Connections nr Crossgar.
At that time I wasn’t overly concerned with fuel prices so wasn’t tracking cost change.
@Wifiwits
I can’t recall the exact flow temp, high 30s/low 40s. Easy to adjust with the return mix valve.
Mine was ground floor, for me it was simpler/faster to suspend the floor as it was solid beech. Didn’t need to wait weeks for a finished slab to dry out. Laser levelled the ‘joists’ floating on saddles so the contct between insulation blocks/spreader plates was sound.
