Thankyou all!

Let me try and explain some of my "mad proffesor" logic - rightly or wrongly

Efficiency
- the target temp is a room air temp of 19oC - 21oC
- i'd assumed (ASS of U and Me) that the more of the waste heat (the return boiler tempurature) used, the more efficient the boiler?

Boiler Size
Put it in myself 6 years ago - 95btu combi - way obversized for heating a 2 bed bungalow - but I wanted to fill a bath!
Other than the quality of the thing, I have no complaints - a combi fan!

Insulation
200mm Loft - no walll - new extension will be to building regs

"Hydrotherm Hydropulse boiler" wow! sounds like some body enema device!


Can I "please" rephrase my question

What would you do?