Heat Greek vs Skill Builder mainly heat pump, but some reference to condensing gas boilers.

[robinbanks]

I've never seen a heat pump

Look like every aircon unit in every film you've ever watched

I can't see how they are cost effective

My system cost me 5 grand, and the RHI paid me 7
I can't see how that's not cost effective!

Can you get someone to fix short notice?

I called Vaillant out once, circulator pump issue fixed under warranty

How reliable?

I've never touched it. "Servicing" it amounts to washing any crap out of the vanes. Never done that either. Been churning out warm water for 8 years now

Saving worth the cost of installing?

I don't have gas. Monobloc systems can be mostly DIY installed and maintained. Overall I'd estimate mine's been cheaper to run than a gas boiler

I was thinking "passivhaus" standards.

Then you don't need a formal heating system at all, and certainly not one as expensive as an HP. Keep a couple fan heaters in a cupboard

Insulation does not have to be particularly good

Insulation should be particularly good in all properties and (in tandem with straight proofing) should be the primary focus of any upgrade, not the heating system

If you get the insulation right you don't need heating, and both wallet and planet thank you ongoing