Honeywell Evohome or Geniushub

Jeez, they know how to charge, and some

What's the payback time on that?

Surely in diy, payback is in the pleasure of getting the damn system installed and working in spite of the manufacturers best efforts to bugger up the product! That's why my workshop has a wood burning stove even though it's never used for woodwork. I know the logic is a bit strained, but it's late!.

I'd rate Genius over Honeywell any day - I have experience of installing their stuff. If you have a problem and ring Honeywell - good luck...

If you ring HeatGenius, you speak to a bloke in England because the company is English. I've even spoken to one of the two founders back when I was checking it out.

I've asked questions about mixing in UFH heating with regular CH and have had useful and precise answers back in a day.

The system IME is extremely reliable and as it's their only product they're not going to drop it like Google drops web apps. The only risk is the company goes under - but the system does not depend absolutely on their cloud portal - it will work locally if you can expose the IP address.

Conversely, I rang Myson with a simple question: how much power does your Lo-Line fan convector consume (on the fan) as it will be sitting on the CH circuit fused at 3A along with 2 pumps a boiler and UFH valves.

"Dunno..."

So essentially, a big manufacturer means nothing in this this field, unless they are a specialist and have a reputation to protect. Honeywell are too generic - they churn products all the time.