UFH design for combi boiler

[EvilDonut]

ive got a 32KW combi with 8 rads and am going to heat a large open plan extension with a wet UFH system (35 m2)

Doing this DIY and I know nothing about heating engineering.

My plumber, who is a decent heating engineer, mentioned I’d probably need a header on the UFH manifold so as to not upset the return temp / modulation etc.

Sound reasonable? Any other designs? How should I go about sizing the header? (No ive not calculated overall heat loss, do I need to?) Anything else obvious I might have missed?

Cheers!

 

[muggles]

Close-coupled tees should be sufficient for a UFH manifold, shouldn't need a full header. You shouldn't be sizing anything though, leave that to him - that way, if it's wrong, he can't blame you

 

[EvilDonut]

Ok cheers, I’ll look into that.

He’s not actually doing any of this work for me, he just gave me a couple of tips on UFH while he was installing my boiler, so I wouldn’t expect him to be sizing it for me.

 

[EvilDonut]

So am I also right in thinking I don’t need an automatic bypass valve IF I get either a low loss header or close coupled tees?

LLHs seem more appropriate for large systems, mind is fairly small so don’t want to go overkill.

 

[picasso]

Not sure what your heating hengineer is talking about regarding return temps, keep it simple and stick it on an s plan with an automatic bypass.

 

[EvilDonut]

I'd happily do an s plan if I could get that working with my one or two nest setup (with opentherm, not on/off) - I've just posted another separate thread about that