suprima 30kw pipe sizing off flow and return

[Readingplumber]

Hi,

I have noticed that the suprima 30 kw boiler has 22 mm coming out of the top, but the plumber when connected to it increased the pipe size to 28mm pipe?

Im just wondering why didnt the manuracturer just have 28mm coming out in the first place?

Are there any other boilers where this applies?

Thanks again

 

[Ockyvines]

It's just the physical size of the boiler that makes the connections 22mm but the plumber was right to increase them to 28mm straight away.From memory(its a long time since I fitted one) 35mm was recommended

 

[Readingplumber]

Thanks for your answer Ockyvines, -
Please can you clarify this for me i am confused -
One theory at rule of thumb pipe sizing is 22mm carries 23 kw and 28 carries 28kw - max - which makes sence of the increasing boiler size to 28mm in the above post.

Central heating pipe sizing

But then in the plumbing nvq level 3 book by john thompson pg 187 -
He says the maximum run for 22mm pwk is 13 kw and 28mm 22kw

Any help on the matter is appreciated, is is the later one based on the actual radiators only whilst the first one is based on the primarys?

Thanks for your time

 

[Ockyvines]

Forget all those figures in this case.
The manufacturers instructions supersede any other calculations or regs.
These boilers will soon overheat if you run 22mm primaries