Central Heating Pipe Sizes

[SalmonP]

Hi,

I'm replacing an ideal Mexico with a Potterton Promax SL (30Kw). The original heating pipework is 28mm from the boiler. I'm upgrading the system, so fitting a 3 port valve and also a magnaclean. Space is fairly tight and the pipework needs a fair bit of rerouting, so I was going to do the first couple of meters of the flow and return in 22mm instead of the 28mm currently installed.

Does anyone think there would be any issues with this?

Cheers

 

[GasBod]

nope

 

[xr4x4]

I do...

30kw and above normally needs 28mm flow and return, check the spec of the boiler.

 

[SalmonP]

Thanks to both of you.

xr4x4, the promax has 22mm connections although it does say in the MI that the 30Kw "should" have 28mm flow and return by means of a reducer. However, I'm looking for any possible adverse effects of first couple of meters of the flow and return being 22mm? is it really going to make any difference in terms of system performance?

 

[onlyfitidealboilers]

Anything above 60,000 btu / 18kw needs 28mm as per most manufactures

 

[onlyfitidealboilers]

nope

 

[SalmonP]

onlyfitidealboilers, In the promax range the only one which there is mention of 28mm flow and return is the 30kw, the 24kw is fine with 22mm. The Worcester 30CDI regular boiler, another one I was looking at for this job, is 22m flow and return, so back to the original point, without referring to MI, is there any sh*t going to hit the fan if the first couple of meters were 22mm?
[/i]

 

[twgas]

I'd say 28mm from the boiler.
You say you'll be fitting a 3 port valve, I'd be inclined towards 2*2 ports, what's there at the moment?

 

[SalmonP]

twgas, it was gravity hot water, pumped central heating, so there were no valves there originally

 

[Dan Robinson]

30kw through a 3port valve on 22mm?

what other bits of the instructions do you think are not worth bothering with? what does your installer think?

 

[ianmcd]

different thread you are replacing an Ideal mexico with a Promax !!!! after at least 25 years of good service dont expect your new boiler to give you any where near as good service value

 

[GasBod]

nope

instead of the stupid shocked smiley can you please explain how a boiler with 22mm f and r connections can benefit to being upgraded to 28mm?

 

[dcawkwell]

Nope.

30kw is fine on 22mm pipe the boiler has only 22mm flow and returns!

 

[Dan Robinson]

probably only has a 15mm gas inlet, but doesn't make it appropriate to run a 15mm gas supply does it?

 

[Agile]

Salmon P, have you considered why you want to fit a 30 kW boiler?

Do you think bigger is better?