Radiator 15mm and 22mm pipe

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Hi, I have my builder and plumber having different opinions and would like to know if they have put the right pipe sizes in the house for the radiators. This is really frustrating as makes controlling the heating for my family a real pain.
This is a 3 storey house with 8 radiators.
Plumber changed the supply coming into the house so it was 22mm.
System boiler / unvented cylinder, not a combi boiler.
Builder reckons it doesn't make a difference, but the plumber says it does but reckons 'levelling the system' will sort it out.
Some of the radiator pipes are 22 mm and some are 15mm. e.g. downstairs are 22mm. upstairs bedrooms are 15mm. Do they all need to be 22mm?
My biggest worry is that its all ok, but in a years time when they have all left, then boiler breaks and other problems and I am left to fix it.

Other problems I seem to be facing are:
Boiler seems to make some squealing sound too.
Boiler pressure keeps dropping every few weeks and then switches off boiler.
Not sure if this is related to the pipes being different sizes
Thanks
Rob
 
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It is very common to pipe both downstairs and upstairs with a flow and return "spine" of 22mm pipe, with relatively short lengths of 15mm pipe from each of flow and return spines to each radiator. It's a pretty foolproof approach proved there isn't an unusually large number of radiators.

When you say upstairs pipes are 15mm, do you mean the final run to each radiator is 15mm, or that all upstairs central heating pipework is 15mm?

If the former (radiators only), then its not an issue.

If you mean the latter, it could be an issue. Its generally accepted that 15mm pipework is capable of carrying sufficient hot water to provide heat of between 6 and around 9 Kw, depending on temperature drop per radiator, at a speed which doesn't cause noise. If your upstairs radiators add up to 6Kw or less you shouldn't have an immediate issue. If they add up to more, then it needs careful sizing to determine if it is an issue now. In either case you may well be limited should you wish to have more heat (e.g. an extension) in future.
 
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thanks for the reply.
The upstairs bedrooms are all 15mm, none are 22mm. Not sure about the kw of heat it carries. But it does have about 5 radiators and a towel rail the its all connected to.
What's the impact? Efficiency of boiler poor or will break the boiler?

Would it be ok if I changed this to 22mm going up to the radiator and then teeing off to 15mm so approx. 1-2metres are 15mm (possibly for each rad). Reason is because the rads are now hung off the wall and so want to avoid chasing the walls again.

thanks
 
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Are the radiators heating up ok? If so don't worry about it, it won't affect the boiler or efficiency.
 
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