15mm water main supply

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Hi, My plumber is looking to fit an Ideal Logic Max Heat only boiler which will be supplied by the mains with unvented hot water cylinder and expansion tanks.

He said that my water mains pipe is around 15mm and would prefer 22mm, he said he would fit 22mm where he can. Would incoming15mm main (ground floor cupboard) work ok with the new boiler, any disadvantages ?

I can see a 22mm water supply in the kitchen.

Thanks.
 
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It's all about pressure and flow, especially when it comes to an unvented cylinder. If there is adequate dynmaic pressure and flow a 15mm pipe can deliver suitable flow, only issue is the flow can become noisy.

What is the system suppyling in the way of bathrooms, outlets etc?
 
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Hi. I can see 22mm under the kitchen sink then going to 15mm. I cannot see bathrooms as all pipes hidden but probably 15mm. My incoming main (downstairs cupboard) is 15mm with a 22mm gas supply. The plumber has tested the water pressure with an outside tap to be 4 mbar and around 18 flow. Will probably check further with the plumber who is looking to do the install. Many thanks.
 
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if you already have a 22mm supply, and easier if you have suspended wooden floors with a crawlspace, this might be a good time to consider upgrading your pipes.

do you mean 22mm copper?

if it is a plastic, steel or lead pipe, the bore is smaller due to wall thickness.
 
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The ideal would be 22mm up to the cylinder then 22mm out up to where it branches.

The key here is what the mains will have to deal with all at one time, that's when the dynamic pressure and flow becomes key. You need your plumber (makes sure he is qualified to install unvented HW cylinders - see his ticket - and ensure there will be a LA building certificate delviered once it's installed) to check the pressure and flow when several outlets are open at the same time.
 
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you haven't mentioned what the system will need to supply, bathrooms/baths/showers etc?? The focus needs to be on how many outlets the system will need to supply all at the same time and how much of a delivery drop off you are willing to accept.
 
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Many thanks everyone. I’m all done for now. Great suggestions though.
 

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