Pipe sizes and new boiler

[shayan]

Hi,

I need some advice as I think I have hired a cowboy plumber who came with good recommendations...

Have a 3 story house (via loft conversion).

2 Radiators in Loft (1 Single Large, 1 Bathroom)
4 Radiators on the first floor (1 Large, 1 Medium, 1 Small, 1 Bathroom - All single)
5 Radiators on the ground floor. (2 large double, 2 medium, 1 small).

The job was to repipe all houses inc bathroom, new radiators and install a new boiler.
The boiler installed is a 40kw combi boiler.

A plumber has used 15mm plastic pipe throughout the property with an exception of 2m 15mm copper pipe coming out of the boiler.

Also, the pipe from the boiler on the ground floor to 2 bathrooms on the first floor and the loft is 15mm. Is this sufficient or should it be 22mm? Will 22mm cause flow issues?

My understanding was that we need to use a 22mm pipe from the boiler for hot water radiator feed and only use 15mm when splitting at each floor?

What is the recommended approach for a property of my size?

Thanks for all the help. This is stressing me out...

 

[cross thread]

You are correct,undersized pipe.

 

[shayan]

You are correct,undersized pipe.

How bad is it? Bad enough to have to redo it all or is it liveable?

I am unable to test the central heating as Kitchen/Extension part is not yet connected and the work is not yet complete...

 

[Razor900]

You are correct,undersized pipe.

Really? How can you know that?

Is it a combi or system boiler and cylinder? Would be pointless putting the water side of a combi on bigger than 15mm

 

[cross thread]

I should be resolved now as it will cause problems down the line.

 

[cross thread]

Really? How can you know that?

Is it a combi or system boiler and cylinder? Would be pointless putting the water side of a combi on bigger than 15mm

 

[shayan]

Really? How can you know that?

Is it a combi or system boiler and cylinder? Would be pointless putting the water side of a combi on bigger than 15mm

It's a single Baxi Platinum+ 40kW Combi Boiler with no storage/cylinder installed.

 

[cross thread]

I read it as a 40 kw combi with 15 mm from the boiler feeding all the rads .

 

[shayan]

I should be resolved now as it will cause problems down the line.

I will probably have to pay to get this replaced... What problems am I looking at if I stick with the 15mm pipe from the boiler to all rads?

 

[Razor900]

To be fair its not exactly clear from the first post.

With that small a load it will all work even with 15mm pipe to the rads. It'll just take a little longer to warm up.

 

[shayan]

To be fair its not exactly clear from the first post.

With that small a load it will all work even with 15mm pipe to the rads. It'll just take a little longer to warm up.

Thanks, Razor, that has put my mind at a bit of ease.
So is the work acceptable or should I complain to least switch over the main loop (before it splits at each floor) to 22mm?

 

[Madrab]

The proof of the pudding will be when it's all finished and up an running. TBH though, any more than 2 med sized K2 rads on 15mm will struggle IME. The target is to have all the rads heating up at the same time, on a wholly 15mm system over 3 levels, that will take a while.

The norm would be to have a backbone of 22mm from the boiler to each level and then branch to 15mm to each rad. That will maximise heat up times.

 

[vulcancontinental]

Large singles, medium doubles, bathroom radiator. When did we start using vague adjectives rather than actual kW's, residual pump head, velocity and ∆T to decide on pipe sizes?

 

[Madrab]

I guess it's because a lot of DIY'ers wouldn't know where to start if quoting residual pump head, ∆T's, carrying capacity @ specific velocities, etc.

So it's easier to understand using basics, that being said there could have been a bit more detail as to the actual KW ratings or actual size of all the rads.

 

[vulcancontinental]

I guess it's because a lot of DIY'ers wouldn't know where to start if quoting residual pump head, ∆T's, carrying capacity @ specific velocities, etc.

So it's easier to understand using basics, that being said there could have been a bit more detail as to the actual KW ratings or actual size of all the rads.

Yes, that's for sure but he's possibly been caught out already with someone he suspects is a cowboy plumber.

Solution? Ask, with minimal information, for advice in a group that might or might not be populated with competent people and he can't even look into our eyes or watch body language to get feedback regarding our competence.

Ask around the local area, someone must have had work carried out by a knowledgeable engineer. It'll cost but less than putting it right later.