wrong size pipes?

[duj666]

hi my plumber has run 15mm pipework from 1st floor to ground floor which then feeds 4 rads all doubles 2 * 1000*600 1 1200*600 and 1 1400*600 is this acceptable or should it be 22mm ? any advice would be great.

 

[Agile]

Well I would have done it in 22 mm but I am like that!

The general rule of thumb is 15 mm to no more than three rads. Most people say a max of 4 kW on 15 mm.

But if its well balanced and a condensing boiler then I dont thinkt here will be any problem.

Tony

 

[duj666]

thanks i'ma bit concerned because the rad on the end of the run is a 1400 by 600 double and we have to have it on max to get it warm sorry forgot to say its a combi vailliant 837

 

[Agile]

Did this plumber do any balancing?

 

[duj666]

boiler was fitted downstairs with pipework running up to first floor with 22mm pipe for about 1 metre then all rads upstairs and downstairs come from 15mm 10 in total. he has agreed to change upstairs to 22mm but says the feed downstairs in 15 is fine I just want to make sure he gets it right this time.

 

[Whitespirit66]

By doing a total of the output of all the rads on this part of the system, I would say that 15mm is undersized. I would definitely have done it in 22mm.

The output of the 4 rads comes to approx 26,000 BTU, and 15mm is only really good for 15,000 BTU. Therefore, you may struggle to get them to heat up properly.

 

[duj666]

thanks Ive had the plumber back out and he has finally agreed to replace with 22mm pipe thanks for your help.