Flow / return pipesizes

[DaveJ]

I've just had a new coni built on the back of our house which meant the existing central heating boiler had to be moved.

I've installed a few systems in the past but wanted a Corgi Registered company to do the job (my house!). I was a bit unsure about the pipe sizes he used, took 22mm copper from the boiler but dropped down to 15mm plastic before joining back up to the original 22mm copper pipes before the pump ("Y" system).

His explanation was that the system will still work alright, in fact it'll heat up quicker as there is not as much water

I wondered what the thoughts of other members would be on this, If anything I would have thought it would put more strain on the pump.

Ta Dave

 

[Gees]

I would have done it myself. As for the explanation abt. the pipe sizes? Seems a bit iffy to me. Did ho have his own hay??( for the horse )

 

[oilman]

I wish I had the figures for the heat flow vs pipe diameter, but bearing in mind I think you need 28mm to shift 90.000 btu (if I'm misinformed here please let me know) then you either have a very small boiler or 15mm is not going to allow the heat to move.

 

[COG]

As you said more strain on the pump and more velocity noise if he reduced down too early,the majority of systems would require 22 direct to the three way, but each system is very individual

 

[DaveJ]

Thanks for the feedback - it's confirmed my suspicions. I think I'll replace the 15mm pipe with 22mm before the new carpets go down.

Mind you, the company said it would take one plumber half a day to move the boiler and it would cost me £250. In the end it took four of them two full days (still cost £250) so I don't think I came off too bad - it'd cost me a lot more in time and bruised knuckles!