Advice needed for central heating pipework

[David Chambers]

I have a 30i Combi gas boiler in my loft the 22mm flow and return coming from the boiler runs along the loft and down the outside wall and back into the house under the concrete floor.Could I cut this 22mm flow and return pipework about 6 feet from the boiler in the loft and reduce to 15mm run it down the inside kitchen wall and into the 15mm pipework going to the kitchen radiator and then fit 2 blanks on the 22mm pipework outside as i do not want to lift part of the concrete in the bedroom floor to get at this flow and return . I am hoping that doing this will make the heat up quicker at start up time. Overall length in 22mm pipework is about 50 feet twice across loft and down the outside wall .

 

[John D v2.0]

No you need 22mm for the main pipes especially on a long run. Also the system should be reasonably balanced in terms of pipe length already, connecting elsewhere you might end up with very unbalanced flow.
If the heat up is slow there may be a restriction or pump issue. Do all rads heat up slowly or just some?

 

[John D v2.0]

John D has obviously failed to note where the pipes are running (unless of course, I have totally misunderstood the question, which is possible - due to the aforementioned reason)

I did notice, but although a bit strange and I wouldn't do it, it's not much worse than running in any other unheated space eg list or floor void, as long as they are correctly insulated for heat loss and protected against frost. It certainly wouldn't make a massive different to heat up time in the absence of any other issue eg low flow.
OP, are the pipes insulated?

 

[FiremanT]

Is that you back, Agile.

Modding all over the place.