Plumbing problem with radiators

[Tommer]

I have just had a new boiler fitted and also new rads which i fitted my self(rads only) the boiler is functioning great but two of the four rads up stairs will not get hot. they have at one point got warm but fail to get to full temp, Can some one give me some advise as to what the problem may be.

Regards
Tommer

 

[muffking]

Which was fitted first, boiler or rads as the plumber presumably would have bled the system once plumbed in.

If it's a combi and you fitted the rads after the boiler was fitted then check the water pressure in the boiler and bleed the offending rads.

 

[clarkerothwell]

try balancing system, turn hot rads off, see if cold ones get hotter. water will always flow the easiest path, which sometimes might mean not enough hot water to rads furthest away or badly plumbed rads, of course after checking whats been said in other replies.