no heat in rads Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[ukbill]

hi i have 12 rads in my house all work except 4 which seem to be the furthest from the boiler the flow and return drop to these rads from above and the pipes are hot above but nothing seems to drop down to these rads if i undo a valve from 1 of these rads i get the rad hot by draining the water through but the heat wont stay i have changed the pump and there is no air in the system any help plz

[htg engineer]

Pump on speed III ?

Type of system ?
size of pipework ?

Turn off all but the 4 problem radiators, what happens ?

[ukbill]

the pump is on speed 2 the system is a valiant boiler which is not a combi boiler it feeds a cylinder i have tried to turn off the other rads but still no heat to the other 4 rads i have been told that its possible the pump is not strong enough it is a 15 60 grunfoss the pipe work is 22 mm but reduces to 15mm to the rads and sorry but the rads i have is 22 not 12 would it solve the problem by having a larger pump installed

[htg engineer]

put pump on speed III

for 22 radiators you'll need more than one 15-60 pump.