no heat in rads

by **ukbill** » Sun Mar 23, 2008 7:44 am

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

by **htg engineer** » Mon Mar 24, 2008 4:18 pm

Pump on speed III ?

Type of system ?
size of pipework ?

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

by **ukbill** » Wed Mar 26, 2008 7:33 pm

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

by **htg engineer** » Wed Mar 26, 2008 9:08 pm

put pump on speed III

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