i want to add some leak sealer to my radiators but its a sealed system, instructions mention a filling loop. where is this?

david, November 2008

Leak sealer will not fix a leak on a pressurized system.You will waste time and money trying.

chris(retired gas engineer 30 years), November 2008

careful.

Some modern boilers don't get along well with leak sealers, you could do more harm than good here.

BunSlinger, November 2008

Good question...normaly located by the boiler or even part of it...but not always!
Easy solution is to isolate one rad (shut of both valves) and drain it (undo union connecting to rad-after valve) when empty remake union and remove complete bleed valve to create access into rad,use a funnel to add sealant and refit bleed valve,be sure to tighten all fittings and open the valves up again and carry on as per instructions.
If your rads are very old you may not be able to remove the bleed valve..check first.

corgisteve, November 2008