Draining the central heating system

[ambercelery]

Hi.
I have an old four bedroom house and no matter what I do, i cannot get 3 radiators to work. They are not all located in the same area of the house so whilst i dont think the system is balanced properly, I think that the system may well need flushing (having read various web sites) and have some fernox adding to the system to clean and protect it.

My problem comes with knowing how to flush the system. I keep seeing it says attach a hose and drain the system. I can do this fine but it says to turn the boiler off but to leave the pump running. I do not know how to do this. I have a Bermuda back boiler (in the lounge) and a Grundfos pump. When i turn the heating on, the boiler and pump come on but i cannot see any way of turning the pump on, without the boiler - so that the water can get pumped out of the system. Can anyone help me?

I believe once i have done this, I can add the cleaner to the tank, bleed th system, leave it running for a while, and then drain it again. And do it all again but this time adding protector to the system and leaving this in.

 

[kevplumb]

turn the boiler stat off

you shouldn't need the pump on to drain the system

 

[Gasman1015]

It is merely a case of just turning the boiler thermostat to zero, to stop boiler firing.
Do not run the pump dry.

See the Reference section, on how to flush an open system.

 

[namsag]

If you have a gravity system ,there is a good chance the anti-gravity valve is partly blocked and not allowing proper flow around the system. So when you drain and flush system change this at same time. If you have one it will be on flow pipe from boiler usually within 3 feet of boiler .Brass and and about 3 inches long

 

[bab]

some old timers will leave the pump running with the boiler stat on 0 . they fit a drain off on & let the system stay fillin as it is draining. ONLY critieria is to let the drain run slower than the ballvalve so small F/E tank in attic stays full & boiler stat is off. pump would become a little noiseier than normal depending where it is. NOT be the book flushing & is not gona remove anything life the proper job but it dont cost owt either. good idea to add a desludger into the system the week before u do it (instructions on bottle) drain as said for an hour or so then drain completly then refill adding inhibiter. MUST STRESS giving advice on what u wana do not what is text book to do.