Draining and Filling System

[shankton]

Having decided that Power Flushing my new system is going to be an expensive option I am going down the route of draining and cleaning the system myself.

I simply have a combi boiler and no tanks, to drain the system is it as easy as undoing the draining valve I have outside the house and letting gravity do it's job and the water flow out of the pipe, or do I need to do something with the boiler other than make sure it is turned off.

Once this is drained I then fill the system back up by closing the valve I opened to drain it and turn the tap on under the boiler which I use to top the system up after bleeding the rads??

When I have drained the system once I intend to then add chemicals to leave in there to try and cleanse the system can anyone recommend any?

When I finally fill the system I guess some sort of inhibitor would be good to add again any suggestions?

Thanks

 

[boilerbeasty]

I did this on my combi yesterday and it worked fine. I had added some Fernox SuperConcentrate Central Heating Restorer (about 25 quid, comes in a mastic gun cartridge for adding through a radiator). just over a week ago, let it run around for a while. Then yesterday I drained it out, filled with cold water, drained again etc. It took quite a few goes before the water was clear. I got quite a lot of brown water, and some (thin) bits of black-brown scale. I don't think it was very seriously scaled cos its quite a new system and I descaled the heat exchanger manually. Just didn't have any/enough inhibitor in.

After that, I added the central heating protector, which is the general inhibitor. Other brands are available, but these Fernox ones are handy for adding to sealed systems when you don't have a tank to pour into. More expensive though.

If your radiators are very badly sludged/scaled, you might want to drain the system and remove them one-by-one and stick a hose pipe through them. Bit messy but more efficient than filling/emptying the whole system.