I think I need to flush my central heating system?

[Niall76]

Can someone help me and explain how I can flush the system please?

I have an old Baxi (about 14 years) which isn't a combi. It heats the central heating and hot water (which is then stored in a tank upstairs). There is a small header tank in the loft with an inflow which appears to be operated by a stop cock. ( I assume it only fills very occasionaly as it's pretty scummy looking.

Anyway, I replaced a radiator downstairs as it was hanging off the wall and was pretty ropey looking. Everything is fine with it. It filled no bother and is lovely and hot.

In the bathroom the rad is very rusty on the bottom so I thought I'd replace it before it leaks. I know the flow was poor as it never heats up properly (Barely gets warm). While it's off I thought I'd check the waterflow. I did this by opening the return valve - no problems and plenty of flow. Did the same on the TRV side and it the most pathetic dribble. I checked the little pin and it moves freely. I even dismantled the valve ( I could see doen the pipe) and still the same poor dribble. (It's microbore pipe). I didn't want to shove anything down it to attempt clearing it as the mess I imagine would really annoy my wife.

So, what's the best course of action? I have a drain off valve outside my front door so I think I can drain it easily enough by tying up the stop cock to stop it refilling?

As it happens I suspect that another rad in one of the bedrooms is suffering the same problem. It never heats up properly. It gets warm at the top but is cold at the bottom! The flow pipe is very hot and the return pipe is very cold.

I'm confident with tools and don't mind doing it (plus I really cant't afford paying someone to do it) but I would like to know how to do it first and any stumbling blocks? Also - are there any products I should buy to help?

Cheers

 

[ChrisR]

See
the FAQ
the Kamco site

and you can hire a flusher for £50 or so.

 

[Niall76]

Okay - I've had a read on the open system. To minimise disruption I'm now wondering if I could simply add a product (Fernox?) to clean out the system? If I add the product to the feed tank and then drain off some of the old water to get it into the system? Run the system for a while to get it moving in there. Then, tie up the ballcock at the feed tank in the loft. Then, using the drain valve outside the front doordrain the system down and a lot of crap will come out with it? Then refill the system and see how it goes?

Or is this a totally stupid bodge?

 

[broxy]

Use this via a radiator http://www.bargainplumbingshop.co.uk/pm-853-31-superconcentrate-central-heating-cleaner.aspx

However it's no way as good as having all the radiators off the wall and giving them a good flush through with a hose

 

[Niall76]

Thanks Broxy, I could also take every rad off and flush trough with a hose - I have no problem with that. Should I still drain the whole system as I describe as well as every rad?

Sorry to be a pest.

I had a look at the Kamco site and when I can afford it I'll probably get them to flush out the whole system but it'll probably be next year before I can afford it. So, with next winter to get through I thought this may be a suitable stop gap? I do however get the boiler serviced every year.....