Powerflushing is it necessary

[jon]

So far I've managed to get 4 quotes for the installation and supply of a new combi/condenser boiler. Two of them recommend a powerflush (one of them being British gas, the other one just happens to have a mate who does them). The other 2 said they will just run cleaner through the system, etc.

Is powerflushing just a gimmick, or is it the best way of cleaning the system prior to the installation of a new boiler. Just for ref, the cost of said powerflush is £250.

The rads are approx 30 years old, single fin, but have no cold spots. When I took one of the downstairs rads off to decorate, I noticed the usual amount of black water (about a third of a cup).

TIA

Jon

[Ian Stirling]

If you're willing to do a little DIY, you can simply remove each radiator, take it outside, and then connect the hose to each side until it runs clear.

[jon]

Cheers Ian,

but would there be any 'gunk' in the connecting pipes, or does it only sit at the bottom of radiators, as that is where it is produced?

Jon

[Ian Stirling]

Mostly, it sits in the corners and crevices of the radiators as I understand it. However, I don't reall yknow.

[bigcat]

good god

Sounds like you just answered your own question.

NT

[John Rumm]

Sounds pretty clean then...

Remember also that once it is converted to a pressurised system it is easy to run a continuous stream of water through the pipework under mains pressure from the filling loop.

One enhancement I made to our system that works very well was the inclusion of a drain point piped through the wall to a gully outside - makes draining the system so easy and mess free in comparison. Combined with the filling loop it also gives a ready path for flushing.

[jon]

An exceptionally cunning idea. Think I'll be doing the same.

Cheers

Jon

[Aidan]

You could hire the power flushing machine and DIY. If you've had a long term corrosion problem, e.g. pumping over, the corrosion products from the inside of the radiators are the black magnetite sludge which tends to lie in the bottom of the pipes. In this case, you'd probably have lost a few rads to rust. Flushing the rads out won't shift this, but it usually clears out any blockages in the rads, better than power flushing can, so it's usually beneficial.

If the system was properly set up & corrosion inhibited, there shouldn't be much sludge at all.

I've seen 15mm od pipes reduced to 7or 8mm bore by sludge. This was a long term corrosion problem. BG had been doing the system maintenance for a long time. The sludge is very sticky stuff, I'm not convinced power flushing shifts all of it. However, it should shift any that is liable to re-locate into your new boiler. If you drain the system and it dries out, a lot of sludge becomes mobile when you re-fill and start the pump.

I'd recommend it. If you DIY the fitter will probably provide no guarantee as to sludge damage. The waterways on modern HE boilers & combi plate heat exchangers are very narrow compared to old cast iron stuff. They are more liable to blockage by water borne sludge.

Good idea, but drain c*ck inside, make sure it can't freeze.