Power flushing CH system

[Guy Snape]

I've just had a new central heating pump put in as the old one was leaking to earth and tripping the rcd switch.

The plumber said there was probably a lot of sludge in the system and this could have damaged the old pump, and I should think about having a power flush. However, when he drained the system, the water coming out of the hose looked clear, and a quick google on this group suggests that a power flush isn't necessarily worth doing.

Is it worth my taking a radiator off and flushing it myself to check for sludge? Or is the clear water (although I only checked it once during the process) from the draining down sufficient proof that it doesn't need doing? Any other suggestions I haven't thought of are very welcome

- this is a long way from being my area of expertise.

- guy

[Phil L]

If the rads are noticably cold at the bottom when the heatings on high, then they may need flushing.

I did two in a couple of hours yesterday, simply turned of the flow at each end, uncoupled and with the help of a friend, carried into the back yard for a serious blast out with the hosepipe - the sludge was the blackest of black, and my jeans, despite three washes, are still stained. One of the rads was particularly bad, and judging from the sludge on the patio, there must have been at least a few kilos of the stuff in it - only the top 2 inches ever got hot, and this is a 6 foot long radiator!!

[John]

Presumably some parts of the pipe runs are even lower than the bottom of the radiators. Whilst the flow through a pipe may have a purging effect, you will also have sludge settling in the pipes.

[Ed Sirett]

That's when things start to go really wrong.

[Phil L]

The ones I flushed seem to be working perfectly, although I agree that, as my pipes are lower than the rads, these too must be full of shit. I still have one radiator downstairs to do (upstairs ones are fine), but surely, emptying the downstairs ones, must in some way help towards clearing the sludge in the pipes?

[John]

I have never had a great deal of sludge when I have removed radiators for decorating - any sludge removed must help - I wish systems always had a sludge trap that was easily serviceable.

There must be a heck of a lot for it to effect the radiators.

[Ed Sirett]

Indeed so. When there is that much a sludge trap isn't going to hack it. Mostly sludge isn't a problem especially with modern systems but when it give symptoms then the matter is usually beyond simple measures.

[Garry]

ide quoted text -

Would a regular dose of cleaning chemicals and new concentrate each year, stop the build up of sludge.

Garry

[Ed Sirett]

Sludge does not build up in any significant quantities until there is a problem. Under normal circumstances all that is needed is to maintain the inhibitor concentration, oxygen (gaseous or dissolved in fresh water) will not be entering the system anyway, hence no corrosion and no sludge.