Dirty Water in Radiators after Flush

Roaming

Hi all!

We've had work on going in our attempt to revamp the house we bought two months ago. Part of this included having CH system flushed, radiators bled, refilled and balanced. The reason we needed this done was because at random points in the day/night one/some of them would start knocking/banging/sounding like a motor had gone off. Sometimes this would happen on its own and sometimes after use of hot water somewhere in the house.

The plumber we engaged advised that a system flush, refill and rebalance and bleeding of radiators would sort out the problem. The problem still persists however!

His next guess, the TRVs must be bust. He unscrewed one of the TRVs - an old Honeywell make - and pressed down on the spindle which went down with a 'clunk'. We were told this shouldn't happen because this means that its busted and needs replacing.

QUESTION: Is that what the above that should imply?

Also, we drained one of the radiators today to take it off the wall in order to repair and decorate behind it. Most of the water came out greyish and when we tilted it, the last bits came out very dark grey like oil. Should this be happening after the system has been flushed?

And on that note, is there a difference between flushing a system and power flushing a system?

Your help and advice would be much appreciated!

Many Thanks!

keystone

Roaming wrote: »

His next guess....

Oh thats not good.

QUESTION: Is that what the above that should imply?

Would you mind rephrasing the question - its making my head spin.

Also, we drained one of the radiators today to take it off the wall in order to repair and decorate behind it. Most of the water came out greyish and when we tilted it, the last bits came out very dark grey like oil. Should this be happening after the system has been flushed?

Inevitable. The only way to get all the gunk out of the rads is take them off the wall and flush them through with a hose out in the garden. Nothing to be overly worried about. Don't forget to top up the inhibitor when you refill it.

And on that note, is there a difference between flushing a system and power flushing a system?

About £ 500.;)

Cheers

Roaming

Sorry about making it sound vague. Would a 'clunk' noise on pressing down the spindle (from where he unscrewed the TRV) mean the valve or the TRV is busted/broken?

Roaming

And 500 pounds ok, but in practice what is the difference between the two flushing/power flushing?

SailorSam

If you're going to take them out into the garden to flush, don't forget to slide them down the stairs upside down. Otherwise all that sludge will come out while you're moving it.

keystone

Roaming wrote: »

Sorry about making it sound vague. Would a 'clunk' noise on pressing down the spindle (from where he unscrewed the TRV) mean the valve or the TRV is busted/broken?

Not necessarily it may have been stuck due to carp and just went down with a bang when he leant on it. Is he implying that the springs are knackered and the valves are bouncing thus causing a banging noise?. Not entirely convinced meself but he's seen it and felt it and I haven't.

Sorry to say this but I've got a feeling your system is still full of carp and the flush hasn't cleared it. Banging could be scaled up boiler, failed boiler stat, failed pump, poor circulation due to air or sludge or a magnetite blockage.

Could you describe your system please in some detail including make/model etrc of boiler Have you got an F&E tank in your roof? If so do me a favour - pop up there and tell me if the water in it is cold or not - whilst system is hot and running of course.

Cheers

keystone

Roaming wrote: »

And 500 pounds ok, but in practice what is the difference between the two flushing/power flushing?

With the sort of flush you've had done them a cleansing chemical is put into the system and allowed to circulate for 2/3 weeks. The idea is that this breaks down the sludge and when the system is drained most of it (being in suspension) flows out. The system is then flushed through with with clean water. Such a flush will not remove a solid magnetite blockage.

A powerflush is done over a matter of hours though (at least 4/5). A more virulent chemical is introduced and a bi directional powerful pump attached. The combination of the chemical plus the back and forth operation of the pump removes the majority of the carp. But it must be done properly or its a waste of time. This type of flush won't remove a solid blockage either.

Thats a very simplistic description but hope it helps.

Cheers

Ruski

IMHO a clunking TRV is an old uni-directional valve that has been fitted on the return pipework - check for an arrow indicating direction of flow on the valve body - the flow of the water suddenly pops the valve down on it's seat by forcing behind it, not against it.

Have a look and let us all know.

HTH

Russ

Roaming

Hi Ruski!

I've checked and the TRVs are on the end where the arrow points inwards towards the radiator. Is that the correct end then?

Also, I have tried the 'pressing the spindle' thing again and there doesn't seem to be the same 'clunk' when it goes down or on return.

What could have caused it to do so before?

The radiators still make the vibrating/rattling/motor like sound albeit a bit less since we now have the heating turning on and off throughout the day because of the timer we have has added. Not really sure what is going on. :-/

Roaming

keystone wrote: »

With the sort of flush you've had done them a cleansing chemical is put into the system and allowed to circulate for 2/3 weeks. The idea is that this breaks down the sludge and when the system is drained most of it (being in suspension) flows out. The system is then flushed through with with clean water. Such a flush will not remove a solid magnetite blockage.

A powerflush is done over a matter of hours though (at least 4/5). A more virulent chemical is introduced and a bi directional powerful pump attached. The combination of the chemical plus the back and forth operation of the pump removes the majority of the carp. But it must be done properly or its a waste of time. This type of flush won't remove a solid blockage either.

Thats a very simplistic description but hope it helps.

Cheers

Hi Keystone!

He didn't do a powerflush, that is for sure. He also didn't however talk about having put in any chemicals which needed to be drained a few weeks later either. I think he may have just drained and refilled the system but can't say for sure. :-/ He did whatever he did in a matter of an hour or so.


Is there any way of verifying what he did?

keystone

Well drained it he may of. It doesn't sound as though it was flushed for one minute. Post #6, paragraph 2, first sentence. Sorry but I think you still have sludge/a blockage in the system. Did you check the header (feed and expansion) tank?

Cheers