DIY Doctor

Main navigation

Results after a power flush?

Postby Hadyn98 » Sun May 10, 2009 9:19 am


I was wondering what the water in the radiators should look like after a 'professional' power flush has been done?

I drained the entire system (to change the pump) after a company had been in to do a power flush, and the water coming out was brown. After refilling the system I went to look at the tank in the loft and it was still brown. Feeling around, I scooped up what must be metal deposits etc.

Is this normal? I was told by the engineer that the water was running clear after the power flush...

(In addition, most of the radiators were completely turned off, and I had to turn them on again before they heated up.)

£350 and I'm not very impressed.
Rank: Labourer
Progress to next rank:
Posts: 3
Joined: Sat May 09, 2009 4:57 pm


Simply Build It

Postby willie gas » Sun May 10, 2009 2:23 pm

hi i have never piped open vent pipe into the water in tank in loft, as it could drag dirt & crap into system. after power flush water in system will still be brown but most of the sludge should have been removed. it sounds like your c/heating system is piped up wrong.a good way to pipe up your system so you dont have pumping over or drawing air in is follow flow pipe from 3 port valve (the pipe which gets hot first) 1, 3 port valve 2, pump 3, tee which should be 22mm cold feed from tank in loft followed very close by 4, 22mm open vent pipe which goes up & over the tank in loft. all this might be in your airing cupboard. if the flow pipe is not arranged in that order you will get lot of air, noise & sludge. the sludge is the rotting of your system. GOOD LUCK.
willie gas
Rank: Apprentice
Progress to next rank:
Posts: 10
Joined: Fri May 08, 2009 5:24 pm

Postby rosebery » Sun May 10, 2009 4:00 pm

How long did it take him to do the powerflush? How long ago was this done? A week, a month, a year ago or what?

If you have "brown" water in you header tank when you drain it the "brown" water will come out at the bottom.

A Powerflush won't clear the F&E tank out but I would say that that should have been done although it doesn't seem to have been.

Brown water indicates pumping over. Go in your roofspace and see if anything comes out of the vent pipe. If it does what is happeneing is that you are cycling hot water through the F&E tank and drawing oxygen into your system which is causing rust (= brown water) as it rots your radiators.

There are many thread here on the subject of pumping over. Do a search and you'll find both causes and solutions.

Rank: Project Manager
Posts: 2022
Joined: Wed Sep 26, 2007 8:55 pm

Postby oakesave » Wed Aug 12, 2009 7:35 pm

I came to ask the same question. Had a new combi boiler fitted three weeks ago. Not used the central heating yet. Removed the radiator in the room with new boiler to re-decorate and find water in the radiator is black with small particles. Is that normal?
Rank: Labourer
Progress to next rank:
Posts: 1
Joined: Wed Aug 12, 2009 7:27 pm

Postby plumbbob » Sat Aug 15, 2009 11:10 pm

It does depend on how much black is in the water. No central heating is going to be totally clear, but any large quantity of sludge can damage a condensing boiler's delicate heat exchanger.

Many engineers recommend fitting a Magnaclean to remove and prevent a build up of particles.
Rank: Project Manager
Posts: 1891
Joined: Wed May 07, 2008 9:59 pm

Postby DEEARR2 » Sun Aug 23, 2009 10:23 am

It is standard practice and in accordance with manufacturers instructions that all new boiler installations have the heating systems totally flushed out prior to commissioning. Failure to comply could invalidate the warranty and have detremental effects on the boiler parts in the short tern. It would also be expected that a corrossion inhibitor be installed to help prevent sludge forming. I would suggest you refer to the benchmark notes left by the installer and confirm the system had been prepared for commissioning. If this is not available contact the installer. There is no way that the system water should be in the condition you mention in such a short period.
Rank: Ganger
Progress to next rank:
Posts: 160
Joined: Sun Oct 12, 2008 8:49 pm

Display posts from previous
Sort by
Order by

  • DIY How to Project Guides
  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!

  • Related Topics