powerflush

bilibala

hi! all

can someone tell me roughly how a powerflush is done so I
know if the job is done properly. What are the benefits
of having one?
thanks!

Daz1

Not sure of the exact procedure but had mine done last week. They attach a pump to the central heating system and I presume it pumps fresh water round the system under pressure to flush out all the sludge and particulate matter that builds up in the pipes, radiators etc

EliteHeat

For open vented systems (those with a header tank in the loft) that are left unprotected, corrosion builds up over time and results in a thick, black sludgy material called magnetite circulating around the central heating system.

This causes a number of problems including poor heat dissipation, premature wear of ancillary components, pumping over etc.

When a combination boiler is installed in a system such as this without being properly cleansed then it will result in the very quick failure of critical internal components such as heat exchangers leading to intermittent hot water delivery.

The power flushing process is designed to remove as much of this contamination as possible with the least possible disruption and mess.

The power-flushing machine is basically a bucket with a powerful pump attached to it, together with large bore hoses capable of circulating water and chemicals at high speed but low pressure. The better machines are able to alternate the direction of the flow which helps in agitating and putting into suspension much of the baked on corrosion.

The process is fairly simple, but quite time consuming. The domestic pump is removed and the power-flushing machine is connected in its place. The header tank open vent is capped as is the cold feed to the system. This effectively means that the power flusher is now temporarily taking the place of both the pump and the header tank.

Next the system is refilled (if it had to be drained) using the PF machine. At this point the boiler is usually turned off and all controls are manually set to allow water to circulate freely around the system. The machine can now be set to dump the easily removable contamination and replace that dumped water with fresh mains water. This process continues until the system appears to be fairly clear.

At this point I would turn on the boiler and allow the system temperature to rise to about 45 degrees. This should result in a bit more sludge being activated and dumped. Heat activated chemicals can now be added and it is extremely important to remember that the dumping process is now temporarily suspended – otherwise you throw away £30 worth of gear.

The chemicals will immediately start to remove the more stubborn corrosion system-wide and it is now time to target individually radiators. All but one radiator is turned off, so the entire force of the PF machine is dedicated to one radiator. The objective is to achieve the most uniform temperature across all the entire surface area of the radiator. A rubber mallet helps to dislodge sludge and the operator should be alternating the flow of the PF machine to further agitate the corrosion. When this radiator is operating satisfactorily, it is turned off and the next one is opened up. This process continues until all radiators have been treated and then the dumping process can restart. This is usually done on a radiator-by-radiator basis, as described before.

When all radiators have been treated, they can all be opened up again and the dumping process resumes until the operator is happy that all seems to be clean. At the point the acidity of the system water can be tested, this should be neutralised until a level of PH7 is achieved. Anti-corrosion chemicals (inhibitors) should now be added to prevent further corrosion and the PF machine can be detached and the system is now reinstated to its original state.

If you want to further safeguard your system then now would be a good time to add a magnetic filter to the return pipework to the boiler.

A properly conducted power-flush is time consuming and very, very boring. The technique to power-flush a combi system is different to that described here. If you see a system being power-flushed via radiator connectors to a temporarily removed radiator then this is being done in the worst possible way and will not be effective. It is unlikely that an average system can be properly power-flushed in less than 6 hours.

An alternative approach to power flushing is to physically remove each radiator and flush outside using a garden hose. This should really always be preceded by circulating a chemical de-sludger for at least a couple of weeks and should really be followed by the installation of a magnetic filter.

Finally, power flushing has the ability to uncover latent defects in the system. It is sometimes the case that the very corrosion that is causing the problem is actually also keeping it leak-proof. When the corrosion is washed away some systems start leaking. This can occur in radiators and also the internal coil within the hot water cylinder. This is uncommon but does happen.

For very badly sludged up systems, you should consider replacing the radiators as an alternative to power flushing. The system should still be chemically cleansed and protected as described before though.

Hope this helps.

plumb1_2

Good post EH, but you should get more sleep, posting @06-50am;)


I would recomend that you ask your plumber for the test results, before and after for the PH & TDS test's, they would be happy to do this.

niteowl_2

Many thanks for very useful and detailed information. :T


I just posted in another thread about whether or not we need a powerflush, at least I know what to expect now if we go ahead with it, or an alternative to powerflush.

Niteowl

http://forums.moneysavingexpert.com/showthread.html?t=83083&page=2&highlight=powerflush

bilibala

Thank you EH for the info.
A friend of mine just had a powerflush done and she said the
corgi engineer took 1hr 45 mins to do the powerflush and used
2 litres of chemical. Does using more chemical mean they can
do it in less time? My friend thinks maybe her system is not that "clogged up" so that's why he did it in the amount time...

gartshore

it was too quick should take at least 4 hours .

plumb1_2

bilibala wrote: »

Thank you EH for the info.
A friend of mine just had a powerflush done and she said the
corgi engineer took 1hr 45 mins to do the powerflush and used
2 litres of chemical. Does using more chemical mean they can
do it in less time? My friend thinks maybe her system is not that "clogged up" so that's why he did it in the amount time...

I would get your friend to ask the plumber to explain why it only took a short time to do the flush. It doesn't matter if he used 10 litres of fluid, it is not possible to correctly do a flush in that amount of time.

Also ask him to do a TDS( total dissolved solids) test, and show her the results, it should be within 10% of the incoming mains sample.
And test the inhibitor for the correct dosage.

You can also get another plumber to do this test (£40 average), and give a report.

Imo she/he has been ripped off.

plumb1_2

gartshore wrote: »

it was too quick should take at least 4 hours .

And that is the min time, which i have not yet achieved. And unlikely to do so.

rdpro

my quote today was from 6hr to a day and a half

gartshore

it all depends on the condition of the system.