powerflush

basill

Friend has a combi boiler producing hot water and running 5 rads
hot water has failed, apparently caused by the use of second hand rads, plumber has quoted £200 for a replacement valve plus £150 labour. A powerflush is recommended for £250 more.

I`m incline to trust the diagnosis as the plumber is known to us but £600 is alot. What is involved with a power flush, is it a DIY job?

B

alanobrien

basill wrote:

Friend has a combi boiler producing hot water and running 5 rads
hot water has failed, apparently caused by the use of second hand rads, plumber has quoted £200 for a replacement valve plus £150 labour. A powerflush is recommended for £250 more.

I`m incline to trust the diagnosis as the plumber is known to us but £600 is alot. What is involved with a power flush, is it a DIY job?

B

This is a subject that bugs me a great deal.
There is a place for power flushing but only if the system is badly sludged and then you need to find out and resolve the reason for the sludging as well as power flushing.

If you get a quote for a new boiler from BG their little leaflet states something like "Many leading boiler manufacturers will void your warrenty unless the system is power flushed prior to installing the new boiler."

This is nothing short of BS, the manufacturers generally state the system should be adequately or correctly flushed before installing the boiler. I have forwarded that particular leaflet to trading standards for them to look into.

You can DIY powerflush if you wish. You can hire one from HSS hire http://www.hss.com/ for £50 for a day plus your cost for the chemicals. Search for item code number 51610 on their www site.

You could just remove the rads and flush through with a hose in the garden, however the lack of hassle in having to remove the rads is where power flushing comes into its own.

But only if the price is right..........

robowen

Thats right, most manufacturers ask for flushing out of the system. This to remove the system of any residue from soldering. If using powerflux to solder joints, powerflux is corrosive and can do lasting damage if not flushed out.

When fitting new boilers to old systems, plumbers should flush out the system at commisioning. It should be done again after a couple of days and then inhibitor added.

A lot of rogue plumbers try to get everything done in a day and are not bothered about what happens in a couple of years time.

I assume the valve you mentioned is the divertor valve ?? if so, then the diaphram is replaceable to most valves and should not need a complete replacement - unless completely rusted up. Should take him 1-2 hours max(allowing for tea break !).

rob

basill

Thanks for that info much as I had thought. The job was done on the cheap ( not in the long run!), the boiler was new or nearly new the rads were 2nd hand, all worked ok for a couple months, Original installer too unreliable to contact again. It seems cr*p from the old rads has damaged the boiler. The powerflush is recommended to prevent the same thing happening again. I will pass the diaphragm suggestion on though. Corgi plumbers dont come cheap these days so maybe best to have an iffy install properly sorted to prevent further visits?

B

Poppycat

I think we had a power flush early this year after several months time had elasped for a new condensing boiler, replacing an old combi, we kept the old rad. Basically he fiited a hospipe to the rad in kitchen, boilers on 1st floor. Connected that up to a big round thing like a big hoover outside, It flushed the rads out before replacing it with clean water I think he put some stuff in to keep rads from going rusty. It took about 4 hours of work.

Avoriaz

Ian, would power flushing be able to cope with and solve an airlock in our system.

We have a normal 2 storey house with full c/h. A less than competent plumber made some modifications to our heating system with the result that we now have an airlock in the system severely restricting the flow to the radiators in the front bedroom and the front room immediately below.

We were having an extension built and we needed some additional radiators. While he was doing this work he managed to reverse the water flow to these two radiators at the front of the house. This would not normally be a problem but we had thermostatic valves on the radiators so the t valves were now on the return side and no longer on the flow side as required. We did not want him to swap the valves over as this would have been inconvenient so we asked him to swap the pipe work over and correct his error. He said it would be easier to swap the pipes over in the front bedroom so he lifted some floorboards and swapped the pipes over there. He has obviously introduced some high spots in the pipe work that have trapped air and are blocking the water flow.

It was early summer so we did not notice the problem until the following winter, by which time we had a new fitted carpet in the bedroom. I have tried to get rid of the air by closing down most of the other rads and turning up the pump but this has only partially worked. I really want to avoid having to lift the carpet and boards to fix the problem.

The c/h layout is fairly normal. It is a gravity fed system from a tank in the loft. The boiler is on the ground floor and the pump in the airing cupboard on the first floor. The two problem radiators are fed by a pipe run from the airing cupboard under the first floor board. This feeds the bedroom radiator and there is a vertical feed down to the ground floor radiator.

Would your power flushing system be able to clear the air out or would we risk damaging the system. Also, if it did work, is it likely that air would soon become trapped again and render the exercise pointless?

We will lift the boards and do the job properly if we have to.

Thanks

plumberian

Hello Avoriaz

Apologies for the delay. I don't log on regularly to this forum so if you've been waiting please do accept my apology.

Although powerflushing can remove airlocks (usually) it would be an expensive way of doing it and unless you ahve some other problems that could be sorted at the same time I would not advise you to go down that route.

In addition, if your system is prone to airlocks the likelihood is that you'd end up with the same problem at some time in the future. In the circumstances I'd say go ahead and have the work rectified so that there are no high points in the pipework.

As for any risk of damaging the system..well there is a theoretical risk of removing so much rust and/or sludge that a pinhole leak in a rad could be uncovered. That's never happened to me (yet, touch wood) and I take the view that of there is an inherent weakness to a rad then better to have someone there when it goes because it could, in theory, go at any time.

To recap, I think you'd be wasting your money if you had a powerflush done just to get rid of the airlock.

To Plumb1, here's an example of what I mean.

Last week I did a job for a customer who has a Glowworm conventional condensing boiler that was installed a year before she moved in ( two years ago). An extended warranty had been taken out so when the boiler started cutting out she called them and they came out and replaced the heat exchanger which was partially clogged with large rust particles.

Once they did that she was told by their service engineer that if she did not have the system powerflushed (and preferably a Magnaclean installed) they would not/would be very reluctant to replace another heat exchanger.

The lady runs a very tidy house and didn't want to take the chance of that and so called me in to powerflush it and have the magnaclean installed.

I think it would be a good idea to put a complete list of manufacturers on my site . I'm having a revamp done shortly so I'll see if there is time to have it done at the same time and will post a copy on this forum.

plumberian

Poppycat wrote:

I think we had a power flush early this year after several months time had elasped for a new condensing boiler, replacing an old combi, we kept the old rad. Basically he fiited a hospipe to the rad in kitchen, boilers on 1st floor. Connected that up to a big round thing like a big hoover outside, It flushed the rads out before replacing it with clean water I think he put some stuff in to keep rads from going rusty. It took about 4 hours of work.

A word of warning.

A powerflush should wherever at all possible be done by connecting to the pump valves ( a minimum pipework size of 22mm).

If it's connected to radiator pipework then the amount of water that can be pumped around to shift stuff is immediately reduced as radiator pipework (in all but the rarest cases) is only 15mm.

Avoriaz

Ian, thanks for your reply.:beer:

I take your point about the expense of power flushing when it might not even solve the problem or might just solve it for a while.

However I really don’t want all the aggro and disturbance of removing fitted carpets, underlay and floorboards etc. The site is under a bed in the front bedroom so doing the job properly will be a real pain.

Maybe my system would benefit from a power flush anyway and, if it fixes the airlock, that is an added bonus. I think I would be prepared to spend the money and hope for a long lasting cure.

If I understand the process correctly, I can hire a suitable pump, and fit it instead of my normal pump and then power flush the entire system. I have lockable valves either side of my pump and that is easily accessible in the airing cupboard.

Maybe I will get a firm in to do it but I normally like to tackle things myself. Sorry, I’m not a very good customer for guys like you. In your opinion, what is a reasonable charge for doing this. I live in Surrey which tends to be pricey for plumbing services.

Thanks.


Edit: a power flush kit costs £51 plus VAT to hire from HSS. Chemicals are extra. So, for well under £100 I can DIY a power flush and hopefully sort out my airlock. I think it is worth doing.

Ian, please don’t be offended that I am not taking your good advice. Even if the airlock problem remains or returns, at least I will know I have a nice clean c/h system and as you say a power flush may alert me to pinhole problems etc. Thanks again for taking the time to post. It is appreciated.

plumberian

If you;re happy doing it then you will save yourself a sizeable chunk of money.

The price depend entirely upon how big your system is, but to give you a guide, if I were to travleo up from Wiltshire it would be a minimum of £450.00.

Hope that helps.

All the best and good luck, Ian

vertical_fool

There's a good guide written on www.diynot.com for doing a mains flush. I hope to do mine in around two to three weeks.

Vertical