Is powerflushing likely to solve my C/H problems?

Method 4 involves draining the system first, then using a wet-and-dry vacuum to collect the odd drips.

A radiator half full of sludge and water doesn't drip at all once it it upside down.

Andy

Not all combis do but Worcester Greenstars do.

I don't have much experience of microbore, but could the OP have a problem with blocked manifolds?

If so, a powerflush could help IMHO.

YAPH wrote on Dec 14, 2009:

OK, well that seems to rule out a failing pump as a possibility, which leaves the question of why the system has become blocked up (if that's what's happened) in a relatively short time.

The boiler itself was definitely installed in February 2003 which makes it nearly 7 years old. According to the check list left by the installers, the system was "flushed in accordance with the boiler manufacturer's intructions" with a cleanser described as "Sentinel x 400" and an inhibitor "Sentinel x

Is there anything else in the system I should check (or get checked) before I ask someone to start removing and flushing out the radiators?

Why would a combi have a pump for the hot water?

MBQ

Why would a combi have a pump for the hot water?

The pump is not for the hot water but to circulate the primary hot water round the heat exchanger. This then heats the mains water which comes out of the tap.

Another item which could affect CH circulation is the motorised diverter valve which redirects hot water from the gas->water heat exchanger, which by default goes through the PHE to heat DHW, to the CH. If this valve isn't opening properly you'd get poor circulation through the CH system

The W-B boilers with thermal stores built in use the pump for the hot water.

The only one that springs to mind is the Hiflow 400 which has a heat bank of around 50-60 litres. This still uses the pump/circulator to heat the cold mains water through the plate heat exchanger.

Which model/s are you referring to?

Heliotrope Smith wrote on Dec 16, 2009:

Hey folks! Please I'm just trying to get my C/H sorted out. As far as I know my boiler is a Worcester/Bosch Greenstar HE Combi. The hot water works fine, but the radiators are not getting hot. Is likely to be the pump not working, the radiators/pipes blocked up, or something else?

YAPH wrote on Dec 15, 2009:

That seems like a possibility. I'll mention it to whoever I get to sort out the system. Thanks.

All the hiflow models.

On re-reading most of the thread, it seems to me that you've already received as much useful advice as you're likely to get. What more do you want - someone to wave a magic wand so that it all starts working again?

You've obviously got insufficient flow through the radiators. The fact that

In view of the fact that the microbore pipes have been in place for many years, *they* - and/or any associated manifolds - are the most likely source of the blockage. A power flush *may* shift it, and is less messy than other methods - but by far the most effective solution is the one which has already been suggested by several people. That is, remove and wash out each radiator *and* - more importantly - while each radiator is off, thoroughly flush out the pipework. This is easy with a pressurised system because you can use the filling loop to keep the system topped up, and open each radiator valve in turn until you get a good flow of clear water coming out of it.

Obviously, if you're not going to DIY it, replace 'you' with whoever you employ to do it but - either way - this is what needs to be done.

Roger Mills wrote on Dec 17, 2009:

OK - point taken. I'll shut up now and get it done :-)

In message , Mike Lane writes

I power flushed my system (8mm microbore) by hiring the power flusher for GBP45.00 (weekend rate) back in 2003. It came complete with a box of sludge remover which was charged on the basis of how many bottles were used.

The only problem was getting the CH pump off (the flusher replaces the pump). Other than that I was able to flush the whole system, forwards and backwards to my heart's content until the water ran clear as a mountain stream compared with the coal black sludge that came out when I started.

I also drained/flushed every downstairs radiator individually as a last resort..

I had the boiler replaced shortly after this and noted that the plumber hadn't added any inhibitor to the system. He apologised and tipped a bottle into the header tank! Needless to say, I drained the system enough to get it into the pipes as it was unlikely to get there on its own for some time.

They do not have two pumps.

Frank Spencer wrote on Dec 18, 2009:

Thanks - that's useful to know. I'll probably first try flushing out the radiators and pipes separately as has been suggested. If that doesn't work the power flusher might be a last resort.

I don't think you quite understand. All the Hiflow models that have a heat bank use it only to heat the water. The water in the heat bank stays there, it circulates around the plate heat exchanger via the pump giving up its heat to the mains water.

The water in the heat bank does not come out of the taps.

Hello Mike

Do you know if the plastic piping is barrier-type pipe? That can make a difference. The first types of plastic microbore did not have an oxygen barrier in them and allowed the ingress of oxygen. Which might account for the sludge build-up in the system. It's not that old.

Nothing to easily be done about that if it's non-barrier without upheaval and large expense. You asked for some advice....

As an expert, in your shoes, I would find a local EXPERIENCED powerflushing plumber or, ideally a firm that specialises in powerflushing. As in anything, an enthusiasm for the job counts when it comes to the end result.

Here's what we would advise you to do if you called us. Not that we could help you directly. Your miles away from us.

Anyway.... firstly I let you know that some systems kind of reach a 'tipping point'.

There's no way of predicting when it's going to happen; I've lost count of the number of people who wish they'd known enough about their system to realise that something needed to be done as soon as they had suspicions of problems ahead.

Your local plumber is doing the right thing by recommending that the rads are taken out and flushed out with mains pressure and brute force with a rubber mallet. That's got to be done right.

Then the rads go back on and then the primary to the coil and through the boiler are flushed through with mains pressure.

Important: an experienced powerflusher would know not only when to do a mains flush (sometimes called hard-flush), but also when to stop and go back to a softer approach. Flow rates would be monitored and a judgment made on how to proceeed. In this instance I would not add Hyperflush (Kamco) in advance to cope with the ally heat exchanger in your boiler. Normally yes, for a couple of weeks before cleaning. But, if the flow and return are pretty bad then I wouldn't risk encouraging the rust to float around. The answer is to isolate the boiler, flush through the pipework only (after the rads are clean). THEN, dose up with Hyperflush for a week or two.

Whilst drained down I'd put a Magnaclean on if you don't have one already.

The last step is the flush itself. For more info about that you can look at my site at

That's the belt and braces approach to doing right by your heating system.

If the specialists up your way charge less than =A3600 for THAT kind of service you're a lucky man.

And good luck with it. In your situation, give as much info as you can to whoever you choose to employ. That's a real headstart in the hands of a professional.

If I can help you any more do feel free to ask. I don;t know why more people don't install their own systems. It's not exactly rocket science.

Regards, Ian