Is powerflushing likely to solve my C/H problems?

[ARWadsworth]

Old towels or plastic sheet for the few drops that escape.

The water does not pour out like a mains cold tap.

Adam

[ARWadsworth]

You also would not want to face the wife if you ever emptied the black gunge from a radiator into her clean bath.

Adam

[Andy Champ]

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

[YAPH]

Not all combis do but Worcester Greenstars do.

[Mark]

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.

[Mike Lane]

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

100" being used. Of course this job might have been skimped - I've no way of telling.

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?

[Man at B&Q]

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

MBQ

[Heliotrope Smith]

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.

[YAPH]

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

[Mark]

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

[Heliotrope Smith]

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?

[Mike Lane]

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?

[Mike Lane]

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.

[Mark]

All the hiflow models.

[Roger Mills]

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

*some* get hot and that the HW works ok suggest that the pump and diverter valve are ok - and that the poor flow is due to a *blockage*.

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.

[Mike Lane]

Roger Mills wrote on Dec 17, 2009:

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

[Frank Spencer]

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.

[Doctor Drivel]

They do not have two pumps.

[Mike Lane]

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.

[Heliotrope Smith]

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.