power flushing a central heating system

I have been having problems with a few radiators in the house, which do not warm up at all, when the heating is switched on. Having read about all the symptoms of sludge build up, it looks like power flushing is the way to go, to rid the system of it.
I am intending to try it myself, so any help on it will be appreciated. I need to clarify a few points about the process;
1. I have a Potterton Puma combi-boiler. Do I need to check the type of Inhibitor I need to use, before I put it into the system? 2. Do I need to connect the power flush kit, across each radiator and repeat the process for all of them? 3. I have read conflicting theories about the sequence of events for power flushing the system, i.e., drain the system first, refill, add inhibitor .....etc. Can someone please tell me the sequence in which I need to carry out the whole process?
I figured I needed to do this myself........as BG quoted me 800 to do the whole house, which I thought was bit off a rip off, considering that you could hire the equipment from HSS for 75.00 for a weekend + 20.00 for the chemicals.
Any help on this will be appreciated.
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Have you made sure the radiators are balanced? We had 2 or 3 downstairs radiators which didn't get warm. After balancing them they all get nice and hot. I was surprised how the upstairs ones (closest the boiler) only needed to be on around 1/4 turn. They still get very hot, and means that they're not hogging all the flow which meant the furthest radiators didn't get any.
I'm planning on removing and flushing (just with a hose pipe I guess) and fitting TRVs in the spring, but from what I can see now, they may not even need that (but whilst I've got them disconnected, I thought I would try it). Must admit though, the 11' double radiator is going to be a beast to move!
D
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I would strongly advise eliminating other possible causes for your problem before going to the trouble - and expense - of flushing.
The failure of one or two radiators to get hot could be due to air locks and/or lack of balancing in the system.
Try getting some flow to each of the cold radiators in turn by turning all the other radiators off and - possibly - turning the pump up to a higher speed. This will hopefully get rid of any air locks in the affected circuits - moving any trapped air to where it can be bled out. If this *doesn't* work, then you *may* have a blockage.
Assuming that the radiators *do* get hot by this method, but still don't get hot enough when you turn the others back on, you will need to do some balancing. There is a scientific way to do this - which I believe is explained in the FAQ - but the quick and dirty way is to go round the system a few times progressively turning down the lockshield valves on the hottest radiators until they all feel about the same. [You will probably need to turn the room stat up to max while you do this to make sure that the system doesn't shut down in the middle of the exercise].
Roger
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Sign up to BG's service contract that they keep pushing - then tell them to sort out the rads that don't get hot.
!!!!!!!!!!!!!!!
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No doubt their pre-contract check will find this and refuse the contract based on that. ;) Or only offer it after fixing.
D
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No not so. When I put one of my flats on the BG scheme they were prepared to take on an existing fault and fix it in the standard price so long as I signed up for a year for the full service - money well spent as the tenant is a pain !
Andrew Mawson
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Just to let you know, that I do have BG 3* contract, and had an engineer come round to balance the system, but has made no difference. Also clearing sludge is not covered by this contract(SURPRISE!!!). However, taking your advice, I will try and balance the system myself, before I proceed with manually flushing the radiators. If this does not work, what do you suggest I do?
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You need to remove the radiators, and take them outside and give them a good flush out with a hosepipe. And then flush the pipework which feeds each radiator.
Roger
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Incidentally, what is covered by the contract? (or what other exlcusions are there?)
D
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