Non-motoring > Heating- draining radiators Miscellaneous
Thread Author: Bobby Replies: 14
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New Sat 21 Oct 23 23:33 
 Heating- draining radiators - Bobby
Friend lives in a small 2 bed mid terrace. Has a system boiler ie has hot water tank.

Turned on her heating first time this year and she says the bottom of all the radiators are cold. Too are all hot.

I am guessing this is maybe due to sludge in system and going to involve draining system down?
She has a drain valve outside her back door.

Any advice on what process/steps to follow?
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New Sat 21 Oct 23 23:50 
 Heating- draining radiators - smokie
Probably needs a power flush. Otherwise it'll be a matter of taking off each rad and flushing it through with the hose - and then you won't have flushed the pipework or hot water cylinder etc.

If you are savvy enough to connect it you can hire them for a weekend for not too much.

Remember to put some inhibitor in when you're done. You could also fit a magnetic device in the circuit to better manage further build-up.

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New Sun 22 Oct 23 06:27 
 Heating- draining radiators - martin aston
Either method is a bit of a faff so allow a whole day. Power flushing still requires each rad to be dealt with individually. Sticking the power flush into just one rad won’t clear the whole system. The labour involved in doing them properly is why plumbers charge a fair bit. Also I think they recommend sticking in a pre flush solution a few days before to loosen the gunge but I may be out of date on that.

Taking off rads can be tricky if it’s not something you’ve done before. I asked my plumber to flush one of mine last year while servicing the boiler but he timed out and left it to me. “Just take it off the wall” he said. Easier said than done as the micro bore was flexing whenever I tried to loosen the connection. I gave up to avoid making it a worse situation. Maybe I was unlucky but don’t underestimate the scope for rad removal to be tricky and messy for we amateurs. You can bet that in a whole system most rads will be easy but a few might be a bit of a challenge.

One tip is that standard washing machine hoses use the same thread on their connections as the rads. So, once off, you can attach the hose to the rad with the other end to a standard outside tap and flush the rad through.
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New Sun 22 Oct 23 12:03 
 Heating- draining radiators - smokie
The power flush does the whole system not just one rad.

I put in some juice some weeks before to loosen things up.

You them shut every radiator, run it forwards, then backwards, then forwards (and on and on) till the water is running clean. Then you open one rad (I think they recommend the first in the system) and do the same, close that and do the next - and so on.

it does take hours but done properly imo it has to be much more effective than trying to break down the gunge with chemicals and draining.

There are many videos on how to do it - here's a manufacturer one www.youtube.com/watch?v=TJn9LrRfXm8

Always worth remembering that dislodging the sludge can expose "new" problems - i.e. leaks! But it can also make a system considerably more efficient and cheaper to run.

.

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New Sun 22 Oct 23 17:13 
 Heating- draining radiators - martin aston
Thanks for that smokie. I had a useless plumber who just attached the power flush, opened all the rads, and did none of the shutting off and back flushing you describe. He didn’t do the rad by rad approach you rightly describe.
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New Sun 22 Oct 23 08:17 
 Heating- draining radiators - Zero
Done it to my place a couple of times over the years. Its a whole day job, isolate each rad, disconnect, carry outside, flush with hosepipe, carry in, reconnect, fix leaks. Messy too, black Scheiße comes out the rad when disconnected, its capacity to stain unparalleled.
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New Sun 22 Oct 23 09:07 
 Heating- draining radiators - bathtub tom
Done it once, the black stain in the garden took years to disappear. Not too long after, the worst rad sprung a leak at the bottom and flooded the place. I suspect the sludge was contributory.
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New Sun 22 Oct 23 09:55 
 Heating- draining radiators - tyrednemotional
...taking the radiators off and flushing them individually is a pig of a job, and then getting them back on again without a leak (particularly if they've been nipped up tight before) is even worse.

I suspect if the symptoms are bad the following may be insufficient, but given the foregoing I'd be inclined to try a chemical solution first. The cost and effort are significantly less so worth an initial try.

A good dose of cleaner run for some weeks (subject to instructions) and then drained down (you should be able to check whether it has improved things) and then refilled with water and inhibitor avoids removing the radiators and limits fiddling largely to the drain point.

I've tended to use Adey MC3+, which you can dose through the header tank, or via a pressurised version through a radiator bleed valve. (The latter is rather more convenient, as it goes straight into the system without draining, but can be a bit challenging to inject, the former requires access to the header tank, and an initial partial drain to get it into the radiators).

It's worth cleaning the header tank as well on final refill, as with contaminated systems they're often "grungy".

As an example only, (Other Screwfixes are available ;-) ) both versions available here (the drop down menu gives the header tank version).

www.toolstation.com/adey-mc3-central-heating-cleaner/p73824
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New Sun 22 Oct 23 10:10 
 Heating- draining radiators - sooty123
Messy too, black Scheiße comes out the rad when disconnected, its capacity to stain
>> unparalleled.
>>

Same here, stained a rug getting the rad outside. Not possible to get the stain out.
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New Sun 22 Oct 23 18:48 
 Heating- draining radiators - Bobby
Thanks for all the feedback.

Decided it’s definitely a job that I don’t want to volunteer to help with. Previously it’s the type I would try and then cause a leak or drop gunge on a carpet or whatever and end up making things worse and feeling guilty.

Experience now tells me to walk away!
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New Sun 22 Oct 23 19:57 
 Heating- draining radiators - Kevin
Sensible to walk away from that. Too much risk.

Though it seems a bit odd that all the rads are exhibiting the same problem at the same time. Any sludge usually gets deposited where the flow is weakest which tends to be one particular radiator showing symptoms first. The sludge doesn't solidify so it can sometimes be cleared by turning off all the rads but the dodgy one, opening both valves fully, switching the pump to max and then whacking the bottom of the rad for a few minutes to disturb the gunge and see if it clears. That used to work with the hallway rad in our previous house. Our current house has a drain valve fitted to each downstairs rad so changing rads has been a bit easier for me.
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New Sun 22 Oct 23 22:53 
 Heating- draining radiators - CGNorwich
Worth getting it done professionally but it’s not cheap. Expect to pay from £400 to £900 for a chemical flush.
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New Mon 23 Oct 23 11:46 
 Heating- draining radiators - Manatee
Cost me £1000 a few years ago. They didn't disconnect any rads. Just circulated the fluid whilst banging the rads with rubber hammers. The charge included fitting a magnetic filter. It did help.

Prior to the 60s, most houses didn't have CH. From the mid -late 60s onwards, there was a huge industry fitting CH on 10 year home improvement loans. There must still be millions of homes with 40-50 year old heating circuits full of sediment. Mine was a microbore system fitted in the 70s. No amount of flushing was going to make it perform well.

In general they don't seem to be fitted with any regard to future replacement, possibly because that would have been difficult. To replace the underfloor circuits in our new house would require digging up screed and removing ceilings.
Last edited by: Manatee on Mon 23 Oct 23 at 11:48
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New Mon 23 Oct 23 21:10 
 Heating- draining radiators - slowdown avenue
taking a large rad off the bracket will be a 2 man job
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New Mon 23 Oct 23 21:42 
 Heating- draining radiators - James Loveless
Eighteen months ago, when we started to have circulation problems that eventually led to a new pump and new boiler, our plumber (and assistant) took off every single radiator in the house (all eleven), turned it upside down and flushed it with a garden hose while using a rubber hammer. This failed to clear the lounge radiator, which we replaced. There was an huge amount of crud on the drive, looking like coffee grounds. Fortunately there was no staining.

The plumber didn't think it was worth doing a power flush. After all that, there had to be several cleanings of the magnetic filter. Since then, no problems.
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