I'd drain, then remove the rads, and then flush properly wiht the rads out of the house. Bear in mind that you will still need to flush the system when the rads are back in.
If you have enough stuff in the radiator, you'll largely just push it forward to the next place it gets caught if you do it in situ. As I guess you've found out from last time.
Alternatively, especially if you cannot get the rads off the wall, disconnect the pipes and reconnect a hose pipe to each end. Then flush it.
I did once do this to a whole system, but it took a lot of water pressure to push water all the way through the whole system, it then took ages until the water ran clean, and even then I was turning radiators on and off one at a time.
Best one at a time if you can bear it.
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A very common fault. Usually caused by corrosion after not using an inhibitor for many years.
Cheap way: Remove each radiator in turn, carefully take outside (you know about the staining properties of iron oxide!) and flush out with hose. Drain and flush running water through as much of the pipework as possible. Reinstall all radiators, empty a supply (one can or bottle should be sufficient for a 4 radiator system) of flushing compound (sentinel and fernox do one) into header tank or one of the radiators if it is a closed system. Refill with water and run upto full temperature for a number of days. Drain down again flush several times with fresh water. Refill with inhibitor (again sentinel or fernox). Bleeding and getting rid of air locks may be required at each of the intermediate stages. If you want more detail I can give this but would need to know type of CH system (sealed or unsealed etc).
Moderate cost: Hire a flushing pump and chemicals, do much same as above.
Costly way: Call BG (or your favourite heating systems operative) and ask for a quote...likely to be in the £500-600 pound range
Warning: if the system is very badly corroded then flushing and cleaning may expose small leaks. Left well alone the leaks will still happen but not at a time of your choosing!
hth
StarGazer
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Thanks. It was BG who flushed it last time, a Kamco flush IIRC at about £400. Seemed very thorough, he turned everything off, replaced my pump with the flush pump, flushed it backwards and forwards time and time again until it was clear, then turned on one rad, flushed till clear, turned it off and so on. Took about 4 - 5 hours IIRC, and cleared a strange noise and an overflow which we had been suffering. He put inhibitor in afterwards.
System is actually 9 rads so will require a fair amount of chemicals I guess. When you say "flush several times with fresh water" in the cheap option, do you mean somehow attach a garden hose to the system or something more exotic?
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There may be some info in
www.honestjohn.co.uk/forum/post/?t=19812
I would take the rads off and flush them individually.
My approach is as follows
Get some heavy duty polythene from a builder?s suppliers or from a local builders site. I then lay it under the rad and curl it up the skirting and tape it to the skirting as high as possible and secure with masking tape or similar. I use a 1 litre plastic ice cream container or similar container to catch the liquid and a bucket. When you shut off the valves try to note how many turns on the non knob end so that you try to retain the balance of the system. I then undo one nut and allow the contents to drip or run slowly into the container. It may help to undo the bleed valve and or use a lever to ease the pipe away from the rad. Decant into the bucket at regular intervals. As a precaution I always do up the nut in between times. When the rad appears empty I repeat the process at the other end in case the rad is not level. I plug each outlet with kitchen roll or rag before I move it from its site. Carrying it upside down reduces spillage risks.
To flush it, stuff the hose in and blast away. Invert the rad, fill it and the empty it and you shake it all about. Keep going till it runs clear.
The black gunge ( Magnatite?) will stain so be wary where you do the flushing.
Not sure what the legalities are for proper disposal.
My system has two external drain cocks to assist draining / flushing. A modification to consider for your system?
Some light reading from a trade forum.
www.gas-news.co.uk/cgi-bin/discus/board-auth.cgi?f...l
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The quickest way to remove a rad:
Close both valves.
Bit of kitchen roll under each connection.
Loosen the fittings. Might get a slight dribble.
Lift the rad slightly to get off the wall brackets.
Swing the rad down so it rests on the floor.
The connections are now the highest point and can be undone with minimal spillage.
Carry the rad outside upside down.
You can do this when decorating to make life easier. Just tighten the fittings with the rad on the floor to stop any leaks.
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Just to add my two euro's worth.
Nick here has it dead right. That is the perfect technique to remove radiators. You need enough play in the feed pipes of course to lift it off the brackets but otherwise its perfect.
Lifting off and flushing out each rad in turn is the best way.
Never ever use the flushing agents that want to stay in the system for a day or two. I tried it one, it flushed out crap and deposited it in the pump. (which no longer did)
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The quickest way to remove a rad: Close both valves. Bit of kitchen roll under each connection. Loosen the fittings. Might get a slight dribble. Lift the rad slightly to get off the wall brackets. Swing the rad down so it rests on the floor. The connections are now the highest point and can be undone with minimal spillage. Carry the rad outside upside down.
Easier said than done. BEWARE
Radiators are not light or easy to lift or carry especially full and down stairs.
I would empty first to reduce the risk to my back.
Obviously if you have a helper it is better. I have to do it solo.
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What a fantastic idea, swinging them down. I know these are going to be ultra messy and that might just be the answer.
I'm inclined to go for the cheap option first, in the New Year. I'll start by cleaning the 3 problem rads (well, only 2 now, as I did one yesterday) and giving it a flush - I do have a couple of drain points but again am concerned in case there is some seepage where I attach the hose. More polythene methinks.
Thanks again guys
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If it was power flushed & treated with inhibitor not too many years ago, and it has clogged up again, then I'd reckon that there is a defect that is allowing air to get into the water(F&E tank incorrectly set up, pumping over, negative pressure at pump inlet, etc., etc.). The black magnetite was formerly the inside surfaces of your radiators. Power flushing has simply removed the corrosion products but has not identified and rectified the cause of the corrosion.
A heating system will last indefinitely, if properly installed and if the corrosion inhibitors are maintained.
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Its not difficult to remove rads without making a mess. My method used hundreds of times as a plumber was to use a low level plastic washing up bowl which I keep specially for this job.
Obviously turn off both valves and place the bowl under one of the valves and on top of an old towel.
Crack one of the valve unions until it starts leaking and running into the bowl.
Then open the bleed valve to allow air into the radiator. When the bowl is half full nip up the union again and turn off the air bleed. Repeat as many times necessary depending on the size of the rad.
No black gunge will come out at this stage until the rad is almost empty.
When apparently empty disconnect at each end and with rag underneath each valve and preferably with an assistant lift one end of the rad and pour the remainder which is now black ink into the bowl.. Turn the rad upside down and carry it outside to flush through with a hose. No problems.
Then comes the question of why your rads are blocking up.. This has been discussed many times and my experience stretching back over many decades is that it appears much more prevalent nowadays reading forums such as this, than it did in the past despite fernox and other additives.
In fact until about the early 70s we never used anything at all and many systems are running today from that era without this problem. We are now entering chemistry of which I have no knowledge but on a more practical basis I would be looking at the following.
The worst scenario you can get with a central heating system is fresh water entering the system After the initial flush and fill we always believed that the water became inert which meant going the colour of ink over the years but with no adverse affect.
We would look at the following?does water ever blow over the expansion tank into the small make up tank.. This is lethal as it captures air (oxygen) and takes it back down into the system resulting in rapid corrosion of steel radiators. Could it be that you have a Primatic cylinder which has been blamed for the same problem in the past.. Could you have a leak in the coil of an indirect cylinder enabling primary and secondary water to mix. This should show by occasional overflow from one of the tanks (whichever is the lowest)
However whatever the cause there has to be a reason. I called at a friend only last week who I installed heating for as a favour in 1969. I asked him if he had replaced anything. Only the boiler everything else is original. And some of these rads were second hand when I put them in. To my mind if some systems can run indefinitely without sludge or corrosion it points to the system rather than a ?they all do it? explanation.
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Good post there, Alvin, and thanks for probably confirming my long held belief that original/inert water, in c/h and probably cars, is better than cycles of flush & refill.
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....and I'd assumed "they all do it".
Certainly some food for thought there. The basic system is well over 17 years old but I've had some new rads, what with extensions and decorating projects.
I'm going to print these posts to save the techniques, and investigate further. All in due course!
Thanks again...
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I have had the hot water cylinder perforate a couple of times -- takes about 10 years. It seems the copper gets dissolved into the fresh cold water entering the hot tank at the bottom.
I have also fitted a few better looking radiators.
My approach now is to drain my system into containers, let the water settle, and then re-use it. I find there is no radiator bleeding to do except for just after carrying out the work. The lack of a need to bleed shows the reaction with the iron is much less.
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"I have had the hot water cylinder perforate a couple of times"
Have you got a water softener, by any chance?
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"I have had the hot water cylinder perforate a couple of times" Have you got a water softener, by any chance?
Or naturally very soft water?
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Yes, good stuff, Alvin.
A couple of other points.
The corrosion is caused by dissolved oxygen. The two sources for this are either;
i) absorption from the air by the mechanisms mentioned above (and also absorption through the walls of non-barrier plastic tube); and/or
ii) from the water by electrolysis, indicating galvanic/bi-metallic corrosion. Hydrogen is also produced by galvanic corrosion & collects in the radiators, hence the well-known ?collect in a jar & ignite? test. For galvanic corrosion to occur, the water has to be acidic.
A corrosion inhibitor would usually contain;
i) an oxygen scavenger (typically sodium sulphite) to combine with any dissolved oxygen before it corrodes the radiators or ferrous components; and
ii) a pH adjuster (typically sodium hydroxide), to ensure the water is alkaline, usually around 9 pH. Anything below 7 is acidic.
There will always be some oxygen absoption. Inhibitors are cheap, replacing rads is expensive.
?my experience stretching back over many decades is that it appears much more prevalent nowadays?
The reason for this is probably the widespread use, over-use and abuse of modern acid fluxes. These make it unnecessary to pre-clean most soldered joints, but (and it is a big but) they contain hydrochloric acid. If the residues aren?t properly flushed and neutralized, they will make the system water acidic and start raging galvanic corrosion. Traditional solder fluxes (and fluxes for gas work) are pH neutral and require meticulous pre-cleaning of the joint.
?thanks for probably confirming my long held belief that original/inert water, in c/h and probably cars, is better than cycles of flush & refill.?
No, don?t try that with a car. The difference is the ethylene glycol in the (traditional) antifreeze. This will react with any absorbed oxygen to make an acidic compound (oxalic acid, I think). When the reserve alkalinity is exhausted, galvanic corrosion starts to attack the engine parts. Drain, flush and refill every 2 or 3 years to maintain the pH is usually recommended. Modern OAT antifreeze is different, but I know nowt about it.
Apologies to any chemists; I?m an engineer.
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I think you have an excellent point there afm. Have never used these new fluxes but for another reason.
In 1967 copper tube was unavailable (probably the Rhodesia problem) for a large project and we used a type of stainless steel tube which was also used in domestic housing for heating systems. Awful material to use but this tube could be used with Yorkshire capillary fittings and a special flux was required. It was made by Eutectic.
A few years after the remainder of this flux was still sitting on the shelf and a man opened it up and the now clear liquid accumulated at the top spilled over his hand. He was very badly burnt and admitted to Hospital and finished with a disfigured hand. This incident made me wary of aggressive fluxes.
Moving on a number of years a friend moved into a house and a while after asked me to help him repair a leak on a heating pipe. It turned out to be the stainless tube and was corroded so badly it could be crushed by hand. Luckily he was on the BG 3 star plan. The fitter arrived and couldn?t understand how Derek had got on this plan as BG would never cover anyone with this type of tube. I asked the fitter if BG knew the reason for this corrosion and he explained that their boffins blamed the flux not being completely flushed out.
However he was covered and BG replaced every tube and fitting in the house.
As an apprentice in the 1950s I recall stripping out steel heating pipes from very old buildings and there was never a trace of rust or corrosion showing and there was no fernox around then. And of course no flux needed for steel.
So I think yours is the best explanation. I had also wondered if the steel used for panel rads was rubbish similar to the first Jap cars we imported.
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"Have never used these new fluxes...."
I think you're in a very small minority. Most plumbers use them; many use lots of flux. I have seen copper pipework encrusted with green flux residues/corrosion one day after installation. Active fluxes are very convenient (for the installer) and, if they do cause corrosion, it will probably appear long after the warranty has expired.
I must read the manufacturers' recommendations, I'm sure they can be used without adverse affects.
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Well today I successfully had three rads off and cleared them out - boy were they gungy! I managed to use the tip about laying the rads down before full removal which saved a lot of mess.
I've taken no further action yet but will do - however, thanks for the advice. I now have hot rads...
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