I wish to do a thorough descaling and de-sludging of my sealed CH system, and have bought a large tub of Fernox DS40 to accomplish this (I hope).
I note on the instructions that it says to allow 7 days for it to work on all-steel systems, but only 4 *hours* for those containing aluminium rads.
My problem is that I have a combination of both.
Can anyone suggest a work-flow I can use here to ensure a proper job is done throughout, please?
Note: My system is split into 2 circuits, with flow control valves operated by the timer programmers. All the aluminium rads are located on the downstairs circuit and the older steel one's on the upstairs. Obviously, I *can* isolate the alu rads by screwing down the valves, but this would mean I would have no heat to downstairs at all for around a week, and winter is not over yet. And no, the job can't wait until the Spring. However, if it's a must, then I will do it. :-(
It isn't really the limescale I want rid of, as much as the black stuff. I have had a persistent pressure loss for some time now and I'm buggered if I can find it. Hence I have had to frequently top up the system with more fresh (oxygenated) water via the filling loop. Being a lazy bastard, I haven't been quite as diligent about refreshing the anti-corrosion inhibitor, so I keep clogging up my DHW heat exchanger. I have just swapped it out with my handy spare for the 4th time now, and it's getting to be a pain in the derriere as this occasion is only 3 months on from the last swap out! I figure that my combi main heat exchanger also has collected much of the muck, and to cut a loooong story short, I just want to clean the whole fecking lot out once and for all and shove some anti-leak chemical in (which I have also obtained) before another fresh dose of corrosion inhibitor.....
As the crucifix seems to have stopped working, this may be the only path left.
You must try to find the leak. With no puddles on the floor, it is probably going out the pressure relief valve, or even across to the DHW side and out the tap.
Another one along these lines is leaking spindles on radiator valves. A small leak may only be happening when the system is hot and of an amount that it is evaporated by the heat without showing very much or at all from the caps. Try going around and removing each cap for a look. Replace any radiator valves showing signs of leaking with new, good quality ones such as Pegler. Spindles of motorised valves are another candidate.
Pressure relief valve is certainly a favourite. If this is leaking, then a replacement is the solution since they are impossible to repair reliably.
Concerning a thorough system clean; a better approach, which would not have issues with different materials and use of chemicals, would be to remove each radiator in turn, take it outside and flush it with a pressure washer or hose on the mains. While the radiator is removed, flush system water out at the radiator position from the valves. This means that crud is flushed out and not around the system and is much more effective than circulating an acid cleaner. Care, because sludgy water is an indellible dye. Small sandwich bags rubber banded over radiator tails is a good plan while moving them around.
An alternative that would be better than adding a cleaner and circulating would be to rent a pressure flushing machine and use that to power flush the system.
I replaced the DHW Watersection valve in 2001 due to corrosion, which I accidentally discovered when I couldn't turn the attached adjusting wheel which alters the dhw flow rate. It had locked up solid due to not replacing the the combicare cartridge often enough. I have done so religiously ever since, and the wheel still keeps on turnin! Can't see any sign of weeping or corrosion although it is all a bit packed with gubbins in there to get a proper view. I don't feel any moistness when I run my fingers around the many joints there. :-s
Yes, and there were occasions when we observed small drips coming from the vent pipe outside the front door. But this was before we replaced the CH pressure vessel last summer, and I dont' *think* it has happened again since, although I will try taping a plastic sandwich bag around the end to catch the drips if any.
I have also done a mains pressure back flush through the boiler and vented out through the PRV by turning the valve knob to open it fully and allowing it to 'shunt' back into the closed position. As you will know, they are sprung loaded and when you pass a certain point of no return, the valve slams shut again. I realise that it is not advisable to do this, as grit can get trapped etc in the seal and cause a leak. But I power flushed it at mains pressure at the same time as operating the valve, so hopefully it shouldn't have trapped any debris?
Yup, see above. Told you it was a loooong story! :-((
I am now of Andy's view that it must be a weeping rad valve or someat similar. Hence my current choice for introducing a leak sealer chemical, just to eliminate that area of possibility.
Hi Andy. Yes, this is a conclusion I have come to, hence my current project to introduce anti-leak chemical into the system. But I want to de-sludge it all first.
See my reply to EricP.
Gulp. I did all that when I put the new boiler in in 1997. I was a fit young thing then! Don't want to go through all that again in a hurry, especially as it's winter still and I was hoping a chemical treatment would suffice for my purposes. If I was replacing the boiler, then I would replace all the remaining steel rads and valves too. But I hope that won't be necessary for at least another 6 - 12 months, as I have several other major projects on hand at present to occupy me with.
'Tis an idea. Hadn't thought of that. But I liked the fact that the DS40 states it *would* return the rads and pipework to bare metal condition. :-s
ps. I do realise that it could of course be leaking *internally* as you imply. However, that would suggest an intermittent pressure loss situation occurring? When I went away for Xmas for a week it had still dropped the usual .1 to .15 of a Bar when we got back home and no-one had been using any taps, and we don't have any dripping ones. :-s
Typical! You have your way with me and I divulge my whole boiler life story, much agin my better judgement, and then you sod off and leave me holding the .. errr .. toolbox. Pah!
The concern is how much metal it will remove in the process. The effectiveness also depends on how much crud there is because the solution can only dissolve so much. Is it at a level where the bottoms of the radiators feel cool in the centre?
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