De-sludging a CH system

[Nick]

Any suggestions for doing so please? We will be replacing the aged back boiler in a couple of months. The chap that will do the job has suggested that desludging prior would be a good idea. I fully agree but don't know how best to do so. Conventional fully pumped system. Two motorised valves (CH & DHW), TRV's fitted to all but one rad. Two zones. Will probably replace all TRV's in the process as they are donkeys years old. System always has inhibitor, Fernox or Sentinel (can't remember), but hasn't been flushed for more than 20 years. I could go for a professional powerflush as I can't do it myself. Too many years & not enough diy time. I can drain the system completely and add chemicals. Then drain again, add more (other,if needed) chemicals and do this repeatedly. Given that I have at least a couple of months, this seems a good option as I would prefer to do it myself if at all possible. I realise that such drastic treatment will show up any potential weaknesses in the system (rusting rads etc), but now is the time for me to get it done. I hope this may not cause too many problems. I have been told that hydrochloric acid might be a good starter and also to be careful with it. I have a fair quantity of HCL as we use it regularly. I would not know what rate to administer this at. Alternatively Fernox DS-40 or similar. Any thoughts or recommendations would be very much welcomed. Time is not of the essence, but now is a good time to start.

Best wishes to all for a very happy and preposterous new year.

Nick.

[Vass]

"Nick" wrote in message news: [e-mail]...

Any suggestions for doing so please? We will be replacing the aged back boiler in a couple of months. The chap that will do the job has suggested that desludging prior would be a good idea. I fully agree but don't know how best to do so. Conventional fully pumped system. Two motorised valves (CH & DHW), TRV's fitted to all but one rad. Two zones. Will probably replace all TRV's in the process as they are donkeys years old. System always has inhibitor, Fernox or Sentinel (can't remember), but hasn't been flushed for more than 20 years. I could go for a professional powerflush as I can't do it myself. Too many years & not enough diy time. I can drain the system completely and add chemicals. Then drain again, add more (other,if needed) chemicals and do this repeatedly. Given that I have at least a couple of months, this seems a good option as I would prefer to do it myself if at all possible. I realise that such drastic treatment will show up any potential weaknesses in the system (rusting rads etc), but now is the time for me to get it done. I hope this may not cause too many problems. I have been told that hydrochloric acid might be a good starter and also to be careful with it. I have a fair quantity of HCL as we use it regularly. I would not know what rate to administer this at. Alternatively Fernox DS-40 or similar. Any thoughts or recommendations would be very much welcomed. Time is not of the essence, but now is a good time to start.

Best wishes to all for a very happy and preposterous new year.

[Phil L]

You can do what I did:

Drain system down completely and re-fill with fresh water.

Allow to run for a few days and drain off.

Add a de-sludging agent and re-fill, Sentinel was the one I used, and allow it to run for a further few days.

Drain the desludging agent out and rinse through the system by allowing the drain valve to stay open while you are refilling the system....at this point it's worth going around the downstairs radiators and opening and shutting valves off in order to force the water to take different routes to get to the drain valve, this is probably a 2 man job as you don't want the system to get too pressurized, so the inlet valve may have to be turned down or off periodically to allow the water to find it's way through the system.

When you are satisfied that the system is clean enough, refill and add the inhibitor.

[A Plumber]

Power flushing will certainly find the weak spots in the system, if your on meter they use a lot of water,personally if you've had fernox in I would drain down, take each rad off (can inspect) in turn, flush with hose pipe until water is clean, refit and refill and run heating for w hile then drain down again. then fill again with inhibitor when new boiler is fitted I certainly wouldn't put hydrocloric acid in, don't think it would do the system much good.

[John]

I think it will be a gravity system so over-pressure won't be a problem

[Tim Streater]

Just a posting note. I tend not to read your posts because they come over as an amorphous mass and I can't be bothered to disentangle them. Do you have lots of separate paragraphs in the above, or just one?

If you have lots of separate paras, could you separate them with a blank line so it's easier to read? Or if it's one para, perhaps it shouldn't be.

Well exactly.

[VAG_dude]

Have a look at this:

the system afterwards with Sentinel X100 or Fernox MB-1/Fernox Protector F1.

So are you not replacing the radiators?

[John]

Have a look at this:

the system afterwards with Sentinel X100 or Fernox MB-1/Fernox Protector F1.

So are you not replacing the radiators?

If the radiator have a "top bung" then if you remove that you can screw in a straight coupling (I used a shut off valve) that is then connected to a bit of pipe and then a hose pipe. No need to remove the radiator.