Sealed System flushing advise.

[daveyrach]

So in my house I have a 35kW Combi boiler on a sealed system in my house. Before Xmas we had a new towel rad fitted in our bathroom by my uncle and he added some cleaner and said give it a fortnight and he would come back and flush it and talked me through how to so it.

No as much as I love my uncle he is not the most reliable(some might say like most tradesmen) but the cleaner is still in there.

I am a competent DIY'er and have done various plumbing jobs but he was planning to flush using the filling loop and mains pressure, I have given up trying to contact him and have been reading up on it. What I read was to drain the system close all rads bar one and opening the filling loop (with drain **** open of course) wait till water runs clear then open the next and close the previous until all rads have been flushed. Does this sound right?

I do also have inhibitor to put in after which is easy.

Does all this sound hunky dory?

[johnnyrod]

Mains pressure is too high so you don't want to just open the loop valve and leave it unattended. What you don't have is some pipes with a drain at one end and a boiler at the other, so if you really want to clean the stuff out then fill it with water then pump it round a bit then drain and refill. Don't forget you'll need all the rads open so at least set all the TRVs to full. Ideally you'd also open the lockshield valves but then you'd have to balance the whole lot again, not really worth the bother TBH. If you can't be bothered to refill it twice then a good drain down once should do the trick, the flushing stuff will be well diluted by the time it's all full again.

[daveyrach]

What would happen? I have seen and read about it being done numerous times and its what my uncle was going to do. I suppose draing and refilling a few times would do the trick and less time consuming.

[johnnyrod]

I dunno what your pressure gauge on the boiler says but mains pressure can be over 3bar which I will bet is too high, and I doubt it'll get out as fast as it gets in. The pressure relief valve would (should) operate first, if that isn't enough then the expansion vessel will pop and/or any joints could give up, and then you've got some fun with a capital F.

A single refill and drain would be enough before refilling and adding the inihibitor. Also it means you know the volume of water you've used - if you run it through you can only guess that you've done it properly. How come you've put the flushing stuff in anyway? If you think you have a (potential) problem with sludge then while the system is drained down you could get a magnet e.g. http://www.plumbworld.co.uk/magnacle...ing-1374-15134

Have just re-read your original post (sorry) about opening the rads one by one. Yep this would work I guess, it's a bit like a DIY powerflush. You'd really want to open the lockshield valves fully in which case you need to set them at least roughly back to where they were to make sure it's all balanced when you turn it back on again. You'd also want to think about the order you flush them in as you'll only have a few drain points, and potentially could wash rubbish back towards one you've just done.

Sorry a bit rambling!

[daveyrach]

Its OK the stuff was put in as we only moved in 12 months ago and we had a new Rad fitted so seemed like a good idea as we have not maintenance records, can't hurt can it. I will just drain and refill then.

[johnnyrod]

There are some flushers that are fairly acidic so you cant leave them in for long, but they're more effective. Others are less of both but can be left longer.

[Teejayexc]

Originally Posted by johnnyrod

There are some flushers that are fairly acidic so you cant leave them in for long, but they're more effective. Others are less of both but can be left longer.

Is this line of work where you got your username from ?

[daveyrach]

Originally Posted by johnnyrod

There are some flushers that are fairly acidic so you cant leave them in for long, but they're more effective. Others are less of both but can be left longer.

Well no probs so far and my wife seems to think rads are hotter than they were before especially at the bottoms. Would rather get it out as the bottle said 14 days max and it has been 3 1/2 months.

Yeah I'd defo give it a flush as the cleaners can be acidic as said above.

What I'd do:

1. Turn the heating on for an hour or so to get it all nice and hot + circulating around the system
2. Turn boiler off and isolate the power to it
3. Attach hose to drain off and open
4. Make sure thermostatic valves are all open (don't touch the other end because as said said above, rebalancing the system is very time consuming even for an experienced engineer)
5. Open the bleeds on radiators upstairs (make sure the air is sucking in)
6. Same with downstairs rads.
7. Look at the colour of water being drained (if really dirty I'd full and drain again afterwards)
8. Once stopped close drain off. Tighten all bleeds.
9. Refill system using filling loop (wants to be 1.2 bar ideally, but 1.5 or so if fine)
10. Bleed rads starting from downstairs and going up (checking boiler pressure and topping up when required)

You do really want to get some inhibitor in there to protect the system but on a sealed system you need to take the air bleed out and attach an elbow or something (when the systems empty ofc). Maybe your uncle could come back and drain some water out of a rad and do that for you?

Well, that's enough from me on a Friday night lol. Hope that little lot helps .

[johnnyrod]

Originally Posted by Teejayexc

Is this line of work where you got your username from ?

Har har no, I'm a habitual fiddler, plumbed my last house from the stopcock up, worked out rad sizes, moved the boiler etc.