re. money saving diy system flush

[johnscales]

Hi all.

Was looking for a cost effective way to flush my central heating system and came across this thread :
//www.diynot.com/forums/viewtopic.php?p=230827#230827

Sounds a good idea given the feedback the chap received but sounds to be for a combi boiler system judging buy the terminology.

Can anyone tell me how this can be done with a gravity fed system.
I'm about to replace several radiator TRVs in my house and will be draining the entire system and flushing to do so. Seems like it would make sense to make such a change now as I intend to maintain them regularly thereafter too.
I added a rad to the system last year and had fun and games squeezing into the loft to shut off the supply and deploy the inhibitor.

Thanks
Jmac

 

[JohnD]

If you have time, I would add Sentinel X400 and run it for up to 4 weeks before draining and rinsing. You will know it is starting to work when the circulating water goes jet black with loosened sediment. If you can do basic plumbing and can afford an extra £100, fit a Spirovent or Magnaclean as well. Do all the cleaning before you drain and remove your old radiators if you possibly can.

I think you probably mean you have gravity feed to the HW cylinder and pumped CH. A full gravity system has got quite rare since about 1960

If you have pumped CH and pumped supply to cylinder as well, then you probably mean you have what we call an open vented system with a small feed & expansion tank in the loft. This is very common. If so, bale out the F&E and sponge it clean to remove all mud and dirt before you start cleaning and adding chemicals. Otherwise you will just be adding extra dirt to the system.

If you do have gravity HW, then a lot of sediment will stay in the HW circuit even after it has been loosened by the chemical

Add X100 corrosion inhibitor at final fill when clean.

If you find brown fungal or white bacterial growth in the F&E tank, report back here for more advice.

 

[johnscales]

Thanks JohnD.

I was trying to avoid going up into the loft but after conversation with my colleague here at work it seems like i'll have to.
I think i'll follow your advice here. I had a rad moved due to extending the room two years ago (not by me) and the system was flushed then. I changed the rad (single to double) last year to combat the cold and flushed it then as well.
On neither occasion was the feed and expansion sponged so i'll do these steps first. I just hope the temp doesn't drop too much from here on in as it was a bast*** doing it last Jan in the freezing cold.

Cheers

ps.
Spot on with guessing the type of system I have.
pps.
Must I really drain around a litre of water from the rads before putting the sentinel (also 1ltr) in the f&e. I did it last time but it seemed unnecessary as i'm sure the 1ltr excess gets vented out somewhere.

 

[JohnD]

yes you do need to. preferably a bucketful. otherwise the chemical will just lie in the F&E doing nothing.

 

[johnscales]

Oh..
Wish me luck.

As an aside, and probably worthy of another thread all together, I will be changing 4 of my TRV's as they've been in place since the property was built 26 years ago. 2 are stuck open and 2 stuck shut. Gently tapping to free up the springs in these stopped working years ago.
My colleague here said that he changed all his TRV's for terrier wheelhead valves years ago and hasn't had problems since :
http://www.screwfix.com/prods/87216...Valve-10mm;jsessionid=XHL025AH4BX1YCSTHZOSFFA
Would you go along with this. I just wondered because I like knowing between 1 and 6 (or what ever the highest number is) what is cold and what is warm rather than guessing which the terrier valve looks like i'll end up doing.

 

[JohnD]

those Pegler Terriers are good as lockshields, but you really ought to have TRVs on the other end. Danfoss RAS C2 is a good one and not excessively expensive. How many do you need?

I see Screwflix have a Pegler TRV on offer at the moment. Pegler is a very good brand.

 

[johnscales]

Cool, will check that out as I need 4.

One last q JohnD.
How do I give a thanks here? Is is the thumbs up symbol?

 

[JohnD]

look for the

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you have mail. look at your messages.