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Flushing CH system

This idea is probably crazy, but I'd like to hear why.

This mission is to flush the CH, including rads without removing rads. (I have some rads not getting as hot as I believe they should - the usual LSV adjustments and bleeding has been done). I believe some rads have been in there 35 years.

  1. Close all rad valves and LSVs
  2. Turn boiler to minimum (just on to allow pump to work)
  3. Turn pump to maximum speed.
  4. Open up CH drain tap (the header feed can fill faster than it will drain.)
  5. Let run for (say) 10 mins

(1 through 5 flush out the pipework)

  1. Fully open the valve and LSV of one rad.
  2. Let run for (say) 10 mins
  3. Close the valve and LSV.
  4. Move on to next rad.

(6 through 9 flush out one rad at a time)

  1. Set system back to normal.

A little knowledge is a dangerous thing. I have very little plumbing knowledge so I could be extremely dangerous.

Just thinking aloud. Great newsgroup.

Thanks in advance. Stan

Reply to
Stanley Morgan
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I'm beginning to think maybe it was a crazy idea. If it doesn't go precisely to plan, the boiler and/or pump may be at risk.

Ah well, just thinking outside the box.

Reply to
Stanley Morgan

If the pump is pushing water towards the drain tap, there's *no* *way* that the header will fill faster than it drains - and you'll end up with cavitation in the pump.

Chances are that there's a direct route from header tank to drain tap which

*doesn't* go through any radiators - so it probably won't flush the rads very well.

Why not bite the bullet and remove the rads - one at a time - and give them a good wash out with a hosepipe. While each rad is off, open each of its valves in turn - and drain until it runs clear - to flush out that section of the pipework. Depending on the layout of your pipework, you may need to be a bit creative in order to find a way of flushing the pipes which go to the boiler and back.

Reply to
Roger Mills

Have you tried balancing the system? I find that the usual cause of rads not heating up, rarely total blockage.

If you know the pipework arrangement and know that the feed into the system is into the opposite part of the system from the drain-off c*ck (e.g. feed into return, DOC on flow) then what you propose is good. Often you'll find the drain takes water almost directly from the feed, but even then the one-radiator at a time procedure should help flush a certain amount out.

Reply to
YAPH

I am doing mine tomorrow. I added some Sentinel X400 (sludge remover) a few months ago.

I plan to drain down fully. Refill, then drain down again. Then keep my hose on the drain point and just let the system refil / drain for a few minutes.

Reply to
Slider

Hi Slider, In the end I decided for a slightly less ambitious and dangerous approach, and coincidentally I also purchased Sentinel X400 this weekend (I think £14 at B&Q). I've already drained down and put it in, refilled and bled.

I thought I'd run it for a week with valves and LSVs in usual position. Then note positions and run a week with everything fully open.

I like your idea about keeping it running (ie draining and filling at same time for extra flushing.

Cheers, Stan

Reply to
Stan

To remove deposits you need 'velocity' so the water will entrain the deposits. The amount of deposits removed by simply draining a gravity system is very limited and is hardly 'flushing'..

Reply to
Edward W. Thompson

True, but evry little bit helps. Let me guess, you work for a "flushing" company :-)

Reply to
Slider

Well I did mine yesterday, bit of a pain as all the downstairs rads have to be drained individually. Drained from the kitchen rad which drained all upstairs and itself. Then had to go round and drain the other 5 downstairs individually. Anyway, kept the hose and two of the rads, the kitchen one and the larger lounge one and just let the system fill then drain for about

15 minutes. Refilled and bled and all good now. I added 1.5 litres of Sentinel X100 inhibitor so all is good now. I bled the bathroom rad late last night and all that came out was clear water!! :-)

I agree, not as good as a professional powerflush but they cost big bucks.

Reply to
Slider

I bled the bathroom rad late last night and all that came out was clear water!! :-)

I agree, not as good as a professional powerflush but they cost big bucks.

Slider, How long did you leave the sludge remover in the system ? Did you run it with all valve and LSVs fully open with sludge remover in ? When you were letting the system refill and drain simultaneously, did you have none/some/all air vents open ?

It sounds like you got a great result if bleeding gave you clear, not back water.

Stan

Reply to
Stan

Sludge remover has been in the system since probably June / July, although the heating has only been on the last month or so.

Never toucher the LSVs. I balanced the system back in May, so didn't want to change anything.

I bled all the rads whilst refilling / draining until all the air was expelled, then left it filling / draining for about 15 mins

Reply to
Slider

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