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Emptying cemtral heating tank

Discussion in 'Plumbing and Central Heating' started by camerart, 5 Apr 2012.

  1. camerart

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    Hi,

    I'm moving a radiator, and need to empty the pipework.

    I've locked the ballcock up in the small tank (Central heating) this feeds the coil inside the hot water tank, and no valves.

    First I closed all of the other radiator valves, then I emptied the pipework at each end of the old radiator. Checked the tank and it's still full. Shouldn't it have emptied?

    Cheers, Camerart.
     
  2. SimonH2

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    This really belongs in Plumbing ...

    From what you describe I'd expect the F&E (Feed and Expansion) tank to be empty. Did you leave the valve open on the rad you are moving ? If not then you'll have drained the rad but not the pipework.
     
  3. camerart

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    Ok, I'll move it to plumbing, thanks.
     
  4. JohnD

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    how much water came out of the valves at the ends of the old rad when you opened them after removing the radiator?
     
  5. camerart

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    About a 1/2 gallon.
     
  6. JohnD

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    do the pipes to the rads come down from the ceiling?

    when you look in the feed & expansion tank, how deep is the mud in the bottom, and what colour is the water?

    do you know when it last had inhibitor or cleaner added?
     
  7. camerart

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    The pipes come along the hall ground floor, from boiler ground floor.

    The tank had about 3 gallons in it, with a brown covering of sludge about 1" on the bottom. I syphoned it out, then put cleaner in. Then I noticed the outlet is 5inches up, so the chemical is still in there. I have inhibitor for later. I doubt it has had inhibitor in for 30 years, if any. When I drained the water, it was black.
     
  8. JohnD

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    it is very possible that there is now a blockage in the feed and expansion pipe. Most usually it is where the 15mm joins onto the large circulating pipes. If you hold a magnet against this T-joint, is it attracted? If so it will be the black iron oxide sediment. Unless it is a compression joint that you can undo, you will have to cut out and replace the blocked section.
     
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  9. camerart

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    WOW! I bet you are correct. When I was syphoning the tank, the syphon kept blocking. There's a compression joint handy, on the silver downpipe, which might give you an idea of it's age. I predict a soaking in dirty water this morning.

    Thanks JohnD, I would have never guessed.
     
  10. 45yearsagasman

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    If it has blocked in this area, block off the cold feed outlet in the exp tank before you start cutting the cold feed, and have some towels to hand.
     
  11. camerart

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    OK. I just did JohnD's check with a magnet, and it's not magnetic till I get to the 28mm, which I think must be steel pipe, as it's magnetic all along. I'm just off to attack it.

    Thanks.
     
  12. camerart

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    First I scooped the chemical cleaner out out the expansion tank. Then tried to loosen one side of the compression fitting at 15mm to 28. It moved a little, then I realised I wasn't going to be able to tighten it as there is no room.

    The outlet of the Expansion tank is 4 inches up, and there is a little extra thread poking out from the seal, so I soldered a length of 15mm to a fitting, screwed it onto the outlet, and made a little pump. Violent pumping and the blockage cleared. Then I added some garden hose to syphon it from the bucket.

    All working, again with a new rad in the kitchen.

    JohnD's prediction that there might be a leak was correct, and my prediction that I will get soaked was also correct, so happy days.

    Thanks all, Camerart.
     
  13. JohnD

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    time to use your cleaning chemical soon! :p

    I like your pump idea.
     
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  14. camerart

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    I left it in the tank 'for next time!'

    I didn't explain well. I scooped the chemical into a bucket, pumped the blockage clear, then attached a hose to the pump pipe and syphoned the chemical into the system.

    It could have been diluted though with all the messing about, will it still work?

    In hindsight, I think I should have finished the job, then emptied the water out of the Kitchen radiator, and poured the chemical into one of the top plugs.
     
  15. camerart

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    I left it in the tank 'for next time!'

    I didn't explain well. I scooped the chemical into a bucket, pumped the blockage clear, then attached a hose to the pump pipe and syphoned the chemical into the system.

    It could have been diluted though with all the messing about, will it still work?

    In hindsight, I think I should have finished the job, then emptied the water out of the Kitchen radiator, and poured the chemical into one of the top plugs.

    Thanks for your help.
     

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