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Discuss Do i need to drain entire system? in the Central Heating Forum area at

  1. Gary jackson

    Gary jackson New Member

    Hey guys...the plumber i had booked to change a radiator and valves has gone awol....its in my childs bedroom where its too cold to leave it any longer forcing me to do it myself ..the heating is run off a worcester 35cdi question is do i need to drain the whole system first or is there an easier way?..tks for your help
  2. Last Plumber

    Last Plumber Plumber GSR

    It depends how good at Plumbing you are. It's a short job for a Plumber. If you're a DIY person with little Plumbing experience, I recommend you drain down at least to below the rad in question.
    • Agree Agree x 1
  3. Gary jackson

    Gary jackson New Member

    Thanks...the rad is on middle floor of need to drain off quite bit then
  4. moonlight

    moonlight Plumber GSR

    You could lock off all the radiators above and the floor you are on and just drain the pipework, and the radiator you are working on.
    • Like Like x 2
  5. jtsplumbing

    jtsplumbing Plumber GSR

    good opportunity to clean system, put a cleaner in system first run it for a couple of days, drain system, do radiator, refill adding new inhibitor to system
    • Agree Agree x 1
  6. SimonG

    SimonG Trusted Plumber Top Contributor!!

    I wouldn't drain.
  7. Vee

    Vee Plumber GSR

    I wouldn't drain either.
  8. Gary jackson

    Gary jackson New Member

    Whats best way without having to drain? Tia
  9. sammathias

    sammathias Plumber GSR

    best way for me personally:
    1. turn off both rad valves
    2. vent rad into small tub or onto cloth(this should stop showing that both valves have shut off completely) turn vent back off.
    3. Rag/blue roll under radvalve, have a rolled up pipe of blue roll ready to plug end of rad once you disconnect radvalve from rad with two spanners making sure the valve is held firm.
    4. repeat on other valve so you can then lift rad off which will still be full of water
    5. attatch hosepipe to radvalve and drain off excess pressure into a bucket (only 4/5 litres of water allowing you to change valve.
    6. same other side making sure the valves are turnt off when installing.
    7. hand rad to correct height allowing for connection to rad valves.
    8. top pressure on boiler back up
    9. vent rad and top boiler back up again 1.5bar cold.
    check for leaks.

    That makes sense to me...honest!!!
  10. Gary jackson

    Gary jackson New Member

    Great you think draining off about 5 ltrs from each valve should be enough to change to new valves? I suppose I just hose off enough until there is virtually nothing coming through?
  11. SimonG

    SimonG Trusted Plumber Top Contributor!!

    Unless there's automatic air vents open.
  12. SavageW

    SavageW Plumber GSR

    To change the rad an valves withought draining the system,you’ve got to have an amount of plumbing knowledge I would say,sammathias has given you a step by step guide.I’d personally want to check charge of expansion vesse once I’d dumped the pressure on the system before I repressurised .Like SimonG said if you have open AAv’s on your system it’s then a difficult task unless your quick.Not another local guy you could ask to do the job?
  13. Gary jackson

    Gary jackson New Member

    Thanks for all the advice guys...i have tried other local guys but with no luck....i have seen a vid where the guy freezes the pipes below the ras valves so not having to drain the system....i can get one of the freezing kits if need be....what do you think about this method?
  14. sammathias

    sammathias Plumber GSR

    Yeah I personally wouldn't suggest you trying to do it full of water. I dont know what valves you are replacing with what valves. You may need to cut olives off to replace nuts! Usually about 5/10 litres from a combi and the water should stop completely... Unless a rad has started to drain.
  15. fixitflav

    fixitflav Active Member

    It depends on several things. Presumably you want to change to a bigger rad to provide more heat. If this is longer there's more to it than changing the rad. If it's a modern tall narrow one the length between the connections could be the same as the old one, but likely to need different support brackets on the wall.
    If changing from a single to a double you might be OK, but I'd check that the distance from the wall to the c/l of the connections is the same. I'd like to think rad makers design them that way, but not sure. Maybe somebody will confirm.
    What makes you think the valves need changing?
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