drain down or not

Discussion in 'Plumbers' Talk' started by gstarman, Jul 5, 2014.

  1. gstarman

    gstarman New Member

    i work at a school as maint plumber have been asked to remove a basin on the third floor bathroom for new worktop.
    the cold and hot are provided by two twin booster pumps sited in the boiler plant room and tank fed from loft tanks.
    no service valves on basin only old 3/4" gate valves that dont shut off properly especially the cold as the centre spine has popped out and won't move.
    have found a valve in the bathroom at ceiling height (lever valve) so turned it off and found it isolated the cold where i would be working. i assume that the valve is from the cold down service to the booster set because there is a valve there as well.
    i decided to put 2 new 22mm lever valves above the old ones and noticed that when i chopped out the cold that the water was still pumping up through although ceiling valve was off.
    did i need to drain down the cold to the floor below to stop this or the valve by the booster set or turn booster set off as it has to reach a good 60ft and would i have to do the same with the hot am worried about airlocking the system.
     
  2. plumberboy

    plumberboy Well-Known Member

    Just bunge the loft tanks to carry out the repairs,no need to drain down.
     
  3. teabreak

    teabreak Screwfix Select

    Depends how big the school tanks are he might need his swimming cossie and flippers!;)
     
  4. plumberboy

    plumberboy Well-Known Member

    :):):):)
     
  5. gstarman

    gstarman New Member

    thanks for prompt reply
    not able to bung as they are big galvanised tanks, coming from the bottom of tank not the side and is 11/2 galv steel pipework. so wondered by draining down to floor below would relieve the pressure and give me time to stick 2 lever valves and then refill hoping not to air lock, or would the safest option be to turn off booster pumps hot and cold, cold to cylinders, the hws return and flow and cold feed to booster. ps can't swim
     
  6. chippie244

    chippie244 Super Member

    I would use push fit and fit them live, clean the pipes and get everything ready with the valves open and strategic buckets in place. Use a pipe slice to cut the pipe, pop on the valve and close it off.
    As it's a bathroom I presume it's tiled anyway.
     
  7. plumberboy

    plumberboy Well-Known Member

    Personally I would freeze the pipes and then carry out the valve replacements,quicker than draining down system.
     
  8. Dave does Gas

    Dave does Gas Screwfix Select

    Yep freeze kit, I personally prefer the electric ones as I have trust them whereas the gas ones I always feel could pop at any time. You can hire these kits quite reasonably
     
  9. gstarman

    gstarman New Member

    thanx dave
    i know you can freeze ch pipework but heating has to be turned off and cold for it to work with gas, i assume it would be the same for hot water too and have been told that you can't freeze mains water so did'nt think it could be done with boosted water am i correct?
     
  10. plumberboy

    plumberboy Well-Known Member

    You can freeze any water pipes as long as there is no flow through the pipes when your trying to freeze them,I freeze mains water quite often so no worries with that,but always make sure hot pipes are cool when trying to freeze them.;)
     
  11. gstarman

    gstarman New Member

    thanx plumberboy
    seems like all who replied say to freeze pipes take it seems like relieving pressure by opening taps below would work but will give it a go only prob although pupils have ended term there are still people living there as it is a boarding school(matrons and housemistresses) so that might be a bit tricky which is why i thought a drain down to floor below would be less intrusive but will give it a go thanx for the help will let you know how i get on you'll probably hear from me again
     
  12. plumberboy

    plumberboy Well-Known Member

    Good luck.;)
     

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