Megaflo hot outlet stop tap

Discussion in 'Plumbers' Talk' started by Buckers, Sep 9, 2019.

  1. Buckers

    Buckers New Member

    I had a chap in to service the boiler the other day and he pointed out that the stop tap I have on top of the megaflo should not be there. I was kinda distracted by other things going on in the house so didn't really take in the reason.

    Can anyone confirm if this is bad and the reason why if it is?

    IMG_20190908_182605230.jpg
     
  2. Heat

    Heat Well-Known Member

    The chap you had servicing your boiler clearly knows very little about the basics of unvented cylinders.
    Is he qualified in unvented hot water systems? (Although the qualification itself doesn’t mean much apart from legally essential).

    There is nothing wrong with having a valve to that pipe on that position to your unvented cylinder.
    You should contact the guy to ask him why he thought it is wrong.
    Post back on this thread what he says.
    Only thing I would criticise about the valve is it is a gate valve, which is useless and tend to not fully close off or break or seize when used.
    Better it is replaced someday when unit is being serviced with a full flow lever valve.
     
  3. The Teach

    The Teach Well-Known Member

    its not really that bad but not usual,the servicing technician would have carried out many checks to ensure the cylinder installation is working safely & to the manufactures instructions.

    There seems to be a blue lever in the photo,thats the important mains water isolation valve.

    seen a few not fully open gate valves fitted on the outlet to reduce the hot water flow which is not recommended. There are other methods to reduce hot water flow :)

    :D
     
  4. Buckers

    Buckers New Member

  5. Heat

    Heat Well-Known Member

    Not that type (which would be okay, but for gas and yellow handle indicates that) but this sort of valve if completely full bore, -
    https://www.screwfix.com/p/lever-ball-valve-red-22mm/38468
     
  6. Heat

    Heat Well-Known Member

    As @The Teach said, an isolation valve on the mains supply to the cylinder is normally all that is needed. But that valve must be installed BEFORE any of the safety controls and NOT between any controls and cylinder because it could isolate safety components if valve was ever closed off.

    Would be good to see a photo of entire cylinder showing rest of pipework.
    A valve fitted to top outlet that you have can serve a useful purpose and handy for working on hot pipework in house.
     
  7. The Teach

    The Teach Well-Known Member

    To avoid future confusion why not just remove the valve and marry up the pipes with 22mm copper pipe,There is already an adequate mains water isolation valve in the photo,that blue handle marked with an arrow & close.

    TT:)
     
  8. Heat

    Heat Well-Known Member

    Handy though to eliminate risk of destroying unvented cylinder due to vacuum suction if working on a lower floor part of hot pipework.
    Some instructions recommend anti vacuum valve be installed to prevent that.
    Personally I have never installed a valve onto an unvented hot outlet pipe, but it is very useful and does the same job as isolating valves on each tap. Makes working on pipework much safer.
    A lot of plumbers make the mistake of thinking a valve on outlet is dangerous, but the unvented cylinders are not vented, so a valve closed on hot outlet does nothing more than all taps turned off.
     
    Last edited: Sep 9, 2019
  9. Buckers

    Buckers New Member

    Looks like the valve comes before the pressure release:

    The tap on the hot outlet is kinda nice if you want to work on the hot taps because normally when you turn off the main supply the hot seems to run for quite some time while the cylinder pressure drops and ****** away a load of hot water, no?
     

    Attached Files:

    Heat likes this.
  10. Heat

    Heat Well-Known Member

    You are correct. And in opening a tap or cutting a pipe on a lower floor you create a strong suction on the cylinder. They can implode
     
  11. Buckers

    Buckers New Member

    Thanks guys, I have ordered a full bore lever valve with red handle.
     
    Heat likes this.
  12. Heat

    Heat Well-Known Member

    For all it costs it will be worth it for convenience when working at taps etc.
    Operate the lever valve occasionally off and on to keep it from seizing. They are usually excellent, but can seize at gland
     
    Buckers likes this.
  13. The Teach

    The Teach Well-Known Member

    Was going to suggest you also cap off that potentially drippy 15mm redundant pipe in #1 but it's been done that in #9 :)

    Nice newish shiny copper pipes attached to the new slimline megacost. Nice pipe bending many installers would have resorted to push bends :)

    Happy plumbing :)
     
  14. Buckers

    Buckers New Member

    Mmm it was indeed pricey (especially with the new vaillant!) but it was the only one I could find that fit the space at the time! And having all the expansion shizzle inside and not on the wall is just sexy.
     
  15. Heat

    Heat Well-Known Member

    Not so sexy when you have to keep replenishing the air bubble!
    I only use cheaper but still high quality unvented units
     
  16. Buckers

    Buckers New Member

    I haven't done that yet, it's still very new :eek:

    Only issue I have is the 70 year old 15mm service pipe with completely corroded tap in the boundary box are not up to much, very tempted to drop a 32mm plastic jobbie in the ground.
     

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