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Shower option - cast your vote! Cold from loft tank VS Pressure Equalising Valve?

Discussion in 'Plumbing and Central Heating' started by DIYNotIan, 25 Sep 2021.

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Cold from loft tank VS Pressure Equalising Valve?

  1. Cold from loft tank

    1 vote(s)
    100.0%
  2. Pressure Equalising Valve

    0 vote(s)
    0.0%
  1. DIYNotIan

    DIYNotIan

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    First - an apology for monopolising the forum with all my plumbing questions! I'm hoping this will be my last and I'll move onto something else (like choosing a woodburner, which is the next thing on the to do list)...

    My situation... We've having a bathroom refit and will have a new bath with shower mixer tap. We've got an oil boiler and vented system. We're eco minded and are happy with a very weak shower. In fact, that's our preference. So we don't want to install a pump, shower power, new unvented cylinder, etc. etc. There will be another shower in the house too. The cold is currently mains.

    I've narrowed it down to two options:

    1. Put a pressure equalising valve under the bath so the hot and cold have matched pressure.
    2. Run a cold feed from the tank in the loft, so both hot and cold are gravity fed. (The tank is 40 Gallon actual / 60 Gallon nominal).

    Some relevant points for both 1 and 2:

    - Is a 40/60 gallon tank large enough to run the cold and hot from?
    - The tank isn't far away from the bathroom ceiling, so wouldn't need a long run of pipe to get to he shower mixer tap
    - The pipe from the loft would be coming down the tap end wall of the bath, so would need to be chased in / tiled over. However, the mains cold goes up to the loft on the wall too, so there's already a pipe being chased in there...
    - The mains cold comes up from the room below where the bath will be (tap end)
    - The bath panel will be removable, so accessing the PEV wouldn't be an issue
    - Future proofing... Hopefully the boiler has years left in it, but if/when it goes we don't know what we'll go for next. Are PEVs useful in unvented and/or combi boiler set ups (when used with bath shower mixer taps)? I've read very opposing answers to that question!
    - I presume performance will be similar in both set ups, so if there's likely to be a big price difference between the two then that might help decide.

    I'll add a poll for the sake of it.

    A vote, or a thought on any of the above, would be most welcomed.

    Many thanks and have a great weekend everyone.
     
  2. flameport

    flameport

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    If you are happy with a slow trickling low pressure shower, then 40 gallons is more then plenty.
    At 5 litres/minute, that's over half an hour of continuous shower use. In reality far more as it will be refilling while it's being used.

    Hot and cold supplies should be from the same source - both from stored water, or both from the mains.
    While it's possible to use valves and other devices to get them to work with different supplies, it's just another thing to go wrong.

    Just make sure that the shower and taps are suitable for low pressure supplies.
     
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  4. DIYNotIan

    DIYNotIan

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    Many thanks for your reply @flameport

    Have you (or anyone else for that matter) had much experience of pressure equalising valves going wrong?

    Thanks for pointing that out. I got a new old stock Pegler unit which is suitable from 0.1 to 10 bar so should be all good on that front.


    Any other views / thoughts from plumbers and DIYers?

    Cheers
     
  5. flameport

    flameport

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    Ask anyone with an unvented cylinder. Replacing the valve(s) on the inlet is a very common repair.
     
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  7. DIYNotIan

    DIYNotIan

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