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Author Topic: Low pressure non-return valve?  (Read 1498 times)

Womble

  • Joined Mar 2009
  • Stirlingshire, Central Scotland
Low pressure non-return valve?
« on: March 15, 2020, 11:53:42 am »
Hi folks, with all our collective experience of living in rickety old houses, I'm sure somebody will know the answer to this!  :thumbsup:

TLDR Version:  I need to find a non-return (check) valve which will open at a very small pressure difference, and cause minimal pressure drop. Any ideas?

Normal version: Our hot water cylinder is fed from an open vented header tank situated in an upstairs cupboard.

The trouble is, this means there is less than 1m of head above the hot tap in our upstairs bathroom, so if I sing happy birthday twice whilst washing my hands upstairs, at the same time as Mrs Womble is washing her hands downstairs whilst singing staying alive, the flow to downstairs sucks air in via the upstairs tap, which then slows everything to a dribble.

I'd like to install a non-return valve at the upstairs tap to stop this from happening, but I can't find the right type to use. Any ideas?  :thumbsup:




"All fungi are edible. Some fungi are only edible once." -Terry Pratchett

doganjo

  • Joined Aug 2012
  • Clackmannanshire
  • Qui? Moi?
    • ABERDON GUNDOGS for work and show
    • Facebook
Re: Low pressure non-return valve?
« Reply #1 on: March 15, 2020, 12:28:39 pm »
On the back of this, I have a normal boiler, not combi, I have abungalow. Hot water comes through more or less instantly to kitchen, utility room, and my ensuite, but the main bathroom is at teh other end of eh house and it takes about 70 seconds to come through.  Flow seems OK

Is there any way of sorting this other than moving the hot tank into the roof space?
Always have been, always will be, a WYSIWYG - black is black, white is white - no grey in my life! But I'm mellowing in my old age

Womble

  • Joined Mar 2009
  • Stirlingshire, Central Scotland
Re: Low pressure non-return valve?
« Reply #2 on: March 15, 2020, 12:36:25 pm »
Oi! Get your own thread!  :roflanim:


Annie - there are two answers to that one that I know. One is to have the hot water going round on a pumped circuit the whole time (which is costly to do and to run, but tends to be what happens in large buildings like hotels). The other is to install electric trace heating, which keeps the pipes and the water in them hot all the way back to the tank.
"All fungi are edible. Some fungi are only edible once." -Terry Pratchett

SallyintNorth

  • Joined Feb 2011
  • Cornwall
  • Rarely short of an opinion but I mean well
    • Trelay Cohousing Community
Re: Low pressure non-return valve?
« Reply #3 on: March 15, 2020, 12:47:36 pm »
I don't know the answer but will be interested in it as we have a similar situation here, and this could be a cheaper option than pressurising the hot water tank.

However, to solve the immediate problem, I believe that the key thing is to be rubbing soap over your hands for 20s, so my suggestion is to soap up, turn off the tap, do the Happy Birthday twice thing (or whichever song works for you  ;D), turn the tap back on, rinse hands, rinse tap.
Don't listen to the money men - they know the price of everything and the value of nothing

Live in a cohousing community with small farm for our own use.  Dairy cows (rearing their own calves for beef), pigs, sheep for meat and fleece, ducks and hens for eggs, veg and fruit growing

chrismahon

  • Joined Dec 2011
  • Gascony, France
Re: Low pressure non-return valve?
« Reply #4 on: March 15, 2020, 01:04:05 pm »
Doganjo- small separate electric hot water tank and take out the redundant pipe- very important.


Womble- central heating pressure by-pass valve may work. The non-return valve is called a 'check valve' but you would need to ask the supplier about the minimum operating pressure as they are fitted to supplies to mixer taps and showers and outside taps.


Pressurising the hot water tank needs a 22mm house supply or an accumulator as well. Problem is the extra pressure usually causes old pipes to burst.

Womble

  • Joined Mar 2009
  • Stirlingshire, Central Scotland
Re: Low pressure non-return valve?
« Reply #5 on: March 15, 2020, 02:32:21 pm »
my suggestion is to soap up, turn off the tap, do the Happy Birthday twice thing (or whichever song works for you  ;D ), turn the tap back on, rinse hands, rinse tap.


LOL, yes, of course.


Don't worry, this situation is not new because we've only just learned how to wash our hands. It's new because we've both been in the house at the same time this week, which increases the instances of simultaneous hand washing.


I suspect that after another fortnight, Mrs Womble will probably bludgeon me to death, so that will resolve things anyway.
"All fungi are edible. Some fungi are only edible once." -Terry Pratchett

Womble

  • Joined Mar 2009
  • Stirlingshire, Central Scotland
Re: Low pressure non-return valve?
« Reply #6 on: April 23, 2020, 08:42:52 am »
Hi!  :wave:  Just thought I'd better confirm that she hasn't killed me yet.


Oh, and that I solved this problem by buying a regular 15mm single check valve.

As I suspected, the internal spring made it too restrictive for our system - the water did flow, but at a much reduced rate. However, it turns out that the internals of the valve are made in the form of a little plastic cartridge which slides into the brass body. I managed to undo the wire clip holding the cartridge in place, then remove it and pull out the spring which holds the NRV in the closed position.

The valve still works fine, but always opens fully now, and with much less pressure drop. So, I'm just leaving this here for future...
"All fungi are edible. Some fungi are only edible once." -Terry Pratchett

SallyintNorth

  • Joined Feb 2011
  • Cornwall
  • Rarely short of an opinion but I mean well
    • Trelay Cohousing Community
Re: Low pressure non-return valve?
« Reply #7 on: May 31, 2020, 10:08:22 am »
Hi!  :wave:  Just thought I'd better confirm that she hasn't killed me yet.


Oh, and that I solved this problem by buying a regular 15mm single check valve.

As I suspected, the internal spring made it too restrictive for our system - the water did flow, but at a much reduced rate. However, it turns out that the internals of the valve are made in the form of a little plastic cartridge which slides into the brass body. I managed to undo the wire clip holding the cartridge in place, then remove it and pull out the spring which holds the NRV in the closed position.

The valve still works fine, but always opens fully now, and with much less pressure drop. So, I'm just leaving this here for future...

:bookmark: non-return valve low water pressure
Don't listen to the money men - they know the price of everything and the value of nothing

Live in a cohousing community with small farm for our own use.  Dairy cows (rearing their own calves for beef), pigs, sheep for meat and fleece, ducks and hens for eggs, veg and fruit growing

 

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