Check Valve (One Way Valve)

[fantuzzi]

I have just moved the copper cylinder to another location and cold water header tank into the loft space to get a little more head pressure on the hot water, all working fine but when the bath mixer tap is set to a mid position the differential pressure between the cold water (rising mains 15mm) and the hot water (Gravity feed 22mm) the mixer in the tap allows the higher pressure of the cold water to flow into the hot water line. I fitted a 22mm check valve in the hot line to prevent this but now the flow out of the hot bath tap has been reduced. I removed the check valve and had a look inside, there is a flat plate which sits against the seat but the orifice at its largest point is only 15mm, obviously here is the flow restriction.
What size and type of check valve will give me full flow for a 22mm pipe and any idea where the vave can be purchaced as the 2 local plumbing suppliers say the one I have is correct.

 

[Bernie2]

A none return valve fitted on the hot, will only stop cold water going up the hot pipe at the cold side of the fitting in a mains water pressure versus hot gravity situation.

What you may want is a bi-flow mixer or a pressure reducing valve fitted on the cold main by the sound of it.

But if your looking for check valves Arrow advertise some good ones, but just Google "low head loss none return valve" should get you a few answers.

 

[Alanka]

Another solution that I've used a couple of times for customers is to fit a pressure equaliser under the bath. This is a 4-port device that takes two inlets at different pressures (e.g. mains cold and tank hot) and adjusts both outlet pressures to be equal and at the lower pressure. The outlets will then blend perfectly.

They were about £70 last time I bought one (from BES I think) and take a bit of installing, but they work well and solve the problem, even if the mains or tank pressures vary during the day or season (e.g. with mains water demand or tank level).

 

[Phil]

How much? 😱

By-pass, Pressure Reducing Valves & Thermostats<br>Condensate Pump & Fittings


BES also do the low pressure check valves £1.49 + VAT (1/2" BSP)

Check Valves & Strainers & Drain Cocks

🙂

 

[justlead1]

Hi Just run a feed from the cwsc to the shower mixer. `good `luck

 

[Winston]

Do those pressure equalising valves really work? I asked a ts plumber he didnt sound confident at all but I have a situation in my home where it would be a godsend.

 

[Phil]

Yes they work but be warned, if the hot is a poor trickle, then so will the cold.

 

[fantuzzi]

Thanks, I have ordered the pressure reducing valve which I will fit in the circut before the bath mixer, but just comming back to the check vave which is now removed anyway, I have 22mm all the way ie 22mm feed from the header tank to the copper cylinder and 22mm all the way from the copper cylinder to the bath mixer, so I have 3mt head and 22mm flow. The flow is dramaticaly reduced by the 22mm check valve this must be caused by a loss due to opening the valve against spring pressue but the internal porting is only about 15mm so effectivly halving the flow due to the restriction. I would have thought that you can get a 22mm check valve giving full flow ie when opened the internal orifice is 22mm not 15mm?
The above problem is compounded by the new mixer tap, even though it has 22mm feeds when I opened it up to have a look inside the hole in the ceramic disks is a lot less than 22mm, maybe 2 indivdual taps would have been better like the ones I removed before the new bath was fitted.

 

[Winston]

LOL the hot is ok actually but the cold is off the main and just cant compete.

 

[Smcart5]

Is there not a full bore variant of the check valve?

 

[Alanka]

For goodness' sake let's knock this checkvalve business finally on the head!

A checkvalve is USELESS as a means of equalising pressure or allowing two different pressures to blend! All it will do - as has been stated in this thread already - is prevent unwanted backflow from high to lower pressure.

So you won't get cold water flowing back up the hot feed pipe, true, but you won't get any hot water out of the hot feed pipe either! The checkvalve will remain closed as long as the cold water back-pressure is being applied to it.

 

[HTB]

why not just fit a single impellor pump on the hot feed with associated check valves??

 

[justlead1]

Has the plot been lost on this post? For the sake of £30 or less for pipe and fittings, a cold supply from the cistern to the mixer solves the problem. Giving balanced pressures and reduces the likelihood of scalding and back flow. Its plumbing not meccano. Good Luck

 

[Unregistered]

hi i did this fixed a pump and check value but every 2 months it sticks shut any ideas y

 

[PlumbBobBob]

hi i did this fixed a pump and check value but every 2 months it sticks shut any ideas y

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