check valve on shower

[bobb]

I have a problem with a shower which is fed by mains pressure cold and the hot from a vented CH system.

I got cold water pushing through the shower and up through the hot water pipes and into my cold water tank in the roofspace causing it to overflow.

I cured this by putting a check valve in the hot water line. I got a standard brass one from the plumbers' shop.

It works, but every few months the check valve lets by and the cold tank overflows again and I change it for a new one.

Is there a type of non-return/check valve that would be longer lasting?

Or any better solution to this problem?

I suppose I could change the whole shower unit as I guess a seal must be worn to be causing this problem.

 

[kevplumb]

why not change the cold flow to the shower to tank fed
as it should be

 

[brumylad]

I agree with Kev.

Another, but expensive solution if you don't want to do all that pipe work just yet, is to ask your plumbing merchant if he has a pressure reducing valve that will reduce the pressure of the incoming mains water to the shower, to a level similar to the pressure of the hot water (maybe 0.5 bar).

also it might be wise to fit a filter ( line strainer) on the cold water main before the new valve.

 

[bobb]

Yes, Kev. I would put in a separate cold feed but it's a three storey house and it would be a right a**e-ache to run a line down to the ground floor.

Good call Brumylad. I'll try the filter first as it may be dirt under the seat of the check valve. I had assumed the hot water was degrading the innards of the check valve, but it may just be dirt.

If I put in the pressure reducer in the mains cold line, I've got the risk of pushing tank water back into the mains so I'd have to put a double check valve in the cold line wouldn't I, to conform with water regs?

 

[ChrisR]

There should be a double check valve immediately after the main stop cock.
Can't remember if you should have a double or single in the HW pipe to stop your problem, If you use a double you could go up a size to keep the resistance down.

You'd be better off with a pressure balancing valve than a pressure reducing valve. That would match the cold pressure to the hot, so the mixer would work better too.

 

[bobb]

Thanks Chris, sounds like the perfect solution. I'm not familiar with pressure balancing valves but I can see the sense as it takes fluctuations in mains pressure out of the equation. I'll look them up.