cold header overflowing due to thermostatic mixer?

Yarn · 6 Oct 2010

Hello there, I have a cold header and hot cylinder. I have recently 're plumbed' this lot, but it looks like there is a problem. If the hot water is not drawn for a long time then the cold header overflows. I think it is a thermostatic mixer shower that I added. It is connected to the hot from the tank (on its own pipe) and also to the cold main. Even with the shower tap off, if I set the temp to cold (say less than 20) I can actually hear the cold water being drawn It must be going through the mixer and back up the hot pipe - Annoying. My system is only temporary so I am not overly worried, but even if i have the mixer set to hot +38 degrees, after a long period of inactivity the header is overflowing at a small trickle.

I dont know the make of the mixer, yes it was cheap. But does this sound right? could it actually be faulty? what can i do - is it possible to fit a non return valve on the hot?

I actually have a Salamander pump sitting here ready to add to the system, would this be a safe way of stopping the cold return flow?

Thanks.

tincup · 6 Oct 2010

Hi

You have two uneven pressures coming to the shower valve so a nrv should work.
The salmander will need its cold water from cws tank not the mains.

seco services · 6 Oct 2010

thermostatics should really be on equal pressures and it'll more likely say that in your instructions.

so yes you'll have cold mains passing to gravity hot.

as for the salamander pump how do you intend to install that

PEDANTICVINDICTIVEMAN · 6 Oct 2010

I love these joke postings

seco services · 6 Oct 2010

PEDANTICVINDICTIVEMAN said:
I love these joke postings

i'm sure people just chuck the instructions in the bin.

Yarn · 6 Oct 2010

I didn't read the instructions because i *thought* I knew how to fit the shower!!! LOL

I couldn't read the instructions until I had paid for it and trashed the box and basically gone too far any how. Its not the end of the world, I am still getting one every morning anyway. (a shower).

Thanks, for the help. The salamander pump is only a single pump CW50 from memory. TBH i was hoping to still run cold from the mains possible with a pressure reducing valve.

If the current problem is unequal pressure, will a reducing valve solve (then let me fit the salamander)??

seco services · 6 Oct 2010

Yarn said:
i was hoping to still run cold from the mains possible with a pressure reducing valve.

many installs are fitted with prv on the cold mains pump on the hot
but 9/10 times just causes problems.

if you start with equal pressures hot/cold both from the same tank
and just fit a twin pump your more likely to have a trouble free shower.

seco services · 6 Oct 2010

what shower mixer is it model/make ?

Yarn · 6 Oct 2010

Think it is unbranded from Screwfix at a price of about £60.

Regarding the salamander, i already have a single so would rather use it if possible. What sort of problems do you think might occur if i do fit the reducer and pump?

PEDANTICVINDICTIVEMAN · 6 Oct 2010

Screwfix ROFLMAO

Yarn · 8 Oct 2010

PEDANTICVINDICTIVEMAN said:
Screwfix ROFLMAO

Thanks for your input, really helpful. ROFLMAO.

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cold header overflowing due to thermostatic mixer?

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