water pressure- shower problem All aspects of plumbing questions and answers, help, tips and information

[bobby863]

Having just fitted a new thermostatic valve to my shower unit,gravity fed system, I now have plenty of hot water pressure, but very little cold water pressure.The shower head can go no higher than two feet before it stops running cold water-even this is only a trickle..Prior to fitting the new valve, the system worked perfectly.I have tried running the water for an hour but nothing seems to increase the flow.We did empty the cold water tank owing to the leaking valve.
Need any help quickly as we are all beginning to pong!!!

[Perry525]

Unfortunately shower thermostats come in several varieties.
Take a look at the box.
You need a thermostat that will work with a very low pressure.
I would guess you have one for mains pressure.

[bobby863]

[quote="Perry525"]Unfortunately shower thermostats come in several varieties.
Take a look at the box.
You need a thermostat that will work with a very low pressure.
I would guess you have one for mains pressure.[/quote]

The replacement thermostat is the same as the one that was in,(Aqualisa,which has worked perfectly well for tha last 10 years,) but for some reason ,even though we have put the hosepipe through the cold water outlet for the shower,and run for 10 minutes, we still cant get enough cold water pressure through the shower head.When on cold it runs warm but not hot.As soon as you turn to hot its very hot-help !!

[plumbbob]

If I had to fix this, I would firstly ensure the valve was installed the right way round. Then I would remove the valve and examine the filters for debris.

If this proved ok, I would turn the cold water on and see how much comes out of the pipe. Is it blocked? Does it have trapped air? Does it have a good flow?

Incidentally, is it a pumped shower by any chance?

Once the cold flow to the valve has been proved, then the finger points to a valve problem.

[Perry525]

I would guess that you have bought a higher water pressure thermostat than you had before, look carefully.
They come in a variety of "BARS"
You undoubtedly require a minimum 0.1 Bar.
To be fair this info is not always on the box, take a look at the booklet that came with it under * operationg pressure.*
If its not that, check that the pipes are the right way round and the hot water is coming in the correct side.