No cold water coming from the shower

[n20y1d]

We have two showers upstairs, they initially work ok giving warm/hot water but if used for any length of time the water goes too hot, I replaced the thermostatic valve on the main shower but that hasn't worked - so now I have tested the en suite shower - this hasn't been used for years and getting the same issue, the water is fine for a few minutes then goes HOT, if you turn either shower to cold once this has happened no cold water comes out?

I have taken the cold inlet off to the pump to the cold and whilst there was a small amount of grit on the filter it hasn't made any difference - I tried it twice and there is water going between the shut-off valve and the pump which I had to drain each time.

Given it is happening to both I suspect it's the shower pump that needs replacing but just wondered if anyone had any other suggestions I could try. Appreciate any suggestions.


The pump i have is Stuart Turner 46500 Showermate Eco Pump 2 Bar Twin.

 

[Johntheo5]

Looks like the cold end side, I suppose you could just remove the flexible hose at the far end and start the pump with the hose end in a bucket and see if flow is OK. There may be be a non return valve in the discharge which you might be able to inspect.

 

[n20y1d]

Have just turned it on cold only and that is fine, good steady flow of water. So think the issue is occurring once the pump has been on a certain period of time.

 

[CBW]

Is the cold water storage cistern running out perhaps?

 

[Johntheo5]

Have just turned it on cold only and that is fine, good steady flow of water. So think the issue is occurring once the pump has been on a certain period of time.

Does this issue occur with (if) the cold water is flowing from a cold tap only? , not a mixer?.

 

[dilalio]

Are you sure there's not a lever valve somewhere that's been knocked?

I had this a few weeks ago on a pump change. The customer's wife crammed a load of stuff back into the airing cupboard after I'd left and this swung the lever valve shut to the hot supply to showers.

I would remove the thermo cartridge and see if you can get both hot and cold emitting from bare body of valve(s) into the shower area as this means you don't have to worry too much about containing the water.

Maybe you've not put the thermo in properly. Or there may be a stuck NRV or blocked filter in shower inlets.

 

[dilalio]

Is the cold water storage cistern running out perhaps?

If installed correctly, hot should stop flowing first if this was the case.

 

[n20y1d]

Does this issue occur with (if) the cold water is flowing from a cold tap only? , not a mixer?.

The bath/sink taps (neither connected to pump) are not affected

 

[n20y1d]

Are you sure there's not a lever valve somewhere that's been knocked?

I had this a few weeks ago on a pump change. The customer's wife crammed a load of stuff back into the airing cupboard after I'd left and this swung the lever valve shut to the hot supply to showers.

I would remove the thermo cartridge and see if you can get both hot and cold emitting from bare body of valve(s) into the shower area as this means you don't have to worry too much about containing the water.

Maybe you've not put the thermo in properly. Or there may be a stuck NRV or blocked filter in shower inlets

it's affecting both showers, the lever is in the on position, I turned it off to check the inlet on the pump. Managed a shower this morning then it stopped again.

Have since tried it turning it to cold only and it ran for a short while before pump cut out.

 

[Johntheo5]

So, on cold only, it pumps cold for a short period and the pump actually cuts out?, if you run the shower normally, hot&cold, does the pump still cut out or does it just continue to pump hot only?, even if it does just pump hot, then the TMV shut shut off the hot as well with no water from the shower, the pump should then stop?

If the pump is stopping then possbly a flow switch problem, there are two flow switches, one on the hot, the other on the cold, a pressure switch starts the pump and it will stop when both flowswitches detect the flowrate < ~ 1 LPM.

 

[n20y1d]

Is the cold water storage cistern running out perhaps?

Don't think so, as mentioned when I run the bath and sink taps it's fine, only happens with child going through pump

 

[n20y1d]

So, on cold only, it pumps cold for a short period and the pump actually cuts out?, if you run the shower normally, hot&cold, does the pump still cut out or does it just continue to pump hot only?, even if it does just pump hot, then the TMV shut shut off the hot as well with no water from the shower, the pump should then stop?

If the pump is stopping then possbly a flow switch problem, there are two flow switches, one on the hot, the other on the cold, a pressure switch starts the pump and it will stop when both flowswitches detect the flowrate < ~ 1 LPM.

Thanks, just checked and the pump was purchased in 2015 and the water round here is so hard chuck Norris wouldn't drink it..

 

[dilalio]

only happens with child going through pump

 

[n20y1d]

Haha didn't spot that...

 

[n20y1d]

Just to update in case anyone comes across this....

Went out yesterday and purchased a new pump and the shower was fine this morning whilst the rest of the family used it... I went to shower a short while ago and halfway through it went again...

So went up into the loft and found the problem was the hinge on the ballcock on the ancient old asbestos water tank had clogged up so the water tank was filling but only very slowly gave it a quick wiggle/clean and then as soon as I head it refiling it occurred to me I hadn't heard it refilling for a while..... Turns out the outlet for the taps etc is a lot lower than the outlet for the showers.... so this is why I could still get water from the taps but not the shower.

Could kick myself, I'm now £170 lighter but on the plus side, the new pump is virtually silent compared to the old one.