Shower 'pulses' when used

[Alcoblog]

Yes, thermostatic valve, and if I adjust that the pressure comes up for a few seconds and then drops again.

Not sure how I could vary the input pressure, apart from turning down the cold water feed at the mains, but given that the cold pressure seems to be very low would this help?

 

Definitely can't be turned up.

 

I think if I were faced with the same situation, I'd treat the fact that the shower problem happened shortly after the other work as coincidence. I'd be thinking more of a faulty thermostatic valve. I may well be wrong, but that'd be my first thought. Could it be that a fauly thermo-valve is creating the low pressure on the cold as I presume you have good water pressure elsewhere?

[handypandy]

Yes, thermostatic valve, and if I adjust that the pressure comes up for a few seconds and then drops again.

Not sure how I could vary the input pressure, apart from turning down the cold water feed at the mains, but given that the cold pressure seems to be very low would this help?

 

Definitely can't be turned up.

 

If its gravity fed, the cold water comes (or should come) from the header tank, not mains.

There are often little filter washers where the shower mixer body connects to the pipework. If these are clean and water flows freely from the tank, my next guess would be the thermostat.

[Cyclone]

I think if I were faced with the same situation, I'd treat the fact that the shower problem happened shortly after the other work as coincidence. I'd be thinking more of a faulty thermostatic valve. I may well be wrong, but that'd be my first thought. Could it be that a fauly thermo-valve is creating the low pressure on the cold as I presume you have good water pressure elsewhere?

 

Yes, that's entirely possible.

 

It could be coincidence of course, impossible to say really.

 

---------- Post added 29-11-2016 at 13:12 ----------

 

If its gravity fed, the cold water comes (or should come) from the header tank, not mains.

There are often little filter washers where the shower mixer body connects to the pipework. If these are clean and water flows freely from the tank, my next guess would be the thermostat.

 

Possibly it does, I couldn't say without locating the pipes in the loft I guess.

 

I'll get a photo of the mixer valve and pipework, perhaps it's something I can check for myself?

[andrejuan]

This happens in my house if the main stop tap has been turned off and not put back on at the same pressure/position?

[Cyclone]

It would have definitely been off whilst the plumbers were plumbing in the new shower and bath I guess.

[Alcoblog]

It would have definitely been off whilst the plumbers were plumbing in the new shower and bath I guess.

 

Try turning the mains (water) down a bit and see what happens, although if the problem's only just started, without anyone adjusting water pressure, I doubt if it'll be the culprit. There's not a fat lot that can go wrong with a water pipe (apart from leaking), so I still reckon it's the thermostatic valve on the shower, although, as an other poster has said, it could be the filter (if there is one) on the aforementioned valve. Either way, I'd be looking at the valve. If it's not hidden behind wall tiles it's not very difficult to replace/repair.