Shower Thermostatic mixer problem - help.

[wippers]

Hi - I've had a Siadaw shower with thermostatic mixer in for about a year now and it's worked fine until recently.
I am now having problems getting the same amount of heat out of the shower and the pressure seems a bit lower.

I have a dedicated hot water feed from a valve on top of the tank.

I have a Bosch pump for the shower to boost pressure which seems to be fine.

I have removed the thermostatic valve and checked the water pressure for both hot and cold which seems fine (although I cannot compare with previous pressure when this unit was working ok).

I have blown through each side of the thermostatic valve along with the shower head etc and they seem to be blockage free.

One thing that I have noticed is that when I turn OFF the hot water tap in the bathroom after some use, the pump for the shower briefly kicks in for about a second.

I think I need some help???

 

[ChrisR]

CHeck the temperature of the thermostat on the hot water cylinder. You can set it up to about 60, but don't go higher.

Later in the year the cold water will be less cold, so you can turn the HW temp down again.

 

[tamz]

Might have a bit air in the hot side. Run it without the pump for a bit.

 

[wippers]

Cheers for the advice so far.

I've tried the shower with no pump and that doesn't seem to have solved the problem.

The thermostat on the tank is set at 60 deg. but when I feel the pipe coming from the surrey flange to the pump it doesnt' feel anywhere near as hot as the heating pipes. Is this right? I can comfortably hold my hand on the copper pipe.
The water out of the taps seems fine though. Could there be a problem with the surrey flange?

 

[TicklyT]

I've just changed a cylinder thermostat that didn't exactly do what it said on the tin.

Although wound up to 70, most of the time it was either switching at about 40 - 45 degrees, or not switching on at all.

It may be worth taking some measurements of your hot cylinder temperature to see if all is well.

 

[rob251]

is the pump a negitive head pump

 

[wippers]

Not sure if it's a negative head pump sorry. How can I find out?

Also, I have now touched the pipe from the surrey flange to the pump whilst the shower is actually running and it feels plenty hot enough.

Having removed the thermostatic mixer valve, the water seems to be reasonable pressure on the hot although not a much as the cold. The water seems as hot at the normal taps in the house.

Is this maybe pointing to the mixer?

 

[tamz]

Try adjusting the max temperature stop setting on the shower. If you have the manual it will tell you how in there.

 

[rob251]

check the fillters