Gravity Fed Shower Problem

[CamperPete]

I hope I've posted this in the correct area, apologies if not.

I have a Bristan Pisa gravity fed shower that has a complete mind of it's own as to what temperature it'll shower you.

It's either cool, luke warm or red hot, it's seems to be a lottery as to which one it'll be.

The hot water in the rest of the house is always a steady temperature, the hot water cylinder is hot, the pipe that runs from the cylinder to the back of the shower (with the cut off valve) is hot even when the shower is cool or luke warm.

I assume this shower unit is a simple mixer type system and maybe something is blocking it now and again or some sort of air lock is happening but I've not a clue as to 1) releasing an air lock or 2) dismantling the unit to see if there's something that may be blocking it now and again.

I had a plumber round and he quoted me £650 for a new shower unit (albeit a power shower which I know I can buy for £120)...... hence I decided to ask for some professional advice on here as it may be a simple solution to the enlightened and I wouldn't need a new shower unit.

Thanks in advance

Pete.

 

[Softus]

The Pisa has a thermostatic valve, and in your case this is faulty.

Some valves have a replaceable was capsule, on others you can change only the entire cartridge. Bristan will tell you what to buy to fix this problem.

 

[CamperPete]

Great, thanks very much.

 

[Softus]

You're welcome.

BTW, when I said "was capsule", I meant "wax capsule".