Bristan shower runs cold

[stevefromnewcastle]

Hope someone out there can help.

I have a Bristan Prism thermostatic shower. Just replaced the cartridge and it won't get hot.

I disassembled and refitted, it seemed fine but when trying to use it, adjusted the temperature down slightly and it has gone completely cold again.

With the old cartridge back in, the temperature is OK (there is a reason for changing it). I have noticed that the new cartridge has an extra seal in one position and one seal less in another position, although this may not be relevant.

Loads of hot water from taps etc so the boiler is OK.

I know it is a bit sad posting this on Christmas eve but I'd love to get it working for the holidays.

Can anyone help?

 

[Slugbabydotcom]

With the old cartridge back in, the temperature is OK (there is a reason for changing it). I have noticed that the new cartridge has an extra seal in one position and one seal less in another position, although this may not be relevant.

Apart from my curiosity about your reason for changing the cartridge your answer lies in the above.

There is obviously something wrong with the new cartridge! Can you move a seal so that they both look the same?

Why did you want to fix something that wasnt broken?

 

[stevefromnewcastle]

Thanks for the reply. The reason for replacing the cartridge is :
We are having some problems with the combi boiler. The manufacturers say it is the shower and cold water is leaking back into the hot water system.

Although we are not convinced they are right, we have isolated all mixer taps etc on the system which left only the shower.

I was reluctant to change seals around as I assumed the new one would come with all the seals required, but then again so should the original one!

I will give it a try and let you know. Thanks again.

Steve

 

[Slugbabydotcom]

The reason for replacing the cartridge is :
We are having some problems with the combi boiler. The manufacturers say it is the shower and cold water is leaking back into the hot water system.
Steve

So we could be dealing with half a story here. Tell us more about the boiler problem.

A shower usually has non return valves and these are more likely to be the cause of your problems than the cartridge

 

[stevefromnewcastle]

I was trying to keep the question as simple as possible, but if you can help with the other problem I will be eternally grateful. Here we go....

Approx a year ago we extended our house and had a new Alpha boiler fitted to cope with the new rads etc. The hot and cold water piping was extended to serve the new rooms. The boiler is fairly high capacity. It is a combi with a hot water reservoir. (don’t have the model number to hand but can get it).

The main problem is when running a bath, the water runs very hot for approx 5 mins (we think until the reservoir is empty) then it cools down to luke warm. The boiler should start up and keep the water hot.

We have had Alpha engineers in who say there is nothing wrong with the boiler. They say that they is a shower or mixer tap on the system where cold water is leaking back into the hot water. Our plumbers are sceptical but at the recommendation of Alpha have fitted a non return valve on the hot water output from the boiler – it hasn’t solved the problem.

The confusing thing is that the hot tap in the kitchen and the bathroom work fine. They will supply hot water constantly. I have tried excluding any mixer taps etc from the system by turning off the isolation valves. The only device I can’t do this with is the shower as the pipework is behind the tiles.

As the Alpha engineer insists it is the shower at fault, I sourced a new cartridge for it. That brings us back to the shower question.

I have still been having problems with the new cartridge.
Old cartridge as it was (apparently missing a ring seal) work fine but we suspect it allows cold water back into the hot system.
New cartridge with all the seals on it, sometimes gives hot water, then goes stone cold and stays that way.
Old cartridge with all seals on it seems to work OK, so this is how I have left it.
The conclusion must be that the new cartridge is faulty.

Another possible clue is that the boiler overflow drips constantly (24/7)

Hope I have included all relevant info. My next step is to tear up the shower room floor to fit isolation valves!

 

[brian100]

Hi Steve, If you haven,t yet sorted out the problem with your shower I think I know the answer, if cold water is going into the shower valve and back into the hot water pipework it is because the non return valve inside the shower valve is faulty, this, when operating correctly prevents the cold water going into the hot water piping, to do this you have to remove the shower valve, take the non return valve out of the HOT inlet side and replace with a new one, refit the shower valve, sometimes its as well to replace them on both hot & cold sides.
I had a similar problem with the cold water mixing with the hot when the shower was on and this is what solved the problem, you can order the parts from Bristan or a number of other online outlets, I am a retired plumber but it is a job you could do yourself if your the DIY type, good luck

 

[seco services]

Hi Steve, If you haven,t yet sorted out the problem with your shower

Fri Dec 28, 2007

i would think so 3 yrs on. wouldn't you ?