Thermostatic Shower running cold

[Jimeni]

Hi,
I have a hot water tank and a thermostatic shower (Bristan). I replaced the shower when we bought the house as it was luke warm no matter how I adjusted the temp (The hot water pipe was boiling but it wasn't feeding it through out the shower)
After replacing it with a similar unit it worked fine for about 5 months but now its back to being luke warm cold (again hot water pipe is boiling).
I think the cold is mains fed as its very high pressure, is this the problem? Any idea why it working for a few months?
The flow isn't great so considering a power shower, what type should I be looking at?

My boiler is: Ideal icos HE12

Thanks in advance for help.

Jim

 

[seco services]

Bristan what model ?
you should of ran it on equal pressures.
you have probably knackered the cartridge.

 

[holty]

proberbly check valves failing due to mains eventually pushing back the hot. not a good set up at all.should be tank fed cold.if access to cold supply could try using a prv and cranking it down. but not an ideal solution.

 

[Jimeni]

Not sure of the model, at least I know whats knackering it now.
I know nothing about plumbing and looks like previous owners knew nothing either as I just replaced what they had, whoops.

With the current pipe work setup would a power shower work? Would it handle the cold water pressure and pump the hot through?

Thanks for your diagnosis, makes things a bit clearer.

 

[seco services]

you need to get rid of the cold mains and take a cold supply from the loft tank.
then they will be both equal pressures

 

[Jimeni]

Cheers Seco,
I just popped in the loft and checked the pipes, the cold has a red valve to isolate it, I've turned that to partially off and the shower runs mostly with hot water now and although the flow isn't great (it never was) its running at the right temp.
Is this a stupid thing to do?

 

[holty]

well, there goes the mains supply theory out the window thats hoping the cold supply is tank fed because a gate valve shouldnt be on mains. wouldnt be the firs time though.trace the pipe back were does it come from

 

[Jimeni]

Hehe, I'm a numpty. Yeah comes from an insulated tank. I have that tank and also a water heater in the airing cuboard, I really dont get why I have a water heater when the boiler heats the hot water. Sorry I'm such a newbie to this (my first house!)

Can someone recommend a good book/website where I can look at different central heating setups and work out how mine works?

 

[holty]

that water heater in your cupboard is the dhw cylinder which is heated up either by a coil from the ch circuit or immersion.

 

[holty]

try this for a book, its what my apprentice uses a college http://www.amazon.co.uk/gp/product/0435402501/ref=cm_rdp_product/275-0959917-5258718

 

[Jimeni]

Cheers holty, that makes sense, cheers for the book recommendation, will take a look. I wish I did basic electrics and plumbing at school!

 

[seco services]

know we know its not mains cold but tank fed i would be looking at the check valves or filters.

never knew they done basic electrics and plumbing at school.

 

[holty]

they did electronics at our school,shame i wasnt listening at the time