Mixer Shower and Combi Boiler problems

wlowry

Hello,

I have problems keeping a stable temperature in my shower. I have a Potterton 24KW Combi Boiler and an Aqualisa Aquamixa Bath/Shower mixer. The shower is older than the boiler but I have replaced the original cartridge with a combi boiler one.
The problem is that in Winter the water flow rate from the boiler seems to be very poor. Running the shower sometimes does not even turn the hot water on or if it does it soon turns off afterwards (whilst the shower is running). The problem doesn't seem to occur when filling a bath and the boiler has had major work done on it recently so seems unlikely to be the problem. Can anyone suggest if I need a repair done or if I'm not running the shower in the right way (DHW temperature)?
I have cleaned and descaled the showerhead but had no improvement.

Thanks

nofoollikeold

Is the right regulator fitted to the cartridge. Should be a pink cartridge with a yellow regulator. Olive green or blue regulators are for bigger boilers and might be too restrictive for your shower.

wlowry

I'm not at home but believe that it is the yellow regulator. I definitely have the pink cartridge and have not changed the regulator as I believe the yellow one was already fitted to it. I'll check when I get back.

jk0

I have the same problem. It's because the shower uses cold water as well as hot.

I run the basin tap until it gets hot, then switch on the shower, and shut off the basin. Still needs gradually increasing in temp as I'm showering though.