Potterton Puma - Water Temperature

[SteveKat]

I have a Potterton Puma 100e. Works fine in every respect, except that the water temperature doesn't stay constant when taking a shower - it goes from hot, to cold and back again constantly - hot-cold-hot-cold....etc. The cycle of hot to cold probably takes a minute or so. I inherited this boiler when I moved into my new house a couple of months ago, and it's been doing it all the time. Not sure how old it is - I'd guess between 7-9 years. Just had British Gas look at it under a Homecare agreement and they said I'd need a thermostatically controlled mixer. I'm sceptical about this, as I've had other combi-boilers in previous properties with only very basic mixer taps, but never had any such problem...

Is there a fault with this boiler? Am I being fobbed off? Any advice would be much appreciated!

 

[baxpoti]

Does the hot water stay at a constant temp from the bath tap?

 

[SteveKat]

Yes, I believe so.

 

[baxpoti]

Then your shower is at fault!

 

[SteveKat]

Sorry, should have been clearer here - there's no seperate shower - it's on the bath-tap mixer...

 

[baxpoti]

You need to accurately measure the temp at a hot outlet with approx 12lt/min flow over a period of 2-3 minutes.

Let us know the outcome.

 

[Gasguru]

Is the cold bath tap off the mains?