Potterton Puma 80 - shower running hot and cold

DoraDoesDIY · 31 May 2009

Hi,
My Potterton Puma 80 boiler is making my shower run hot then cold, hot then cold.
I have also noticed that when I turn the cold tap on in the kitchen.No water will come out of it.Bathroom cold taps work fine.
The guage underneath the boiler has 2 hands on the dial(one black hand and one red hand).Where should these hands be pointing to?
I'm guessing this is the pressure gauge????
I think the pressure has dropped.How do I increase this pressure,and what should the guage be reading?
And help much appreciated.
Many thanks,
Thea.

glasgowgas · 31 May 2009

the black "hand" is the pressure indicator for your central heating

it should be between 1 & 1.5 bar

the red "hand" is an indicator line that you can move to show what
the pressure should be. when you have filled and vented boiler and system and the black hand is between 1 and 1.5 move red hand to same

their should be a silver braided hose between the 15mm cold feed and the 22mm return pipe,usually 2 x 1/4 turn valves, sometimes 1 x 1/4 turn valve. open valve slowly, observe gauge and close when desired pressure is set.

when you have done this come back on this forum and we will try and sort the rest of it for you!!!!!

bengasman · 31 May 2009

Chances are the diverter is playing up, common problem with these.

DoraDoesDIY · 31 May 2009

Hi,

Thanks for the reply GlasgowGas/Bengasman.

The black hand (pressure indicator) on the pressure gauge was at '0'. I located the valve, opened it, and the black hand is now at 1.5. (The red hand (indicator line) is set at around 1.6).

Currently with this gloroius weather we are having the CH is swiched off.

When I run the shower, the boiler fires up (you can hear it/see the flame), and after about 20 seconds the water has reached the desired temperature. You can then hear the boiler fire down and after about 45 seconds the water then runs to cold. This process of the water running hot to cold and the boiler firing up and then down again continues until the shower is turned off.

Do you know if this is a fixable? Either by myself of would I need a professional.

Many Thanks,
Thea.

glasgowgas · 31 May 2009

defer to bengasmans knowledge,

probable diverter valve fault, replaced one for mother in law
couple of years back,not to hard for a diyer with a bit of experience,

if you have the manufacturers installation,servicing & repair manual and you feel up to it go for it.

if unsure get a RGI in to fix it.

you also have a leak somewhere if your system was at zero

DoraDoesDIY · 31 May 2009

Thanks Glasgowgas.

Yes I do have the 'Installation & Service Instructions'. Will probably get my dad to help me with replacing the Diverter Valve.

With regards to the leak - could this be caused by a constant dripping tap?

The cold tap in our kitchen has dripped constantly since we moved in. Dad has tried to replace the washer but the fitting has just been too tight to undo. May need some younger strength for that one

One last thing - Ive read a few other posts and tried this:
If I turn the CH to 'Constant', then the shower actually runs hot (not intermitantly hot/cold). Does this indicate that the Diverter Valve is stuck to CH mode. (Excuse me if this is wrong, just a girl who like to try and figure things out).

Will start looking in to purchasing a Diverter Valve now.

Thanks for your help on all of this.

Thea.

mickyg · 31 May 2009

There's also a chance the heat exchanger could be scaled up, very common on these horrible biflos in hard water areas. Depends where you are in essex, the west is very hard but the east is not to bad. You may not have a leak, its normal for pressure to drop over long periods of time.

bengasman · 31 May 2009

mickyg said:
You may not have a leak, its normal for pressure to drop over long periods of time.

Where does the water go if there is no leak?

mickyg · 1 Jun 2009

bengasman said:
mickyg said:

You may not have a leak, its normal for pressure to drop over long periods of time.

Click to expand...

Where does the water go if there is no leak?

not water...gases. Surely your not suggesting a sealed system never needs topping up?

bengasman · 1 Jun 2009

I would hope no topup is needed outside annual service.

mickyg · 1 Jun 2009

bengasman said:
I would hope no topup is needed outside annual service.

the op never said its been serviced

seeing as it appears the first time they've ever topped it up, i'd say there's no leak

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Potterton Puma 80 - shower running hot and cold

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