Potterton Puma 80e CH Pressure Switch

[GeeTee]

Boiler is a Potterton Puma 80e Combi

Got up this morning to no DHW or CH and the Low Pressure light on the boiler lit up. Checked the gauge and it was down near zero.

Just had some plastering / decorating done with a few rads being taken on and off so presumed the system hadn't been topped up afterwards.

Anyway filled it up to just over 1bar but the low pressure light stays on. So whipped out the multimeter and found that the CH pressure switch is staying closed regardless of the pressure in the system (took it to about 2.5 bar).

With the switch disonnected the boiler works fine on both CH and DHW. It is also holding pressure fine.

I'm thinking perhaps some crud got in the system with the rads being on and off and bit of it is stuck in the switch. Can the switch be stripped and cleaned or should I just buy a new one (only about £20) to be safe?

If I keep an eye on the pressure gauge is there any problem using the boiler until I can get a new switch on Monday?

I'll drain it down fully when I do the switch and give it few fill / run / drain cycles before inhibiting it to get any other crud that may be in there out.

Thanks
Graham

 

[gas4you]

For the sake of £20 go for a new one. No one on here will recommend running the boiler without the switch wired in as it is a safety device integral to the boiler.

Also if anything untoward did happen your house insurance would be invalid

 

[clf-gas]

Had same symptoms on one off my breakdowns on sunday, W/B though.

If your confident that the system is full, then for two days you can by-pass and get a replacement on monday.

 

[clf-gas]

Its only there to ensure the HE is not running dry Dave, two days wont do any harm.

 

[gas4you]

I agree and personaly would do this to my boiler but do not feel comfortable in suggesting to op

 

[clf-gas]

I totally agree with you Dave, From Grahams post and the way he's discribed finding the fault I feel comfy he's no numpty and will do as he says.

If he does'nt then

 

[GeeTee]

Thanks Guys

I'll go with the new switch option. Thinking about it, if it is a bit sticky it could potentially stick the other way and not detect a low pressure situation - not worth the risk or the bother of messing with the existing one.

I'm not using the CH at the moment anyway so it'll only be run for a bit of washing up and a shower in the morning.

I was quite surprised that the circuit is not designed to failsafe i.e. an open circuit stopping the system in case of a dislodged wire between the switch and PCB. Guess that would be too sensible

Thanks again.
Graham

 

[timmy74]

clean the original one with a bit of wire be a bit of crap inside

 

[GeeTee]

clean the original one with a bit of wire be a bit of rubbish inside

No thanks. For the reasons already discussed.

 

[ChrisR]

Wouldn't advise that in most cases. A fair number still don't work, or leak if you poke things up them. That means you have to drain down again, which always makes me cross . (DON'T use the boiler isolating valves, they'll leak)

 

[GeeTee]

(DON'T use the boiler isolating valves, they'll leak)

Haven't touched them to date for exactly that reason. Always drain the whole system down.

Price of a bottle of inhibitor vs having to mess about replacing one of those blighters - I know which option I'll take. Besides I only seem to have to drain down every 18 monhs or so (last time was to change the diverter wax head), so refreshing the inhibitor at this interval can't do any harm.

Thanks all.
Graham

 

[chaps]

the hole where water pressure goes in gets blocked up with sludge and muck in heating system, just release the pressure, remove it and poke it clear, dont stab it as you damage it, just poke it clear. replace and refill vent as required. job done.
(i been a heating engineer(corgi) for 19 years, never brought a new one)

 

[Bambergaspipe]

For the sake of £20 go for a new one. No one on here will recommend running the boiler without the switch wired in as it is a safety device integral to the boiler.

Also if anything untoward did happen your house insurance would be invalid

Words right from my mouth, I don`t wish to be rude but you are an a***sshole meddling in things to which you don`t understand. Sorry, I hope your family are not around

 

[GeeTee]

wtf? Is that aimed at me?

What's to understand? It's just a pressure switch. Right next to it is a handy pressure gauge that I am perfectly capable of reading before I have a shower.

I suppose I am running that entirely real risk that the gauge has also broken and coincidentally stuck at 1 bar when in fact there is no water left in the system. So I'll get in the shower and the world will end, a veritable apocalypse, summoning the 5 horsemen to our lands.

Thanks again for the non-abusive replies.
Graham

 

[gas4you]

I suppose I am running that entirely real risk that the gauge has also broken and coincidentally stuck at 1 bar when in fact there is no water left in the system.
Graham

You won't believe how many times I have had this on Ideal Mini Combi's. When you bang the guage it reads different everytime