potterton puma 100e low pressure and resets....

[kevineaton77]

hi guys, hope all is well and that you may be able to shed some light on this.

btw, i am a computer engineer, so can help with your pc problems if you like...however, i know nothing at all about boilers, so i hope you experts can help.

moved into new house about 3 months ago.
have a potterton puma 100e combi boiler, which is about 6 years old i think.
its been "system lockout"-ing out about once every 3 days or so, and a reset fixes the problem. this is ok, a bit annoying, but it doesnt matter.

however, a few days ago, it came up with "low system pressure" and refuses to do anything. i looked this up in the destructions and it says that the central heating system pressure is low if this comes on.

have tried turning power off and resetting, no joy
the pressure gauge is reporting 1.5 bar.

then bled all the radiators, there was some air but not tons (although, i dont really have a point of reference)
the system pressure dropped, so i brought it back up to the red needle on the pressure gauge (@ ~1.5 bar) by refilling the system with the "combi mate" valve that is below the boiler.

the gauge seems to be working, i.e. it drops when the rads are bled, and goes up when i put water back to the system.

however, the low system pressure light remains lit and it wont heat water or do the central heating.

have put the pressure up to 2 bar to see if this helps but it doesnt, and then taken it back down to 1.5 by bleeding the rads again.

none of my radiators appear to be leaking.
i have some of the old repair tickets for the boiler, and it says that 2 years ago the low pressure valve was replaced

anybody got any ideas please???

cheers
kev

 

[kevplumb]

item 19 page 9 of the insallation instructions

if memory serves the switch goes open when under pressure

 

[kevineaton77]

thanks for the quick reply,

i guess that would make sense, is there any way to test the thing without killing me or blowing up the house????
i guess if its not opening then the sensor would think that it has zero pressure?

 

[kevplumb]

power off

disconnect one wire and insulate

power on

if the low pressure light is out its the switch (usually)

DONT run the boiler like this tho

sometimes the switch/ thread is full of gunge and just needs clearing out

 

[kevineaton77]

ok cheers, will give this a go.

thanks again

 

[gazthepottertonengineer]

they normally get blocked up with sludge !!

it wont cause too much of a problem even if you do run it with it disconnected as we made a cheap version of the puma just called a combi which they didnt even bother to put this on, so they could cut costs worse case scenario it will just trip out the o/heat stat

 

[kevineaton77]

hi guys, thanks for all your help.

i wimped out of the whole thing and got a plumber mate of mine to look at it, he banged the low pressure valave a few times and hey presto, its up and running again. yes!
so , you were all correct by the looks of things. just gonna wait and see if it stays working now.

thanks again.

kev