Potterton Puma 80 Boiler Low Pressure warning light

[slant]

My Potterton Puma 80 boiler is showing low pressure warning. Ive looked at numerous other posts to check problem. The pressure is in fact way over in the red (4 bar), ive bled radiator to get it down to +- 1 1/4( black gauge now sits on red gauge). Ive also followed 2 yellow wires from PL12 on modulation control board to behind the board( by removing retaining screw and pulling board down) to what i believe to be the CH water pressure switch as noted on boiler wiring diagram, however ive noted that the diagram for CH water pressure switch is square with 1 & 2 connectors for yellow wires where the "switch" at back of board is round with 3 x connectors( 1 insulated) with 2 yellow wires going in. In a previous post it is recommended to disconnect these wires to override safety feature that stops boiler firing and let it run for a minute, then reconnect which apparently fixes problem by resetting it, this in my case did not work. Another post suggest putting 1 of the yellow wires into the 3rd unused connector, running system then returning wire to original position, again this didnt work? Lastly a suggestion is made of cleaning a blockage out of the switch( and excuse my lack of knowledge but we are presumably not talking about a conventional sort of switch as it has no"switch" mechanism that i can see...is it internal?), however there is no explanation as to how to remove and clean the "switch".

If at all possible i would like to fix this myself/clean the switch as i already had the boiler looked at 4 months ago as the timer wasnt working and that cost me a whopping £400 by the time it was resolved. Please help.

[superdupergasman]

Why not get a maintenence cotract with BG, £300 over the year.

Saftey check and repair, plus if anything else goes wrong then they will fix it.

You could link together the two wires on the WPS and if it works then
you should be cleaning the WPS out.

Drain some water off and reduce the pressure back down to 1.5 bar or you might pop a pipe or rad!!!

[AlanE]

It's a pressure operated switch. Normal problem is muck in the inlet to switch or the part of the boiler where the switch fits.

Normally just a case of cleaning. Maybe a replacement switch.

[slant]

Thanks for the reply.

Sadly i have been meaning to take out a boiler maintenance plan with EDF (my supplier) but like BG i believe the boiler has to be in working order first. (Theres a lesson here some where).

[slant]

It seems simple enough to remove the switch but Im not sure of the correct procedure in terms of shutting the boiler down and or what to do with the water pressure as it is currently at 1.5 bars. Is this something I can do without a corgi technician( ie not illegal). If it is can someone walk me through the steps. Thanks again.

[Agile]

Its quite easy to do but f you are not that familiar with the kind of thechniques involved then you could get yourself into more problems that you started with!

Obviously you have to isolate the electricity and drain the system pressure from somewhere suitable which is going to reclose afterwards!

Tony

[superdupergasman]

BG will encopass the cost of a repair into a contract for £300...

you need to tell them its broken and they will fix and take you contract.

[WDIK]

why no one has made refrence to this Im not quite sure but click on the blue text

ps its encompass

[AlanE]

Because he is not suffering from low pressure simply the boiler thinks he is because the pressure sensor switch is blocked.

[superdupergasman]

WDIK wrote:

why no one has made refrence to this Im not quite sure but click on the blue text ps its encompass

The first question states the pressure is up at 4 bar.

[slant]

Thank you all for your replies. I have not yet replaced or cleaned the switch as shortly after posting this problem i gave the switch a couple of light taps with a hammer to see if this may dislodge any dirt ( suggested on another forum). When i turned boiler back on the red low pressure light had indeed gone away but the boiler still did not fire, then a few minutes later the pilot light went out. I left the system for about 1/2 hour, relight the pilot light and the the boiler fired up fine. The boiler has worked fine for a couple of days then this morning it would not fire up again ( low pressure light is still not showing). I am going to try clean the switch or replace it if cleaning it doesn't work. Is this still the right route to take given the low pressure system light is not showing? I

[Agile]

If the LP light is off then it implies that its not working for another reason!

Tony