Worcester 28i Junior - not working (no continuity on overheat stat loop)

[tomton]

Hi All,

Woke up to a cold house this morning
Red light flashing so I've tried to reset the boiler number of times but no luck.
Fan is working, pump is working and there is spark but it doesn't fire up.

Got my multimeter and boiler manual out and started going through fault finding.
Turns out there is no continuity on overheat stat loop (orange).
I took the cover off and checked the wiring to the stat and noticed that there is additional sensor on the same orange loop that is not indicated on any of the diagrams in the manual.
I've checked the mysterious sensor and that's where the continuity ends. I then tried to bypass it and the boiler fired up.

My questions:
what is this additional sensor and would it be safe to bypass it
where can I get it from and can it be replaced without draining the system

Some pics below.
No. 4 on the diagram is the overheat thermostat and like I said there is nothing else indicated next to it but on the next photo you can see additional sensor being wired on the same orange loop.

Thanks in advance for any help.

 

[Dan Robinson]

Put the cover back on and call a professional.

 

[gigz]

Its a pressure sensor. As previous advice. Get a GSR in.

 

[tomton]

Thanks for your replies.

First of all I would never attempt to try to fix it myself but I like to know what is wrong with the appliance before I get the professional out (be it boiler, washing machine, etc.)
I've had bad experiences with "professionals" who replace working parts and waste my time and money.

Back to the problem, yes it's a pressure sensor but it seems to be optional part as like I said before it's not being shown in the manual and also there is no reference to it anywhere in the booklet.
I managed to source the part from local merchant and and after speaking to nearly 10 local plumbers I've found one who was willing to come round today and replace it.
Bit of a pain as he had to partially drain the system but it didn't took too long.

Boiler is working fine now, total cost £95.

 

[simond]

Very common problem on this boiler, most spares merchants have one on the shelf.