Sabre HE 3 second blinking green then flashing red when on?

Grounding one probe of the meter is probably best - the other way may not give a meaningful reading and might confuse because a closed switch i.e. operated - will give a reading of 0V.

You will do best to set up the meter and then ask the boiler to run - and observe the pressure switch operating as the fan spins up - HOWEVER - for the pressure switch to operate the boiler needs to have its outer case properly fitted...

You might first isolate power from the boiler and check out the switch using the continuity (buzzer) setting on the meter as you suck and blow into the switch.

To check that the fan is actually making the switch operate will require a test lead attached to the switch or the circuit board and exiting outside the enclosure. A poor seal on the case will have an effect on the operation of the switch.

I am not qualified or experienced to offer this advice - I just guess.

Alternatively you might consider calling in a specialist engineer - Not British Gas who will insist on considerable up-selling.

Good Luck...
February 2016

I will get a multimeter today to test.
I guess I earth one terminal and touch one of the power leads as the boiler tries to ignite or will just putting a multimeter across the terminals do the same thing?
cheers for your help.
Toby

Toby
February 2016

You ask...

How can I test if power is getting to the differential power switch?

The flippant answer is with a Multimeter - they're inexpensive.

A better question is - Is the air pressure switch operating?

First the fan runs - then the air pressure switch operates - then the pilot flame is lit - then the main burner ignites. Each step dependent on the previous.

Good Luck...
February 2016