St Croix Revolution- error code 2 issue

[riggy469]

I have a St Croix Revolution that is about 10 yrs old. We typically only run it at night on the lowest setting (1) as it’s tied into our ductwork and keeps the house comfortable.

Last few days have been pretty cold so I’ve bumped it to (2) and (3) on two different occasions. Both times, the unit would run for a while (1-3 hrs) but then shut off with an error code #2. If I run it on the lowest setting, it will run for hours on end with no issue.

I’m going to try the dollar bill test shortly on the main door and ash pan door, as the gaskets are original. According to the manual and reading online the most common culprit is a negative pressure issue.

Any ideas?

 

[Mt Bob]

My Furnace isn’t burning and the number 2 LED light is blinking. This diagnostic light
indicates the vacuum switch no longer senses Negative Pressure in the firebox area of the
Furnace. What caused the Furnace to go out?
a. The door of the unit was left open longer than 60 seconds. (See solution)
b. The ash pan door was left open for longer than 60 seconds. (See solution)
c. The combustion fan is not running. (Defective fan or control board)
d. The vacuum switch is defective.
e. The vacuum hose is disconnected
f. The vent system is plugged with fly-ash.
Solution: If the fire is out, re-light the Furnace. If the fire is still burning make sure all
doors are securely latched and hold down the On/Off button (approximately 5
seconds) until Furnace starts up again. This will re-start the Furnace in the start-up
program