Posted by: Karolina Hupfauer on November 11, 2003 at 11:38:14

We are having problems with our 1 year old Rheem/Ruud Achiever 90 Plus Furnace. Usually it works/heats great, but sometimes, when more heat is required, the flame just does not kick on. On the printed circuit board, the first led light is on, but the second light sends a 'blink twice' error code. It does so for awhile, then goes into an idle mode, then repeats the error message code again.
To correct the problem: All we have to do is remove the furnace front panel, (we feel the air being sucked in), and the pilot flame comes on right away.
The furnace has a cold air return, and is located in a large room, however our home is extremely well insulated without any draft.

Answer:
'Without any draft' might be the cause of the lockout. Try leaving the door to the room open and open a nearby window 1/2-inch to see if that stops the flame failure. It might be the house is too tight to provide enough combustion air, so the pressure switch keeps the flame off. If the problem goes away with the air available; then you might need a fresh air inlet in the room.