Initial Start-up Problem

[14hvac]

What are some problems that might cause an old comfortmaker HSI to have the burners ignite, shut down and then have the fan turn on. The sequence of operation seems fine and it only happens on the first try. I can't get the furnace to do it the rest of the day.

After the first ignition sequence the furnace returns to normal operation. It's confusing....any help on this matter?

Shawn

[Phelps]

What do you mean by the first try? WHY should there be a first try as opposed to a 4th try before the 5th try?, let's say. What makes the first try the first try? Is the first try the one where you get up in the morning and decide to turn up the thermostat from some colder night time temperature?

I have heard a lot of people having that very problem and to be honest, it's hard to pinpoint because you can go there and then it is fine after you show up. It becomes a guessing game where you wonder if contacts have gotten colder and shrunk and made poor connections due to the cold. Or if it is internal in the control board, or if flame sensor that creates millivolts has an initial hard time making current when the metal is colder, or ?

It never hurts, and is a relatively easy job, to remove the flame sensor first (held in by just one screw) to brighten it up with some emery cloth. That's just a good maintenance thing to do, anyway.

Let us know how you make out.