If you look on the control box cover behind the top panel, there should be a diagnostic code chart to tell you what the two flashes indicate. On my DGAT model furnace, two flashes indicate the centrifugal switch on the combustion air blower motor housing is stuck open.

If there is no noticeable difference in the flame after the blower comes on, you are probably ok. Every now and then I notice some orange in the flame on my gas stove and I attribute that to dirty gas in the supply.

Well, now I'm no closer to a decision than I was before I posted

Just remembered that your model furnace may be one that was sublect to a factory fix due to heat exchanger failures. Check with Coleman on this.

A little yellow at the tip of the flame is good but orange is not. Does the flame appear to be dancing around?

I have contacted the manufacturer with no response. I'll try again, maybe someone else's e-mail this time. Thanks.

My sling psychrometer shows 18% R.H. in the house. Any thoughts on my question?

We all are aware that there is no room in our furnace closets to install a humidifier. I have a pulse misting system in the box but have discovered that my ductwok is fiberboard (fiberglass). I'm wondering if introducing a mist directly into the duct will saturate/damage it. Any thoughts are appreci...

Does the furnace stay on when the dryer is on? It is possible that 20"w.c. could cause problems with the valve. Did you actually make that "homemade" gauge or just install a manufactured one? There should be a regulator on your tank that can be adjusted if it is working properly. 14&q...

Well, that's good news I guess. Maybe it was a combination of the t-stat wiring and the board being cleaned.

Make sure the burner tube and burner orifice/spud are clear with no obstructions.

Check behind orifice/spud for spider/web/bugs.

There's no way to be certain what the problem is without checking for 24VAC at the gas valve for starters when the ignitor goes off. It wouldn't hurt to check that there are no loose wiring connections in the control circuit (thermostat included) and if per chance you have a battery operated thermos...

Can you check for 24VAC at the gas valve terminals when the ignitor goes off?

Cheryl, One question for you so that Robert, the moderator here, will have as much info as possible. When you say you hear a click at times then the ignitor goes off, is there no burner ignition at all or does it light and then go off? It would help if you had a voltmeter to check for 24VAC across t...

By the way, you might want to keep that old thermocouple, or reinstall it and keep the new one handy for future replacement, if needed.