Hi all. I have a 30K BTU Modine, and it is in my wife's greenhouse since last winter. We bought it new along with the greenhouse.

Everything went along pretty good last year, I hung the unit from the framing of the house. But, it became apparent it should be down low, so the heat would rise and not blow hot air on the plants.
So I set about doing this yesterday. Disconnected everything, lowered the heater down, I had purchased additional exhaust pipe to extend it down.

Reconnected everything and when I flipped the breaker back on, the exhaust gas fan came on, even though the stat wasn't calling for heat. And this became the problem.

The exhaust fan would run all the time. If I called for heat with the stat, after the proper/normal time, the blower fan would come on. BUT, the propane (Honeywell)valve would never open and ingnite.

Someting has it locked out. I checked and verified the air proving sensor was OK, the Honeywell valve was flashing 5 times, indicating "flame signal out of sequense". How could this be? It hadn't fired!

After checking everything over and over, the unit then (after turning the breaker back on), would turn the exhaust fan on for a few seconds, then lock the whole unit out. 6 flashes of the Honeywell valve.

How do you diagnose these Honeywell valves to find out what is causing the trouble?