You say it runs for five minutes, Do you mean the blower blows or the burner burns?
I have had a problem with my Attwood where it would start normally, the blower came on, a few seconds later the burner ignighted, things started warming up and then it shut down.
Turns out I had a bad control board (Replaced with a Dinosaur board and all is fine now) but a bad thermocouple in the burner housing or a bad connection between the two can do that too.
The board was failing to read the signal (0.480 volts) from the flame sensor (Thermocouple) and thought ignition had not occurred.
I think I know why this happens.. It appears to folks at Dinosaur boards agree with me as they protected against this specific failure. But hey... IT works now.
