First off you heater is working correctly...by that I mean it is getting 12V DC power from battery to circuit board and then to gas valve solenoid and spark electrode (12V has to go thru thermal cut-out, both t-stats to get to board and then from board to gas valve & spark electrode)
Power only goes to gas valve solenoids for about 6-8 seconds when power is being supplied to spark electrode.
When main flame lites off a 'signal' is generated by 'flame ionization' and is sent back thru spark electrode to circuit board....this signal holds power on gas valve solenoids to keep them open until circuit is broken by normal t-stat opening.
Lighting off and then only running for a few minutes could be:
*Dirty main burner tube and/or orifice (main flame needs to engulf spark electrode). Clean burner tube with small bottle brush. Clean orifice with alcohol. (Need to remove burner tube and orifice to clean)
*Misaligned burner tube...gas should flow straight down tube
*Misaligned burner spreader...should be parallel to end of burner tube
*Dirty combustion/exhaust U tube...clean with bottle brush/blow out with compressed air
*Low/lazy flame.......adjust air shutter....nice clean blue flame with tinges of orange at tip
Sounds like it needs a good cleaning......spider webs/bug nests/debris etc. will disrupt flame
Is it time for your medication or mine?
2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31