[A/S] Intermittent furnace fault

["nickcrowhurst <NickandSandra@xxxxxxxxxxx>" <NickandSandra@xxxxxxxxxxx>]

Our Suburban Furnace model NT-30k has an intermittent lock-out fault, 
when the blower runs, but there is no heat. This occurred twice 
yesterday, after a week without a problem. I have fitted a new 
regulator, new OPD valves, new thermostat, and have taken the furnace 
to the recommended dealer for a full service and fault diagnosis. No 
fault was found. The gas supply will support four gas burners on the 
hob and the water heater at the same time, so I guess the new 
regulator is okay. My last thought is maybe water in the gas sytem. 
When I changed the OPD valves I emptied the tanks completely, so 
maybe I lost some drying agent. Perhaps I can get a fresh gas bottle 
and regulator connected directly (somehow) to the furnace, bypassing 
the trailer gas lines. When the furnace failed during last night, the 
water heater pilot went out during the same night. This is unusual, 
but it might be coincidence. Do any of you have any suggestions? I'm 
stuck for ideas, and I'm cold! Thanks, from Nick.