The regulator maintains stable gas pressure over full range of required gas flow. A programmable controller reads one of two type-R thermocouples and controls a variable speed blower, which speeds up or slows down to raise or lower the furnace temperature. A butterfly valve is used to fine-tune the air pressure before it enters the recuperator to be preheated for the burner. As the blower adjusts the air pressure, the proportionator proportionally adjusts the gas flow. The ALO valve provides high-fire gas adjustment. Safety: flame monitoring unit energizes the ignition transformer only after purging the atmosphere inside the furnace with fresh air. It then initiates a trial-for-ignition period of 10 seconds during which the spark plug (standard) fires, and the redundant/automatic gas valves allow gas flow to the burner. If the UV Scanner sees a flame, the shutoff valves stay open and the spark plug is de-energized. Otherwise the valves close and a manual reset is required. The redundant automatic shutoff valves shut off the gas immediately if any of the following incidents occur:
1. Loss of blower pressure sensed by air pressure switch.
2. Excessive fluctuations in gas pressure sensed by gas pressure switch
3. Loss of flame (detected by UV scanner)
4. Hi Limit Controller reads unsafe temperature value from second thermocouple.
Optional automatic dialer can be programmed to call selected phone
numbers if temperature drops below or rises above given set-point
and/or if gas valves shut.
