West side unit: low gas pressure safety tripped Bled air from gas line Reset unit, firing heat normally at this time East side unit: low gas pressure safety tripped Bled air from gas line Air pressure switch not closing due to clogged filters Installed normal 20x25x2 filters in it Unit heating normally at this time **we recommend standard flat panel (non-pleated) throw away 20x25x2 filters** Also recommend modifying ductwork so it pulls from outside air and not from the new building addition. Currently, this unit is pulling air from the new addition.