I recently bought this home and it was told that the furnace did not work. I had the gas turned on and the pilot lit and stayed on fine. I had the front cover off, when I turned on the switch the furnace called for heat, when control valve opened, a big flash of flames came out the front. I emediatly shut it off. Could it be the pilit didn't light the gas as quick as it should of and the gas built up? Also does anyone know how old is the furnace? Rheem, Model UGDA-100A-AR Thanks in advance. Will