At 22:28hrs station 2 was alerted to the 2-26box in the 500 block of Loch Haven Rd for the fire alarm sounding. Upon arrival of units crews found nothing visually evident from the exterior. An audible fire alarm was sounding. Crews made entry into the building and found smoke conditions in the hallway. Crews upgraded to the commercial building fire. Upon further investigation crews found a heating unit on fire in the ceiling of the building. Crews extinguished the fire and secured power to the unit. Crews used positive pressure ventilation to remove smoke conditions. Due to the fire alarm system this situation was brought under control quickly before in was able to spread into the ceiling space. Crews were on scene for just under 1 hour.