Defrost Methods

• Drain pan and drains also heated
  
  
• Fan is off until coil temp. in low enough to freeze water droplets
  
  

Electric

• Most common method
  
  
• Lower first cost higher operating cost
  
  
• Heat and moisture released into the space
  
  

Hot Gas

• Most efficient method
  
  
• Fast defrost with mineral space temp. rise
  
  

Water

• Not common, 50 F water sprayed onto coil at 3 Gpm, fast defrost, requires more maintenance
  
  
• Need a planned defrost – defrost timer and some initiated defrost
  
  
• Timed defrost (pressure difference measured)
  
  
• When unit stops automatic starts defrost