Guest Blog: “Heat Pump Defrost Problems Not Only Hurt Your Wallet, They Mess With Your Home Comfort,” By Keith Graff at Gra-Tac Heating and Cooling.

Bryant Heat Pump Bowling Green KY Defrost Problem

By Keith Graff, Gra-Tac Heating & Cooling
Thursday, February 21st, 2013 11:00 AM CST

When a heat pump looks like this, the heat transfer goes away and it definitely needs to defrost or it will cost you on your electric bill and your comfort level.  The first thing to do is look at the unit in the next 30 minutes to an hour, if the ice or frost is gone – everything should be normal.  Heat Pumps regularly freeze and thaw during normal operation, so seeing ice or frost on a heat pump is part of the normal process.  If the ice doesn’t go away, is constantly formed in irregular frost patterns, or just keeps getting thicker (we have seen heat pumps covered in ice, several inches thick), it’s time to call an experienced HVAC Technician.

There are many causes for ice or frost on a heat pump.  Some times it is just normal, the coil is below 32 degrees and the humidity level is high enough that you couldn’t stop ice from forming – but that is what the defrost controls are for.  Other causes that should be immediately looked at by an HVAC Technician are:


  • Low Refrigerant can cause irregular looking frost patterns, with the cost of refrigerant today, all leaks should be found
  • Bad Defrost Boards or Sensors can cause units to freeze into blocks of ice
  • Stuck Reversing Valves can also cause units to freeze into blocks of ice or worse be stuck in air conditioning
  • Freezing Rain can cover the top of the unit, not allowing air to move over the coil, which will result in more ice
  • Condenser Fan Motors that stop in the winter will cause defrosting problems
  • Some times it’s bad not to see some frost, the Defrost Board may be set to defrost too often – which is almost as bad

There are corrective actions for each of these scenarios, that an experienced HVAC Technician can take care of.  But some times it is better to just replace the system with a new one, like in this case.

Trane XB13 Heat Pump

This Trane XB13 Heat Pump is almost 30% more efficient than the Bryant Heat Pump (when it was new) that it is replacing.  The Trane Heat Pump also has DEMAND DEFROST, where the older Bryant Heat Pump had a Timed Defrost.  Demand Defrost is always better than Timed Defrost.  Timed Defrost sees it is under 32 degrees outside and counts the run time from 30, 60, 90, and some times as high as 120 minutes of run time and then goes into defrost, clearing the coil.  Every time a Heat Pump goes into Defrost, it switches to air conditioning mode, cooling the house down (not that much, because it brings on the electric heat or back up heat to keep the home warm – READ EXPENSIVE $$$) to clear the coil and start the cycle again.

For more questions about heat pump defrost or replacing your current heat pump with a new more efficient heat pump by Trane, call your local Trane Comfort Specialist Dealer.

Gra-Tac Heating and Cooling brings that experience and knowledge of the market that no other can to our area. That’s why we are excited to have them join as a partner of Buy Local Bowling Green and contribute this great info. We look forward to working with ‘Gra-Tac Heating & Cooling’ and hope you contact them when you need to make your home have the feeling of comfort every home deserves. Go check them out online or on facebook.

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