Hybrid heating system and method

Abstract

A hybrid heating system ( 10 ) and method in which an indoor coil ( 12 ) of a heat pump ( 14 ) is located upstream of a heat output of a non-electric second heat source ( 22 ), e.g., a gas or liquefied petroleum gas furnace. The heat pump ( 14 ) continues to operate even at low temperatures, i.e., below 0° F., and the non-electric second heat source ( 22 ) supplements the heat output of the heat pump ( 12 ) as needed to maintain a desired indoor temperature, thereby maximizing economic benefit from the heat pump ( 12 ).

1 . A heating system comprising:
 a heat pump having an indoor coil and operable to generate a first heat output; and   a non-electric second heat source configured to introduce a second heat output downstream of the indoor coil,   wherein the heat pump and the second heat source operate substantially simultaneously when a demand for heat exceeds the first heat output of the heat pump.   
   
   
       2 . The heating system as set forth in  claim 1 , wherein the heat pump is a high-efficiency heat pump having a coefficient of performance of 3 or better. 
   
   
       3 . The heating system as set forth in  claim 1 , wherein the non-electric second heat source is a natural gas furnace. 
   
   
       4 . The heating system as set forth in  claim 1 , wherein the non-electric second heat source is a liquefied petroleum gas furnace 
   
   
       5 . The heating system as set forth in  claim 1 , wherein the non-electric second heat source is a high-efficiency variable capacity non-electric furnace operable to provide different amounts of heat so as to more closely supplement the first heat output of the heat pump. 
   
   
       6 . The heating system as set forth in  claim 1 , further including a first temperature sensor located downstream of the indoor coil and operable to monitor the first heat output, and to control operation of the heat pump. 
   
   
       7 . The heating system as set forth in  claim 1 , further including a blower located downstream of the indoor coil. 
   
   
       8 . The heating system as set forth in  claim 1 , further including a second temperature sensor located downstream of a heat exchanger component of the non-electric second heat source. 
   
   
       9 . A heating system for heating an enclosed space to a desired temperature, the heating system comprising:
 a housing having an intake opening and having an exhaust opening located downstream of the intake opening;   a heat pump operable to generate a first heat output, the heat pump having an indoor coil located substantially within the housing;   a blower located within the housing and operable to push air in the downstream direction; and   a non-electric second heat source configured to provide a second heat output within the housing downstream of the indoor coil,   wherein the heat pump and the second heat source operate substantially simultaneously when a demand for heat exceeds the first heat output of the heat pump.   
   
   
       10 . The heating system as set forth in  claim 9 , wherein the heat pump is a high-efficiency heat pump having a coefficient of performance of 3 or better. 
   
   
       11 . The heating system as set forth in  claim 9 , wherein the non-electric second heat source is a natural gas furnace. 
   
   
       12 . The heating system as set forth in  claim 9 , wherein the non-electric second heat source is a liquefied petroleum gas furnace. 
   
   
       13 . The heating system as set forth in  claim 9 , wherein the non-electric second heat source is a high-efficiency variable capacity non-electric furnace operable to provide different amounts of heat so as to more closely supplement the first heat output of the heat pump. 
   
   
       14 . The heating system as set forth in  claim 9 , further comprising a first temperature sensor located downstream of the indoor coil and operable to monitor the first heat output, and to control operation of the heat pump. 
   
   
       15 . The heating system as set forth in  claim 9 , further comprising a second temperature sensor located downstream of a heat exchanger component of the non-electric second heat source. 
   
   
       16 . A heating system for reaching and maintaining a desired temperature of an enclosed space, the heating system comprising:
 a housing having an intake opening and having an exhaust opening located downstream of the intake opening;   a heat pump operable to generate a first heat output, the heat pump having an indoor coil located substantially within the housing;   a first temperature sensor located downstream of the indoor coil and operable to monitor the first heat output, and to control operation of the heat pump with regard to reaching and maintaining the desired temperature;   a blower located within the housing and operable to push air in the downstream direction;   a non-electric second heat source configured to introduce a variable second heat output within the housing downstream of the indoor coil, the non-electric second heat source having a heat exchanger,   wherein the heat pump and the second heat source operate substantially simultaneously when the first heat output of the heat pump is, by itself, insufficient to reach and maintain the desired temperature; and   a second temperature sensor located downstream of the heat exchanger of the non-electric second heat source and operable to monitor the combined first and second heat outputs, and to control operation of the non-electric second heat source and the blower with regard to reaching and maintaining the desired temperature.   
   
   
       17 . The heating system as set forth in  claim 16 , wherein the heat pump is a high-efficiency heat pump having a coefficient of performance of 3 or better. 
   
   
       18 . The heating system as set forth in  claim 16 , wherein the non-electric second heat source is a natural gas furnace. 
   
   
       19 . The heating system as set forth in  claim 16 , wherein the non-electric second heat source is a natural gas furnace.