Supplemental hot water heat for forced air furnaces

Abstract

A hot water heat exchanger system for a forced air furnace includes a radiator having a water inlet and a water outlet. A first water conduit is mounted in fluid communication between the water inlet and a hot water outfeed line of a hot water tank. A water pump is mounted on the first water conduit for urging hot water from the tank into the radiator. A second water conduit is mounted in fluid communication between the water outlet and a cold water infeed line into the tank. The radiator is mounted into a plenum of the furnace so that air forced from the furnace into outflow ducting of the furnace by operation of a furnace fan in the furnace flows through the radiator, wherein the fan is actuated by a temperature sensor in the furnace. The pump is thermostatically controlled by a first thermostatic sensor. A furnace heater of the furnace is thermostatically controlled by a second thermostatic sensor. The first thermostatic sensor is for actuating the pump in a first temperature range between a desired temperature and a lower threshold temperature. The second thermostatic sensor is for actuating the furnace heater in a second temperature range, wherein the second temperature range is a range of temperatures below the first temperature range.

What is claimed is:  
     
         1 . A hot water heat exchanger system for a forced air furnace comprising: 
 a radiator having a water inlet and a water outlet,    a first water conduit mountable in fluid communication between said water inlet and a hot water outfeed line of a hot water tank,    a water pump mountable on said first water conduit for urging hot water from said tank into said radiator,    a second water conduit mountable in fluid communication between said water outlet and a cold water infeed line into said tank,    said radiator mountable into a plenum of said furnace so that air forced from said furnace into outflow ducting of said furnace by operation of a furnace fan flows through said radiator, said fan actuated by a temperature sensor in said furnace,    said pump thermostatically controlled by a first thermostatic sensor,    a furnace heater thermostatically controlled by a second thermostatic sensor,    said first thermostatic sensor for actuating said pump in a first temperature range between a desired temperature and a lower threshold temperature,    said second thermostatic sensor for actuating said furnace heater in a second temperature range wherein said second temperature range is below said first temperature range,    whereby, as a sensed temperature sensed by said first and second thermostatic sensors drops below said desired temperature into said first temperature range, said pump is actuated so as to heat air in said plenum by hot water circulation through said radiator thereby actuating said fan to force air warmed by said radiator into said outflow ducting,    and whereby, if said radiator cannot maintain the sensed temperature in the first temperature range so that the temperature sensed by said first and second sensors drops below said lower threshold temperature and into said second temperature range, said furnace heater is actuated to assist in elevating the sensed temperature to the desired temperature.    
     
     
         2 . The device of  claim 1  wherein an air reservoir, for dampening pressure fluctuations in said first water conduit, is mountable in fluid communication on said first water conduit.  
     
     
         3 . The device of  claim 1  wherein said first and second thermostatic sensors are mountable in a single thermostat housing.  
     
     
         4 . The device of  claim 3  wherein said first and second thermostatic sensors are mercury switches.  
     
     
         5 . In a hot water heat exchanger system for a forced air furnace including: 
 a radiator having a water inlet and a water outlet,    a first water conduit mounted in fluid communication between the water inlet and a hot water outfeed line of a hot water tank,    a water pump mounted on the first water conduit for urging hot water from the tank into the radiator,    a second water conduit mounted in fluid communication between the water outlet and a cold water infeed line into the tank,    the radiator mounted into a plenum of the furnace so that air forced from the furnace into outflow ducting of the furnace by operation of a furnace fan flows through the radiator, the fan actuated by a temperature sensor in the furnace,    the pump thermostatically controlled by a first thermostatic sensor,    a furnace heater thermostatically controlled by a second thermostatic sensor,    a method of hot water heating of air flowing through the furnace comprising the steps of: 
 (a) adjusting said first thermostatic sensor for actuating said pump in a first temperature range between a desired temperature and a lower threshold temperature, and  
 (b) adjusting said second thermostatic sensor for actuating said furnace heater in a second temperature range wherein said second temperature range is below said first temperature range, 
 whereby, as a sensed temperature sensed by said first and second thermostatic sensors drops below said desired temperature into said first temperature range, said pump is actuated so as to heat air in said plenum by hot water circulation through said radiator thereby actuating said fan to force air warmed by said radiator into said outflow ducting,  
 and whereby, if said radiator cannot maintain the sensed temperature in the first temperature range so that the temperature sensed by said first and second sensors drops below said lower threshold temperature and into said second temperature range, said furnace heater is actuated to assist in elevating the sensed temperature to the desired temperature.  
 
   
     
     
         6 . The method of  claim 5  comprising the further step of mounting an air reservoir, for dampening pressure fluctuations in said first water conduit, in fluid communication with said first water conduit.  
     
     
         7 . The method of  claim 5  comprising the further step of mounting said first and second thermostatic sensors in a single thermostat housing.  
     
     
         8 . The device of  claim 1  wherein said first and second thermostatic sensors include thermostatic controllers cooperating therewith, said controllers selectively adjustable so as to allow adjustable setting of said desired temperature and said lower threshold temperature.  
     
     
         9 . A hot water heat exchanger system for a forced air furnace comprising: 
 a radiator having a water inlet and a water outlet,    a first water conduit is mounted in fluid communication between said water inlet and a hot water outfeed line of a hot water tank,    a water pump is mounted on said first water conduit for urging hot water from said tank into said radiator,    a second water conduit is mounted in fluid communication between said water outlet and a cold water infeed line into said tank,    said radiator is mounted into a plenum of said furnace so that air forced from said furnace into outflow ducting of said furnace by operation of a furnace fan flows through said radiator, said fan actuated by a temperature sensor in said furnace,    said pump thermostatically controlled by a first thermostatic sensor,    a furnace heater thermostatically controlled by a second thermostatic sensor,    said first thermostatic sensor for actuating said pump in a first temperature range between a desired temperature and a lower threshold temperature,    said second thermostatic sensor for actuating said furnace heater in a second temperature range wherein said second temperature range is below said first temperature range,    whereby, as a sensed temperature sensed by said first and second thermostatic sensors drops below said desired temperature into said first temperature range, said pump is actuated so as to heat air in said plenum by hot water circulation through said radiator thereby actuating said fan to force air warmed by said radiator into said outflow ducting,    and whereby, if said radiator cannot maintain the sensed temperature in the first temperature range so that the temperature sensed by said first and second sensors drops below said lower threshold temperature and into said second temperature range, said furnace heater is actuated to assist in elevating the sensed temperature to the desired temperature.    
     
     
         10 . The device of  claim 9  wherein an air reservoir, for dampening pressure fluctuations in said first water conduit, is mountable in fluid communication on said first water conduit.  
     
     
         11 . The device of  claim 9  wherein said first and second thermostatic sensors are mountable in a single thermostat housing.  
     
     
         12 . The device of  claim 9  wherein said first and second thermostatic sensors are mercury switches.  
     
     
         13 . The device of  claim 9  wherein said first and second thermostatic sensors include thermostatic controllers cooperating therewith, said controllers selectively adjustable so as to allow adjustable setting of said desired temperature and said lower threshold temperature.