Space Heater with Microprocessor Control

Abstract

A space heater has a microprocessor control that is configured to receive signals from at least the (i) ignition sensor associated with the burner, (ii) the flue pressure sensor, (iii) the secondary header temperature sensor, (iv) the fire box thermistor, and (v) the condensate sump level sensor, and in response thereto, control at least the operation of (a) the inducer, (b) the convection fan, (c) the condensate pump, (d) the burner ignitor, (e) the burner gas valve, and (f) the main gas valve.

1 . A space heater comprising: 
 a burner assembly having a plate supporting a burner and burner valve operatively connected to a gas supply regulated by a main gas valve of the space heater, the plate supporting an ignitor for igniting gas discharged from the burner, the plate supporting at least one ignition sensor configured for sensing the presence ignited gas exiting the burner;    a fire box having a generally box shape with left and right heat exchanger surfaces, top and bottom heat exchanger surfaces, and a rear heat exchanger surface defining an interior of the fire box, the burner assembly disposed in the fire box interior, the fire box having a fire box thermistor adapted to sense fire box temperature;    panels spaced from and surrounding portions of the fire box to form a plenum;    a secondary heat exchanger disposed in the plenum and exterior to the fire box adjacent the rear heat exchanger surface of the fire box, the secondary heat exchanger operatively connected to the fire box and receiving a flow of combustion gases from the fire box, the secondary heat exchanger comprising a corrugated flexible steel tube with a turbulator disposed inside the tube to induce spiral flow of the combustion gases passing through the secondary heat exchanger;    a primary header disposed in the plenum and exterior to the fire box adjacent the rear heat exchanger surface of the fire box in a generally vertical arrangement, the primary header operatively connected to an outlet of the secondary heat exchanger;    a secondary header disposed in the plenum and exterior to the fire box adjacent the rear heat exchanger surface of the fire box in a generally vertical arrangement, the secondary header having a temperature sensor adapted for sensing temperature of combustion gases flowing through the secondary header;    a tertiary heat exchanger disposed in the plenum and exterior to the fire box adjacent the rear heat exchanger surface of the fire box below the secondary heat exchanger, the tertiary heat exchanger comprising a plurality of finned tubes supported by and communicating with the primary header and the secondary header whereby combustion gases exiting the secondary heat exchanger pass through the primary header into the tertiary heat exchanger and flow into the secondary header, the tubes of the tertiary heat exchanger having turbulators disposed therein for inducing a spiral flow therein;    a condensate collection assembly arranged in the plenum below and operatively connected to the secondary header through a depending flow portion of the secondary header, the condensate collection assembly comprising a pump and a sump, the pump being configured to pump condensate entrained in the combustion gases from the sump to a condensate tray disposed atop the top heat exchanger surface of the fire box, the condensate collection assembly having at least one sensor adapted to sense a level of condensate in the sump;    an inducer mounted on the depending flow portion of the secondary header, the inducer being configured to draw combustion gases out of fire box and through the secondary and tertiary heat exchangers and discharge to a flue having a pressure sensor for monitoring pressure in the flue downstream of the inducer;    a convection fan located in the plenum configured to draw air from a room in which the space heater is situated into the plenum below the fire box and to pass the air over the secondary and tertiary heat exchangers and over the condensate tray before discharging the air to the room; and    a microprocessor control for the space heater being configured to receive signals from at least the (i) ignition sensor associated with the burner, (ii) the flue pressure sensor, (iii) the secondary header temperature sensor, (iv) the fire box thermistor, and (v) the condensate sump level sensor, and in response thereto, control at least the operation of (a) the inducer, (b) the convection fan, (c) the condensate pump, (d) the burner ignitor, (e) the burner gas valve, and (f) the main gas valve.    
   
   
       2 . The space heater of  claim 1  wherein the secondary heat exchanger tubulator is made from a material that is anodic relative to the combustion gases and the material forming the tube of the second heat exchanger.  
   
   
       3 . The space heater of  claim 1  wherein the tertiary heat exchanger tubulators are made from a material that is anodic relative to the combustion gases and the material forming the finned tubes of the tertiary heat exchanger.  
   
   
       4 . The space heater of  claim 1  wherein an interior of the tubes of the tertiary heat exchanger are accessible via at least on of the primary and secondary header.  
   
   
       5 . The space heater of  claim 1  wherein an interior of the tube of the secondary heat exchanger is accessible via the primary header.  
   
   
       6 . The space heater of  claim 1  wherein the burner assembly includes first and second burners.  
   
   
       7 . The space heater of  claim 6  wherein the microprocessor operates the inducer at a variable rate depending upon a number of burners in operation.  
   
   
       8 . The space heater of  claim 6  wherein the microprocessor is further configured to sense a temperature in the room and operate at least one of the first and second burners in response thereto.  
   
   
       9 . The space heater of  claim 8  further comprising a thermostat configured to generate a signal in response to a temperature in the room.  
   
   
       10 . The space heater of  claim 6  wherein the first and second burners have different heat generation ratings.  
   
   
       11 . The space heater of  claim 10  wherein the burner plate has openings adjacent each burner and the openings are dimension to regulate air flow to the burner to maximize combustion in accordance with the burner rating and inducer fan capacity.  
   
   
       12 . The space heater of  claim 1  wherein the flue comprises an inner pipe surrounded by an outer pipe and air for combustion flows through the outer pipe before being introduced to the burner.  
   
   
       13 . The space heater of  claim 12 , wherein the inner and outer pipe are made from a polyvinyl chloride material.  
   
   
       14 . The space heater of  claim 1 , wherein the tertiary heat exchanger tubulators are removably insertable into the finned tubes of the tertiary heat exchanger.  
   
   
       15 . The space heater of  claim 1  wherein the secondary heat exchanger turbulator is removably insertable into the corrugated tube of the secondary heat exchanger.  
   
   
       16 . The space heater of  claim 1 , wherein the secondary header is made from a polyvinyl chloride material.