Inducer speed control method for combustion furnace
AssigneeTrane International Inc.
InventorsGordon Jeffrey Hugghins, Stephen Kowalski, Robert G. Roycroft
Life of this patent
Estimating the term…
Abstract
In a multistage combustion furnace having a motor driven inducer blower and a pressure sensing device or set of switches for sensing pressure in the combustion gas flowpath through the furnace, a high firing rate blower speed and low firing rate blower speed are set based on the blower speed setting required for a medium firing rate. Each particular furnace, having its own pressures and combustion gas resistance to flow characteristics, may be provided with a database of inducer blower motor speeds required to achieve predetermined pressures in the combustion gas flowpath for a variety of combustion gas venting systems generating such resistance.
Claims16
A method for operating a multistage combustion furnace, said combustion furnace including a heat exchanger including at least one combustion gas flowpath, an inducer blower for inducing the flow of air and combustion gases through said flowpath, for discharging combustion gases to a vent conduit, a blower motor drivably connected to said blower, pressure sensing means for sensing the pressure within the combustion gas flowpath at a predetermined location, a combustion fuel control valve and a control system including a microprocessor operably connected to said control valve, said blower motor, said pressure sensing means and to a thermostat for receiving signals for a call for heat for a space serviced by said furnace, said method comprising:
- starting said combustion furnace at a first firing rate in response to a call for heat by said thermostat;
- starting said blower motor at a predetermined speed for said first firing rate;
- learning a blower speed for said first firing rate, wherein the blower speed at which said pressure sensing means is actuated is the learned blower speed for said first firing rate;
- and
- determining a blower speed for said blower for a different firing rate based on the learned blower speed for said first firing rate.
A method for operating a multistage combustion furnace, said combustion furnace including a heat exchanger including at least one combustion gas flowpath, an inducer blower for inducing the flow of air and combustion gases through said flowpath, for discharging combustion gases to a vent conduit, a blower motor drivably connected to said blower, pressure sensing means for sensing the pressure within the combustion gas flowpath at a predetermined location, a combustion fuel control valve and a control system including a microprocessor operably connected to said control valve, said blower motor, said pressure sensing means and to a thermostat for receiving signals for a call for heat for a space serviced by said furnace, said method comprising:
- starting said combustion furnace at an intermediate firing rate in response to a call for heat by said thermostat;
- starting said blower at a predetermined speed for said intermediate firing rate;
- learning a blower speed for said intermediate firing rate, wherein the blower speed at which said pressure sensing means is actuated is the learned blower speed for said intermediate firing rate;
- and
- determining a blower speed for said blower for a different firing rate based on a multiplier applied to the blower speed learned for said intermediate firing rate.
A method for operating a three stage combustion furnace, said combustion furnace including a heat exchanger including at least one combustion gas flowpath, an inducer blower for inducing the flow of air and combustion gases through said flowpath, for discharging combustion gases to a vent conduit, a blower motor drivably connected to said blower, pressure sensing means for sensing the pressure within the combustion gas flowpath at a predetermined location, a combustion fuel control valve and a control system including a microprocessor operably connected to said control valve, said blower motor, said pressure sensing means and to a thermostat for receiving signals for a call for heat for a space serviced by said furnace, said method comprising:
- starting said combustion furnace at a first firing rate in response to a call for heat by said thermostat;
- operating said blower motor at a first blower speed for said first firing rate;
- learning a blower speed for said first firing rate, wherein the blower speed at which said pressure sensing means is actuated is the learned blower speed for said first firing rate;
- and
- determining second and third blower speeds for said blower for second and third firing rates based on said learned blower speed.
Dependencies are inferred from the claim text.