# US 5,347,981 A · Pilot pressure switch and method for controlling the operation of a furnace

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- Number: US 5,347,981 A
- Document ID: US5347981A
- Status: Granted
- Kind: A
- Application number: 08/117,308
- Filed: 1993-09-07
- Granted: 1994-09-20
- Earliest claimed: 1993-09-07
- Assignees: Goodman Manufacturing Company, L.P.
- Inventors: Malcolm Southern; Walter Wolenski
- Web page: https://patentgrep.com/patent/US5347981A

## CPC

- F23N 5/245: {using electrical or electromechanical means}
- F23N 2225/04: pressure
- F23N 2225/12: room temperature
- F23N 2227/22: Pilot burners
- F23N 2229/00: Flame sensors
- F23N 2233/02: in stacks
- F23N 2233/10: forcing air through heat exchangers
- F23N: REGULATING OR CONTROLLING COMBUSTION (control devices specially adapted for combustion apparatus in which combustion takes place in a fluidised bed of fuel or other particles F23C10/28; condition responsive controls for regulating combustion in domestic stoves with open fires for solid fuel F24B1/187)

## Abstract

A pilot pressure switch for a furnace detects the fluid pressure within the pilot line for a pilot flame, and upon the fluid pressure in the pilot line exceeding a predetermined value, an electrical signal from a thermostat may be passed to a furnace blower control to operate the furnace main blower and furnace vent blower.

## Claims

### Claim 1

A pilot pressure switch for a furnace having a continuously burning pilot flame in fluid communication with a furnace gas valve by a pilot line disposed between the pilot flame and the gas valve, the furnace also including a thermostat and a blower control with at least one wire disposed between the thermostat and the blower control, comprising:
a means for detecting the fluid pressure within the pilot line, the fluid pressure detecting means being disposed in fluid communication with the pilot line; and
a means for controlling the passage of an electrical signal through the at least one wire in response to the fluid pressure detected in the pilot line, whereby if the fluid pressure detected in the pilot line exceeds a predetermined fluid pressure, the electrical signal from the thermostat passes through the at least one wire to the blower control.

### Claim 2 (depends on 1)

The pilot pressure switch of claim 1, wherein the means for detecting the fluid pressure is a diaphragm switch.

### Claim 3 (depends on 1)

The pilot pressure switch of claim 1, wherein the means for controlling the passage of the electrical signal is a single pole, single throw electrical switch which is operatively associated with the means for detecting the fluid pressure.

### Claim 4 (depends on 2)

The pilot pressure switch of claim 2, wherein the means for controlling the passage of the electrical signal is a single pole, single throw electrical switch which is operatively associated with the diaphragm switch.

### Claim 5

A method for controlling the operation of a furnace having a continuously burning pilot flame in fluid communication with a furnace gas valve by a pilot line disposed between the pilot flame and the gas valve, the furnace also including a thermostat and a blower control with at least one wire disposed between the thermostat and the blower control, comprising the steps of:
detecting the fluid pressure within the pilot line;
controlling the passage of an electrical signal through the at least one wire in response to the fluid pressure in the pilot line; and
permitting the electrical signal to pass through the at least one wire from the thermostat to the blower control when the fluid pressure detected in the pilot line exceeds a predetermined fluid pressure.

### Claim 6 (depends on 5)

The method of claim 5, including the step of not permitting the electrical signal to pass through the at least one wire from the thermostat to the blower control when the fluid pressure detected in the pilot line is less than the predetermined fluid pressure.

### Claim 7 (depends on 5)

The method of claim 5, including the step of utilizing a diaphragm switch disposed in fluid communication with the pilot line to detect the fluid pressure in the pilot line.

### Claim 8 (depends on 5)

The method of claim 5, including the step of utilizing a single pole, single throw electrical switch to control the passage of the electrical signal through the at least one wire.

### Claim 9 (depends on 8)

The method of claim 8, including the step of closing the single pole, single throw electrical switch to permit the electrical signal to pass through the at least one wire, when the fluid pressure detected in the pilot line exceeds the predetermined fluid pressure.