Fuel enrichment system for fuel-fired appliance

Patent metadata

Field	Value
Publication number	US-10876744-B2
Application number	US-201715457712-A
Country	US
Kind code	B2
Filing date	Mar 13, 2017
Priority date	Mar 13, 2017
Publication date	Dec 29, 2020
Grant date	Dec 29, 2020

Abstract

A fuel-fired heating appliance has two fuel flow paths to a burner, each actuatable to a closed state and to an open state. A heat exchanger is in fluid communication with an area proximate the burner. A controller executes the steps: (a) while the first fuel flow path is closed, opening the second flow path; (b) following ignition of fuel flowing from the second flow path, opening the first fuel flow path; and (c) following step (b), closing the second fuel flow path while opening the first fuel flow path.

First claim

What is claimed is:

1. A fuel-fired heating appliance, comprising:
a burner;
a first fuel flow path connecting a first fuel source and a first fuel-air mixing chamber;
a first valve disposed in the first fuel flow path controlling a first flow of fuel through the first fuel flow path at a first flow rate;
a second fuel flow path connecting a second fuel source and a second fuel-air mixing chamber, wherein the second fuel-air mixing chamber is located below the first fuel-air mixing chamber as a continuation part of the first fuel-air mixing chamber and is adjacent to the burner;
a second valve disposed in the second fuel flow path controlling a second flow of fuel through the second fuel path at a second flow rate;
an air flow path between an air source and the burner;
a heat exchanger defining an interior volume in fluid communication at an input end of the heat exchanger with an area proximate the burner so that combustion gas generated by combustion of a mixture of fuel and air at the burner is received through the input end into the interior volume;
an induction draft blower in fluid communication with an outlet of the heat exchanger, the induction draft blower configured to operate at different speed levels to draw the mixture of fuel and air to the burner;
an igniter proximate the burner so that actuation of the igniter ignites the mixture of fuel and air;
a sensor configured to detect the existence of a flame;
a controller in operative communication with the first valve, the second valve, the igniter, the induction draft blower, and the sensor; and
a computer readable medium containing program instructions executable by the controller to cause the controller to execute a method comprising the steps of:
(a) actuating the first valve to a first state of the first valve to block the first flow of fuel,
(b) actuating the second valve to a second state of the second valve to pass the second flow of fuel at the second flow rate,
(c) while the second valve is in the second state of the second valve, operating the induction draft blower at a first speed level to draw the mixture of fuel and air to the burner, wherein fuel drawn from the second fuel flow path and air drawn from the air flow path are mixed in the second fuel-air mixing chamber,
(d) actuating the igniter to ignite the mixture of fuel and air proximate the burner until a flame is detected by the sensor,
(e) following ignition of the mixture of fuel and air, operating the induction draft blower at a second speed level, wherein the second speed level is greater than the first speed level,
(f) actuating the first valve to a second state of the first valve to pass the first flow of fuel at the first flow rate, wherein fuel drawn from the first fuel flow path and air drawn from the air flow path are mixed in the first fuel-air mixing chamber prior to entering the second fuel-air mixing chamber and then the burner, and
(g) following step (f), actuating the second valve to a first state of the second valve to block the second flow of fuel.

2. The appliance as in claim 1 , wherein the first fuel flow path and the air flow path at least partially overlap.

3. The appliance as in claim 1 , wherein the first fuel source is the second fuel source.

4. The appliance as in claim 1 , wherein
a third valve is disposed in the second fuel flow path so that in a first state of the third valve, the third valve blocks flow of fuel through the second fuel flow path and, in a second state of the third valve, the third valve allows fuel flow through the second fuel flow path at the second flow rate,
the controller is in operative communication with the third valve, and
the third valve is a pilot valve which is configured to control operation of the first valve, so that the first valve is in the first state of the first valve if the third valve is in the first state of the third valve.

5. The appliance as in claim 4 , comprising a housing that defines at least part of the first fuel flow path and at least part of the second fuel flow path.

6. The appliance as in claim 5 , wherein the first valve is disposed in the housing, and the third valve is disposed in the housing.

7. The appliance as in claim 4 , wherein step (a) comprises actuating the third valve to the second state of the third valve.

8. The appliance as in claim 7 , wherein step (g) comprises actuating the third valve to the second state of the third valve.

9. The appliance as in claim 1 , wherein step (f) comprises actuating the first valve to the second state of the first valve for a predetermined period of time before actuating the second valve to the first state of the second valve at step (g).

10. The appliance as in claim 1 , wherein the induction draft blower further comprises a removable cylindrical extension that extends upward beyond the blower and into a removable cylindrical lower hood or skirt of a flue pipe.

11. The appliance as in claim 1 wherein the second flow rate of the second fuel flow path is lower than the first flow rate of the first fuel flow path.

Assignees

• Rheem Mfg Co

Inventors

• Batson Mickey E
• Reed Shawn A
• Cogburn Tyson J
• Whalen Nathan T
• Farley Darryl J

Classifications

• F24H9/2085

  using fluid fuel · CPC title

• F24H9/1881

  using fluid fuel · CPC title

• F23D14/04

  induction type, e.g. Bunsen burner · CPC title

• F23L17/005

  using fans · CPC title

• F23L15/02

  Arrangements of regenerators · CPC title