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US 10,330,329 B2Granted
Indirect gas furnace
AssigneeGreenheck Fan Corporation
InventorsEric Baker, Brandon Krautkramer
Life of this patent
Estimating the term…
Abstract
A high turndown furnace for an air handling system. In one example, the furnace includes a plurality of tubes divisible by four with a first modulating valve supplying gas to ¼ of the tubes and a second modulating valve supplying gas to ¾ of the tubes. In one aspect, the furnace is capable of providing a 16:1 turndown. In one aspect, the furnace is capable of providing seamless turndown operation throughout the entire firing range.
Claims24
A heating system comprising:
- (a) a first plurality of burner tubes;
- (b) a second plurality of burner tubes, wherein the second plurality of burner tubes includes three times the number of tubes in the first plurality of burner tubes;
- (c) a first plurality of burners connected to each of the first plurality of burner tubes;
- (d) a second plurality of burners connected to each of the second plurality of burner tubes;
- (e) a gas manifold including a first inlet in fluid communication with a first plurality of outlets and including a second inlet in fluid communication with a second plurality of outlets, wherein the first plurality of burners is operably connected to the first plurality of outlets and the second plurality of burners is operably connected to the second plurality of outlets;
- (f) a first modulating valve operably connected to the gas manifold first inlet;
- and
- (g) a second modulating valve operably connected to the gas manifold second inlet
- (h) wherein the heating system has a turndown ratio of at least 12:1 and has seamless modulation between a minimum heating output and maximum heating output with the maximum heating output being no greater than 12 times the minimum heating output.
6 more elements
A method of operating a heating system having a maximum system output, the method comprising:
- (a) modulating a first control valve to control a first burner tube section such that a temperature setpoint is maintained over a first operational range, the first operational range being between 1/16th of the total maximum system output and ¼th of the total maximum system output;
- and
- (b) modulating the first control valve and a second control valve to respectively control the first burner tube section and a second burner tube section such that the temperature setpoint is maintained over a second operational range, the second operational range being between ¼th of the total maximum system output and the total maximum system output
- (c) wherein the heating system has a turndown ratio of at least 12:1 and has seamless modulation between a minimum heating output and maximum heating output with the maximum heating output being no greater than 12 times the minimum heating output.
1 more element
A heating system comprising:
- (a) a first burner section including a first plurality of burner tubes, a first plurality of burners connected to each of the first plurality of burner tubes, and a first modulating valve for controlling a firing rate of the first plurality of burners between a first minimum firing rate and a second minimum firing rate;
- (b) a second burner section including a second plurality of burner tubes, a second plurality of burners connected to each of the second plurality of burner tubes, and a second modulating valve for controlling a firing rate of the second plurality of burners between a second minimum firing rate and a second maximum firing rate;
- (c) wherein the heating system has a minimum heating output equaling the first minimum firing rate and has a maximum heating output equal to the sum of the first and second maximum firing rates, wherein the maximum heating output is no greater than 12 times the minimum heating output such that the heating system has a turndown ratio of at least 12:1, wherein the heating system has seamless modulation between the minimum heating output and the maximum heating output.
Dependencies are inferred from the claim text.