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US 8,286,594 B2Granted
Gas fired modulating water heating appliance with dual combustion air premix blowers
AssigneeLochinvar, LLC
InventorJim C. Smelcer
Life of this patent
Estimating the term…
Abstract
A water heating apparatus uses a low range blower assembly and a high range blower assembly, each providing a variable flow of premixed fuel and air to a burner assembly. Appropriate choice of the operating ranges of the blower assemblies can provide a high turndown ratio approximately equal to the product of the turndown ratios of each of the individual blower assemblies. Turndown ratios as high as 25:1 are achievable.
Claims34
A water heating apparatus, comprising:
- a combustion chamber;
- a burner assembly located within the combustion chamber;
- a variable flow premix low range blower assembly communicated with the burner assembly for supplying premixed fuel and air to the burner assembly, the low range blower assembly being operable over a low flow rate range extending from a low range low end to a low range high end;
- a variable flow premix high range blower assembly communicated with the burner assembly for supplying premixed fuel and air to the burner assembly, the high range blower assembly being operable over a high flow rate range extending from a high range low end to a high range high end, wherein the high range high end is greater than the low range high end;
- and
- a control system operably associated with the low range blower assembly and the high range blower assembly to selectively operate one or both of the blower assemblies as needed in response to heat demand on the water heating apparatus.
3 more elements
A water heating apparatus, comprising:
- a combustion zone;
- a burner apparatus extending into the combustion zone;
- a first variable flow premix blower assembly for supplying premixed fuel and air to the burner apparatus, the first blower assembly having a first blower flow rate range extending from a first range low end to a first range high end so that the first blower assembly has a first turndown ratio at least equal to the first range high end divided by the first range low end;
- a second variable flow premix blower assembly for supplying premixed fuel and air to the burner apparatus, the second blower assembly having a second flow rate range extending from a second range low end to a second range high end so that the second blower assembly has a second turndown ratio equal to the second range high end divided by the second range low end, the second range low end being substantially equal to or less than the first range high end so that there is no substantial gap between the first and second flow rate ranges;
- and
- a control system operably associated with the first and second blower assemblies to selectively operate one or both of the blower assemblies as needed in response to heat demand on the heating apparatus, wherein the first and second blower assemblies together provide a continuous combined turndown ratio at least as great as the sum of the first and second turndown ratios.
3 more elements
A method of operating a water heating apparatus, the method comprising:
- (a) supplying premixed fuel and air to a burner assembly of the apparatus via a low range blower assembly at a flow rate within a low flow rate range;
- (b) supplying additional premixed fuel and air to the burner assembly via a high range blower assembly at a flow rate within a high flow rate range, the high range extending higher than the low range and there being no substantial gap between the low range and the high range;
- and
- (c) via an automated control system, selectively operating the blower assemblies as needed in response to heat demand on the water heating apparatus so that premixed fuel and air is supplied to the burner assembly over a substantially continuously variable combined flow rate range extending from a low end of the low flow rate range to at least a high end of the high flow rate range.
1 more element
Dependencies are inferred from the claim text.