Abstract: A fire tube heater apparatus includes a shell, with a tube bundle received in the shell and a burner section communicated with the tube bundle. The tubes in the tube bundle have circular inlet and outlet end portions with a flattened, serpentine intermediate portion. The intermediate portion has a width greater than the inlet outside diameter and a tube thickness transverse to the width less than the inlet outside diameter.

Abstract: A water heater apparatus includes a fuel-air transfer arm connecting a blower outlet to a burner inlet. The transfer arm includes a continuously curved 180° bend portion and at least one inwardly extending internal flow disrupter located in the 180° bend portion for improving fuel-air mixture distribution across the burner inlet.

Abstract: A dual chamber burner assembly is provided for use with a heater apparatus having dual combustion air premix blowers. The burner assembly includes first and second interior zones communicated with first and second foraminous outer wall portions. First and second fuel and air inlet passages are communicated with the first and second interior zones, respectively.

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.

Abstract: A method of controlling a modulating water heater supplying water to a system includes sensing a parameter which changes corresponding to a change in system flow rate, the sensed parameter being a parameter other than system temperature, and then modulating output of the heater in response to a change in the sensed parameter. Early detection of system flow rate changes permits early modulation of water heater output before the changes in flow rate have had time to significantly impact the system temperature.

Abstract: A control system is provided for a modulated heating system including a plurality of modulating water heaters, which may be modulating boilers. A deadband control scheme provides for reduced cycling of the modulating heater when total system heat demand falls between the maximum output of one heater and the sum of the maximum output of that one point and the minimum firing point of the next subsequent heater.

Abstract: A control system is provided for a modulated heating system including at least one modulating water heater and a controller. A deadband control scheme provides for reduced cycling of the modulating heater when total system heat demand falls between the maximum output of one heater and the sum of the maximum output of that one point and the minimum firing point of the next subsequent heater. Condensation of flue gas products is prevented by monitoring flue exhaust temperature for each heater and controlling the modulation of each heater to maintain a minimum heater output sufficiently high to prevent condensation of flue gas products from that heater. Rapid reaction to changes in system heat demand is provided by sensing changes in flow rate in a primary loop of the system and anticipating resulting changes in temperature thus allowing for change in heater output prior to the time the change in flow rate has fully impacted system temperature.

Abstract: A control system is provided for a modulated heating system including a plurality of modulating water heaters, which may be modulating boilers. A deadband control scheme provides for reduced cycling of the modulating heater when total system heat demand falls between the maximum output of one heater and the sum of the maximum output of that one point and the minimum firing point of the next subsequent heater.

Abstract: A water heater apparatus includes a water conduit having an inlet and an outlet. A primary heat exchanger has a water side defining a portion of the water conduit. A burner is operatively associated with the primary heat exchanger for heating water in the water side of the primary heat exchanger. A variable flow blower provides pre-mixed combustion air and fuel gas to the burner at a controlled blower flow rate within a blower flow rate range. This apparatus allows the heat output of the water heater to be continuously varied within a substantial flow rate range having a turn down ratio of as much as four to one.

Abstract: A burner apparatus includes a mounting head having a fuel inlet opening defined in the mounting head for receiving combustion air and fuel gas through the opening. An inner support structure is attached to the mounting head. The inner support structure defines an interior zone communicated with the fuel inlet opening of the head. An exterior layer of flexible woven heat resistant material is received about the inner support structure and defines an exterior flame attachment surface. The mounting head may include a radial opening defined therethrough. An igniter is located outside of the mounting head adjacent the radial opening so that the igniter is proximally spaced from a combustion zone surround the burner apparatus. The burner apparatus may include a plurality of foraminous back pressure plates located in the interior zone distal of the igniter for balancing the pressure of the fuel gas/combustion air mixture along the length of the burner.

Abstract: A burner apparatus includes a foraminous burner surface having a multitude of openings through which flames can extend. The burner surface is irregularly shaped so that flames extending from the openings are directed in an irregular pattern whereby eddy currents are generated and effectively disrupt oscillation of the flames to result in reduced noise generation from flame oscillation.

Abstract: A heating apparatus includes at least first and second burners located in a combustion chamber wherein the burners are separated by a divider for deterring uncombusted fuel flowing from a firing burner to an area adjacent to a non-firing burner. In another aspect of the present invention, the burners are used to heat water in a multiple staged heater.