Refrigeration – Structural installation
Reexamination Certificate
1999-07-28
2002-04-16
Doerrler, William (Department: 3744)
Refrigeration
Structural installation
C062S298000
Reexamination Certificate
active
06370899
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to heating, ventilating and air conditioning (HVAC) equipment and more particularly to single package HVAC equipment adapted to be mounted on the wall of a structure to condition the air in an enclosed space within the structure.
Single package wall mounted HVAC equipment is well known. Cost, serviceability, safety, and reliability are several factors that contribute to successful wall mounted HVAC units. Manufacturing cost and installation cost contribute to the overall cost of the equipment. Moreover, noise generated in the air supply from the HVAC units is limited by application and governmental regulations.
In the past, wall mounted HVAC units have been made with a preassembled cabinet which must be maintained intact during installation to prevent damage to the unit. This has necessitated supporting and positioning of the unit against the wall of the structure while at the same time attempting to insure that the air return and air supply duct flanges on the back of the cabinet align with the air return and air supply passages through the wall. Because the workmen could not see the duct flanges sufficiently while supporting the unit in position against the wall and because of the weight of the unit required auxiliary lift equipment to support the unit while it was being positioned on the wall, these prior art units were frequently installed with the duct flanges improperly aligned with the air return and supply passages through the wall. This has resulted in damaging the duct flanges so as to leave cracks at the wall/duct flange interface. These cracks allowed dust and small debris from the wall structure to enter the air passage through the unit and also allow air being forced out the air supply passage in the unit to escape. Moreover, the wall structure behind the cracks was exposed directly to the radiant heat from the electric resistance heater just inside the air supply duct flange. Since both the debris and wall structure were exposed to the high temperature from the heater, the heaters in these prior art units sometimes caused fires. Moreover, the efficiency of the unit was frequently reduced due to this air leakage through the cracks around the damaged duct flanges. Because the entire weight of these prior art units had to be supported by the auxiliary lift devices while the unit was positioned on the structure, the likelihood of injury and the cost of installation has been relatively high.
Some prior art wall mounted HVAC units have attempted to move the electric resistance heater away from close proximity to the air supply outlet so as to reduce the likelihood of fire from the heater. As a result, the air circulation blower was moved downstream of the indoor refrigerant coil and the heater was moved upstream of the air circulation blower. While the positioning of the heater reduced the likelihood of fires, the air circulation blowers discharged directly out of the air supply opening from the unit producing an unacceptably high noise level when no noise attenuation duct structure was located downstream of the air circulation blower. Moreover, when the air circulation blower was moved downstream of the indoor refrigerant coil, fresh air was typically introduced into the circulating air stream to the space being conditioned downstream of the indoor refrigerant coil also. This has resulted in making it more difficult to accurately control the temperature in the conditioned air being supplied back to the enclosed space.
Prior art single package wall mounted HVAC units have typically located the control box within the cabinet assembly so that the front service panel had to be removed while the service personnel gained access to the electrical and refrigerant check points in the control box for servicing the unit. This has made it difficult for the unit to be operated in the manner necessary for accurate servicing by the service personnel because the air passage through the unit had to be left open to the outside air. As a result it was difficult to accurately service the unit.
Prior art single package wall mounted HVAC units frequently have power disconnect devices that allow the power to be disconnected from the electrical components of the unit. However, these prior art units were constructed so that the disconnect devices did not have to disconnect power from the electrical components before the control box cover was removed. As a result, removal of the control box cover while power was still supplied the electrical components increased the danger of shock and damage to the electrical components of the unit.
These prior art single package HVAC units were typically manufactured with the back panel first attached to at least one of the side panels. In order to install the system components, it was necessary to temporarily support the other side of the various divider plates and other support structure eventually supported by the other side panel. This has not only made manufacturing tolerances difficult to maintain in order to insure proper cabinet alignment and also made access to the various components within the cabinet for electrical and refrigerant connections more difficult due to the presence of the back panel early in the manufacturing process.
Examples of prior art HVAC unit constructions are illustrated in the following prior art patents:
U.S. Pat. No.
Inventor
Issue Date
3,871,188
Vold, et al.
March, 1975
4,733,543
Blair
March, 1988
5,140,830
Sawyer
August, 1992
5,301,744
Derks
April, 1994
5,444,990
McGill, et al.
August, 1995
SUMMARY OF THE INVENTION
These and other problems and disadvantages associated with the prior art are overcome by the invention disclosed herein by providing a single package HVAC unit which can be easily mounted on the wall of the structure, which is easily serviced, inexpensive to manufacture and install, and which is safe to operate and maintain. The single package HVAC unit incorporating the invention has a first lightweight cabinet subassembly that can be mounted on the wall of a structure so that the air return and air supply duct flanges on the first cabinet subassembly can be easily visually aligned with the air return and air supply openings through the wall and a second heavier cabinet subassembly mounting all of the mechanical and electrical components of the unit that is installed on the first cabinet subassembly after it is installed on the wall. A hook means is provided that permits the second cabinet subassembly to engage the first cabinet subassembly in an initial tilted position and then pivot on the first cabinet subassembly to the final position overlying the first cabinet subassembly to facilitate alignment between the cabinet subassemblies during installation. The hook means may be at the top of the cabinet subassemblies so that the weight of the second cabinet subassembly causes it to pivot toward the final overlying position on the first cabinet subassembly. The invention further includes a blower assembly repositionable in the air circulation passage through the cabinet assembly so as to attenuate the noise transmitted to the space in the structure being conditioned yet maintain the required volumetric air supply output from the HVAC unit. The cabinet assembly is sized so that the blower assembly can discharge air into the air circulation passage downstream of the indoor refrigerant coil and out of alignment with the air supply outlet from the HVAC unit. The invention also includes a heater means repositionable within the air circulation passage through the cabinet assembly so as to maintain the desired orientation of the heater means to meet the operational design of the heater means. The invention includes a fresh air damper construction located in the vicinity of the air return opening into the HVAC unit and immediately downstream of the indoor refrigerant coil so that fresh air is induced into the air stream passing through the HVAC unit downstream of the indoor refrigerant coil. Likewise, the invention includes a safety interconnect means between
Fay Paul F.
Hobbs Shelton P.
Crispaire, a division of Airxcel, Inc.
Doerrler William
Jiang Chen-Wen
Powell B. J.
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