Improving Commercial HVAC Efficiency and Performance with Engineered Access Solutions
Selecting the appropriate latching and hinging solutions can help achieve the overall efficiency, energy savings and improved performance.
Today’s commercial building equipment and systems, including heating, ventilation and air-conditioning (HVAC) systems, are becoming smarter and more integrated to help maximize long-term performance and value. Building owners and facility managers are constantly on the lookout for new and more effective tools to reduce repair costs, minimize downtime and keep the operating environment in their buildings in optimum condition.
Commercial HVAC units, for instance, are demanding more cost-effective and cost-efficient equipment performance. In turn, HVAC equipment manufacturers have been improving HVAC enclosure designs to be more energy-efficient. Enclosures designed with thicker doors and panels help eliminate leakage and enable the unit to handle the heating/cooling load without excess energy demands.
These enclosures are not perfectly sealed boxes, however. They include doors and removable panels—in some cases, quite large—for maintenance and repair access and other activities. Changing designs and physical dimensions of these doors call for new latching and hinging technology. Compression latches and hinging technology can improve access to these enclosures and help HVAC equipment suppliers satisfy their end-use customers.
Engineering HVAC energy efficiency
HVAC units are as essential to our modern world as data centers, cell phone towers and switching equipment. All are examples of “backbone” systems we employ to make the modern world work. In the case of commercial HVAC units, they keep our workplaces, retailers, hospitals, schools, travel terminals and myriad other locations comfortable and supplied with fresh air whenever in use.
These systems share several other characteristics: They use expensive, high-technology equipment that typically operates for long periods of time—for many building environments, HVAC units run 24/7. HVAC systems are heating/cooling vast volumes of air to precisely controlled temperatures and then moving that air continuously, making them major energy consumers. According to U.S. Department of Energy studies of commercial buildings, HVAC equipment typically accounts for 39% of a building’s energy usage.
The smooth operation of this compression latch series aligns the cam behind the frame and draws it up tight with a single continuous half-turn motion, which can prevent air leakage or vent hot air from the enclosure interior.
For building owners and facilities managers, improving the energy efficiency of their HVAC systems plays an important role in controlling costs and improving margins. That means they will be looking to HVAC systems suppliers who are improving the efficiency of their systems.
To accomplish this goal, HVAC OEMs are creating new enclosures that use heavier metal panels with improved insulation. This design update reduces energy loss from two kinds of air leakage: infiltration and exfiltration. Infiltration is leakage of unconditioned air into the HVAC unit from outside the enclosure. Exfiltration is leakage of air, typically conditioned air, from inside the unit through the casing to the outside. Both types of leakage increase the amount of energy required to supply conditioned air to the space.
Enclosure access doors are one of the key areas where leakage can develop. Many standard enclosures have been constructed with single-skin wall panels and single-layer doors, with a layer of fiberglass insulation adhered to the panels. These tend to be more flexible, expanding and contracting with the on-off cycles of the air handling units. This flexing, over time, can lead to fatigue on the panel seams, and also affects the seams where access panel doors meet the enclosure walls.
Newer generation access doors are typically double walled and insulated, with the total thickness of the door ranging from 40 to 60 millimeters. These double-panel doors are typically constructed of two separate panels with a thick layer of foam insulation between the panels. Depending on the door size, they can typically weigh between 35 to 50 pounds.
Some doors are just standard panels that open to allow access to control equipment; others are full, man-size doors that enable personnel to enter the enclosure. There are even some very large panels, designed to be removable, that facilitate access to large pieces of equipment inside. Using a heavier access door in these applications increases a high perception of quality and creates an important competitive value for HVAC system providers.
This hinge series allows a large HVAC door to be “lifted off” its frame quickly and easily, without the need for separate tools.
Securing larger doors
The incorporation of larger, heavier enclosure doors calls for different latching and access control solutions. If not properly equipped, doors can become weak points in the enclosure envelope.
Regardless of size, the door still needs to close securely in order to create a near-airtight seal to prevent leakage. Insulated doors typically have a layer of closed cell foam material applied around the door opening, which functions as a gasket to create a secure seal. While standard latching mechanisms were used to secure older enclosures with single sheet metal doors, newer double-skin doors require a different type of latching solution capable of securing a door panel up to 60 millimeters thick. The best solution for this type of door is a compression latch, which holds a panel or cover closed by using a cam action and, at the same time, compresses a gasket around the inside of the door to seal it.
While a compression latch is the right solution for a double-walled door panel with insulation, improper installation of the latch could squeeze the insulation too much, damaging the foam and creating a void that could reduce the insulating factor. There are specialty cam latches designed to avoid this problem that can be rigidly mounted to the door with a sleeve and firmly attached to the door without squeezing the foam insulation when closed.
In some cases, these doors have very large dimensions, so a single latch may not be sufficient to fully secure the door. Multi-point latching systems, which allow multiple latch points at the top, bottom and middle of the door to be controlled by one actuator, can provide a simplified access solution for oversized doors.
When selecting a cam or compression latching solution for any enclosure door, it is important to take the following design requirements into consideration:
4Environment. With the majority of HVAC equipment located outside, enclosure OEMs must ensure that their equipment meets environmental protection and durability requirements. Enclosure OEMs can maintain compliance by incorporating latches that are tested to UL, NEMA or IP standards.
4Safety. The interior of HVAC enclosures containing boilers or other high-temperature equipment can generate a level of heat that can be harmful to maintenance technicians if they open the door quickly. There are latching systems that when first actuated allow the hot air to be slowly released before the door is fully opened. The operator can then actuate the latch a second time to safely access the enclosure.
4Security. Most latches used on HVAC enclosures are available in multiple head styles with a range of locking mechanisms. Choices include simple slot and hex head styles, which can be opened with a standard maintenance tool, and key lock actuated, which provides a higher level of security for equipment located in a publicly accessible area. Latches that are compatible with padlocks are also commonly used to deter unauthorized users, and are often used in lock out, tag out situations.
4Ease of use. Simple opening is an important ergonomic characteristic, especially to maintenance technicians servicing large facilities such as warehouses, production facilities, hospitals, business parks and other multi-building locations. Being able to access the enclosure door with simple tools creates a positive user experience and creates an overall impression of quality and value for the entire HVAC system.
Intuitive enclosure access
Like latches, hinges are an essential access component in the overall design of the HVAC enclosure, but they go beyond simply joining the panel to the frame. While relatively simple in terms of functionality, the technical capabilities of the latest hinge technology provide design engineers with new options for enhancing the performance of and interaction with panel doors.
It’s often the case that when maintenance technicians open an enclosure door, they want it to stay open while they access and work on a control panel or carry out equipment maintenance. Rather than attach an external secondary door stay to prop the door open, detent hinges allow a door to open to a preset angle and click into position.
Fixed-position detent hinges allow a door to open to a preset angle and click into position for easy access, versus having to attach an external secondary door stay to prop the door open.
Constant torque hinges fulfill the same function with a greater range of possibility, providing smooth opening operation and infinite positioning of the door, opening as far as a technician desires, and remaining in position until pushed close. These hinges allow for intuitive movement of the door, holding it at any point throughout the full range of motion when stopped, with the amount of effort required to move the door just enough to respond to deliberate motion.
In addition to opening, in certain HVAC systems, large doors may also need to be easily removed to accommodate the replacement or upgrade of large equipment. There are a range of removable hinges available that have been engineered for very simple removal without the need for separate tools, allowing a door to be “lifted off” its frame. As with latching solutions and hinges previously mentioned, HVAC equipment OEMs and enclosure suppliers should select hinges that comply with standards for external use environments and provide durability and long operating life when exposed to the elements.
Selecting the right components
To maximize HVAC system energy efficiency, HVAC enclosure designers ultimately need to select the appropriate latching and hinging solutions that will satisfy two basic functional requirements: easy opening and secure closing.
Component selection should be based on a door’s dimensions, thickness and weight. This includes choosing the proper number of hinges for the door’s size and determining whether a standard latch with just one latching point or a multiple latch configuration is required. The level of security needed for each latch—simple tool actuation or more secure key actuation—should also be taken into consideration.
When choosing a high volume supplier of latching and hinging solutions, HVAC designers should evaluate the strength of a vendor’s supply chain: Do they have a global footprint? Do they have background in regional requirements in terms of environmental standards? How well can they supply products in different regional markets in a timely fashion?
The best suppliers are typically equipped with a strong supply chain and ample product available to meet production requirements. They will also be able to supply expert support and advice on the best latching and hinging technology to use on specific enclosure designs—especially those with insulated doors that call for access solutions engineered specifically for those applications.
As HVAC OEMs continue to improve the design and energy efficiency of their enclosure systems, selecting the appropriate latching and hinging solutions to complete those designs can help achieve the overall efficiency, energy savings and improved performance that the latest generation of HVAC systems are engineered to provide.
Energy Information Agency, 2001. Commercial Buildings Energy Consumption Survey. Washington, DC: U.S. Department of Energy.