Shift to bulkhead evaporators

Cheyne Rauber, general manager of Rifled Air Conditioning Systems Inc. (RAC), says that the company’s most popular evaporator, the BH-20, meets an increased demand for bulkhead evaporators.

“Over the last five years, we have recognized a major shift in demand from the standard hang-down style evaporators to the new bulkhead style evaporators,” Rauber says.

One of the key factors driving this trend is that bulkhead style evaporators are designed to give an integrated appearance into the front and rear bulkheads of the bus. Another key factor is that the design combines style and function with minimal cabin intrusion, Rauber says.

RAC has made new improvements to its BH series evaporators:

• A redesigned four-hole drain pan, which creates a positive drain of the condensation/water that is created during normal operation of the a/c evaporator. With four drains, the orientation of the bus does not affect the draining capability, since there is always a low point for proper drainage.

• Rivet nuts have been added to the sides of the BH series evaporators. This upgrade provides installers different mounting options to fill a larger range of install applications.

RAC has also recently redesigned its website with updated articles and air-conditioning relevant content, including updated wiring diagrams and service documents.

Meeting demand for rooftop units

Some of American Cooling Technology (ACT)’s most recent product developments include an expanded rooftop product line and additional bulkhead mounted in-wall evaporators, such as the EV-2.

ACT officials say that the application of rooftop air-conditioning systems and components has been an industry-wide trend within the past few years.

Condenser coils located on the roof of the bus have access to cooler, cleaner air, which contributes to both higher capacity from the a/c system and less maintenance, compared to coils that are located under the floor of the bus. Having an a/c option atop the bus also gives bus manufacturers more flexibility with design and use of space.

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To satisfy the growing demand for skirt system alternatives, ACT offers a complete line of roof-mounted condensers: the CR-2, CR-3 and CR-4.

The CR-2, a two-fan condenser, has been available for a number of years, and the CR-4 was released in 2011. However, ACT wanted to offer a complete line, so in January 2012, it went into production for the CR-3.

In the past, ACT commonly placed two CR-2 condensers into medium-size buses that were too large for one CR-2 and too small for a CR-4. The introduction of the CR-3 provides additional flexibility for a/c system installation choices.

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  “Having these different capacities available now gives us flexibility for customer requirements — and reduces the chances of having to oversize or undersize a system,” says Dave Oberdorff, president and CEO of ACT. “The expanded product offering fills a market niche for capacity and application in fitting the product to the bus.”

The CR-3 rooftop condenser features three high-capacity 12-inch fans, a lightweight aluminum frame, a durable TPO cover and O-ring connections for maximum leak protection. The heat rejection coils are an enhanced copper tube expanded into aluminum fins. The CR-3 is typically applied as a system in a single circuit design with an evaporator, compressor and drivers control.

While the CR line of rooftop condensers is still part of a standard split system, ACT has also been working with Espar (Eberspächer) to make a complete rooftop set available to customers. These systems include the field-proven AC-310 for conventional school buses and the AC-350 for the larger transit-style buses.

The latest addition to the Espar rooftop product line is the AC-353G4 series, which is now available in a standard and a narrow version, depending on the bus roof contour.

The AC-353 rooftop series offers additional options for enhanced HVAC features, such as long-life brushless evaporator and condenser motors, adjustable fresh air, and electronic drivers control with diagnostic capabilities.

New rooftop series launched

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  Trans/Air Manufacturing Corp. is now offering a new rooftop climate control system for school buses as well as commercial vehicles.

The RT65 is a compact, low-profile, roof-mounted unit that is the first in a series of rooftop climate control systems that will be introduced by Trans/Air over the next year, company officials say.
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The RT65 can be installed in various configurations to suit a range of vehicle sizes and a/c specification requirements. Systems are offered with EC4.0 electronic controls and free-blow or ducted air distribution, as well as a heat option.

The RT65 system can be installed in single or dual configuration. A single RT65 roof-mount system with a 13 CID automotive compressor ranges from 40K (SAE) to 64K (IMACA) Btu/hr. A dual RT65 configuration, with dual 13 CID automotive compressors or a single TM43 transit compressor, ranges from 80K (SAE) to 128K (IMACA) Btu/hr.

Trans/Air officials say that a distinctive feature of the RT65 is the unique orientation of the evaporator blowers. Blowers are mounted to either side of the center aisle, providing more head clearance, and are oriented toward the front and rear of the bus for maximum air flow. RT65 ducted air distribution configurations can be adapted to any OEM style duct work.

Rooftop units keeps a low profile

Thermo King’s StudentAIRE heating, ventilation and air-conditioning (HVAC) solutions are designed to be compact and affordable for school bus operators, manufacturers and dealers.

The solutions include a high-performance a/c system requiring minimal space; a bulkhead evaporator for small to mid-size school bus applications; and two split a/c systems. All of the units will be available for order in the first quarter of 2014, Thermo King officials say.

One of the key StudentAIRE offerings is the Slimline Rooftop Air Conditioning System (SLR), a lightweight, ultra-low profile heating and a/c unit for school bus applications with a design that offers enhanced airflow, easier installation and better service accessibility, according to the company.

The SLR offers a low roof profile — measuring about 6 inches above the roof — and provides significant space savings while reducing the potential for impact with trees or buildings. The unit is designed to maximize headroom by measuring 3.5 inches inside the vehicle.

Utilizing state-of-the-art structural foam molding and weighing in at 124 pounds, the modular unit is easy to install and maintain, providing easy and safe access for maintenance from inside the bus — an industry first for rooftop systems, according to Thermo King. The unit allows for 90% of components to be serviceable from inside the bus.

Additionally, the SLR can be installed in the middle of the bus for more uniform air flow while distributing the weight evenly between the axles.
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Keeping the driver cool
ACC Climate Control Inc. offers a “Driver’s Vent Cool” package for many school bus applications. This feature allows for the flow of cooled air to be directed to the driver from the front in-wall design evaporator.

With the sun load experienced at the driver’s location, ACC Climate Control officials say that the Driver’s Vent Cool package is an effective and economical way to keep the driver cool as he or she takes care of the precious cargo on board — the children.

Electric units target fuel efficiency

Mobile Climate Control (MCC) offers a complete a/c line for all applications and environments. Company officials say that MCC’s new rooftop platform provides low operating cost, and its newly redesigned evaporators and condensers are highly efficient and lightweight.

MCC has recently developed fuel-efficient electric rooftop and rear-mount units to allow bus operators to realize the lowest fuel costs possible, company officials say. The electric a/c product line includes the Eco 136E rooftop model and the RM35E rear-mount model.

The company’s conventional a/c units include the Eco 353 and Eco 136 rooftop models and the RM Series of rear-mount models.

MCC also offers a full range of low-cost drivers’ defrosters and heaters for OEM installations.

MCC has a large service and support network, and a full line of service parts is accessible online through the company’s web-based parts portal.

Systems meet school bus needs

Spheros’ Arcticsphere split a/c system is designed for school buses and can be tailored to match vehicles’ application requirements.

Spheros’ in-wall and ceiling mount evaporators are available with performance ranges of up to 60,000 Btu/hr. These evaporators are configured with the company’s skirt- or roof-mounted condensers (up to 84,000 Btu/hr.) to provide the required a/c performance.

Spheros also offers rooftop units that are suited for school bus needs. The CC145 offers 42,000 Btu of cooling capacity, and company officials say that it is lightweight and easy to install.

The CC335/355 are available in single loop and/or dual loop, offering cooling capacity of up to 136,500 Btu and meeting all climate system requirements.

Spheros officials say the company offers easy maintenance, high performance, low life-cycle cost and a three-year warranty on the Arcticsphere and CC rooftop line of a/c products.

FOR MORE INFORMATION
To find out more about air-conditioning products for school buses, visit these companies’ websites.

• ACC Climate Control, www.accclimatecontrol.com
• American Cooling Technology, www.actusa.us.com
• Espar, www.espar.com
• Mobile Climate Control, www.mcc-hvac.com
• Rifled A/C Systems, www.rifledair.com
• Spheros North America, www.spheros.us
• Thermo King, www.thermoking.com
• Trans/Air Mfg., www.transairmfg.com