Products : Design Features for 30 to 60 Ton Units (MB Series)

Modular Construction
The MB-HRG unit design concept is to provide a unit that will facilitate on site handling and can be installed in locations difficult to access. All units can be broken down into separate modules that can pass through a 36” wide standard door or service elevator. No refrigerant piping requires disconnection, maintaining circuit integrity. Water piping connections are made with the use of heavy-duty bronzed-bodied unions so no welding or brazing is required in the field. Single supply and return connections to the unit are standard. This creative design allows the installer to transport and located the modules in the equipment room without the use of heavy-duty cranes or lifts.

Building penetrations or interior wall penetrations are not normally required on retrofit jobs where space is at a premium. The 30 ton module can be easily broken down into 3 separate modules the fan module, main heating/cooling module, and the economizer filter bank. The MB 40 through 60 ton units can be broken down into 6 separate modules, two each as previously mentioned. Very few competitive equipment manufacturers have this capability.

CABINET, CASING AND FRAME
For heavy-duty structural support, an internal angle iron framework is utilized. The angle iron members are attached using ½ inch bolts and locking nuts for ease of disassembly and re-assembly. The base-pan assembly is constructed in 14 gauge galvanized steel. Exterior panels are made of 18 gauge, G90 Galvanized steel providing protection against corrosion. All panels are insulated with ½ inch thick dual density Neoprene backed fiberglass insulation for thermal and acoustic performance. Insulation meets the erosion requirements of UL 181. Base rails are provided to assist rigging the unit on site. All components are located for ease of inspection and service. Major components are out of the unit’s air stream to allow maintenance while the unit is in operation. Service access is through the removal of access panels located on the unit.

COMPRESSORS
All units utilize high efficiency scroll compressors. The MB360 has two compressors, while MB480-MB720 units contain four compressors for efficient part load control, quiet operation and system redundancy. Each compressor has its own independent refrigerant circuit and is protected by individual branch fusing. Additional protection is provided by thermal overloads and high and low pressure safety switches. Suction and discharge Schrader valves are provided for manifold gauge connections to facilitate servicing. Compressors are mounted on vibration isolators.

The entire condensing section is isolated from the air-handling compartment by the use of an insulated bulked partition designed to minimize sound transmission.

CONDENSERS (water to refrigerant heat exchangers)
All condensers are coaxial tube-in-tube for maximum heat transfer efficiency and performance. Inner water tubes are either copper or optional Cupro-nickel with large internal diameters for reduced water-side pressure drops. Outer tubes are steel, painted for corrosion protection. All condensers are rated at 450 PSIG operating refrigerant pressures and 400 PSIG water-side pressures. Condensers are individually leak tested. All condensers are chemically cleanable. Please consult the factory for cleaning procedures. Units are designed for single water supply/return connections with modules being connected by the use of heavy-duty bronze unions.

Externally equalized balanced port thermostatic expansion valves are utilized for wide range refrigerant metering control. Superheat shifts are minimal from cooling to heating operation ensuring stable operation in both the heating and cooling modes. All TXV’s are factory set and are field adjustable for specific operating conditions. Reversing valves are large bodied to minimize refrigerant pressure drop. Line voltage solenoids are utilized to reduce transformer loading. All refrigerant components are accessible from the front of the unit for service and maintenance.

DX COOLING/HOT GAS REHEAT COIL
Evaporators are enhanced in, rifled tube type for maximum performance. Large face areas ensure low air side pressure drops and reduced face velocities to prevent condensation carry over and maximum moisture removal.

Coils are either three or four rows deep, depending on unit model, are cleanable. They are mounted in a small area, sealed drain pans to inhibit condensate buildup levels.

All drain pans are galvanized steel with Archem type coating for corrosion protection. Optional stainless steel pans are available. Bottom outlet fittings in drain pans ensure free draining. Optional
condensate overflow switches are available.

Each refrigerant circuit is independently piped allowing part load operation in the event of component failure.Compressor and evaporator staging is such that air stratification is kept to a minimum.

The lower evaporators on each module are staged first to keep coils wet and enhance condensate removal. I the event of an evaporator failure only the individual coil need be changed compared to the full face evaporators utilized by some
manufacturers.

ELECTRICAL
All units are completely wired and tested at the factory prior to shipment. Wiring complies with NEC requirements and units are UL 1995 safety certified and listed. Single point power supply is standard on all models. Each module has its own power block simplifying wiring in the field for knock down capabilities. Supply air fan motors are protected by use of a solid state adjustable current motor starter with reset.

Extra starter heaters are not required. All compressor power circuits are branch fuse protected. Control circuit power is provided by a factory mounted 100VA low voltage transformer with an integral reset table circuit breaker. Solenoid valves are line voltage to reduce transformer loading. All refrigerant circuits contain a high pressure cut out switch, low pressure safety switch floss of charge protection.

REVERSE CYCLE OPERATION
All MB series units are capable of operating in the reverse cycle heat pump mode for efficient, cost effective heating. The MA DE Series is the only self-contained dehumidifier heat pump unit in its class. This feature allows the designer to take full advantage to building diversity, transferring excess heat from areas with a net cooling load to areas requiring heating providing a truly energy efficient system.

FILTERS
All MB Series units come with standard 4 inch 30% efficiency pleated filters. Optional 65% 4 inch pleated filters are available. Filters are removable from the sides of the frames through filter access panels. Throw away construction filters should be field installed to protect the main filters during the construction period.

TESTING
All completed units are leak checked, evacuated and factory charged with R-22. Units are 100% run tested prior to shipment

PERFORMANCE
For unit performance under specific conditions, please contact EPS, Inc. Engineering Department.

FAN MODULE
The fan module contains either one or two forward curved high-pressure class II fan assemblies depending on the model size. The fans are double width, double inlet welded assemblies statically and dynamically balanced. The fan module is isolated from the main module by the use of rubertex gaskets providing excellent vibration isolation and quiet operation. The modules are bolted together with ½ inch diameter bolts and locking nuts. Each fan is powered by its own motor and drive assembly. Motors are mounted on individual motor platforms for stable operation and belt tension adjustment. All assemblies include 150,000 hour re-greaseable pillow block bearings with large diameter solid steel shafts for high torque/speed operation. Drive packages comprise multiple belt, fixed pitch blower pulleys and motor sheaves sized for specific application requirements of CFM, external static pressures and motor horsepower. All components are easily accessible for general maintenance. Motor are open drip proof NEMA TFRAME E high efficiency EPACT rated with sealed ball bearings.

DEHUMIDIFICATION
Indoor air quality is a major concern in the design and operation of today's buildings. Humidity levels, if not properly controlled, can play a major role in the development of fungal growth which is a major cause of the problem. Controlling the space temperature alone will not assure proper humidity control. To bring the humidity to an acceptable level requires cooling the air to a relatively low temperature, which can result in uncomfortable conditions within the space, and increase the evaporation rate of the pool. The air, after dehumidification, needs to be reheated to avoid this problem. Typically, electric heat has been applied to do this, but probably is the most expensive option, adding significantly to operating costs. A alternative would be to use hot water if it is available. Again, this represents an additional operating cost. Additional hot water piping will be needed, increasing initial costs. The MB Units offer a factory installed Hot Gas Reheat Option that uses the hot refrigerant gas to reheat the air. Hot gas reheat operation is controlled through space humidity levels and only operates when needed.

RELIABILITY

ENERGY EFFICIENCY

QUIET OPERATION

 

Due to continuing research and development,
design specifications are subject to change without prior notification.