Hammond Mfg. - Climate Control General Info

Sizing an Air Conditioner
General Specifications for All Air Conditioners
Product Summary

The Need for Environment Control
With wide spread use of micro-electronics in today’s control systems, temperature management takes on a new priority in order to ensure steady and reliable performance. The maintenance of a correct operating temperature may combine both cooling and or heating inside an enclosure which can protect against costly down time and system failures.

General Selection Considerations

Cooling

Conditions	Solution	Advantages	Disadvantages
Maximum desired enclosure temperature is 10°F or 5°C above maximum outside ambient.	Oversize the Enclosure	Easy to implement, no maintenance. Maintains NEMA rating of the enclosure.	Dissipates small amount of heat. Larger enclosure size takes up more space.
	Install ventilation louvers	Economical solution, very little maintenance, easy to implement.	Dissipates limited amount of heat. Dirt, oil or fluids could enter the enclosure. NEMA rating is affected.
	Install filter fans	Less expensive than air/refrigeration systems. Relatively high amount of heat removed, some termperature control by using thermostats.	Must maintain filters. NEMA rating can be affected. Limited use in hostile environments such as chemical applications.
	Use an air/air heat exchanger	Easy to install, small power consumption, temperature control via thermostat. Maintains NEMA rating of the enclosure.	Must maintain filters.
Maximum desired enclosure temperature lower than maximum outside ambient.	Use an air conditioner	Easy to install. Temperature control via factory installed thermostat. Removes large amounts of heat. Maintains NEMA rating of enclosure, dehumidifies enclosure air.	Must maintain filter. Generally not to be used when outside temperature is below 59°F (15°) or above 130°F (52°C).

Circluation

Conditions	Solution	Advantages	Disadvantages
Localized heat or "hot spots".	Install circulation fans in the enclosure.	Economical solution, no maintainance, easy to install. Maintains NEMA rating of the enclosure.	Dissipates small amount of heat.

Heating

Conditions	Solution	Advantages	Disadvantages
Outside temperature is below minimum allowable equipment operation range.	Heat with radiant heater.	Economical power consumption. Reliable, can be temperature controlled.	Consumes energy, takes up internal panel space.
Condensation occurs.	Heat with radiant heater to maintain temperature above the dewpoint.	Economical power consumption. Reliable, humidity can be controlled.	Consumes energy, takes up internal panel space.

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Sizing an Air Conditioner

The proper selection of an air conditioner is determined by the following steps:

Step 1 - Internal heat load quoted as Watts that must be dissipated.
Step 2 - The exposed surface area of the enclosure.
Step 3 - Temperature differential required between maximum inside temperature and maximum outside ambient.
Step 4 - Final calculation of the above.

Step One

1 Watt = 3.413 BTU/H

Determine the internal heat load (in Watts) that must be dissipated.

Step Two

1 m² = 10.76 ft²

Calculate the exposed surface area of the enclosure:

2(h" x w") + 2(h" x d") + (w" x d")	= Area (ft²)

144

(Example for freestanding enclosure)

Step Three

1°C or 1°KΔT=1.8°FΔT

Determine the temperature differential by subtracting the maximum allowable temperature inside the enclosure (Ti) from the maximum ambient temperature outside the enclosure (To).

To-Ti = DT

Step Four

(Watts x 3.413)

+

[1.25 x Area ft²

X

DT (°F)] = BTU/H
Capacity Required BTU/H.
Capacity Rating

The DTS/DTT offering is available in the most popular selection of cooling capacities, sizes, voltages and mounting configurations. Available capacities range form 1,200 to 12,00 BTU/H in both side mounting an dtop mounting models. All models use powerful radial fans for maximum air circulation inside the enclosure in ambient temperature of 125°F (+52°C). Models from 2,000 BTU/H capacity are equipped with thermal expansion valves for optimal use of the evaporator heat exchange surface under all operating conditions. For additional protection of the compressor motor, these valves are supplied as standard with Maximum Operating Pressure control devices (MOP). For energy conservation, the use of hot gas bypass valves is limited to the unload starting and control of large compressors from 8,000 BTU/H upwards.
All air conditioners were developed, designed and subject to final inspections in accordance with international Standards.

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General Specifications for All Air Conditioners

Construction:	Outer shell of sheet steel.
Closed Loop Cooling:	Ambient outside air is never mixed with clean dry enclosure air.
Operating Temperature:	Minimum +46 F (+8 C) Maximum +125 F (52 C). Optional low ambient kit is available
Gasketing:	Is provided and/or installed on all units to maintain NEMA ratings specified.
Templates:	Provided on all units for easy layout of cutouts and mounting.
Power:	Available in 115 V 60 Hz, 110 V 50 Hz and 230 V, 460 50/60Hz 3 phase.
Filter:	Removable filter mat made from synthetic fibers are reusable and can be rinsed clean.
Refrigerants:	All models use environmentally friendly R134a.
Fans:	All blower motors are thermal protected and sealed with permanent lubricants.
Condensate Disposal:	Built in condensate evaporators are standard on most models. All units feature a condensate drain fitting complete with hose attachment.
Insulation:	Cold components, lines and evaporator compartment insulated for maximum efficiency and protection against condensation.
Quality Assurance:	Prior to charging, the refrigeration system is hermetically sealed with all joints brazed under protection gas atmosphere to exclude any internal scale. After a thorough leak test every unit undergoes safety and function checks, then is serialized and packed into sturdy boxes prior to shipment.
Installation Manuals:	Included with all models are detail drawings, mounting, schematic and wiring diagrams, a trouble shooting checklist and warranty information.

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