Outdoor air design condition: 1% dry-bulb/mean coincident wet-bulb, 1977 ASHRAE Handbook.

EER = (Energy Efficient Ratio) BTU cooling output per watt of electrical input.Comparison base to conventional system 60° S.A.; 25°delta T.

EUC = energy use comparison to conventional system with an EER of 8.

SA  = Supply air temperature leaving I/D unit at 1% design condition.

I/D efficiency: indirect = 60%(DB - WB x .6); direct = 90% (DB -WB x .9).

Note: Sea level psychrometric chart used 5000 ft. elev. will increase S.A. temperature 3 to 4%.

The VARI - COOL Modular I/D System

	Screened intake cowl
	Indirect evaporative cooler
	Damper section (optional)
	Return air connection & damper sections (optional)
	Filter section (optional)
	Direct evaporative cooler
	Supply air fan section (optional)
	Conventional heating section, hot water coil, etc. (optional)
	Supply Air
	Secondary fan & plenum
	Conventional chilled water or direct expansion cooling coil (optional)

The VARI-COOL modular equipment design consists of matching components to provide single I/D two and three stage system from 2000 CFM to 8000 CFM of supply air (nominal capacity of 4 to 20 tons). These systems allow the design engineer many selection options to tailor the equipment to meet desired criteria. In addition, factory assembled parallel units can be selected to provide single station units to nominal 20,000 CFM.

The Indirect Unit

The modular 60 series indirect unit is available in seven nominal sizes in 1000 CFM increments; the model 2S (2000 CFM) to the model 8S (8000 CFM). The indirect unit includes the water pump and accessories, factory mounted float valve, water distribution and filtering system, water make-up, drain and overflow fittings. The water bleed assembly is piped to the overflow fitting. Duct connections are provided on the inlet and outlet of the primary (dry) side an d secondary (wet) sides.

The nominal heat exchange efficiency (sensible cooling) at 1000 CFM per core primary air and 800 CFM per core secondary air is 60% of the wet bulb depression.

The Direct Unit

The direct unit is furnished in six matching sizes to the indirect unit. As with the indirect unit they are in 1000 CFM increments. Sizing is from 2000 CFM to 8000 CFM. The duct connections match the equivalent size indirect unit. The cabinetry construction and corrosion resistant protective coating are to the same specification and high standards of the indirect unit.