Trane Model 180 GEV, 120 GEH manual Features and Benefits, Boilerless Control/Electric Heat option

Figure 18: Model GEH with Waterside Economizer package

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Features and

Benefits

Boilerless Control/Electric Heat (option)

The boilerless electric heat option is composed of a nichrome open wire design.

This single stage of electric heat is used as a primary heating package to lock out compressor operation in the event that entering-water tempera- tures reach below 58 F (14.4 C).

On a call for heating, the electric heater is activated, locking out the compres- sor. Once the entering water tempera- ture rises, above 58 F (14.4 C), the unit resumes normal compressor heating operation.

For geothermal applications, the boilerless controller is adjustable. The ranges are 25, 35, 45, 55, and 60-degrees F (-3 .9 , 1.7, 7.2, 12.8 ,

Figure 17: Boilerless control/electric heat diagram

15.6C). Trane factory sets the controller to 55-degrees F prior to shipment.

See Figure 17 for boilerless control/electric heat diagram.

Waterside Economizer (option)

The beauty of the waterside economiz- er is it’s ability to take advantage of any loop condition that results in cool water temperatures. A prime example would be during fall, winter and spring when cooling towers have more capacity than required and could be controlled to lower temperatures for economizer support.

Another more common inexpensive means of free comfort cooling includes buildings systems where perimeter heating and core cooling are needed. In this system, the perimeter units extract heat from the building loop while in the heating mode, forcing the building loop temperature to drop. Where as, the core are of a building may require cooling in summer or in winter based upon light- ing, people and equipment.

If the water-source system design contained an econo- mizing coil option, the mod- erate temperature loop water circulated through a core water-source system can provide an inexpensive means to satisfy room com- fort without operating the water-source heat pump’s compressor.

During economizer mode, fluid enters the unit, and passes by a water tempera- ture sensing bulb. This tem- perature sensing bulb deter- mines whether the two posi- tion, three-way valve will direct the water through the waterside economizing coil, and to the heat pump condenser, or through the condenser only. If the water tempera- ture is 55 F or less, fluid will flow into the economizing coil, while simultane- ously halting mechanical operation of the compressor.

Mechanical cooling will continue on a call for second stage from the thermo- stat. The factory built waterside econo- mizer is available on all 1/2 to 5 ton GEH models.The 1/2 through 5-ton GEV may be ordered to accept a field pro- vided waterside economizing package. See Figure 18: Model GEH with Waterside Economizer package.

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