Trane GEV - Manual (Page 15)

Features and
Benefits
WSHP-PRC003-EN
R
15
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 ,
15.6 C). 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.
Figure 17: Boilerless control/electric heat diagram
Figure 18: Model GEH with Waterside Economizer
package