13
Fresh Air
Ventilation
Application
Considerations
Water-Out
(source)
Water-In
(source)
Water-Out
(load)
Water-In
(load)
Exhaust
Air
Fresh
Air
(Closed) Ground
Loop Heat
Exchanger
Geothermal Space
Heating and Cooling
Fresh Air Ventilation
with Water-to-Water Units
Water-to-Water
and Fresh Air
Ventilation
Geothermal energy systems take
advantage of the fact that
subsurface earth temperatures are
constant year-round, which makes
the earth an ideal heat source and
heat sink for heat pumps.
The above design goes further than
just space heating and cooling.
Fresh air ventilation is achieved by
using Trane water-to-water units
teamed with a hydronic outside air
unit, and exhaust air unit to meet
total building requirements.
In the cooling season, the
evaporator water from the heat
pumps is circulated through a
hydronic coil in the makeup air unit
to provide cooling and
dehumidification. The condenser
water is used to provide reheat
energy to temper the ventilated air
in accordance with the building
needs. After leaving the reheat
hydronic coil, the condenser water
is then returned to the building loop
for further heat rejection.
In heating, the water-to-water units
switch to hot water generation. The
water for ventilation air tempering
first circulates through the hydronic
coil to the exhaust air unit to pick
up heat from the building exhaust
airstream. The water then
circulates through the water-to-
water heat pumps for further heat
introduction before being used by
the makeup air unit hydronic coil to
heat the makeup air to maintain
building requirements. This
ventilation system incorporates its
own constant volume pumps to pull
system water off the loop and
return it. There is no need for
additional heat injection using
boilers for this system. (See Page
14 for mechanical example).
Typical Benefits
q Annual energy savings means
lower energy costs
q Building comfort and climate
control
