System information

26
Geothermal Applications
ClimateMaster: Smart. Responsible. Comfortable.
Ducted Forced Air System
The most common type of heating and cooling distribution system
is the ducted forced air system, which delivers warm or cool air
to the living space. Water-to-air packaged units or split system
heat pumps are typically connected to a central duct layout, which
distributes conditioned air to the various zones. As in all forced
air systems, properly designed and sealed ductwork is crucial to
occupant comfort.
A fl exible connector is recommended for both discharge and return
air duct connections on metal duct systems to eliminate the transfer
of vibration to the duct system. To maximize sound attenuation
of the unit blower, the supply and return plenums should include
internal fi berglass duct liner or be constructed from ductboard for
the fi rst few feet. Application of the unit to uninsulated ductwork
in an unconditioned space is not recommended, as the unit’s
performance will be adversely affected.
Ductwork should be designed so that air velocities do not
exceed the following:
Hydronics (In-Floor, Fan Coils)
Hydronic installations (radiant fl oor heating, fan coil heating/cooling)
allow geothermal technology to be applied to distribution systems
other than forced air ducted systems. The most popular geothermal
hydronic application is radiant fl oor heating using ClimateMaster
water-to-water heat pumps ( Tranquility
®
TMW or THW Series).
The distribution of heat at occupant level as shown in fi gure 15,
not only provides better comfort, but also reduces heat loss, since
hot air is not rising above occupant level, and therefore lowers the
temperature difference at the ceiling. Radiant fl oor heating systems
typically operate for 10% to 20% less than forced air systems. Since
geothermal systems operate for 30% to 50% less than conventional
heating and cooling systems, the combination can be lead to
substantial energy cost savings.
Homes with radiant fl oor heating may or may not require cooling.
If cooling is desired, ClimateMaster recommends a separate
water-to-air unit with ductwork dedicated to cooling. If space is not
available for a separate unit, chilled water may be used with fan coil
units, although controls diffi culty and system switch-over lag time
may be obstacles to using one water-to-water unit for both heating
and cooling.
All water-to-water units used in heating applications require
a buffer tank to prevent equipment short cycling and to allow
different fl ow rates through the water-to-water unit than through
the hydronic heating delivery system. A buffer tank is also required
for cooling applications if the water-to-water unit(s) is more than
20% larger than the cooling load and/or multiple fan coil units will
be used.
Figure 14: Typical Vertical Unit Installation
Using Ducted Return Air
At least one 90° elbow should be included in the supply duct to
reduce air noise. For airfl ow charts, consult catalog data for the
series and model of the specifi c unit.
All ductwork should be designed in accordance with
recommended practices as outlined in one of the following
industry guidelines:
• Air Conditioning Contractors of American (ACCA) Manual
G “Selection of Distribution System,” Manual T “Basic Air
Distribution” and Manual D “Residential Duct Systems”
• Sheet Metal and Air Conditioning Contractors National
Association (SMACNA) “HVAC Duct System Design”
• American Society of Heating, Refrigerating, and Air
Conditioning Engineers (ASHRAE) handbooks.
Supply Return
Main Ducts
900 fpm
(274 mpm)
600 fpm
(183 mpm)
Branch Ducts
700 fpm
(213 mpm)
600 fpm
(183 mpm0
Registers,
Diffusers, and Grills
(Face Velocity)
750 fpm
(229 mpm)
600 fpm
(183 mpm)
Figure 15: Forced Air vs. Radiant Heat
The Heating/Cooling Distribution System
Flexible canvas duct
connector to reduce
noise and vibration
Use turning vanes in
supply transition
Internally insulate return
transition duct to reduce
noise
Rounded return
transition
Rev.: 6/2/09S
Internally insulate supply
duct for the first 4’ (1.2m)
each way to reduce noise