American Dream Ultra Performance Geothermal Copper Series, Installation And Service Manual

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Page 14 000744MAN-02 25 MAY 2009
A duct system capable of supplying the required air flow is of
utmost importance. AMERICAN DREAM Geothermal
recommends that the static pressure be kept below 0.2 inches
of water total. In some instances the number of floor diffusers
will actually double when compared to the number that would be
used for a hot air oil-fired furnace. Refer to
TABLE 15 at the
end of this section.
1. Generally allow 100 cfm for each floor grill.
2. All leads to the grills should be 6'' in diameter (28sq.in. each).
3. The main hot air trunks should be at least 75% of the square
surface area of leads being fed at any given point.
4. Return air grills should have a minimum of the same total
square surface area as the total of the supply grills.
5. The square surface area of the return trunks should equal
the square surface area of the grills being handled at any
given point along the trunk.
It is VERY IMPORTANT that all turns in both the supply
trunks and the return trunks be made with TURNING RADII . Air
act like a fluid and, just like water, pressure drop is increased
when air is forced to change direction rapidly around a sharp or
irregular corner.
It is recommended that flexible collars be used to connect the
main trunks to the heat pump. This helps prevent any vibrations
from travelling down the ductwork. If a plenum heater is in-
stalled, the collar should be at least 12” away from the heater
elements.
The first 5-10 feet of the main supply trunks should be insu-
lated with acoustical duct insulation to further inhibit any noise
from the unit from travelling down the ductwork. If a plenum
heater is installed, insulation should not be placed within 12” of
the heater elements.
Drawing 000606CDG shows a typical installation.
DUCT SYSTEMS - GRILL LAYOUT
Most forced air heating systems in homes have the floor grills
placed around the perimeter of the room to be heated. Supply
grills should be placed under a window when possible to help
prevent condensation on the window. As mentioned in the pre-
vious sub-section, supply grill leads should be 6'' in diameter (28
sq.in. each) to allow
100cfm of air flow.
In a typical new construction, there should be one supply
grill for every 100sq.ft. of area in the room. When rooms require
more than one grill, they should be placed in a manner that pro-
motes even heat distribution, such as one at each end of the
room. It is always a good idea to place a damper in each grill
supply or place adjustable grills so that any imbalances in the
heat distribution can be corrected.
HEAT PUMP SIZING
TABLE 12 depicts averages *WILL VARY WITH ENVELOP
EFFICIENCY* as a rough guideline to the size of home
each heat pump size can handle.
THE TABLE ABOVE IS FOR INFORMATION ONLY, IT
SHOULD NOT BE USED TO SELECT A UNIT SIZE. It simply
shows on average what size unit is required for a typical two-
level home (main level and below grade basement) with R-20
walls, R-40 ceiling and average size and number of windows.
The Heated Area is the area of the main level, The tables ac-
count for a basement the same size as the heated area.
AMERICAN DREAM Geothermal HIGHLY RECOMMENDS
THAT A PROPER HEAT LOSS/GAIN ANALYSIS BE PER-
FORMEDE BY A PROFESSIONAL INSTALLER WITH CSA
APPROVED SOFTWARE BEFORE SELECTING THE SIZE OF
UNIT REQUIRED FOR THE APPLICATION. For heating
dominant areas, we recommend sizing the unit to 100% of
the heating design load for maximum long term efficiency
with minimal supplementary heat. The unit should be in-
stalled as per CSA 448.2-02.
There are many factors to consider when sizing the heat
pump. Some of these factors include the number of levels, the
size of the windows, the orientation of the home, attached ga-
rage, bonus rooms, walk-in basement, coldest outdoor tempera-
ture, etc. The heat loss program will take all of these factors into
consideration in its calculations. An undersized installation will
not be as efficient and will require expensive supplementary
heat to maintain a comfortable temperature in the home, and the
cost savings of having a geothermal heat pump are greatly re-
duced.
Once the total heat loss has been calculated, the unit can
be sized using the performance tables (from the specifications
document) in conjunction with the minimum expected entering
liquid temperature of the ground loop (well water temperature for
ground water system). The heat pump output must be able to
match the total heat loss at the selected entering water tempera-
ture in order to provide a comfortable environment with minimal
auxiliary heat.
DUCT SYSTEMS - GENERAL
Ductwork layout for an AMERICAN DREAM heat pump will
differ from traditional hot air furnace design in the number of
leads and size of main trunks required. Air temperature leaving
the heat pump is normally
95º -105ºF (35-40ºC), much cooler
than that of a conventional warm air furnace. To compensate for
this, larger volumes of lower temperature air must be moved
and consequently duct sizing must be able to accommodate the
greater air flow without creating a high static pressure or high
velocity at the floor diffusers.
Sizing and Ductwork
TABLE 13 - Heat Pump Size vs. Hot Air Grills
Size (tons) # of Grills (@100cfm)
2 11
3 14
4 17
5 21
TABLE 12 - Heat Pump Size vs. Heated
Area
Size (tons) Sq.ft. Sq.m.
2 1,000 100
3 1,400 130
4 2,000 185
5 2,600 240