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14- Restore power to unit.
15- Cleanup once unit is operating properly, caulk any open joints, holes or seams to make the unit completely air and
water tight.
16- Leave this instruction manual with owner or in an envelope to be kept near unit.
VIII -
Op era tion
How It Works
The unit contains an Energy Recovery Wheel (ERW) that is a new concept in rotary air-to-air heat exchangers. Designed
as a packaged unit for ease of installation and maintenance, only the connection of electrical power is required to make the
system operational.
When slowly rotating through counter flowing exhaust and fresh air streams the ERW adsorbs sensible heat and latent
heat from the warmer air stream and transfers this total energy to the cooler air stream during the second half of its rotating
cycle. Rotating at 50-60 revolutions per minute, the wheel provides constant flow of energy from warmer to cooler air
stream. The large energy transfer surface and laminar flow through the wheel causes this constant flow of recovered
energy to represent up to 85% of the difference in total energy contained within the two air streams.
Sensible and latent heat are the two components of total heat. Sensible heat is energy contained in dry air and latent heat
is the energy contained within the moisture of the air. The latent heat load from the outdoor fresh air on an air conditioning
system can often be two to three times that of the sensible heat load and in the winter it is a significant part of a
humidification heat load.
During both the summer and winter, the ERW transfers moisture entirely in the vapor phase. This eliminates wet surfaces
that retain dust and promote fungal growth as well as the need for a condensate pan and drain to carry water.
Because it is constantly rotating when in the air stream, the ERV is always being cleaned by air, first in one direction then
the other. Because it is always dry, dust or other particles impinging on the surface during one half cycle, are readily
removed during the next half cycle.
During the heating season, when outdoor air temperatures are below 15
o
F, it is recommended to use the (optional) low
ambient kit (field installed).
Low Ambient Kit is appropriate for climates with limited HVAC system operation when outdoor temperatures are below
10
o
F.
The frost threshold is the outdoor temperature at which frost will begin to form on the ERV wheel. For Energy Recovery
Ventilators, the frost threshold is typically below 10
o
F. Frost threshold is dependent on indoor temperature and humidify.
The table shows how the frost threshold temperatures vary depending on indoor conditions
FROST THRESH OLD TEM PERA TURE
IN DOOR RH AT 70
o
F
FROST THRESH OLD
TEM PERA TURE
20%
0
o
F
30%
5
o
F
40%
10
o
F
Because Energy Recovery Ventilators have a low frost threshold, frost control options are not necessary in many climates.
Where outdoor temperatures may drop below the frost threshold during the ERV operational hours, exhaust only frost
control option is available.
Low Am bi ent Kit (Op tional)
Low Ambient Kit turns off the supply blower when outdoor temperatures fall below the frost threshold. The exhaust only
thermostat set points are field adjustable. Supply fan operation is automatically restored when the exhaust air temperature
rises above the thermostat set point. Provisions for introducing make-up air into the building when the supply blower is off
to avoid depressurization should be considered.
Re cov ery Wheel Mode
On a thermostat call for blower operation in heating, cooling or continuous blower, the ERW will rotate between fresh air
and exhaust air streams. Both the fresh air and exhaust air blowers will also be operating to overcome the air resistance of
the ERV.