Routine Maintenance
UNT-SVX07E-EN
123
Individual coil types determine how to properly winterize
the coil. To determine the coil type find the “Service Model
No of Coil” on the coil section nameplate. The coil type is
designated by the second and third digits on that model
number. For example, if the model number begins with
“DUWB,” the coil type is UW; if the model number begins
with “DW0B,” the coil type is W.
Note:
On many unit sizes, there are multiple coils in the
coil section. Be sure to winterize all coils in a given
coil section.
To winterize coils:
1.
Remove the vent and drain plugs.
2. Blow the coil out as completely as possible with
compressed air.
3. Fill and drain the coil several times with full strength
glycol so that it mixes thoroughly with the water
retained in the coil.
4. Drain the coil out as completely as possible.
5. To ensure no water remains in the coil, do not replace
the vent and drain plugs until the coils are put back into
service.
Moisture Purge Cycle
By it’s very nature, any HVAC unit with a cooling coil serves
as a dehumidifier, reducing the surrounding air’s ability to
hold water vapor as its temperature falls. This normally
doesn’t present a problem when the unit is running.
However, when the fan stops, water vapor condenses on
the cold metal surfaces inside the air handler and remains
there until the air warms sufficiently to re-evaporate it.
This damp, dark environment—though temporary—can
encourage the growth of mold, mildew, and other
microbial contaminants.
Providing a moisture purge cycle 15 to 30 minutes after
shutdown disperses the cold, humid air inside the air-
handling system more evenly throughout the building.
This four-step cycle:
•
Closes the outdoor air dampers.
•
Turns off the cooling coil.
•
Opens any variable-air-volume terminals connected to
the air handler.
•
Operates the supply fan for 10 to 15 minutes.
Air movement discourages water condensation and
hastens re-evaporation of any condensate that does
happen to form. This simple preventative measure
effectively combats microbial growth and curbs moisture-
related deterioration of air-handling components.
Cleaning Non-Porous Surfaces
If microbial growth on a non-porous insulating surface
(closed cell insulation or sheet metal surface) is observed:
1.
Disconnect all electrical power to the unit.
2. Wearing the appropriate personal protective
equipment, use a brush for sheet metal surfaces or a
soft sponge on a foil face or closed cell foam surface to
mechanically remove the microbial growth.
Note:
Be careful not to damage the non-porous surface of
the insulation.
3. Install a block-off to prevent spray from going into a dry
section of the unit and/or system ductwork.
4. Thoroughly clean the contaminated area(s) with an
EPA-approved sanitizer specifically designed for HVAC
use.
5. Rinse the affected surfaces thoroughly with fresh
water and a fresh sponge to prevent potential
corrosion of the drain pan and drain line
6. Repeat steps 4 and 5 as necessary.
7.
Confirm the drain line is open following the cleaning
process.
8. Allow the unit to dry thoroughly before putting it back
into service.
9. Replace all panels and parts and restore electrical
power to the unit.
10. Be careful any contaminated material does not contact
other areas of the unit or building. Properly dispose of
all contaminated materials and cleaning solution.
WARNING
Hazardous Voltage!
Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Failure to disconnect power
before servicing could result in death or serious injury.
