Installation

5
3. Controls (cont’d)
3.3 Defrost
The unit functions are controlled by integrated controls in the unit
which may include Exhaust Only Defrost or Recirculation Defrost
(via the recirculation module - B6LC and B12LC units only). In cold
temperatures, defrost cycles will remove frost from the recovery
cores to maintain good operation.
E
XHAUST ONLY DEFROST (OPTIONAL)
Frost removal occurs when the supply blower de-energizes, the
supply air damper and the core damper close and the exhaust
fan continues to circulate only warm inside air through the heat
recovery core to maintain ventilation. This process prevents the
build up of ice in the core. Defrost is temperature initiated at 23°F
to -22°F and time based.
RECIRCULATION DEFROST MODULE
(OPTIONAL - FACTORY INSTALLED)
The Recirculation Defrost Module is only available with the B6LC
and B12LC units. The defrost cycle is electronically controlled in
response to the outdoors temperature 23°F to -22°F. On a call for
defrost, the supply air damper in the recirculation module closes,
exhaust fan is de-energized and the supply fan continues to
recirculate warm air through the heat recovery core or energy
recovery core. It is possible to extend the defrost times during very
cold weather by removing the jumper JU1-F on the circuit board
as shown in Appendix F. For dimension and weight changes to the
B6LC and B12LC models with recirculation defrost, see Appendix
B-2 and B-4.
3.4 Remote Wall Control (Optional)
Remote mounted wall control options can be used to control the
ventilators from a location remote to the installed unit location. The
connection from the ventilator to the control is low voltage and
requires a 4 conductor (24 ga. minimum) LVT cable. Models are
available with a dehumidistat control. The following two options are
available.
SLIDE SWITCH TYPE
Dehumidistat to engage high speed exchange. Slide switch operation
supporting continuous low exchange and continuous high exchange.
VT10W (
FOR B1600705 UNIT ONLY)
Ideal for pool dehumidification. Dehumidistat to engage high speed
exchange. Push-button operation supporting: intermittent (stand-by)
ventilation, continuous low exchange, continuous high exchange,
maintenance indicator light and exchange indicator light.
WARNING
!
A negative building pressure may develop during the
defrost cycle with possible backdrafting fumes from
combustion equipment.
5. Maintenance and Service
5.1 Bi-Monthly Maintenance
Bi-monthly maintenance should include:
A
IR FILTERS
The standard foam filters are washable. Under normal conditions
it is recommended that they be cleaned every two months. More
frequent cleaning may be required under extremely dirty operating
conditions. Use a vacuum cleaner to remove the heaviest portion
of accumulated dirt, then wash with warm water.
A medium efficiency filter for the supply air stream is available from
your supplier. This filter is disposable and should be replaced when
it becomes dirty.
B6LC and B12LC units
 Washable foam filter
 MEF filter - optional
B1600705 unit
DRAIN PANS AND INTERIOR OF UNIT
With the filters removed from the unit, the foil faced insulation
surfaces and the drain pans should be wiped clean with a soft cloth
and mild cleaning solution. Also ensure that the drain fittings are
free from dirt and are draining freely.
WARNING
!
Disconnect power before maintaining unit.
1
1
2
VL0001
1 or 2
1
VL0002A
4. Airflow Measurement and Balancing
Once installation is complete, the supply and exhaust airflows
should be balanced. This will ensure proper operation and a good
quality installation.
A well designed duct system with properly sized duct runs and equal
static pressure losses of both the supply and exhaust will aid in balancing
the unit. However, it will be necessary to take flow measurements
with the proper equipment to ensure a balanced system.
Before proceeding with balancing, all windows, overhead doors and
walk-in doors should be closed and exhaust systems should be turned off.