Carrier HRVCCLHA - Control Board Operation; Care and Maintenance; Electrical Shock Hazard; Cut Hazard

12
CONTROL BOARD OPERATION
Board Function
NOTE: To ensure proper operation of HRV, configuration
jumpers are located on electronic control board and must match
configuration setup shown on Fig. 19 and 20 under Jumper Table.
Jumpers are factory set and do not require any changes unless
control board is replaced. If control board is replaced, or you
encounter unusual start--up operation, check jumpers to make sure
they are located properly (see Fig. 19 and 20).
Defrost
The HRV continually monitors the outside air temperature. If the
outside air is at or below 23°F(--5°C), the HRV will initiate a
defrost cycle by closing the outside air damper and recirculating
warm indoor air through the heat recovery core. This happens
every 32 min. with 6 minute defrost cycle. During this process,
core is defrosted without the use of electric strip heat. At 5°F
(--15°C), unit will defrost for 6 minutes every 32 min. At -- 17°F
(--27°C), the unit will sense a need to defrost every 20 minutes with
a 6 minute cycle. See the Troubleshooting section for a control
logic explanation. See Figures 2, 21 and 22.
STALE AIR
FROM BUILDING
FI
L
TERED
A
IR
TO BUILDING
A92383
Fig. 21 -- HRVCCSVU Airflow Durin g
Recirculation and Defrost
ST
A
LE
A
IR
FROM BUILDING
FI
L
TERED
A
IR
TO BUILDING
A92385
Fig. 22 -- HRVCCLVU Airflow During
Recirculation and Defrost
Off and Intermittent/Off Mode
When HRV is Off, K1 relay is open, and K5 relay is ener gized
which closes outside air damper (see Logic Diagram in Fig. 19 and
20).
High--Speed Air Exchange
When high-- speed air exchange occurs, K1 and K2 relays are
energized and K5 relay is de--energized. This opens low--speed
contacts, and closes high--speed contact on K2 relay. This also
opens contact on K5 relay which opens outside air damper. Then,
115VAC is applied between orange and gray wires on Molex plug
(pins 1 and 6) and blower motor runs in high--speed operation (see
Logic Diagram in Fig. 19 and 20).
Low--Speed Air Exchange
When low--speed air exchange occurs, K1 Relay is energized
which closes the contacts. K2 and K5 relays are de--energized. This
keeps low-- speed contacts closed and high-- speed contacts open on
K2 relay, and opens outdoor air damper. 120VAC is applied
between Red and Gray wires on Molex plug (pins 1 and 4) and
blower motor runs in low-- speed operation.
CARE AND MAINTENANCE
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Before installing or servicing system, always turn of f, tag and
lockout main power to system. There may be more than 1
disconnect switch.
!
WARNING
CUT HAZARD
Failure to follow this caution may result in personal injury.
Sheet metal parts may have sharp edges or burrs. Use care
and wear appropriate protective clothing and gloves when
handling parts.
CAUTION
!
Door
HRV door can be removed by unlatching brief case style latches,
then slide door to the right and remove it from hinges. Door must
be in place and secured shut for proper operation.
Filter
Filters in HRV are washable and should be cleaned every 3
months. Use a vacuum cleaner to remove heaviest portion of
accumulated dust, then wash in lukewarm water. Allow filter to
completely dry before reinstalling. A dirty air filter will cause
excessive strain on blower motor. Never operate unit without a
filter. Vacuum out debris.
In addition, regularly check and clean screens on exterior intake
and exhaust hoods when necessary.
HRV