8
The ventilation timer is an electronic timer that
displays the current time. This timer has a battery
backup, so it will not require resetting after a power
outage. Following a prolonged power outage the
display of the timer will flash on and off indicating a
power outage has occurred. The one-minute time
increments of the ventilation timer allow you to
program the ventilation of your home to fit your
schedule.
The ventilation timer has six programs with each
program having one “on” and one “off” event. A
program allows the user to turn the ventilation on at a
certain day and time, then it allows them to turn the
ventilation off at a certain day and time. Each of these
programs can be repeated daily or weekly or during a
specified block of days. All six of the programs operate
independently of each other.
If the timer fails to operate or operates erratically,
check that the control panel receives 24Vac from the
DHV-150H. If 24Vac is present at the control panel,
reset the timer by pressing the reset button at the
bottom center of the timer face. The reset button is the
small recessed button with an
R
beneath it located
below the
1…7
and
h
buttons. Press the reset button
in until the display clears. Release the reset button.
The display will reappear as 00:00. Resetting the timer
will clear the time and all program settings. After
resetting the timer follow the instructions below to set
the correct time and ventilation programs.
The following instructions explain how to set the
ventilation timer. First, set the correct time on the
timer by sliding the switch in the upper right hand
corner of the timer to the clock symbol
⊕
and pressing
the
1…7
(DAY),
h
(HOUR), and
m
(MINUTE) buttons.
Remember that this timer operates on a 24-hour
(military time) clock.
Next, set the ventilation time schedule. Slide the
switch in the upper right hand corner to the program
symbol
P
. “ON” will appear to the right of the time and
the number “1” will appear in the lower right hand
corner of the display. The “1” and “ON” signify the turn
on time for the first program. Press the
1…7
button to
choose the days of the week for this program. You can
choose Mon.-Sun, Mon.-Fri., Sat-Sun, or any single
day of the week. The days chosen are shown along the
top of the display on the ventilation timer. Next press
the
h
button to set the hour for the start of the
ventilation period. Remember that this timer operates
on a 24-hour clock. Then press the
m
button to set the
minutes past the hour to start the ventilation. Now, with
the ventilation start time set; press the
I/O
button. The
word “OFF” should appear to the right of the time and
the number “1” should remain in the lower right hand
corner of the display. The “1” and “OFF” signify the
turn off time for the first program. Set the turn off time
using the
1…7
,
h
, and
m
buttons in the same way as
described above and continue on to the second
through sixth programs. When setting the ventilation
programs, you can return to the current time display by
sliding the switch in the upper right corner of the timer
to RUN. The slide switch in the upper right must be set
to
RUN
for the timer to operate with the scheduled
programs.
The slide switch in the upper left of the timer is used to
choose between automatic and manual operation of
the timer relay. When the slide switch in the upper left
of the timer is set to AUTO mode, the central
conditioning unit will ventilate when the scheduled
programs call for ventilation. When the slide switch in
the upper left of the timer is set to manual (set to hand
symbol on the right), the operation of the timer is
controlled by the
I/O
button only. Pressing the
I/O
button will switch the ventilation timer between ON
(detent) and OFF (detent). As you press the
I/O
button,
“ON” or “OFF” will be displayed to the right of the time.
The “ON” or “OFF” to the right of the time will indicate
if the ventilation timer is on or off. The
I/O
button will
manually override scheduled programs if the timer is
in AUTO mode.
3.6 High Efficiency Air filter
An optional high efficiency air filter is available for the
DHV-150H. ASHRAE Dust Spot Test Method 52-76
rates this filter 90-95% efficient. This filter is much
more efficient than the standard air filter and is able to
catch much smaller particles that can aggravate
allergies.
The high efficiency air filter is 4 inches thick and
should be installed in the filter enclosure directly
behind the standard air filter (See Figure 7). The
standard air filter will act as a prefilter for the high
efficiency air filter and will prolong the life of the high
efficiency air filter.
3.7 Low Pressure Control
If the low side refrigerant pressure drops to 15 PSIG,
the low-pressure control opens and shuts off the
compressor and fan. It is an automatically reset control
that will close when the pressure rises to 35 PSIG. Its
primary function is to prevent damage to the
compressor if a leak develops in the refrigeration
system. It may also open if the unit is A) installed in a
cool area (below 50 F) or B) installed where it is below
40 F and then started. Under these conditions, the unit
will restart within several minutes. Until the unit warms
up, it may repeat the cycle several times.
