Enviro VB09-36, Установка, эксплуатация и обслуживание, Страница: 31 / 40

FORM ET145.18-IOM1 (115)
ENVIRO-TEC 31
Once the room t-stat has been satisfied, it will de-
energize”Y1”. If the compressor has satisfied its minimum run
time, the compressor and fan de-energize. Otherwise, the unit
operates the cooling system until the minimum run time for the
compressor has been completed. After the compressor de-
energizes, the blower is stopped following the elapse of the fan
off delay for cooling.
To be available, a compressor must not be locked-out due to a
high pressure switch; low pressure switch; condensate
overflow switch; freeze-stat trip and the anti-short cycle delay
(ASCD) must have elapsed.
Operation Errors
Each refrigerant system is monitored for operation outside of
the intended parameters. Errors are handled as described
below. All system errors override minimum run times for
compressors.
High-Pressure Limit Switch
If a high pressure limit switch opens. The micro processor
control de-energizes the compressor, initiates the ASCD (Anti-
short cycle delay), and stops the unit fans (soft lock-out).If a
call for cooling or heating is still present at the conclusion of
the ASCD, the micro processor control will re-energize the
compressor and unit fan.
Should a high pressure switch open three times within two
hours of operation, the micro processor control will
permanently lock –out the system compressor, requiring a
manual reset of the system (enter a hard lock-out), by de-
energizing the 24 volt power to unit, or turning the room t-stat
to the “OFF” position then back to either heating or cooling as
required. The micro processor control will flash a fault code
indicating the high pressure lock-out. (See attached table).
Low Pressure Limit Switch
The low pressure limit switch is not monitored during the initial
30 seconds of compressor operation. For the following 30
seconds, the microprocessor control will monitor the low
pressure switch to ensure it closes. If the If the low pressure
switch fails to close after the 30 second monitoring phase, the
micro processor control will de-energize the compressor,
initiate the ASCD, and stop the fan (soft lock-out).
Once the low–pressure switch has been proven (closed during
the 30 second monitor period described above), the
microprocessor control will monitor the low pressure switch for
any openings. If the low–pressure switch opens for greater
than 5 seconds, the micro processor control will de-energize
the compressor, initiate the ASCD, and stop the compressor
(soft lock-out).
If the call for cooling is still present at the conclusion of the
ASCD, the micro processor control will re-energize the
compressor.
Should a low pressure switch open three times within one hour
of operation, the microprocessor control board will lock-out the
compressor (enter into a hard lock-out) and flash a fault code
(see attached table).
Freeze-stat
If a freeze-stat opens, the micro processor control will de-
energize the compressor, and initiate the ASCD. If a call for
cooling or heating is still present at the conclusion of the
ASCD, the micro processor control will re-energize the halted
compressor.
Condensate Overflow Switch
A Condensate Overflow fault occurs if the Condensate
Overflow switch opens continuously for 30 seconds. The
compressor is shutdown regardless of Minimum Run Time and
alarm 15 is set. Fan continues operating in its current state.
The control logs the first incident per compressor request.
Lockout occurs on the second fault occurrence within a
request cycle, requiring reset or power cycling. If the
compressor request is removed, the fault occurrence counter
is reset to zero. When lockouts are removed, the alarm is
reset.
Safety Controls
The micro processor control monitors the following inputs:
1. A suction line freeze-stat to protect against low leaving
water temperatures (opens at 34F and resets at 48F.)
2. A high pressure switch to protect against excessive
discharge pressures (opens at 600 psig +/– 25 psig).
3. A low pressure switch to protect against loss of refrigerant
charge (opens at /– 5 psig).
4. A Condensate Overflow Switch to protect against
condensate overflow
Coaxial Freeze Protection Set Point
The unit allows for field selection of the coaxial freeze
protection set point. Unit utilizes a suction line freeze-stat
factory set for compressor lock-out when leaving water
temperature drops below 35F (resets at 48F). To lower the set
point for low temp heating applications with an adequate
water-antifreeze solution, unplug freeze-stat sensor, located at
P6 on the microprocessor control board and plug in the (pink)
jumper attached to existing harness. By installing the jumper,
the freeze-stat is bypassed allowing for heating operation with
leaving water temperatures below 35F. Use jumper only in low
water applications with adequate antifreeze protection,
otherwise damage can occur.
Random Start
Random start function, upon power up, will impose time delay
of 4 minutes plus a random delay of 1 to 64 seconds. The
random number generator seed is determined by a fixed seed
programmed at the factory combined with the serial number,
model number, and the hours of compressor run time of the
unit.
Compressor Protection
In addition to the external pressure switches, the compressor
also has inherent (internal) protection. If there is an abnormal
temperature rise in a compressor, the protector will open to
shut down the compressor. The micro processor control
incorporates features to minimize compressor wear and
damage. An anti-short cycle delay (ASCD) is utilized to
prevent operation of a compressor too soon after its previous
run. Additionally, a minimum run time is imposed any time a
compressor is energized. The ASCD is initiated on unit start-
up and on any compressor reset or lockout.
Microprocessor Control Unit Flash Codes
Various flash codes are utilized by the microprocessor control
to aid in troubleshooting. Flash codes are distinguished by the
short on and off cycle used (approximately 200ms on and
200ms off). To show normal operation, the control boards flash
a 1 second on, 1 second off “heart beat” during normal
operation. This is to verify that the micro processor is
functioning correctly. Do not confuse this with an error flash
code. To prevent confusion, a 1-flash, fault code is not used.
See Table 6 for list of all flash codes.