1. Designed to Maintain Suction Superheat Anticipate Changing Conditions
MCS FAST SSH
Designed to Maintain Suction Superheat
and
Anticipate Changing Conditions
(Advanced Functions)
Revised 1.0 -June 18, 2018

2. Design Criteria Specialized Startup functions
Specialized Fast Zone Hold function
Specialized EXV Delay functions
Projected Fast Suction Superheat Degrees C

3. System Requirements
1. Requires MCS-Config Version 18.00V or greater.
2. Requires MCS-Connect Version or greater.
3. Requires Magnum HVAC/RTU firmware Ver K hex or greater.
4. Requires Config Type 17.

4. Specialized Valve Startup FUNCTIONS
BASIC DESCRIPTION
EXV TME HOLD
EXV TME QUICK
EXV TME LONG
EXV TME NORMAL
SP 19 EXV STARTUP TIME = 90 SECONDS
SP TARGET
SP 10 ± 2 FAST ZONE (RED LINES)
EXV HOLD CALCULATED 0 to 39 SECONDS (VER 17.25K)
EXV QUICK CALCULATED 40 to 60 SECONDS (VER 17.25K)
SP SECONDS EXV STARTUP (VER 17.25K)

5. Specialized Valve Startup FUNCTIONS (cont)
BASIC STARTUP
EXV TME HOLD
EXV TME QUICK
EX TME NORMAL
EXV TME LONG
HOLD EXV STARTUP
SH < TARG + 5
TAKE CTL & NO CHG VLV%
SH > TARG + 5
TAKE CTL & INCR VLV% BY 1.0
SH < TARG + 5
TAKE CTL & DECR VLV% BY 1.0

6. Specialized Valve Startup FUNCTIONS (cont)
CONTROL TOO FAST, CONTROL CORRECT, CONTROL TOO SLOW
EXV TME HOLD
EXV TME QUICK
EXV > HI TME & < LO TME
EXV TME LONG
HOLD EXV STARTUP
SH > TARG & ROC > 0
TAKE CTL & INCR VLV% BY 1.0
PROTECTS VALVE FOR OPENING SET TOO SMALL
TEST BEGINS AT END HOLD TIME
SH > TARGET DEGREES AND GETTING LARGER

7. Specialized Valve Startup FUNCTIONS (cont)
PROTECTS AGAINST LOW SUPERHEAT DURING STARTUP
EXV TME HOLD
EXV > WAIT TME & < LONG TME
EXV TME LONG
HOLD EXV STARTUP
SH < LOW SH SP & ROC < 0
TAKE CTL & DECR VLV% BY 2.0
PROTECTS VALVE IF OPENING TOO LARGE
TEST STARTS AT END OF HOLD TIME
SH < LOW SUPERHEAT SP AND ROC < 0

8. Specialized Valve Startup FUNCTIONS (cont)
PROTECTS AGAINST LOW SUCTION PSI DURING STARTUP
EXV TME HOLD
EXV > HOLD TME & < LONG TME
EXV TME LONG
HOLD EXV STARTUP
SUCT PSI < LOW SUCT SP & SH > TARG – FAST ZN
TAKE CTL & INCR VLV & BY 2.0
PROTECTS VALVE IF OPENING TOO SMALL
TEST BEGINS AT END OF HOLD TIME
SUCTION PSI < LOW SUCTION SP BUT SH IS ABOVE LOWER LIMIT FAST ZONE
TAKE CTL AND INCR VALVE STARTING % BY 2.0

9. Specialized Fast Zone Hold function
DEFINES STEADY STATE AND WHERE SP 10 USES MPLY IF REQUESTED
FAST ZN +
SH ADJUSTMENT MPLY SP 10 TIME FIELD
SH = TARGET ± (FAST ZN / 2) ROC = 0
TARGET
SH = TARGET ±(FAST ZN / 10) ROC = 0 OR ± .1
SH = TARGET ± (FAST ZN / 2) ROC = 0
SH ADJUSTMENT MPLY SP 10 TIME FIELD
FAST ZN -

10. Specialized Fast Zone Delay function
SP 19 DEFINES DELAY TIME WHEN EVALUATING EXV IN FAST SUPERHEAT
FOR FAST SUCTION SUPERHEAT
USUALLY 1
IF GREATER THAN 1 USED, IT IS ONLY USED WHEN WITHIN FAST ZONE
IF OUTSIDE FAST ZONE SYSTEM DEFAULTS TO 1
FOR FAST DISCHARGE, EVAPORATOR LEVEL SENSOR OR DX RTU
WILL NEED TO BE LARGER DUE TO SLOWER REACTION TIME
WHEN WITHIN FAST ZONE SYSTEM USES VALUE SPECIFIED SP 19
WHEN OUTSIDE FAST ZONE, BUT LESS THAN 2 TIMES FAST ZONE
EXV DELAY TIME IS DIVIDED BY 2
WHEN OUTSIDE FAST ZONE BY MORE THAN 2 TIMES
EXV DELAY TIME IS DIVIDED BY 4

11. Specialized Fast Zone Hold function
DEFINES EXV DELAY TIME WHEN VALUE 4 OR GREATER
EXV DELAY = SP VALUE / 4
FAST ZONE 3
EXV DELAY = 15
FAST ZN +
EXV DELAY = SP VALUE / 2
EXV DELAY = 30
FAST ZONE 2
FAST ZN +
FAST ZONE 1
TARGET
EXV DELAY = SP VALUE
EXV DELAY = 60
FAST ZONE 1
FAST ZN -
EXV DELAY = SP VALUE / 2
EXV DELAY = 30
FAST ZONE 2
FAST ZN -
EXV DELAY = SP VALUE / 4
EXV DELAY = 15
FAST ZONE 3
ASSUMING CONTROL IS BASED ON LIQUID LEVEL SENSOR & SP 19 (EXV DELY = 60 SEC)

12. Fast Suction SH F / PSI Setup
SP 9 FAST SH TRGT 11.0 DEGREES F
SP 10 FAST SH ZONE DEGREES F
SP 14 LIMIT ADJUST PERCENT & 1.5 PERCENT (ASSUMED DECIMAL 1.5)
SP 18 LO SUPERHEAT DEGREES F

13. Fast Suction SH C / BARS Setup
SP 9 FAST SH TRGT 6.0 DEGREES C
SP 10 FAST SH ZONE 1.2 DEGREES C
SP 14 LIMIT ADJUST 0.2 PERCENT & 1.5 PERCENT (ASSUMED DECIMAL 1.5)
SP 18 LO SUPERHEAT 1.0 DEGREES C

14. Fast LEVEL SH Setup SP 9 FAST LVL TRGT 35 PERCENT
SP 10 FAST SH ZONE 2.0 PERCENT
SP 14 LIMIT ADJUST 0.2 PERCENT & 1.5 PERCENT (ASSUMED DECIMAL 1.5)
SP 18 LO SUPERHEAT 1.0 DEGREES C

15. (Support, Literature, App Notes)
MCS FAST SUPERHEAT
For additional information please visit our website
Application Note 116
(Support, Literature, App Notes)
Or call MCS at
5580 Enterprise Pkwy.
Fort Myers, FL 33905
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