Hybrid logic overview – LAARS M4-LHS - Installation Manual User Manual
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M4-LHS Installation and Operation Manual
3
HYBRID LOGIC OVERVIEW
In response to new advancement in condensing boiler design and size, many applications utilize multiple condensing boilers in
addition to the non-condensing boilers. That triggered Laars's design of the M4-LHS. It is intended to manage the two groups of
When Hybrid is selected
as the Boiler Type, the M4-LHS will select the lead group based on the Target temperature switching set point. See "Switch Set
Point" on page 20. The Condensing group of boilers will be the Lead group when the System Temperature is below the System Target
Switching Set Point. However, when the System Temperature rises above the Switching Set Point, the Non-Condensing boiler group
will be the lead group and the Condensing Group will be the lag group.
Basically, the M4-LHS will allow the condensing group of boilers to operate as along as the System sensor is below the Switching Set
Point. See"Switch Set Point" on page 20. During that period, if additional output boilers are needed, the M4-LHS may energize the
Non-Condensing boilers to meet the load depending on the Heavy Load Sequence 2nd Group setting. See"Heavy Load Sequence 2nd
Group" on page 21. When less output is required the M4-LHS will de-energize the lag group of boilers prior to de-energizing the lead
group of boilers.
To eliminate any short-cycling due to rapid changes in the Target Temperature used in the switching, an adjustable Switching Delay
has been incorporated. See"Switch Delay" on page 21.
Each of the condensing and non-condensing groups of boilers can be either modulating or staging. Modulating boilers can be of
4-20mA modulating signal or 0-10V modulating signal. See "Modulating Output Type" on page 23. Staging boilers can be On/Off,
2-Staeg, 3-Stage, or 4-Stage. See "Staging Output Type" on page 22.
For Hybrid settings, See "Boiler Type" on page 19.
To set the Condensing and Non-Condensing boiler types See "HYBRID Modulating Boiler Settings" on page 22.
Above the Switch Set Point
Non-Condensing are the Lead Group
Condensing are the Lag Group
Target Switch
Set Point
= 120°F
Below the Switch Set Point
Condensing are the Lead Group
Non-Condensing are the Lag Group
120°F
140°F
100°F
SWITCH MODE = Target Temperature
SYSTEM
A
B
C
D
1 2
RUN
PROGRAM
DO NOT APPLY ANY VOLTAGE
TO INPUT TERMINALS
3 4 5 6 7 8 9 10 11 12
13
15
14
17
16
18
22
20
19
21
24
23
29
25
27
26
28
32
30 31
L N
-
+
+
T
T
O
O
RS-485
mA
GND
VLT
SYS
A
B
C
D
PWR
CUR / VLT
A
-
+
+
mA
GND
VLT
-
+
+
mA
GND
VLT
-
+
+
mA
GND
VLT
+
mA
TEMP
OUTDOOR
O
O
TEMP
SYSTEM
EXTENSION
MODULE
CUR / VLT
B
CUR / VLT
C
CUR / VLT
D
PROVE
/DHW
SHUTDOWN
/TSTAT
/SETBACK
OD=
25 oF
SYS=
145 oF
<<A>>
B
100%
52%
System
Temp
SYSTEM
A
B
C
D
1 2
RUN
PROGRAM
DO NOT APPLY ANY VOLTAGE
TO INPUT TERMINALS
3 4 5 6 7 8 9 10 11 12
13
15
14
17
16
18
22
20
19
21
24
23
29
25
27
26
28
32
30 31
L N
-
+
+
T
T
O
O
RS-485
mA
GND
VLT
SYS
A
B
C
D
PWR
CUR / VLT
A
-
+
+
mA
GND
VLT
-
+
+
mA
GND
VLT
-
+
+
mA
GND
VLT
+
mA
TEMP
OUTDOOR
O
O
TEMP
SYSTEM
EXTENSION
MODULE
CUR / VLT
B
CUR / VLT
C
CUR / VLT
D
PROVE
/DHW
SHUTDOWN
/TSTAT
/SETBACK
OD=
25 oF
SYS=
145 oF
<<A>>
B
100%
52%
Above the Switch Set Point
Condensing are the Lead Group
Non-Condensing are the Lag Group
Outdoor Switch
Set Point
= 30°F
Below the Switch Set Point
Non-Condensing are the Lead Group
Condensing are the Lag Group
30°F
50°F
10°F
SWITCH MODE = Outdoor Temperature
COND
COND
NON-
COND
NON-
COND
NON-
COND
NON-
COND
COND
COND
Outdoor
Temp
SYSTEM
A
B
C
D
1 2
RUN
PROGRAM
DO NOT APPLY ANY VOLTAGE
TO INPUT TERMINALS
3 4 5 6 7 8 9 10 11 12
13
15
14
17
16
18
22
20
19
21
24
23
29
25
27
26
28
32
30 31
L N
-
+
+
T
T
O
O
RS-485
mA
GND
VLT
SYS
A
B
C
D
PWR
CUR / VLT
A
-
+
+
mA
GND
VLT
-
+
+
mA
GND
VLT
-
+
+
mA
GND
VLT
+
mA
TEMP
OUTDOOR
O
O
TEMP
SYSTEM
EXTENSION
MODULE
CUR / VLT
B
CUR / VLT
C
CUR / VLT
D
PROVE
/DHW
SHUTDOWN
/TSTAT
/SETBACK
OD=
25 oF
SYS=
145 oF
<<A>>
B
100%
52%
SYSTEM
A
B
C
D
1 2
RUN
PROGRAM
DO NOT APPLY ANY VOLTAGE
TO INPUT TERMINALS
3 4 5 6 7 8 9 10 11 12
13
15
14
17
16
18
22
20
19
21
24
23
29
25
27
26
28
32
30 31
L N
-
+
+
T
T
O
O
RS-485
mA
GND
VLT
SYS
A
B
C
D
PWR
CUR / VLT
A
-
+
+
mA
GND
VLT
-
+
+
mA
GND
VLT
-
+
+
mA
GND
VLT
+
mA
TEMP
OUTDOOR
O
O
TEMP
SYSTEM
EXTENSION
MODULE
CUR / VLT
B
CUR / VLT
C
CUR / VLT
D
PROVE
/DHW
SHUTDOWN
/TSTAT
/SETBACK
OD=
25 oF
SYS=
145 oF
<<A>>
B
100%
52%
NON-
COND
NON-
COND
COND
COND
COND
COND
NON-
COND
NON-
COND