LAARS Mini-Therm JVS (Sizes 50-225) - Install and Operating Manual User Manual
Page 30
LAARS Heating Systems
Page 30
DHW Operation The boiler target for DHW calls
is fixed at 180 deg F.
Note: There is no control of a DHW pump, so the
boiler pump runs with the call for DHW.
Limiting The boiler target is limited to a
minimum and a maximum target to ensure that the
water temperature does not exceed the limits.
1. Target Min - The boiler target minimum is
the point at which the stages will start to turn on to
maintain a minimum water temperature. The Boiler
Minimum water temperature is 130 deg F, regardless
of other calculated targets. To ensure that the water
temperature is greater than the Boiler Minimum water
temperature the target is increased to allow the stages
to cycle on by the Boiler Minimum water temperature,
Boiler Minimum target is set to Boiler Minimum +
differential/2.
2. Target Max - The boiler target maximum is
the point at which the stages will start to turn off to
maintain a maximum water temperature. The Boiler
Maximum water temperature is set by setting dip
switch #4: Boiler Maximum 210°F (Off) / 190°F
(On).
To ensure that the water temperature is less than the
Boiler Maximum water temperature the target is
decreased to allow the stages to cycle off by the Boiler
Maximum water temperature, Boiler Maximum target
is set to Boiler Maximum - differential/2.
Auto Differential The control automatically
adjusts differential to prevent short cycling and
maximize the lifetime of components.
WWSD Operation Warm Weather Shutdown -
WWSD feature is selected via dip switch #3, WWSD
Inactive (Off) / Active 70°F (On). WWSD point is
fixed at 70 deg F. Control exits WWSD when the
outdoor temp falls to 65 F. When there is a call for
HEAT and the control is in WWSD the HEAT call will
be ignored. When there is a call for DHW and the
control is in WWSD the DHW call will be satisfied.
WWSD LED turns on when control detects WWSD.
Summary of Dip Switch Settings:
#1 Two Stage (Off) / Single Stage (On)
(Note: Efficiency may be reduced with 2-stage
operation.)
#2 (Off) / Outdoor Reset (On) (Note: Outdoor Reset
is required for residential operation)
#3 WWSD Inactive (Off) / Active 70°F (On)
#4 Boiler Maximum 210°F (Off) / 190°F (On)
#5 Pump Post Purge Inactive (Off) / Active 3 min.
(On)
LEDs State Description
1. Power
2. Heat – On = call for heat; Flashes for Boiler
sensor error
3. DHW – On = call for DHW; Flashes for
outdoor sensor error
4. WWSD – On = Outdoor Reset AND WWSD
Active AND control in WWSD; Flashes for
outdoor sensor error, operation continues with
fixed boiler target of 140°F.
Summary of Input Sensors:
1. Outdoor sensor - monitors the outside air
temperature for outdoor reset mode
2. Boiler outlet sensor -monitors the water
temperature of the boiler outlet supply
3. System Supply sensor - monitors the water
temperature of the system supply
The boiler outlet sensor is required at all times. If
the boiler outlet sensor has any fault then the control
will flash an error and turns all stages off. The
system supply sensor is optional and utilizes primary
/ secondary piping. If the system supply sensor has
a fault then the control flashes an error message and
operates using the boiler outlet sensor (system supply
= boiler outlet).
JVH050
50
83
JVH075
75
83
JVH100
100
82
JVH125
125
82
JVH160
160
82
JVH225
225
82
JVS050
50
85
JVS075
75
85
JVS100
100
85
JVS125
125
85
JVS160
160
85
JVS225
225
85
106
92
136
118
191
166
43
37
64
56
85
74
102
89
131
114
184
160
41
36
62
54
82
71
MiniTherm Series Boiler Natural Gas
Model
Number
Input, MBH
Heating Capacity,
MBH
Net AHRI Rating
Water, MBH
AFUE, %
Table 10. Efficiencies