LAARS Mini-Therm II JVT (Sizes 50-225) - Install and Operating Manual - Manual (Page 27)

Mini-Therm II Hydronic Boiler Page 27
Caution
Two-stage Operating Control (JV100-225 ONLY):
Factory setting is 140°F (60°C). This setting is
correct for most hydronic heating applications.
Adjustments to this setting must be made by an
authorized service technician.
2. Two-stage Temperature Control - JVS 100-
225 are equipped with a two-stage temperature
control which senses inlet water temperature. It
is used to control the firing rate of the main
burners, cycling the gas valve between low, high
and off.
3A. Ignition Control, JVS - When the thermostat
calls for heat and all limits are satisfied a pilot
trial for ignition is initiated. If pilot is not
established a 5 minute minimum delay is
implemented prior to the next trial for ignition.
This cycle repeats until pilot is established or the
system is shut down manually.
JVS 100-225 only - Once pilot is established the
main valve is enabled and controlled by the two-
stage temperature control.
JVS 50-75 only - Once pilot is established the
main valve will open until the limit circuit opens.
3B. JVT Flame Control - The standing pilot JVT
models rely on a flame sensor on the gas valve.
When the thermostat calls for heat and adequate
pilot flame is sensed, the gas valve will open.
The valve will remain open until the limit circuit
opens.
4. Pilot Assembly
JVS - The pilot assembly utilizes an electrode
that is used to generate spark to ignite the pilot
flame as well as sense flame presence.
JVT - The JVT pilot is lit manually and senses
pilot flame via a thermocouple which generates a
signal that allows the gas valve to open.
5. Hi-Limit Switch: Factory setting is 190°F
(88°C). This setting is correct for normal
operations, and should only be changed by an
authorized service technician. Under no
circumstances should the setting exceed 220°F
(104°C).
6. Blocked Vent Switch - JVS and JVT boilers are
equipped with a manual reset blocked vent
switch designed to shut the boiler down in the
event the vent is completely blocked. The switch
is located in the draft diverter opening on the rear
of the boiler.
7. Rollout Switch - JVS and JVT boilers are
equipped with a manual reset rollout switch
designed to shut the boiler down in the event a
flame rollout situation occurs causing excessive
temperatures. The switch is located on the burner
cover.
SECTION 9.
Troubleshooting
9.1 General Boiler Troubleshooting
Table 8 lists some of the more common
problems, causes and solutions encountered when
running the boiler. Most problems occur when the
boiler is being started for the first time after
installation. Careful installation and maintenance will
help ensure years of trouble free use from your Laars
Mini-Therm II boiler.
WARNING
SERVICING SAFETY
Some of the servicing procedures for the Laars
Mini-Therm II JVS and JVT boilers are hazardous
because they involve fuel gas, electricity, moving
parts and procedures which require testing or
temporary bypass of safety controls. For this
reason, the boiler must be serviced only by a
qualified professional service technician.
IMPROPER SERVICE HAZARD
The Mini-Therm II JVS and JVT boilers incorporate
unique design features. Incorrect service of this
heater can result in personal injury or damage to
property. To avoid such hazards, the boiler must be
serviced only by a qualified professional service
technician.
AVERTISSEMENT
PRÉCAUTIONS LORS DES RÉPARTATIONS ET
DE L’ENTRETIEN
Certaines procédures d’entretien et de réparation
des appareils de chauffage à faibles émissions
présentent des changers, car elles mettent en jeu
des gaz combustibles, des composants électriques,
des pièces mobiles et des procédures qui
nécessitent des mises à l’essai ou la dérivation
temporaire des commandes de sécurité. Pour cette
raison, l’appareil de chauffage doit être entretenu et
réparé uniquement par un technicien professionnel
qualifié
DANGERS D’UN ENTRETIEN INADÉQUAT
Les appareils de chauffage à faibles émissions
comportent des caractéristiques techniques
uniques. Une réparation ou un entretien inadéquat
peut entraîner des blessures corporelles ou des
dommages à la propriété. Pour cette raison,
l’appareil de chauffage doit être entretenu et réparé
uniquement par un technicien professionnel
qualifié.