Control Module Operation - Weil-McLain WM97+ Manual

WM97+ -
gas fired water boiler

Control module operation

Temperature settings
control module is set for the proper water temperatures
for the system. Excessive water temperature can cause
significant property damage in some applications.
Multi-temperature systems
includes circuits that require lower temperature water
(radiant slab circuits, for example) as well as higher
temperature circuits (DHW, finned tube baseboard, etc.),
it is recommended to protect low-temperature circuits
with limit controls that are wired to a control module
external limit circuit. Failure to provide regulation can
result in substantial property damage.
Control module features
❏ ❏ Blower speed modulation to control the WM97+ boiler's firing rate.
❏ ❏ Advanced PID response to anticipate system needs based on response
to heat input.
❏ ❏ Graphic and robust text display for ease of operation monitoring and
troubleshooting.
❏ ❏ Preset operating parameters for typical heating systems (finned tube
baseboard, radiant floor, DHW, and others), including target tempera-
tures, reset curves and circulator assignments.
❏ ❏ Control of up to three circulators or zone devices, assignable for each of
the three possible zone inputs. (Boiler circulator controlled internally.)
❏ ❏ Programmable priority assignment for DHW input.
❏ ❏ Integral outdoor reset option, with reset curves matched to the system
type selected.
❏ ❏ Dual sensors for boiler outlet temperature and flue temperature, pro-
viding redundant protection.
❏ ❏ Integral low water cut-off.
❏ ❏ Boiler is shipped with an outdoor sensor, allowing outdoor reset opera-
tion for maximum boiler efficiency.
Sequence of operation
1. Figure 58 is a summary of the operating sequence for the control
module.
2. The symbols shown appear in the display as the control module cycles
the boiler.
3. The wrench symbol appears when a scheduled maintenance date ar-
rives. This informs the homeowner to call the contractor for service.
4. The exclamation mark symbol appears when a problem has been
detected.
Control module setup
BEFORE PROCEEDING, perform essential control
settings as instructed on page 54.
1. See page 55 for an overview of the control module menus. This page
also gives the location of instruction manual information for each of
the main menus.
52
— Boiler Manual
— You must ensure that the
— If the heating system
Figure 58 Control sequence of operation
Display Control action
status
(also see Figure 59, page 53)
graphic
• Check the boiler model listed on the power-up
screen. If it is not correct, turn off the boiler. See
page 55 to change setting.
POWER
• When power is turned on, the screen lists sen-
UP
sors that are detected. If any sensor is not listed,
make sure it is connected correctly. Turn off
power and restart.
• Standby — no calls for heat
• Toggles through no dots, 1 dot, 2 dots, then
3 dots while in standby (wrench symbol will
Standby
show instead if maintenance is needed)
• Call for heat detected
• Display on with BLUE light (space heating) or
PURPLE light (DHW)
• Start min/max on timers if more than one system
is calling — highest priority starts first
• Start circulators for this priority setup
Blower on
• Calculate target temp — If sensor temp is below
target temp, begin firing sequence
• Blower to ignition speed for prepurge
• After prepurge times out, begin ignition cycle
• Activate gas valve and ignition spark
• Continue ignition spark for ignition period
• Turn off spark and use electrode to check for
Ignition on
flame signal
• Flame detected
• Release boiler to modulation
• NOTE: If flame is not detected, the gas valve
is turned off, blower turns on (postpurge), and
control starts cycle again. After 5 failures, the
Space
control waits 60 minutes, then tries again.
heating
• If priority timer times out, switch to next priority
and start priority timer
• If demand satisfied, go to postpurge
• Flame detected
• Release boiler to modulation
• NOTE: If flame is not detected, the gas valve
is turned off, blower turns on (postpurge), and
control starts cycle again. After 5 failures, the
DHW
control waits 60 minutes, then tries again.
heating
• If priority timer times out, switch to next priority
and start priority timer
• If demand satisfied, go to postpurge
• Demand satisfied (temperature reaches target
temperature or limit setting)
• Gas valve off
• Blower to ignition speed for postpurge
Blower on
• Return to standby after purge
• Display turns RED, toggling between graphic
screen and maintenance screen (occurs when
maintenance schedule timer times out)
• Will show during standby only
Maintenance
• Boiler operates as normal
• Display turns RED due to error or limit event
• Flashing display means lockout condition —
display toggles between three screens as in
Error/fault
Figure 87, page 84.
• Warm weather shutdown — the boiler will not
be allowed to fire on space heating if the outside
temperature is greater than the WWSD setting.
WWSD
DHW operation is not affected by WWSD.
Part number 550-142-058/0811