Weil-McLain 550 MBH Nstallation And Operation Manual page 2

®
SlimFit Series 3
SlimFit ™
The
Air enters the boiler enclosure through the air intake adapter (18),
flows through the enclosure, enters the air inlet silencer (5), then enters
the venturi (6). The blower pulls air and gas through the venturi and
pushes the mixture into the burner. The advanced blower design and
air inlet silencer yield very quiet operation.
The automatic gas valve incorporates two solenoid-operated valve
seats. The valve senses the vacuum in the venturi (item 6) caused by
flowing air. Gas flows in proportion to air flow, so fuel/air ratio remains
constant as blower speed/air flow changes.
The horn-shaped air inlet silencer significantly reduces fan noise,
providing exceptionally quiet operation.
When air flows through the venturi, it creates a vacuum that is sensed
by the gas valve to regulate gas flow (see item 4).
The expansion module operates the gas valve, monitors gas pressure
switches and provides a dry contact for the boiler circulator (suitable
for up to 10 amps). Connections for BMS and Boiler-to-Boiler com-
munications also located on board.
The electronic display is used to configure boiler settings and monitor
boiler operation. The buttons allow changing display mode, entering
setting values, and resetting after lockout.
Made with high-grade stainless steel and fiber mesh construction, the
burner uses pre-mixed air and gas. The burner and control provide
modulating firing.
The SlimFit control panel is mounted to a hinged sub panel, allow-
ing the panel to be swung forward and down for easy access to the
electrical connections.
Knockouts are provided in the jacket top panel, allowing conduit entry
directly behind the control panel or near the wall.
The front door is sealed to the boiler assembly around its entire pe-
rimeter.
The burner flame is ignited by applying a high voltage to the ignition
electrode. This causes a spark (from electrode to ground). After igni-
tion, the electrode measures flame signal.
2
COMMERCIAL CONDENSING GAS
Series 3
COMMERCIAL gas-fired water boiler
—
-
FIRED WATER BOILER
The control can operate a single boiler or coordinate with other
SlimFit 550/750 Series 3 boilers in a multiple boiler system.
Control inputs and outputs allow operation of multiple heat-
ing circuits (space heating and DHW, for example).
Up to three priority levels can be set, providing automatic
switch-over on demand.
This manual provides quick set-up information for single
boiler installations.
The Advanced Manual, also supplied with the boiler, provides
instructions for setting up multiple-boiler systems and for us-
ing advanced options for single boilers.
The control responds to signals from the room thermostats,
DHW aquastats (if used), boiler sensors (boiler return, boiler
supply, flue temperature), outdoor temperature and system
sensor, if used.
The control automatically adjusts blower speed (and gas flow
rate) to match boiler output to space heating and/or DHW
heating demand.
The default control settings provide for three space heating
zones. The control can be easily set up for operation with a
DHW zone, with or without domestic priority.
The control setup Wizard is available from the BOILER
SETTINGS menu that appears during initial startup.
The Wizard leads through a step-by-step setup procedure
designed for the application chosen.
Context-sensitive help is available to explain the purpose of
key setup items.
The quartz glass window provides a view of the burner surface and
flame.
A blower plate is used on SF-550 for both natural gas and propane
applications. The SF-750 propane requires a blower plate, but does
not use a blower plate on natural gas.
Boilers are shipped with no orifice installed (not required for natural
gas). The propane orifice must be installed to operate on propane.
Located in bottom of supply manifold.
Boiler Manual
WIZARD
Part number 550-100-168/0516