Weil-McLain SlimFit 3 Series Application Manual

Common Venting SlimFit 550-750 Series 3 Boilers
Common Venting methods and requirements for SlimFit Boilers (SF 550 and SF 750 Series 3)
The SlimFit boiler can be common vented when the following requirements are met.
• Common venting of the SlimFit boiler can only be done in a Category II vent system. All require-
ments for the SlimFit boiler to be vented in a Category II configuration must be met as stated in the
SlimFit Boiler Manual or all subsequent addendas.
• SlimFit boilers can only be common vented with other SlimFit Boilers.
• The maximum number of SlimFit boilers to be common vented together is eight.
• The Vent system for a Category II SlimFit boiler is considered a Designed / Engineered vent system
and should be designed by a professional using accepted engineering practices.
• Vertical Vent only.
• Combustion air must come from the boiler room. See Direct Exhaust – Combustion Air opening
requirements in SlimFit Vent Category II Addendum.
• Must increase venting to 6"or 8" using a 8" to 6" bell reducer at boiler vent adapter for Category II
Vent Connection.
• The Vent System should be designed so that the pressure in the vertical vent pipe is between the
ranges provided in the Table 1, page 2, during all operating conditions (i.e., High Fire through Low
Fire, prepurge, post purge and ignition). If a negative pressure cannot be guaranteed at prepurge and
post purge, a backflow preventer is required on each boiler's vent.
To prevent backflow through boiler, negative pressure must be maintained in vent system at all
times including prepurge and post purge cycles.
• Flue gas temperature should not exceed 210°F; the boiler will shut down and recycle if it does. The
flue gas temperature should typically be within 20°F of the return water temperature of the boiler. If
there is the potential for a wide variation in return water temperatures, the lowest possible tempera-
ture should be used for any calculations.
- continued on next page
Hazard definitions
The following defined terms are used throughout these Instructions to bring attention to the presence of hazards of
various risk levels or to important information concerning the life of the product.
Indicates presence of hazards that can cause severe personal injury, death or substantial property damage.
Indicates special instructions on installation, operation or maintenance that are important but not related
to personal injury or property damage.
Application Guide
for
Series 3
Models 550 and 750 MBH
Commercial Condensing
Gas-fired water boilers
Part No.
®
SF-E009-A/0516