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B. Removing an Existing Boiler From a Common Chimney
Read this only if the MWC boiler is replacing an existing boiler that is being removed from a common
chimney. This section does not apply to the installation of a MWC boiler.
In some cases, when an existing boiler is removed from a common chimney, the common venting system
may be too large for the remaining appliances. At the time of removal of an existing boiler, the following
steps shall be followed with each appliance remaining connected to the common venting system placed
in operation, while the other appliances remaining connected to the common venting system are not in
operation.
(a) Seal any unused openings in the common venting system.
(b) Visually inspect the venting system for proper size and horizontal pitch and determine there is no
blockage or restriction, leakage, corrosion and other defi ciencies which could cause an unsafe
condition.
(c) Insofar as practical, close all building doors and windows and all doors between the space in which
all the appliances remaining connected to the common venting system are located and other
spaces of the building. Turn on clothes dryers and any appliance not connected to the common
venting system. Turn on any exhaust fans, such as range hoods and bathroom exhausts, so they
will operate at maximum speed. Do not operate a summer exhaust fan. Close fi replace dampers.
(d) Place in operation the appliance being inspected. Follow the lighting instructions. Adjust
thermostat so the appliance will operate continuously.
(e) Test for spillage at the draft hood relief opening after 5 minutes of main burner operation. Use
the fl ame of a match or candle, or smoke from a cigarette, cigar, or pipe.
(f) After it has been determined that each appliance remaining connected to the common venting
system properly vents when tested as outlined above, return doors, windows, exhaust fans,
fi replace dampers and any other gas-burning appliances to their previous condition of use.
(g) Any improper operation of the common venting system should be corrected so the installation
conforms with the National Fuel Gas Code, ANSI Z223.1.
common venting system, the common venting system should be re sized to approach the minimum
size as determined using the appropriate tables in Part 11 of the National Fuel Gas Code, ANSI
Z223.1.
WARNING
Never common vent a MWC boiler with other appliances.
Natural Gas and Propane Installation Code.
/NFPA 54 and/or CAN/CSA B 149.1
When re-sizing any portion of the
/NFPA 54 and/or CAN/CSA B 149.1