16
Operations
Room Vents for Combustion and
Ventilation Air
Properly sized vents are vital for the safe and efficient
operation of a pressure washer installed in a confined
space. When combustion and ventilation air are
supplied from inside the building, each opening must
have an area of one square inch for every 1,000 BTUH
input. When combustion air is supplied from the
outside, each opening must have an area of one
square inch for every 2,000 BTUH for horizontal ducts
and one square inch for every 4,000 BTUH for vertical
ducts (refer to NFPA 54).
NOTE: Air vents for combustion and ventilation and
exhaust flue sizing must conform to methods outlined
in current American Standard (ANSI-Z223.1),
National Fuel Gas Code of National Standard of
Canada CSA-149.1 and CSA-149.2 “Installation
Code for Gas Burner Appliances”.
Exhaust Stack
The purpose of venting a gas-fired pressure washer is
to completely remove all products of combustion and to
vent gasses to the outside air without condensation in
the vent or spillage at the draft hood (except in cases of
downdraft or poor stack conditions). Always use strong,
gas-tight, insulated pipe.
The design of this pressure washer depends on natural
draft (heat induced) to pull combustion gas out of the
combustion chamber. The design of the exhaust stack
can have a significant impact on the proper operation of
the burner and coil.
During vent installation, avoid sharp turns, long hori-
zontal runs and improper pitches. Maintain proper
support of vent connectors and joints, observe clear-
ances from all combustibles and top the vent outlet with
an approved cap.
Type "B", due to its temperature rating, can only be
used with natural draft pressure washers. A "B" vent is
designed for exhaust temperatures not to exceed
470°F (245°C).
All venting installations must conform to local codes. In
the absence of local codes, refer to "National Fuel Gas
Code" NFPA 54 and be constructed of materials
approved by the Uniform Building Code.
Vents penetrating ceilings or walls should be double-
wall approved appliance vents and should be one to
two inches from combustibles. Vents passing through
enclosed spaces and vents exposed to the weather
should also be the double-wall type. Sometimes vents
have to be built of such great length that they come
apart at their joints under their own weight. These
should be screwed together at the joints with sheet
metal screws, usually three per joint. If the inspector
indicates that the vent is too close to combustibles, it
may be necessary to chisel away some of the combus-
tible or route the vent pipe around the combustible. The
cross-sectional area of any flue shall not be less that
the cross-sectional area of the flue vent connection
outlet of machine.
The pressure washer includes a collar that will mate
with standard HVAC ducting. The user will be respon-
sible for installation of an exhaust stack. The exhaust
stack should include a Draft Diverter/Inducer, Damper,
Sampling Port and Rain Cap. An adapter can be
installed between the collar and stack to adjust the
diameter from 10” to 8” or 12” to 10”.
Size the stack according to the following (see also
applicable local and national standards regarding
installation of gas-fired appliances):
•
3.5 to 4.4 gpm 10” Collar 8” Stack
•
4.5 to 5.5 gpm 10” Collar 10” Stack
•
6.3 gpm 12” Collar 10” Stack
•
8 – 10 gpm 12” Collar 12” Stack
Draft Diverter/Hood
The draft required to vent
combustion gases is created by the heat inside the
pressure washer coil. A draft diverter helps improve
draft into the stack without pulling more air through the
combustion box and decreasing combustion efficiency.
Landa ENG Operator’s 9.801-511.0 - F
Draft Diverter
Required
8.717-728.0 8"
9.801-040.0 10"
8.717-730.0 12"
Illustration showing air openings necessary
to supply air for combustion when installed
in an enclosed room.
Ventilation
Summary of Contents for ENG Series
Page 36: ...9 801 511 0 Printed in U S A...
