Dexter Laundry SWD EXPRESS - Dryer (On-Premise) - Manual (Page 8)

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CAUTION: The dryer and its individual shutoff valve must be disconnected from the gas supply
piping system during any pressure testing of that system at test pressures in excess of ½ psig (35
mbar). The dryer must be isolated from the gas supply piping system by closing its individual
manual shutoff valve during any pressure testing of the gas supply piping system at test pressures
equal to or less than ½ psig (35 mbar).
6. EXHAUST INSTALLATION. (Refer to Figure 3 at the end of section 6.) Exhausting of the
dryer(s) should be planned and constructed so that no air restrictions occur. Any restriction due to
pipe size or type of installation can cause slow drying time, excessive heat, and lint in the room.
From an operational standpoint, incorrect or inadequate exhausting can cause a cycling of the
high limit thermostat which shuts off the main burners and results in inefficient drying.
Individual exhausting of the dryers is recommended. All heat, moisture, and lint should be
exhausted outside by attaching a pipe of the proper diameter to the dryer adapter collars and
extending it out through an outside wall. This pipe must be very smooth on the inside, as rough
surfaces tend to collect lint which will eventually clog the duct and prevent the dryer from
exhausting properly. All elbows must be smooth on the inside. All joints must be made so the
exhaust end of one pipe is inside the next one downstream. The addition of an exhaust pipe tends
to reduce the amount of air the blower can exhaust. This does not affect the dryer operation if
held within practical limits. For the most efficient operation, it is recommended that no more than
14 ft. (4.25 m) of straight 6 in. (152 mm) diameter pipe with two right angle elbows be used for
each cylinder.
If the exhaust pipe passes through a wall, a metal sleeve of slightly larger diameter should be set
in the wall and the exhaust pipe passed through this sleeve. This practice is required by some
local codes and is recommended in all cases to protect the wall.
This type of installation should have a means provided to prevent rain and high winds from
entering the exhaust when the dryer is not in use. A hood with a hinged damper can be used for
this purpose. Another method would be to point the outlet end of the pipe downward to prevent
entrance of wind and rain. In either case, the outlet should be kept clear, by at least 24 in. (610
mm) of any objects which would cause air restriction.
Provide a screen or grill over the termination of the exhaust or flue outlet such as will prevent the
entry of a ball of 5/8 (16 mm) in diameter while the machine is not operating but will allow entry
of a ball 1/4 (6 mm) in diameter while operating.
When exhausting a dryer straight up through a roof, the overall length of the duct has the same
limits as exhausting through a wall. A rain cap must be placed on top of the exhaust and must be
of such a type as to be free from clogging. The type using a cone shaped “roof” over the pipe is
suitable for this application.
Exhausting the dryer into a chimney or under a building is not permitted. In either case there is a
danger of lint buildup which can be highly combustible.