21
21
Maximum
opening
Minimum
opening
No indent
Identification
Indent
For
Horizontal
vent termination
For
Through the Roof
vent termination
4-9/16”
(116 mm)
4-5/16”
(110 mm)
Figure 18 Restrictor identifi cation
Figure 19 Restrictor locations
Appliance Preparation
Attaching Air Restrictors
There are two types of restrictor supplied with each #535
engine unit. One type is for installations with horizontal
vent termination and the other is for installations with
through-the-roof termination—see fi gure 18.
The restrictors cover part of the openings in the fi rebox
rear wall ports. See fi gure 19.
To fi t the restrictors, remove the center screws from the
rear ports and fi t the restrictors using these screws.
To set the restrictors at
maximum port opening
, slacken
the bottom screws in the ports, slide the restrictors
down as far as possible and tighten the screws over the
restrictors.
To set the restrictors at
minimum port opening
, slide the
restrictors up as far as possible and tighten the screws.
Installations with Horizontal Termination
Do not fi t restrictors if the vertical rise is less than 3 feet.
Do not fi t restrictors if the horizontal run is more than 4
feet.
For installations with a horizontal run of 4 feet or less and
having a vertical rise of 3 feet or more, fi t the restrictors at
maximum port opening—see graph 2.
On a 535, the horizontal vent termination type restrictors
are never set at any position except maximum port
opening.
Installations with Through-the-roof Termination
For vent heights up to 20 feet. Fit the restrictors at
maximum
port opening position.
For vent height above 20 feet. Fit the restrictors at
minimum
port opening position.
1
0
2
3 4 5
6
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16
Restrictors
to be fitted
No restrictors to be fitted
Horizontal Run (Ft) (E in Fig. 5)
Vertical
Rise (Ft)
(D in
Fig. 5)
Graph 2