Installation Requirements
Add total BTUH of all appliances in the conned space and divide by gures
WARNING: All components of gas supply system must be leak
tested prior to placing equipment in service. NEVER TEST FOR
LEAKS WITH AN OPEN FLAME.
below for square inch free area size of each (top and bottom) opening.
1. Air from inside building - openings 1 square inch free area per 1,000
BTUH. Never less than 100 square inches free area for each opening.
See “A” in illustration.
2. Air from outside through duct - openings 1 square inch free area per
2,000 BTUH. See “B” in illustration.
3. Air direct from outside - openings 1 square inch free area per 4,000
BTUH. See “C” in illustration.
NOTE: For further details on supplying combustion air to conned space
see: National Fuel Gas Code ANSI Z223.1 - (latest edition) 5.3.3.
GAS PIPING AND PRESSURES
To provide adequate gas pressure at the furnace, refer to pipe sizing tables.
The unit is equipped for a maximum gas supply pressure of 1/2 pound or
8 ounces. An additional service regulator external to the unit is required to
reduce higher supply pressures to the 1/2 pound maximum.
WARNING: Never expose gas control on unit to greater than 1/2
pound pressure! Pressure testing of the gas supply piping system
must be carried out before connecting the furnace. A pipe cap or
eld-supplied high pressure gas cock must be used during proof
testing of the system.
For Natural Gas
Manifold pressure is regulated by the combination valve to 3.5” water col-
umn. Line pressure upstream of the controls must be a minimum of 5” water
column or as noted on unit rating plate.
For Propane Gas
Manifold pressure is regulated by the combination valve to 10” water col-
umn. Line pressure upstream of controls must be 11” water column mini-
mum and 14” maximum.
NOTE: Gas supply pressures higher than 14” w.c. or 1/2 pound require an
additional service regulator to be added to the unit or supply system.
All piping must be in accordance with requirements outlined in the National
Fuel Gas Code ANSI Z223.1-(latest edition) or CAN/C.G.A.-B149 (.1 or
.2).
When regulations require and for ease of servicing, install a ground joint
union and manual shut-off valve upstream of unit control system.
SIZING BY-PASS AIR DUCT
Directions for Sizing By-Pass Duct
1. From the Pressure Drop Tables on pages 20 and 21, nd the pressure
drop for the Model and Size of unit that is being installed and the allow-
able CFM.
Example: EEDU 125 @ 70° temperature rise
P.D. .25
CFM 1315
2. Subtract the allowable CFM from the actual CFM of the installation to
determine how much air must go through the by-pass duct.
Example: Blower CFM 3000
Allowable CFM -1315
By-Pass CFM 1685
3. Go to the column in the By-Pass CFM Chart that is closest to the pres-
sure drop. Move down in that column until you nd the CFM closest to
the answer in Step 2.
Example: P.D. .25
By-Pass CFM 1650
4. Move to the left column to nd out the required size of the by-pass
duct.
Example: By-Pass Duct
Size is 6”
Depth of the by-pass duct is 18” on both inlet and outlet ends. By-pass
duct must be located on side opposite limit control and 2” from the heat
exchanger side panel.
Note: Not all capabilities are covered in this chart. If your installation is not
covered, the correct size may be determined by consulting your factory
representative.
2 (50mm) MINIMUM
TOP VIEW
FURNACE
BY-PASS DUCT
COL. A
WIDTH*
LIMIT CONTROL
Col. A
Width*
BY-PASS CFM
Pressure Drop Through Heaters
0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50
3” 490 530 610 700 780 830 900 960 1010
4” 630 750 870 980 1090 1160 1250 1310 1400
5” 850 1010 1190 1300 1410 1520 1640 1730 1810
6” 1050 1290 1480 1650 1800 1940 2090 2200 2320
7” 1250 1510 1760 1960 2180 2320 2500 2650 2800
8” 1490 1810 2100 2350 2560 2760 2940 3110 3920
9” 1700 2100 2400 2700 2970 3200 3400 3600 3800
10” 1920 2380 2760 3090 3650 4020 4300 4550 4800
*Depth of by-pass duct is 18” on both inlet and outlet ends. NOTE: By-
pass must be located on side opposite limit control and 2” from side
panel.
Form RZ-C-DH Page 26
Page Number _______ of ______