Reznor EEDU Unit Installation Manual - Manual (Page 10)

Form I-EEDU, Page 10
Manifold or Orifice
(Valve Outlet) Pressure
Settings
6.0 Mechanical
(cont'd)
6.2 Venting Venting must be in accordance with the National Fuel Gas Code Z223.1 (latest edition)
or CSA B149.1 Natural Gas and Propane Installation Code, and all local codes. Local
requirements supersede national requirements.
These power-vented units are designed to operate safely and efficiently with either
a horizontal or vertical vent. (Horizontal vent run is recommended for maximum fuel
savings.)
If a vent cap is shipped with the heater, it is packaged attached to the venter housing.
Detach the vent cap from the housing.
Gas connection sizes are shown in FIGURE 8. After all connections are made, discon-
nect the pilot supply at the control valve and bleed the system of air. Reconnect the
pilot line and leak-test all connections by brushing on a soap solution.
6.1 Gas Piping and Pressures (cont'd)
Measuring manifold gas pressure cannot be done until the heater is in operation. It is
included in the steps of the "Check-Test-Start" procedure in Paragraph 9.0. The follow-
ing warnings and instructions apply.
WARNING
Manifold gas pressure must never exceed 3.5" w.c. for natural gas and
10" w.c. for propane gas.
For Natural Gas: When the heater leaves the factory, the combination valve is set so
that the outlet gas pressure of a single-stage valve or high fire of a two-stage valve is
regulated to 3.5" w.c. Low fire on a two-stage valve is set to 1.8" w.c. Inlet supply pres-
sure to the valve must be a minimum of 5" w.c. or as noted on the rating plate and a
maximum of 14" w.c. NOTE: Always check the rating plate for minimum gas sup-
ply pressure. Minimum supply pressure requirements vary based on the size of the
burner and the gas control option. Most units require a minimum of 5" w.c. of natural
gas as stated above, but units with electronic modulation may require a minimum of 6"
w.c. natural gas supply pressure.
For Propane: When the heater leaves the factory, the combination valve is set so that
the outlet gas pressure of a single-stage valve or high fire of a two-stage valve is 10"
w.c. Low fire on a two-stage valve is set to 5" w.c. Inlet pressure to the valve must be
a minimum of 11" w.c. and a maximum of 14" w.c.
Before attempting to measure or adjust manifold gas pressure, the inlet (supply) pres-
sure must be within the specified range for the gas being used both when the heater is
in operation and on standby. Incorrect inlet pressure could cause excessive manifold
gas pressure immediately or at some future time.
Instructions to Check
Manifold Pressure:
1) With the manual valve (on the combination valve) positioned to prevent flow to the
main burners, connect a manometer to the 1/8" pipe outlet pressure tap in the valve.
NOTE: A manometer (fluid-filled gauge) is recommended rather than a spring type
gauge due to the difficulty of maintaining calibration of a spring type gauge.
2) Open the valve and operate the heater. Measure the gas pressure to the manifold.
To measure the low stage pressure on units equipped with a two-stage valve, discon-
nect the wire from the "HI" terminal on the valve. (Be sure to reconnect wire.)
Normally adjustments should not be necessary to the factory preset regulator. If adjust-
ment is necessary, set pressure to correct settings by turning the regulator screw IN
(clockwise) to increase pressure. Turn regulator screw OUT (counterclockwise) to
decrease pressure.
6.1.1 Gas Supply and Connections (cont'd)
CAUTION: Do not
bottom out the gas
valve regulator
adjusting screw.
This can result in
unregulated manifold
pressure causing
overfire and heat
exchanger failure. Consult the valve manufacturer's literature provided with the furnace for more detailed
information.
WARNING
All components of a gas supply system must be leak tested prior to placing equipment in service.
NEVER TEST FOR LEAKS WITH AN OPEN FLAME. Failure to comply could result in personal injury,
property damage or death.