Reznor VZ - Adjustments; High-Elevation and Propane Conversion; Measure and Adjust Manifold Gas (Outlet) Pressure; Single-Stage

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VZ-VZH-VZT-IOM (08-24) 1047121-A
ADJUSTMENTS
High-Elevation and Propane Conversion
NOTE: Deration is necessary to compensate for low atmospheric pressure at high elevations (>2,000
feet (>610 meters)). This requires replacing the burner orifice (refer to instructions provided with
option DJ20). To convert a natural gas unit for use with propane, refer to the instructions provided
with option DL2.
Measure and Adjust Manifold Gas (Outlet) Pressure
⚠ CAUTION ⚠
Before attempting to measure or adjust the manifold gas pressure, ensure that the gas supply
(inlet) pressure is within the specified range for the gas being used—both when the heater is in
operation and when it is on standby. Incorrect inlet pressure could cause excessive manifold gas
pressure immediately or at some time in the future. Always check the rating plate for the minimum
gas supply (inlet) pressure.
NOTE: Models VZ and VZH have a single-stage combination gas valve. Model VZT has a two-stage
combination gas valve.
Measure and adjust as necessary the manifold gas (outlet) pressure as follows:
1. Remove burner cabinet panel(s) for access:
a. For models VZ and VZT, disconnect combustion air piping from blower if unit is connected to outside combustion
air, unplug blower motor power cable, and remove top blower panel with blower and motor assembly attached.
b. For model VZH, remove side panel.
2. Close combination gas valve to prevent gas flow to burner.
NOTE: Use a water column manometer that is readable to the nearest tenth of an inch.
3. Connect manometer to outlet pressure tap on combination gas valve (see Figure 38).
Figure 38. Combination Gas Valve
SINGLE-STAGE
TWO-STAGE
REGULATOR
SCREW
HIGH-FIRE REGULATOR SCREW
OUTLET
PRESSURE
TAP
OUTLET
PRESSURE
TAP
INLET
PRESSURE
TAP
LOW-FIRE REGULATOR SCREW
INLET
PRESSURE
TAP