Gas Conversion Guide

9
CP-UB-UD-GC (04-21) 1034364-A
⚠ CAUTION ⚠
DO NOT bottom out the gas valve regulator screw. This can result in excessive overfire and heat
exchanger failure due to unregulated manifold pressure.
d. For single-stage or two-stage high fire valve:
(1) Turn knob or switch on top of valve to ON.
(2) Remove cap from regulator screw (see Figure 3) and adjust pressure in accordance with Table 4 by turning
regulator screw IN (clockwise) to increase pressure or OUT (counterclockwise) to decrease pressure.
e. For two-stage low fire valve:
(1) Disconnect wire from HI terminal on gas valve.
(2) Remove cap from low-fire regulator screw (see Figure 3) and adjust pressure in accordance with Table
4 by turning regulator screw IN (clockwise) to increase pressure or OUT (counterclockwise) to decrease
pressure.
(3) Reconnect wire to Hi terminal on gas valve.
f. Turn up thermostat. For models UDAS, UDBS, UBZ, and UDZ, depress and hold door safety switch.
g. Cycle burner once or twice to properly seat adjustment spring in valve and recheck outlet pressure. When
pressure corresponds to Table 4, disconnect manometer and install cap on regulator screw.
h. Check for leakage at 1/8-inch outlet pressure tap fitting. Correct as necessary.
i. Connect manometer to inlet pressure tap (see Figure 3). While heater is operating, measure inlet pressure,
which should be as follows:
(1) between 5 and 13.5 IN WC for all natural gas models
(2) between 10 and 13.5 IN WC for UDAP, UDAS, UDBP, and UDBS propane models
(3) between 11 and 13.5 IN WC for UBX, UBZ, UDX, and UDZ propane models
j. If inlet pressure is not in accordance with step 7i, it must be corrected by adjusting manifold (outlet) pressure
in accordance with steps 7b through 7e.
NOTES:
• Conversion of a unit using these kits does not alter the input rate. Refer to the rating plate on
the heater for the input rate and other appropriate information.
• If adjusted for high-elevation operation, the input rate will be affected.
• The high-elevation adjustment label is not used on units operated at elevations of ≤2,000 feet
(≤610 meters).
k. Refer to APPENDIX for input and capacity values for elevation of installation.
(1) Use permanent marker to fill in appropriate input and capacity values on high-elevation adjustment label
from literature bag provided with unit.
(2) Select location for label on outside of heater access panel that will be conspicuous to anyone operating
or servicing unit.
(3) Ensure that surface is clean and dry and affix label.
l. Observe heater operation for at least one complete cycle to check for safe and proper operation. For models
UDAS, UDBS, UBZ, and UDZ, depress and hold safety door switch.
8. Close control access panel.