11
Service notes:
• The manifold gas pressure is non-adjustable as these are zero-governing gas systems.
• There is usually a drop in supply gas pressure noticed when the water heater’s 24 Volt Gas Control Valve opens during ignition. The
manifold pressure will go from a negative value (during pre-purge) to near zero when gas is owing.
• A sustained drop in supply gas pressure of 1.5” W.C. or more during ignition may indicate the supply gas line is undersized. If the
water heater is experiencing a sustained drop in supply gas pressure of 1.5” W.C. or more and the water heater is experiencing
repeated Ignition Failure fault conditions, intermittent loss of ame or rough starting ensure the supply gas line is sized in
accordance with the current edition of National Fuel Gas Code (ANSI Z223.1/NFPA 54) or the Natural Gas and Propane Installation
Code (CAN/CSA B149.1).
GAS PRESSURE TEST
1. Use the Enable/Disable Switch located on the front of the water heater and put the unit in disabled mode.
2. Turn off the supply gas to the water heater at the main gas shutoff valve serving the water heater.
3. Open the Supply Gas Pressure Test Port on the Gas Control Valve or use the pressure port on the gas valve inlet ange. See Figure 8.
4. A digital manometer (see “Tools Recommended” on Page 2) is needed to check supply gas pressure. To monitor supply gas pressure,
attach a sensing tube from Gas Control Valve Supply Gas Pressure Test Port to one digital manometer.
5. Open the main gas shutoff valve serving the water heater.
6. The manometer connected to the Supply Gas Pressure Test Port should read the “static” (gas is not owing) supply gas pressure.
PORT #2: SUPPLY-GAS
PRESSURE TEST PORT
OFF-SET ADJUSTMENT
UNDER SCREW COVER
UINDER BLUE COVER
Figure 8. BTHS 750-1000 Gas Control Valve Assembly
7. Record the supply gas pressure.
8. Use the Enable/Disable Switch located on the front of the water heater and put the unit in enabled mode. The settings on the water
heater may need to be changed to cause the water heater to operate.
Note: The Operating Temperature Set Point so that the unit can be returned to this setting at the conclusion of this test
procedure. Increase the Operating Set Point if necessary to cause the water heater to have a call for heat.
9. Record the supply gas pressure when the Ignition Activation operating state begins; when the animated Gas Control valve Status Icon
appears on the UIM Screen.
• The supply gas pressure will typically drop as the Gas Control Valve opens.
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