Instructions 7337/7347 Page 2
VENTING
ADJUSTMENTS
Vent connections on all regulators are tapped and screened. This screen and its retainer must be removed before piping the vent to outdoors. Keep the vent line as short as possible. For lines of 10' or less, the pipe may be the same size as the vent condition. For longer lines, the pipe diameter must be increased by one or more sizes, depending on the total length. To improve regulator stability, install a surge arrestor in the vent line near the regulator. A surge arrestor is simply a length of larger diameter pipe with reducers on each end. The volume of this chamber should be 150 in. 3 for 7337 Regulators. Vent lines must be run outdoors. Locate the ends so they will not be subject to dripping water or snowdrifts. Shield the ends to protect them from weather, dirt, or insects. (Bees build nests in them.) Above all, observe local codes and insurance requirements. NEVER vent a regulator to a flue or exhaust system. RELIEF VALVES Regulator internals may be damaged if the outlet pressure exceeds the regulators outlet pressure rating. Excessive pressure may occur during periods of shutdown when gas can leak through the regulator or when a bypass is installed and the gas is trapped by a downstream shutoff valve. To prevent this from happening, a relief valve or other form of overpressure protection MUST be used. Relief valves MUST be installed between the regulator and downstream shutoff valve and then piped outdoors. DO NOT pipe to the burner or combustion chamber. To do so may create a hazardous condition. 7337A-3 and 7347 Regulators are equipped with an internal token relief valve which relieves excess pressure through the regulator vent connection. This vent connection MUST be piped to the outdoors. DO NOT pipe to the burner or combustion chamber. To do so may create a hazardous condition. This internal relief is not a full-flow relief.
1. If used, fully open the 1837D-01 Needle Valve in the sensing line to the 7337-4 Regulator. 2. Slowly open the upstream gas shutoff valve and then the downstream gas shutoff valve. 3. If the 7337-4 Regulator pulsates, slowly close the needle valve until the pulsation stops. 4. Remove the spring adjusting screw cover. 5. With a screwdriver, turn the adjusting screw clockwise to in- crease the outlet gas pressure or counterclockwise to decrease the outlet gas pressure. 6. Observe the results on a pressure gauge.
NOTE: Adjustments should be made only when regulator is in operation (gas flowing).
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