1 HVACR115 – Mechanical for Gas Gas Pressure Regulators

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HVACR115 – Mechanical for Gas

HVACR115 – Mechanical for Gas

Gas Pressure RegulatorsGas Pressure Regulators

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Purpose of a gas RegulatorPurpose of a gas Regulator

• Gas is pressurized at different pressures for delivery– Propane may be stored at 125psi in the tank.– Gas mains on street may be at 10psi

• The regulator reduces the pressure to required levels for use.

• Gas is pressurized at different pressures for delivery– Propane may be stored at 125psi in the tank.– Gas mains on street may be at 10psi

• The regulator reduces the pressure to required levels for use.

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Purpose of a regulatorPurpose of a regulator

• The pressure requirements for individual pieces of equipment are designed and specified by the manufacturer.

• Natural gas is delivered at approximately 5 psig it can be as high as 15 psig .

• The pressure requirements for individual pieces of equipment are designed and specified by the manufacturer.

• Natural gas is delivered at approximately 5 psig it can be as high as 15 psig .

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Purpose of a regulatorPurpose of a regulator

• The typical burner manifold pressure is 3.5” w.c.• The pressure may need to be reduced twice, once

at the meter and once at the appliance to prevent fluctuations.

• The typical burner manifold pressure is 3.5” w.c.• The pressure may need to be reduced twice, once

at the meter and once at the appliance to prevent fluctuations.

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ComponentsComponents

• The components found in the regulator are:– Diaphragm– Spring– Adjustment screw– Valve– Seat

• The components found in the regulator are:– Diaphragm– Spring– Adjustment screw– Valve– Seat

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ComponentsComponents

• The diaphragm separates the spring and adjustment screw from outlet gas and low pressure.

• When the gas leaves the regulator it meets resistance from the burner orifices.

• The resistance causes pressure to build under the diaphragm.

• The diaphragm separates the spring and adjustment screw from outlet gas and low pressure.

• When the gas leaves the regulator it meets resistance from the burner orifices.

• The resistance causes pressure to build under the diaphragm.

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ComponentsComponents

• As pressure reaches the set point the diaphragm lifts the valve closing it.– When the gas valve is open the regulator will not close

completely, metering the gas at the set pressure.– When the gas valve closes the regulator will close since

there is no flow.

• As pressure reaches the set point the diaphragm lifts the valve closing it.– When the gas valve is open the regulator will not close

completely, metering the gas at the set pressure.– When the gas valve closes the regulator will close since

there is no flow.

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Regulator AdjustmentsRegulator Adjustments

• The adjustment for the gas regulator is under the vent cap.

• Turning this screw in the CLOCK WISE direction increases the spring pressure. This increase in spring pressure increases the outlet pressure set point.

• The adjustment for the gas regulator is under the vent cap.

• Turning this screw in the CLOCK WISE direction increases the spring pressure. This increase in spring pressure increases the outlet pressure set point.

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Regulator AdjustmentsRegulator Adjustments

• Turning the adjustment screw out, or counter clockwise, decreases the spring pressure. This decrease in spring pressure decreases the outlet pressure set point.

• Turning the adjustment screw out, or counter clockwise, decreases the spring pressure. This decrease in spring pressure decreases the outlet pressure set point.

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LPG RegulationLPG Regulation

• LP tanks use different types of regulators than natural gas supplies.

• The pressure in the tank can be over 125 psig when the tank is in the sun.

• The pressure must be reduced to 11” wc for use by the equipment before entering the building.

• LP tanks use different types of regulators than natural gas supplies.

• The pressure in the tank can be over 125 psig when the tank is in the sun.

• The pressure must be reduced to 11” wc for use by the equipment before entering the building.

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LP RegulationLP Regulation

• The first lowers the pressure to 5 psig at the tank outlet

• The second lowers the pressure to 11” wc before entering the building.

• This provides for constant pressure as tank pressure changes with temperature.

• The first lowers the pressure to 5 psig at the tank outlet

• The second lowers the pressure to 11” wc before entering the building.

• This provides for constant pressure as tank pressure changes with temperature.

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Venting RegulatorsVenting Regulators

• Some regulators vent through the vent cap over the adjusting screw.

• These regulators are sometimes installed near the equipment and vent to the standing pilot. If a gas leak is passed through the diaphragm the pilot will burn off this gas.

• Some regulators vent through the vent cap over the adjusting screw.

• These regulators are sometimes installed near the equipment and vent to the standing pilot. If a gas leak is passed through the diaphragm the pilot will burn off this gas.

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Venting RegulatorsVenting Regulators

• If the regulator is mounted away from the furnace, but still inside you need to vent it outside.

• All types of vented regulators must be kept clear, nothing can block the vents.

• If the vent is clocked the pressure will build under the diaphragm not allowing it to close the regulator.

• If the regulator is mounted away from the furnace, but still inside you need to vent it outside.

• All types of vented regulators must be kept clear, nothing can block the vents.

• If the vent is clocked the pressure will build under the diaphragm not allowing it to close the regulator.

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Venting RegulatorsVenting Regulators

• The regulator will then not be able to maintain the reduced pressure.

• If a regulator is not operating correctly you need to check the vent FIRST as it is likely blocked.

• The regulator will then not be able to maintain the reduced pressure.

• If a regulator is not operating correctly you need to check the vent FIRST as it is likely blocked.

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RegulatorsRegulators

• Regulators mounted outside must be mounted in a way, or covered, so that water can not get into the vent opening and freeze.

• Regulators mounted outside must be mounted in a way, or covered, so that water can not get into the vent opening and freeze.