Antunes

Antunes is a manufacturer of air differential pressure switches and low gas pressure switches designed for combustion safety and HVAC equipment monitoring applications. Founded in 1955 by August J. Antunes in Carol Stream, Illinois, Antunes introduced its first pressure switch controls for commercial gas appliances in 1964. The Antunes controls product line covers two primary categories used by HVAC and mechanical contractors: SMD Series air differential pressure switches for combustion air proving and draft monitoring, and LGP Series low gas pressure switches for gas train safety in commercial heating equipment. Antunes controls carry UL listing, FM approval, and CSA approval for the specific switch families sold through HVAC and plumbing supply channels. For mechanical contractors and service technicians specifying combustion safety controls, Antunes pressure switches are a documented OEM and replacement-market component in commercial heating system applications.

Product Lines

SMD Series Air Differential Pressure Switches

Antunes SMD Series air differential pressure switches are SPDT snap-action switches designed to prove combustion air flow and monitor draft pressure in HVAC equipment and commercial heating systems. The SMD Series covers pressure ranges from 0.17 to 6 inches water column and 0.17 to 12 inches water column, with 1/4-inch barb connections and a 10-ampere rating. Building and equipment OEMs use SMD switches to interlock draft inducer operation with burner ignition, preventing burner firing when combustion airflow is insufficient.

LGP-G Series Low Gas Pressure Switches

Antunes LGP-G Series low gas pressure switches provide safety shutoff protection in commercial gas trains by interrupting the control circuit when upstream gas pressure falls below the setpoint. The LGP-G Series covers 1 to 20 inches water column with a manual reset, 1/4-inch NPT gas inlet, and an operating temperature range of negative 40 to 140 degrees F. A maximum operating pressure of 2 PSI makes the LGP-G suitable for standard low-pressure gas train applications. Ventless versions are available for sealed enclosure installations.

LGP-A Series Low Gas Pressure Switches

The Antunes LGP-A Series covers 1 to 6 inches water column and 1 to 35 inches water column, addressing gas pressure monitoring across a wider range of commercial heating equipment. Like the LGP-G, the LGP-A uses a manual reset to prevent automatic restart after a low-pressure trip. The manual reset design is a standard safety requirement in commercial gas train applications.

JD-2 Series Pressure Switches

The Antunes JD-2 Series pressure switches extend the controls line for mechanical contractors who need alternative body configurations for retrofit and OEM replacement applications where LGP-G and LGP-A geometries do not match the existing installation.

Why Contractors Specify Antunes

Mechanical contractors and equipment service technicians specify Antunes pressure switches because the SMD and LGP series carry UL listing, FM approval, and CSA approval, meeting the certification requirements for commercial gas appliance and heating equipment safety circuits. The SMD Series has been used in commercial HVAC draft prover and combustion air proving applications since 1964. The 1/4-inch barb connection on SMD switches is compatible with standard pneumatic tubing used in field wiring of HVAC equipment safety circuits. LGP Series manual-reset switches meet the commercial gas train requirement for attended restart after a low-pressure trip. Antunes manufactures at its Carol Stream, Illinois facility with additional production in Suzhou, China.

How to Choose an Antunes Pressure Switch

The most important decision variable when selecting an Antunes pressure switch is the monitored parameter: combustion air flow or gas supply pressure. SMD Series switches are for air pressure monitoring, confirming draft inducer operation before allowing burner ignition. LGP Series switches monitor gas supply pressure, cutting the control circuit if pressure drops below the minimum setpoint.

For SMD Series selection, match the pressure range to the equipment's design combustion air pressure. The 0.17 to 6 inches water column range covers most residential and light commercial applications. The 0.17 to 12 inches water column version suits higher-draft commercial equipment.

For LGP Series selection, match the range to the gas supply pressure. The LGP-G covers 1 to 20 inches water column for standard low-pressure gas supply applications. The LGP-A 1 to 35 inches water column version covers higher-pressure supply circuits in larger equipment. Both use manual reset, correct for gas safety shutoff applications. For ventless installations inside sealed enclosures, specify the ventless LGP-G variant.

FAQs

Where are Antunes pressure switches manufactured?
Antunes manufactures at its facility in Carol Stream, Illinois, where the company has been headquartered since moving to 180 Kehoe Boulevard. Antunes also operates manufacturing in Suzhou, China. The company was founded in 1955 and introduced its first pressure switches for gas appliances in 1964.

What warranty does Antunes offer on SMD and LGP pressure switches?
SMD Series switches carry a 2-year warranty per distributor documentation.

What is the difference between the Antunes SMD Series and LGP Series?
SMD Series switches are air differential pressure switches monitoring combustion air flow and draft, using 1/4-inch barb connections. LGP Series switches monitor gas supply pressure in gas trains, using 1/4-inch NPT gas-rated fittings. Each series serves a distinct safety function in a commercial gas appliance control circuit.

What pressure range is right for a commercial draft inducer proving application?
The Antunes SMD Series 0.17 to 6 inches water column model covers most residential and light commercial draft inducer proving applications. Higher-draft commercial equipment may require the 0.17 to 12 inches water column version. Verify the equipment OEM specification for the required proving switch pressure range before selecting.

Are Antunes pressure switches compatible with residential gas furnace draft provers?
Antunes SMD Series switches can be used as replacement draft provers in residential and commercial gas furnaces where the OEM specification matches the SMD electrical rating (10A) and pressure range. Always verify that the Antunes switch setpoint matches the OEM control board requirements before installation.

What applications require the Antunes LGP-G ventless switch?
The LGP-G ventless switch is required when the switch must be mounted inside a sealed control enclosure where venting to atmosphere is not possible. Standard LGP-G switches vent internally; the ventless version eliminates the vent port for enclosed installations. Check local codes and OEM documentation for ventless requirements.