Pressure Gauges

HVAC pressure gauges fall into four main categories relevant to service technicians. Refrigerant compound gauges read both vacuum and positive pressure and are the standard tool for charging, evacuating, and diagnosing refrigerant circuits. They are sold individually or as part of a manifold gauge set. Differential pressure gauges (including Magnehelic-style models) measure pressure drop across filters, coils, and dampers in commercial air handling and clean-room applications. Oil pressure gauges monitor compressor lubrication circuits. Digital wireless gauges, such as JB Industries models with superheat and subcooling readout, streamline diagnostics on modern systems. Current inventory includes Dwyer, JB Industries, Ametek, Service First, Honeywell, and Trane gauges across all four categories.

A differential pressure gauge for HVAC measures the pressure difference between two points in a system, across a filter, coil, damper, or fan, rather than refrigerant charge. In commercial HVAC, the Dwyer Magnehelic gauge is the industry-standard instrument for monitoring air filter loading: a climbing differential reading signals a filter needs service before it restricts airflow and increases energy draw. These gauges are also used to verify ductwork static pressure, confirm airflow in air handling units, and maintain pressure balance in cleanrooms or isolation rooms. Magnehelic models operate without electrical power using a frictionless diaphragm and magnetic movement system, which makes them well-suited for permanent panel mounting in mechanical rooms.

Analog gauges use a mechanical dial and needle: no battery, durable under jobsite conditions, and reliable for routine charging, leak checks, and pressure verification. Digital HVAC gauges use electronic pressure sensors and display numeric readings on a screen; models with built-in superheat and subcooling readout, such as the JB Industries wireless digital gauge in stock, reduce manual P/T chart lookups and speed up system analysis. Digital gauges are more expensive and battery-dependent but deliver greater accuracy and onboard data. The practical choice depends on the complexity of systems serviced and how frequently superheat and subcooling calculations factor into the work.

Gauge sets are refrigerant-specific: a set calibrated for R-22 will not read R-410A accurately, and using the wrong set can result in misdiagnosis or equipment damage. R-410A systems operate at significantly higher pressures than R-22 systems, so the set must be rated for the corresponding pressure range. Confirm dial scale and maximum PSI rating before selecting. Some multi-refrigerant gauges cover R-22, R-410A, and R-404A with color-coded scales; verify the specific refrigerant scales on the product listing. For R-454B systems (the post-2025 phase-in refrigerant), gauges rated for R-410A may not give accurate readings due to differences in refrigerant properties. Consult the product specs and manufacturer documentation before use.

For fixed differential pressure gauges in HVAC applications, the standard dial sizes are 4" and 4-½." A 4" dial reads clearly from a normal standing distance in most mechanical room installs. Refrigeration compound gauges for manifold sets are most common at 2-1/2" to 3-1/8" in dial diameter; larger dials improve readability on busy job sites. Current inventory spans 1" to 8" dial widths across brands. Filter by dial width in the collection to narrow options for a specific application.

All pressure gauges and tools in this inventory are brand-new manufacturer overstock. They’re not used or refurbished, and they arrive in original packaging. Key specs to confirm before purchasing: pressure range (PSI or inches WC), connection size (typically 1/8" NPT for differential gauges or 1/4" SAE for refrigerant manifold sets), refrigerant compatibility for charging instruments, and dial diameter. Check available quantity on the product listing; surplus stock sells as inventory lasts and identical items are not always replenished.

Orders ship to all 48 contiguous states with options including ground, LTL, and other freight methods depending on order size and destination. Check online for inventory and pickup availability at our various locations. For large or custom shipping needs, the Surplus City team can provide quotes for orders that do not calculate automatically at checkout.