General Filters fuel oil filter cartridge 1A-25B — 10-micron wool-felt, 3/8" NPT, biofuel gaskets

The General Filters 1A-25B replacement cartridge is a UL-listed wool-felt fuel oil filter designed for final filtration in residential and light commercial oil-fired heating systems.

This replacement element fits systems that use a 3/8" NPT connection and is built to handle a 12 P.S.I. working pressure and up to a 10 gallons-per-hour firing rate with #2 fuel oil. Constructed with 10-micron wool felt media, it removes fine particulate from the distribution line to protect burners and improve reliability. The cartridge is compatible with single- or two-pipe installations and is now supplied with gaskets rated for use with biofuel blends.

How does this cartridge protect my burner and fuel system?

The wool felt media captures small solid contaminants that can clog nozzles or damage pump parts, reducing maintenance frequency and keeping combustion components operating cleanly. Being a final-stage filter, it traps particles that upstream filters might miss.

• 10-micron wool felt filtration removes fine particulates.
• 41 sq. in. felt surface and 11.5 cu. in. felt volume for extended capacity.
• UL listing affirms safety and performance standards.

Will it fit my existing oil line and what are the physical specs?

This cartridge uses a standard 3/8" NPT inlet/outlet commonly found on small residential and light commercial fuel systems. Its compact footprint makes retrofits straightforward without significant plumbing changes.

• Connection: 3/8" NPT standard thread.
• Unit size: 5-1/8" high × 3-5/8" diameter for tight installations.
• Operating pressure rated to 12 P.S.I., suitable for typical distribution systems.

How much fuel flow can it handle and how does that affect system performance?

The cartridge supports a firing rate of up to 10 gallons per hour on #2 fuel oil, matching the demands of many small-to-medium burners. Proper sizing ensures steady flow with minimal pressure drop while maintaining filtration efficiency.

• Firing rate: 10 GPH on #2 fuel oil for typical residential burners.
• Designed as a final filter to minimize pressure fluctuation under normal loads.
• Works well in both one- and two-pipe fuel configurations.

Are the materials compatible with modern fuel blends, like biodiesel blends?

The replacement elements are supplied with gaskets compatible with biofuel blends, reducing the risk of seal degradation when using modern fuel formulations. The wool felt media is a proven material for trapping contaminants without chemically reacting with standard fuel oils.

• Now sold with biofuel-compatible gaskets for broader fuel compatibility.
• Wool felt media provides mechanical filtration without chemical additives.
• UL listing indicates tested performance across expected operating conditions.

Who this is for: The General Filters 1A-25B cartridge is aimed at homeowners, HVAC technicians, and facility managers who service small to average-sized residential or commercial oil-fired heating systems. Choose this replacement when you need a compact, UL-listed final filter element with 10-micron wool felt media, standard 3/8" NPT fittings, and capacity to handle up to 10 GPH while remaining compatible with modern biofuel blends.