Rule 140
3 in blower — 135 CFM
Smaller duct-compatible in-line blower for 3-inch ventilation hose; listed draw 2.9 A at 13.6 V rated.
View blower productRule 140 vs 240 Marine Bilge Ventilation Blowers: Duct & CFM
Rule 140 vs 240 Bilge Vent Blowers: 3-Inch and 4-Inch Systems
A bilge ventilation blower should suit the ventilation duct, electrical supply and installation arrangement. Rule's model 140 is a 3-inch in-line blower, while model 240 is designed for a 4-inch duct and has a higher listed open-flow rating. Compare the exact part number before replacing a marine bilge fan.
Three things to check before you order
Ventilation duct size
Confirm the inside diameter of the existing flexible duct or hose: 3 inches for Rule 140, 4 inches for Rule 240. Avoid installing a blower with an unmatched duct connection.
Electrical supply
Both are designed for a nominal 12V marine system. Compare the wiring, fuse protection, switch and listed operating current rather than relying on connector shape alone.
Existing mounting
Check the original fan's position, air-flow direction, supports and access for servicing. Make sure ventilation discharge remains properly routed outside the enclosed area.
Airflow ratings: The values shown are rated open-flow figures. Actual airflow in an installed boat depends on duct length, bends, restrictions and the ventilation layout. A larger CFM number is not a guarantee that an installation meets a boat's required ventilation capacity.
Rule blower size and electrical comparison
| Model / MPN | Vent duct I.D. | Open-flow rating | Rated voltage | Current |
|---|---|---|---|---|
| 140 | 3 in | 135 CFM | 13.6 V rated | 2.9 A |
| 240 | 4 in | 235 CFM | 13.6 V rated | 4.3 A |
How model 140 differs from model 240
Rule 140: This compact in-line fan connects to a 3-inch inside-diameter ventilation duct. Rule lists 135 CFM open airflow, with 2.9A draw at 13.6V.
Rule 240: The larger fan uses a 4-inch duct and has a listed 235 CFM open-flow rating. Its published draw is 4.3A at 13.6V.
Do not treat the catalog airflow number as a direct measure of installed ventilation performance. Verify the existing system's duct size, exhaust location and ventilation requirements before changing blower size or using an adapter.
Electrical and installation considerations
Bilge ventilators should be mounted and wired in accordance with the boat and blower manufacturers' instructions, with suitable overcurrent protection and controls. Check the installation for possible fuel vapors and use the applicable ignition-protected marine components. Ventilation arrangements for gasoline-powered boats have specific safety requirements; do not replace a safety-critical blower with a general-purpose fan.
One catalog listing appears to have unit errors in external body dimensions. For replacement fit, verify the physical blower housing measurements using the current manufacturer dimensional drawing before drilling or moving mounting brackets. These duct connection sizes do not describe the complete outside housing size.
Compare the exact Rule in-line blowers
Rule 240
4 in blower — 235 CFM
Larger duct-compatible in-line blower for 4-inch ventilation hose; listed draw 4.3 A at 13.6 V rated.
View blower productRelated marine ventilation reference
For collectors, hoses and other brands of bilge ventilation parts, see the Attwood bilge vents, collectors and blower identification guide.
Common questions
Can I use Rule 240 on an existing 3-inch duct?
Not as a direct fit. Rule 240 is specified for 4-inch hose. A change to the ventilation system needs to be designed and checked for adequate installed airflow rather than assumed safe with a simple adapter.
Does 235 CFM mean I will get that exact airflow in my boat?
No. That is an open-flow rating. Actual airflow varies with duct length, bends, restrictions and installation quality.
Are these water-removal bilge pumps?
No. These are air-moving ventilation blowers, not submersible bilge water pumps.
Can I arrange local pickup in Kelowna?
UsedRVParts offers viewing and pickup by appointment. Confirm the selected item before travelling.
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