--- title: Fuel Filter Installation Considerations for Gas or Diesel Air Heaters description: Important consideration for fuel filter when installing Velit gas or diesel air heaters. --- [Skip to content](https://help.velitcamping.com/help-articles/fuel-filter-installation-consideration-for-gas-or-diesel-air-heaters#main-content) ![Velit](https://help.velitcamping.com/hs-fs/hubfs/460684741_1701809850568731_4111707878241104706_n.jpg?width=150&height=150&name=460684741_1701809850568731_4111707878241104706_n.jpg) - [SHOP](https://velitcamping.com/) - [CONTACT US](https://velitcamping.com/pages/contact) - [HELP CENTER](https://help.velitcamping.com/help-articles) - SUBMIT TICKET Show submenu for SUBMIT TICKET - [Heater Support Ticket](https://velitcamping.com/pages/heater-tech-support-request) - [AC Support Ticket](https://velitcamping.com/pages/ac-tech-support-request) Open main navigation Close main navigation - [SHOP](https://velitcamping.com/) - [CONTACT US](https://velitcamping.com/pages/contact) - [HELP CENTER](https://help.velitcamping.com/help-articles) - SUBMIT TICKET Show submenu for SUBMIT TICKET - [Heater Support Ticket](https://velitcamping.com/pages/heater-tech-support-request) - [AC Support Ticket](https://velitcamping.com/pages/ac-tech-support-request) - [Back to Velit Website](https://velitcamping.com/) [Back to Velit Website](https://velitcamping.com/?hsLang=en) How can we help you? - There are no suggestions because the search field is empty. 1. [Velit Customer Support](https://help.velitcamping.com/help-articles?hsLang=en) 2. [Troubleshooting](https://help.velitcamping.com/help-articles/troubleshooting?hsLang=en) 3. [Heater Troubleshooting](https://help.velitcamping.com/help-articles/troubleshooting?hsLang=en#heater-troubleshooting) May 12, 2026 # Fuel Filter Installation Considerations for Gas or Diesel Air Heaters ## Fuel filters are commonly improperly installed on air heaters, and here are the reasons why. To use the fuel filter, or not to use the fuel filter, that is the question. Below are various fuel filter types, and an example of an improper fuel filter installation location.  Be sure to watch the video for complete discussion from Velit's lead heater tech. ![20260512-091531](https://help.velitcamping.com/hs-fs/hubfs/20260512-091531.jpg?width=670&height=503&name=20260512-091531.jpg)     ### What's Important For Fuel Filter installation: 1. Fuel filter is optional, if no known contamination in the fuel tank, filter is likely not needed and use is discouraged. 2. Fuel filter should NOT be installed directly before pump as shown in above photo. The filter will be on the wrong axis and should not be directly connected to pump. 3. If used, fuel filter should be on a vertical axis, not horizontal or diagnal. 4. If used, ensure fuel lines are butted up against end of fuel filter inside rubber connectors, allowing no space for air bubbles inside rubber connectors. 5. If using a serviceable fuel filter, ensure caps/ends are screwed tight, and do not loosen during installation of rubber fuel line connectors. 6. Inspect fuel filters for air bubbles, fuel filter should be FULL of fuel. 7. When using fuel filter, ensure the supply/pull side of the fuel lines from the pump to the tank are simple and short as neccessary. This side of the line should not exceed 3-4 feet. Achieve this by locating the pump closer to the tank than the heater. #### Final Thoughts: Fuel delivery, specifically fuel filters and fuel lines, are the most common reason for reliability and performance issues with gas and diesel air heaters. Typically, by following instructions here and in the article linked below, these issues can be remedied and the heater can perform better than ever. Follow this guidance closely. 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