Refilling the Kerosene Heater 1- Do not refill it while it's hot for safety reasons. 2- It is preferable not to refill the heater directly; it is recommended to use a funnel that contains a filter, like the Coleman funnel. The filter in the Coleman funnel has very small pores. The pore sizes in the Coleman Funnel filter are typically: - 100 microns (0.1 mm): this is the common pore size in fuel filters, suitable for removing impurities and foreign particles from the fuel. - 50-200 microns (0.05-0.2 mm): some filters may have different pore sizes, but 100 microns is the standard size. The rust reduction rate when using a funnel with a filter can reach 50-80% compared to direct refilling. - Removes impurities and foreign particles from the kerosene. - Reduces moisture in the kerosene. - Improves fuel flow, ensuring it is consistent and not accelerated.