The hose specs below are for the minimal quality hose. DO NOT USE A CHEAP HOSE! You can either use steel-braided Teflon hydraulic hose from a hydraulic supply store, or the type specified below which is from the NAPA Auto Store (locate a store near you by visiting http://www.napaautocare.com).
The first kind (steel-braided Teflon hydraulic hose) is cheaper, about $2.40 per foot, but requires special fittings (about $2 each end) that any hydraulic supply store can prepare for you. The second type from NAPA is more expensive ($5.95/ft) but can slip on directly onto the Fuel Heater. In my opinion the second type is much safer for high temperature, high pressure fuel. It looks like simple rubber but it is far from it.
FIRE HAZARD!!! DO NOT USE REGULAR FUEL HOSE FROM THE AUTO PARTS STORE because it will crack under the pressure (60+ psi) and high temperatures (180-200 degrees Fahrenheit). The hose type shown here is manufactured by Gates* (full contact below) and its product number is 4219-6204. Your Napa auto parts store knows it as H204 or H-204, available in stores only (not online).
*The Gates Rubber Co.
1551 Wewatta Street
Denver, CO 80202, USA