glow plugs/heater plugs

If you need to heat your tank as well, you could add a 2nd FPHE in series with the 1st FPHE and use that to reheat the oil in the veg oil return line before sending it back to the tank. Nice and simple, and it doesn't heat the oil too much; just warm enough to keep it nice and liquid to aid the flow and reduce problems associated with the oil's high melting point components clogging the lines and fittings.

While on the subject of heating the veg oil tank, I've seen some designs that extend the main coolant circuit all the way back to the veg oil tank where it heats the oil via a coil, before sending it back to the engine. This is not a particularly good idea for the following reasons:

• increased risk of rupturing the coolant and damaging your engine.
• if the heater coil is metal, particularly copper or aluminium [aluminum to our American friends ;) ], it will contribute to oxidation/polymerisation problems in the tank, because these metals are very good pro-oxidants.
• It could heat the oil too much, and again contribute to oxidation/polymerisation problems.

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