Credit is provided by a panel of lenders with whom we have a commercial relationship (so we cannot provide independent advice).

As you can see, diesel heaters are prone to malfunction in the high latitude areas where temperatures are the lowest. Still, even premium heaters from Webasto and Eberspacher experience problems, and suffer from waxing issues. Anything that may get through the screen cannot pose any performance issues or damage inside the pump or heater. It has been proven that fitting this fuel filter unit to the fuel line can increase service periods for the heater and reduce issues associated with poor fuel quality.Eberspacher are quite specific about the fuel to the thing, they provide a page in the manual with drawings showing how to fit the intake.

Opinions are mixed on the need and cost-effectiveness of replacing the tiny internal Espar screen with a more substantial in-line unit.

I bought a 2016 new (although picked up on Dec 31 2016) from the factory with one of the D5 hydronic factory heater options. Regardless of opinion on the need to use the add-on inline filter, I learned that I need to plan my refueling carefully to get the highest grade diesel available, and avoid refueling purely on demand. I only hesitate because the switch to an in-line filter seems to be a PITA given the requirement to adapt different hose diameters to accommodate a large inline filter. So I will likely swap out the little Espar internal filter for an external unit before I put very many hours on the heater.