Split line filtration
Dual in-line filtration
National Oilheat Research Alliance 29
Chapter 6
Filtration
The best way to ensure that clean fuel is
delivered to the nozzle is by installing a quality
fuel filter on every burner. Fuel filters capture
abrasive, blocking, corrosive and biological
contaminants that have the ability to cause a
multitude of operational problems.
Nozzle sizes keep getting smaller as equipment
manufacturers continue to improve the
efficiency of modern appliances. These smaller
nozzles clog more easily than larger ones and
therefore require better filter performance.
Options
Currently, fuel filters fall into one of two
broad categories: spin-on filters and cartridge
filters. Several manufacturers are now supplying
corrosion resistant filter housings and canisters
to address the issue of filter failure from
rust. Installers should consider the benefits a
corrosion resistant material may provide.
In addition to standard configurations, two
types of dual-filtration are now common.
Split line filtration – The suction line is
split into two separate lines, each with its own
filter to double the filter capacity and allow
fuel to flow even as the filter medium becomes
clogged. The lines are rejoined after the filters
before feeding into the burner.
Dual in-line filtration – Two filters are
piped in series. The primary filter removes the
bulk of the contaminants. The secondary filter
removes contaminants that pass through the
primary or flake off the fuel line between the
filters. The secondary filter also removes yarn,
felt or fibers that break off from the primary
filter.
For both types of dual filtration, NORA
recommends both filters always be replaced at
the same time.
A variation of dual filtration is to install a
sludge/water isolator (SWI) before the filter.