Enerzone Euromax EP00070 Installation And Operation Manual page 16

Here is an example to help you calculate Equivalent Vent Length. On the following figure the
EVL can be calculated like this:
 2 horizontal run of 1' = (2 X 1') X 1' = 2' of EVL
 1 elbow 90° or "Tee" = 5' of EVL
 3 vertical length of 4' = (3 X 4') X 0.5' = 6' of EVL
 Total EVL = (2' + 5' + 6') = 13'
NOTE: Do not include the exterior wall termination in the EVL calculation (45° elbow
and termination).
For example, let's imagine an installation consisting of a
horizontal vent coming out at the back of the stove on a total
distance of 8 feet. This horizontal run is followed by a tee and a
6-foot vertical rise. This type of installation is not acceptable. As
you can see, the vent termination is clearly outside the allowed
configuration zone on the chart because the venting system
proposed does not have at least one foot of vertical rise for
each foot of horizontal run.
Instead, if the installation consisted of a horizontal vent coming
O.K.
out at the back of the stove on a total distance of 4 feet,
followed by a tee and a 6-foot vertical rise, it would be
acceptable. The installation end should be within the allowable
configuration zone on the chart since it would have at least one
foot of vertical rise for each foot of horizontal run. Furthermore,
the total vertical rise would be at least 3-foot high.
WARNING: To reduce the risk of smoke spillage there
should always be at least one foot of vertical rise for each
foot of horizontal run. In all cases, at least 3 feet of vertical
rise is needed.
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Euromax Pellet Stove Installation and Operation Manual