Equivalent Vent Length (Evl) - PSG CADDY ALTERNA II Installation And Operating Instructions Manual

NOTE: Follow the vent manufacturer's instructions.
1. Position furnaces, adhering to clearances.
2. Locate position of the hole in the wall; since most furnaces are installed in a basement, make sure that the
hole in the wall is located above ground level. You will need to go up vertically for a few feet, and then go
horizontally toward the wall. If the furnace is vented toward the back, a minimum vertical elevation of 2 feet
is required to maintain an appropriate clearance with the hopper. If the furnace is vented toward the side, a
minimum vertical elevation of 1 foot is required.
3. Always refer to the vent manufacturer for clearance to combustible materials.
4. Install a wall thimble as per the vent manufacturer's instructions.
5. Attach enough piping to penetrate and extend at least 6" beyond exterior walls. To reduce the risk of smoke
spillage and in order to favor a better draft, a minimum vertical rise of 3 feet is required on the outside wall.
Furthermore, there should always be at least one foot of vertical rise for each foot of horizontal run (see
Section 5.7.5: Horizontal and Vertical Vent Chart).
6. To reduce the risk of smoke spillage, never terminate with a horizontal run. If your system terminates with a
horizontal run, add at least 3 feet of vertical rise (see Section 5.7.5: Horizontal and Vertical Vent Chart).
7. Attach cap and seal outside wall thimble with non-hardening waterproof mastic. Termination should not be
located so that hot exhaust gases can ignite trees, shrubs, or grasses or be a hazard to children. Exhaust
gases can reach temperatures of 500ºF and cause serious burns if touched.

5.7.4 EQUIVALENT VENT LENGTH (EVL)

Recommended venting system inner pipe diameter is 4".
To calculate the EVL of your installation, use the following conversions:
NOTE: Horizontal runs shall not exceed 9 feet.
NOTE: Never exceed 30 feet of EVL.
Here is an example to help you calculate Equivalent Vent Length. On the following figure the EVL can be
calculated like this:
Qty Type of pipe
90° elbow or "T"
1
1 45° elbow
1 ft Horizontal pipe run
1 ft Vertical pipe run
Equivalent lenght (EVL)
(ft)
5
3
1
0.5
23