# Effective Vent Length (EVL)

Posted By IHMan, Jan 29, 2013 at 6:59 PM

1. #1

### IHMan Member 2. ```NULL ```

Oct 21, 2010
12
0
Loc:
CT
Dumb Question. If a horizontal run transitions to a vertical run with a 90 elbow does that elbow count as a vertical 90 or a horizontal 90?

2. #2

### imacman Guest 2. ```NULL ```

a 90 is a 90....it's always counted as 5

3. #3

### Enviro Mini Owner New Member 2. ```NULL ```

Jan 2, 2013
78
5
Loc:
East Hampton, NY
Another dumb one. A 5 what?

4. #4

Jun 10, 2008
58
8
Loc:
Rhode Island
5. #5

### Enviro Mini Owner New Member 2. ```NULL ```

Jan 2, 2013
78
5
Loc:
East Hampton, NY
Is there a minimum length. My exhaust is only horizontal.

6. #6

### jtakeman Minister of Fire 2. ```NULL ```

Dec 30, 2008
13,496
1,573
Loc:
Northwestern CT.
Count the equivalent vertical length (EVL) points for the entire mock run as follows: For each 45 degree elbow, add 2.5 EVL; for each 90 degree elbow or Tee, add 5 EVL; for each horizontal foot, add 1 EVL; and for each vertical foot, add 0.5 EVL. Add all the points together.

If the sum is under 15 EVL and you are under 3,000 feet in elevation, you will use the three inch pipe. If you are over 15 EVL use the four inch pipe. You would also use the four inch pipe if your EVL is over 6 and you are above 3,000 feet. You must use the same size pipe throughout
.

7. #7

### Enviro Mini Owner New Member 2. ```NULL ```

Jan 2, 2013
78
5
Loc:
East Hampton, NY

THank You Much.

8. #8

### IHMan Member 2. ```NULL ```

Oct 21, 2010
12
0
Loc:
CT
I was reading the Palazzetti manual and it stated the maximum horizontal run is 10' therefore if I used one 90 tee or elbow the vent for this stove would have to terminate as a horizontal. Is that correct?
The minimum termination clearances were not all that great for this stove. 4' to the side or below a window or door and 1' above. I was under the impression that with make-up air the euro stoves and the better quality stoves the termination clearances were as little as 3-4"

9. #9

### SmokeyTheBear Minister of Fire 2. ```NULL ```

Nov 10, 2008
13,363
1,662
Loc:
Standish, ME
It depends on what tests the stove makers had done. If they didn't have test x done only test a then they can't use a reduced clearance. (this is just an example the tests are not called x and a).

10. #10

### imacman Guest 2. ```NULL ```

I'm still not sure what you're asking here, but in general, the least amount of horizontal pipe, the better. Ash will form in long horizontal runs very quickly & choke the stove. IMO, as soon as the exhaust pipe goes through to the outside, immediately put a cleanout T & get at least 4-5' of vertical installed.

I would NEVER run a horizontal anywhere near 10'.....ever.

11. #11

### Lousyweather Guest 2. ```NULL ```

it seems to be accepted that you should not have over 4' of horizontal run...otherwise the vent is prone to clogging

12. #12

### IHMan Member 2. ```NULL ```

Oct 21, 2010
12
0
Loc:
CT
In my house the ideal spot for the stove is a small 3x5 alcove. The stove would be no more than 2-2.5' from the outside wall. In order to vent through the wall the pipe would need a 90 right from the stove, manual says 10' horizontal run max, if each 90 is the equivalent of 5' of run, how could I then have another 90 outside before I went vertical?

13. #13

### imacman Guest 2. ```NULL ```

How long would the horizontal pipe be if it stopped just as it exited the outside wall?