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VENT LENGTH TABLE - MODULATING FURNACE
MAXIMUM TOTAL EQUIVALENT LENGTH IN FEET FOR VENT AND INLET
ALTITUDE
0-7000 Feet
NATURAL GAS
UH/DHMB060ACV3V
UH/DHMB080ACV3V
UH/DHMC100ACV4V Not Allowed
UHMD120ACV5V
Not Allowed
DHMD120ACV5V
Not Allowed
7000-9500 Feet
NATURAL GAS
UH/DHMB060ACV3V
UH/DHMB080ACV3V
UH/DHMC100ACV4V Not Allowed
UHMD120ACV5V
Not Allowed
DHMD120ACV5V
Not Allowed
9500-12000 Feet
NATURAL GAS
UH/DHMB060ACV3V
UH/DHMB080ACV3V Not Allowed
UH/DHMC100ACV4V Not Allowed
UHMD120ACV5V
Not Allowed
DHMD120ACV5V
Not Allowed
Notes: * - First letter may be "A" or "T", ** - Last two digits may be "A" thru "Z"
1. Minimum vent length for all models: 3' horizontal or 3' vertical
2. DO NOT MIX PIPE DIAMETERS IN THE SAME LENGTH OF PIPE OUTSIDE THE FURNACE CABINET, (Except
adapters at the top of the furnace). If different inlet and vent pipe sizes are used, the vent pipe must adhere to the
maximum length limit shown in the table above (See note 6 below for exception). The inlet pipe can be of a larger
diameter, but never smaller than the vent pipe.
3. MAXIMUM PIPE LENGTHS MUST NOT BE EXCEEDED! THE LENGTH SHOWN IS NOT A
COMBINED TOTAL, IT IS THE MAXIMUM LENGTH OF EACH (Vent or Inlet air pipes).
4. One SHORT radius 90° elbow is equivalent to 10' of 3" pipe and one LONG radius elbow is equivalent to 6' of 3"
pipe. One 90° elbow is equivalent to 7½' of 2½" pipe or 5' of 2" pipe. Two 45° elbows equal one 90° elbow.
5. The termination tee or bend must be included in the total number of elbows. If the BAYAIR30AVENTA termination
kit is used, the equivalent length of pipe is 5 feet. BAYVENT200B equivalent length is 0 feet.
6. Pipe adapters are field supplied. Downflow models, UHM 100 and UHM 120 models include
the 2" x 3" adapter.
7. For Canadian applications ONLY, IPEX 196006 may be used for horizontal and vertical terminations. IPEX 081216,
IPEX 081218, and IPEX 081219 may only be used for horizontal vent terminations. Equivalent lengths are
IPEX 196009 = 5 feet, IPEX 081216 = 11 feet, IPEX 081218 = 16 feet, and IPEX 081219 = 21 feet
Maximum Vent
Length Table
2 INCH PIPE
PROPANE
200
Not Allowed
50
Not Allowed
Not Allowed
Not Allowed
Not Allowed
2 INCH PIPE
PROPANE
100
Not Allowed
25
Not Allowed
Not Allowed
Not Allowed
Not Allowed
2 INCH PIPE
PROPANE
50
Not Allowed
Not Allowed
Not Allowed
Not Allowed
Not Allowed
AIR (SEE NOTES)
2.5 INCH PIPE
NATURAL GAS
PROPANE
200
Not Allowed
120
Not Allowed
60
Not Allowed
Not Allowed
Not Allowed
Not Allowed
Not Allowed
2.5 INCH PIPE
NATURAL GAS
PROPANE
100
Not Allowed
60
Not Allowed
30
Not Allowed
Not Allowed
Not Allowed
Not Allowed
Not Allowed
2.5 INCH PIPE
NATURAL GAS
PROPANE
50
Not Allowed
30
Not Allowed
Not Allowed
Not Allowed
Not Allowed
Not Allowed
Not Allowed
Not Allowed
20
3 or 4 INCH PIPE
NATURAL GAS
PROPANE
200
150
200
150
200
150
200
150
200
100
3 or 4 INCH PIPE
NATURAL GAS
PROPANE
100
100
100
100
100
100
100
100
100
50
3 or 4 INCH PIPE
NATURAL GAS
PROPANE
50
38
50
38
50
38
50
38
50
25
Pub. No. 22-1840-14
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