Venting Requirements; Vent Pipe Length And Diameter - Nordyne M4RC Upflow Installation Instructions Manual

VENTING REQUIREMENTS

This furnace must not be vented with other
appliances, even if that appliance is of the
condensing type. Common venting can result
in severe corrosion of other appliances or their
venting and can allow combustion gases to
escape through such appliances or vents. Do
not vent the furnace to a fi replace chimney or
building chase.
Upon completion of the furnace installation,
carefully inspect the entire fl ue system both
inside and outside the furnace to assure it is
properly sealed. Leaks in the fl ue system can
result in serious personal injury or death due
to exposure of fl ue products, including carbon
monoxide.
• This furnace must be vented in compliance with
the current revision of the National Fuel Gas Code
(ANSI-Z223.1/NFPA54) and the instr uctions
provided below. Consult local codes for special
requirements.
• In Canada, venting shall conform to the requirements of
the current (CAN/CGA B149.1 or .2) installation codes.
Consult local codes for special requirements.
This furnace is classifi ed as a "Category IV" appliance,
which requires special venting materials and installation
procedures. This type of appliance operates with positive
vent pressure and therefore requires the furnace to be
vented to the outdoors and thoroughly sealed. They also
produce liquid condensate, which is slightly acidic and
Furnace FURNACE
(BTU) INSTALLATION
54,000
72,000
90,000
Downfl ow
108,000
1. The length of 2" pipe needed between the inducer and the exit hole (top of cabinet) is 8 3/4" for upfl ow models and 16" for downfl ow models.
2. Subtract 2.5 ft. for each additional 2 inch long radius elbow, 5 ft. for each additional 2 inch short radius elbow, 3.5 ft. for each additional 3
inch long radius elbow, and 7 ft. for each additional 3 inch short radius elbow. Subtract 8ft for each 3" tee.
3. Two 45 degree elbows are equivalent to one 90 degree elbow.
4. This table applies for elevations from sea level to 2,000 ft. For higher elevations, decrease pipe lengths by 8% per 1,000 ft of altitude.
10
WARNING:
SINGLE PIPE LENGTH (FT.)
with 1 long radius elbow
Upfl ow
Upfl ow
Upfl ow
Upfl ow
Table 2. Vent Pipe Lengths
can cause severe corrosion of ordinary venting materials.
Furnace operation can be adversely affected by restrictive
vent and combustion air piping.

Vent Pipe Length and Diameter

In order for the furnace to operate properly, the combustion
air and vent piping must not be excessively restrictive.
• The venting system should be designed to have the
minimum number of elbows or turns.
• All horizontal runs must slope upwards from the furnace
at 1/4 inch minimum per running foot of vent.
• Transition to the fi nal vent diameter should be done as
close to the furnace outlet as practical.
• Always use the same size or a larger pipe for
combustion air that is used for the exhaust vent.
Table 2 specifi es the maximum allowable pipe length
for vent and combustion air for a furnace of known input
rate, when installed with piping of selected diameter and
number of elbows. To use the table, the furnace input rate,
the centerline length and the number of elbows on each
pipe must be known.
When estimating the length of vent runs, consideration
must be made to the effect of elbows and other fi ttings.
This is conveniently handled using the idea of "equivalent
length". This means the fi ttings are assigned a linear
length that accounts for the pressure drop they will cause.
For example: a 2" diameter, long radius elbow is worth
the equivalent of 2.5 feet of linear run. A 90 degree tee
is worth 7 ft.
The equivalent lengths of tees and various elbows are
listed in Table 2. Measure the linear length of your vent
run and then add in the equivalent length of each fi tting.
The total length, including the equivalent fi tting lengths,
must be less than the maximum length in the table.
(See Notes)
OUTLET
3" Diameter
90
90
90
90
90
NOTES:
DUAL VENT PIPE LENGTH (FT.)
with 1 long radius elbow on each pipe (See
Notes)
INLET/OUTLET
3" Diameter
90
90
90
90
90