MG3P Installation Manual

12
Table 2. Vent Protection
Winter
Design
Temperature
Maximum Flue Pipe Length
in Unconditioned and
Exterior Spaces
Without Insulation
(feet)
With Insulation
(feet)*
20 45 70
0 20 70
-20 10 60
* = Insulation thickness greater than 3/8 inch, based on an
R value of 3.5 (ft x F x hr) / (BTU x in.)
Vent Freezing Protection
CAUTION:
When the vent pipe is exposed to temperatures
below freezing (i.e., when it passes through
unheated spaces, chimneys, etc.) the pipe
must be insulated with 1/2 inch thick sponge
rubber insulation, Armaflex-type insulation or
equivalent. Insulating pipe is important to avoid
condensate icing.
• Table 2 lists the maximum length of flue pipe that can travel
through an unconditioned space or an exterior space. The
total vent length must not exceed the lengths noted in Table
1 (page 10). For Canadian installations please refer to the
Canadian Installation Code (CAN/CGA-B149.1 or 2) and/or
local codes.
• For extremely cold climates or conditions of short furnace
cycles (i.e. set back thermostat conditions), the last 18 inches
of vent pipe can be reduced from 3” to 2-1/2”, 3” to 2” or 2” to
1-1/2” if the total vent length is at least 15 feet in length and
the vent is sized in accordance with Table 1. The length of
the 2 inch pipe must not be longer than 18 inches. Smaller
vent pipes are less susceptible to freezing, but must not be
excessively restrictive.
• If a furnace is installed horizontally, make sure the drainage
port in the inline drain assembly is pointed downward to ensure
proper drainage of condensate.
• To prevent debris or creatures from entering the combustion
system, a protective screen may be installed over the
combustion air intake opening. The screens hole size must
be large enough to prevent air restriction
Existing Installations
When an existing furnace is removed from a vent system
serving other appliances, the existing vent system may not be
sized properly to vent the remaining appliances (Example: water
heater). An improperly sized venting system can result in the
formation of condensate, leakage, or spillage. The existing vent
system should be checked to make sure it is in compliance with
NFGC, ANSI Z223.1, or CAN/CGA B149 and must be brought
into compliance before installing the furnace.
NOTE: If replacing an existing furnace, it is possible you will
encounter an existing plastic venting system that is subject
to a Consumer Product Safety Commission recall. The pipes
involved in the recall are High Temperature Plastic Vent (HTPV).
If your venting system contains these pipes DO NOT reuse
this venting system! This recall does not apply to other plastic
vent pipes, such as white PVC or CPVC. Check for details on
the CPSC website or call their toll-free number [phone].
Concentric Vent Termination
A concentric vent termination is approved for use with these
furnaces. Refer to the technical sales literature for part numbers.
Please follow the installation instructions provided with the kit
for proper installation.
Condensate Disposal
The method for disposing of condensate varies according to local
codes. Consult your local code or authority having jurisdiction.
A neutralizer kit is available for use with this furnace. Refer to
the technical sales literature for part numbers. Please follow
the instructions provided with the kit.
This furnace has multiple options for positioning the vent pipe
as described in the Inducer & Venting Options section (page
18). Each of the condensate drain lines must be J-trapped
using field supplied parts.
After the condensate lines are J-trapped, they may be combined
together when routed to the drain. Avoid areas where condensate
drainage may cause problems by dropping onto planters,
patios, etc.
NOTE: Industry research studies indicate that when condensate
is routed to an active drain, household detergents, etc., buffer its
acidity. If the drain is not actively used or if codes require, obtain
a neutralizer kit (usually contains limestone). Proper drains and
connections to the condensate tubing are required as Nortek
Global HVAC cannot be held responsible for water leakage
which occurs due to loose hose connections or improperly
sealed drain line pipes.
CIRCULATING AIR REQUIREMENTS
WARNING:
Do not allow combustion products to enter the
circulating air supply. Failure to prevent the
circulation of combustion products into the
living space can create potentially hazardous
conditions including carbon monoxide poisoning
that could result in personal injury or death.
All return ductwork must be secured to the
furnace with sheet metal screws. For installations
in confined spaces, all return ductwork must be
adequately sealed. When return air is provided
through the bottom of the furnace, the joint
between the furnace and the return air plenum
must be air tight.
The surface that the furnace is mounted on must
provide sound physical support of the furnace
with no gaps, cracks or sagging between the
furnace and the floor or platform.
Return air and circulating air ductwork must
not be connected to any other heat producing
device such as a fireplace insert, stove, etc. This
may result in fire, explosion, carbon monoxide
poisoning, personal injury, or property damage.