Removal Of Existing Furnaces From Common Vent Systems; Combustion-Air And Vent Piping - Carrier 58MCA Installation, Start-Up, And Operating Instructions Manual

Step 1—Removal of Existing Furnaces from
Common Vent Systems
If furnace being replaced was connected to a common vent system
with other appliances, these steps shall be followed with each
appliance remaining connected to common vent system placed in
operation, while other appliances remaining connected to common
vent system are not in operation:
1. Seal any unused openings in common vent system.
2. Visually inspect vent system for proper size and horizontal
pitch. Determine there is no blockage or restriction, leakage,
corrosion, and other deficiencies which could cause an unsafe
condition.
3. Insofar as is practical, close all building doors and windows
and all doors between space in which appliances remaining
connected to common vent system are located and other
spaces of building. Turn on clothes dryers and any appliance
not connected to common vent system. Turn on any exhaust
fans, such as range hoods and bathroom exhausts, so they
operate at maximum speed. Do not operate a summer exhaust
fan. Close fireplace dampers.
4. Follow lighting instructions and place appliance in operation.
Adjust thermostat so appliance operates continuously.
5. Test for flue gas spillage at drafthood relief opening after 5
minutes of main burner operation. Use flame of a match or
candle, etc.
6. After it has been determined that each appliance remaining
connected to common vent system properly vents when tested
as above, return doors, windows, exhaust fans, fireplace
dampers, any other gas burning appliances to their previous
condition of use.
7. If improper venting is observed during any of above tests,
common vent system must be corrected. Vent system or vent
connectors may need to be resized. For any other appliances
when resizing vent systems or vent connectors, system or
connector must be sized to approach minimum size as
determined using appropriate table found in Part 11 of NFGC
or Section 5 of NSCNGPIC.
Step 2—Combustion-Air and Vent Piping
GENERAL
Combustion-air and vent pipe fittings must conform to American
National Standards Institute (ANSI) standards and American
Society for Testing and Materials (ASTM) standards D1785
(schedule-40 PVC), D2665 (PVC-DWV), D2241 (SDR-21 and
SDR-26 PVC), D2661 (ABS-DWV), F628 (schedule-40 ABS), or
F891 (PVC-DWV cellular core). Pipe cement and primer must
conform to ASTM standards D2564 (PVC) or D2235 (ABS). See
Table 5 for maximum pipe lengths and Fig. 31, 32, 33, 34, and 35
for exterior piping arrangements.
In Canada construct all combustion-air and vent pipes for this unit
of CSA or ULC certified schedule-40 PVC, PVC-DWV or
ABS-DWV pipe and pipe cement. SDR pipe is NOT approved in
Canada.
NOTE: Furnace combustion-air and vent pipe connections are
sized for 2-in. pipe. Any pipe size change should be made outside
furnace casing in vertical pipe. (See Fig. 27.) This allows proper
drainage of vent condensate.
Combustion-air and vent pipes must terminate together in same
atmosphere pressure zone, either through roof or sidewall (roof
termination preferred), using accessory termination kit. See Table
4 for required clearances.
Table 4–Combustion-Air and Vent Pipe
Termination Clearances
LOCATION
Above grade level or
above anticipated snow
depth
Dryer vent
From plumbing vent
stack
From any mechanical
fresh air intake
For furnaces with an in-
put capacity less than
100,000 Btuh–from any
non-mechanical air sup-
ply (windows or doors
which can be opened) or
combustion-air opening
For furnaces with an in-
put capacity greater than
100,000 Btuh–from any
non-mechanical air sup-
ply (windows or doors
which can be opened) or
combustion-air opening
From service regulator
vent, electric and gas
meters, and relief equip-
ment
Above grade when adja-
cent to public walkway
* Horizontal distance. † 18 in. above roof surface in Canada.
‡ 36 in. to electric meter in Canada only.
NOTES:
1. If installing 2 adjacent 58MCA or 58MXA Furnaces, refer to Multi-Venting
and Vent Terminations section for proper vent configurations.
2. When locating combustion-air and vent terminations, consideration must be
given to prevailing winds, location, and other conditions which may cause
recirculation of the appliance's own flue products or the flue products of
adjacent vents. Recirculation can cause poor combustion, inlet condensate
problems and accelerated corrosion of heat exchangers.
Furnace combustion-air and vent pipe connections must be at-
tached as shown in Fig 28. Combustion-air intake plug fitting and
inducer housing alternate vent cap may need to be relocated in
some applications.
Fig. 26—EAC Terminals on Control Center
20
CLEARANCE (FT)
U.S.A. Canada
1 1†
3 3
3 3
1 6
1 1
1 3
4* 6‡
7 7
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