![Fig. 12ÐConfined Space: Air for Combustion and](/images/new-backgrounds/54345/5434527x1.webp)
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| SUPPLY | VENT THROUGH ROOF | |
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| AIR | ||
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| OR SIDEWALL | |
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1 SQ IN.
DUCTSPER 4000
TOBTUH* OUTDOORS
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| 12″ |
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| IN. | ||
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| 1 SQ | |||||
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| PER 1000 | |||||
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| CONFINED SPACE |
| BTUH* IN DOOR | ||||||
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| OR WALL | |||||||
INTERIOR |
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| UNCONFINED | ||||||||
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| SPACE | |||||||||
| HEATED |
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| SPACE |
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| 3″ MIN | |||||
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| (FRONT) | |||||
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| 1 SQ IN. | |||||
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| PER 1000 | |||||
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| BTUH* IN DOOR | |||||
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| OR WALL | |||||
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12″ MAX
1 SQ IN. PER 2000 BTUH*
DUCTS
TO
OUTDOORS
1 SQ IN. PER 2000 BTUH*
12″ MAX
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| D |
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| 12″ | |||
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| VENT |
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| MAX | |||||
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| SUPPLY | THROUGH |
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| F |
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| AIR | ROOF |
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| OR |
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| 1 SQ IN. | ||||||
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| SIDEWALL |
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| PER 4000 | |||||||
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| BTUH* | ||
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| CONFINED SPACE |
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| OUTDOORS | |||
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| 1 SQ IN. | ||
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| PER 4000 | ||
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| BTUH* | ||
| B |
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| E |
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| 12″ | ||
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| C |
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| MAX | |||
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| 12″ |
| MAX |
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12″ MAX |
RETURN AIR
*Minimum opening size is 100 sq. in. with minimum dimensions of
NOTE: Side clearance required as needed for
vent pipe, and gas and electrical connections.
A96185
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| RETURN AIR | DUCT |
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| 1 SQ IN. | ||
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| OUTDOORS | PER 4000 | ||
| *Minimum dimensions of | BTUH* | |||
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| NOTES: 1. Use any of the following |
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| combinations of openings: |
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| A & B C & D D & E F & G |
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2.Side clearance required as needed for
vent pipe, and gas and electrical connections.
A96186
Fig. 12ÐConfined Space: Air for Combustion and
Ventilation from an Unconfined Space
For Example:
COMBUSTION AIR FROM OUTDOORS THROUGH
VERTICAL DUCTS
345MAV Furnace | Free Area per Opening | Round Pipe |
Input Btuh | (Sq In.) | (In. Dia) |
40,000 | 10.0 | 4 |
60,000 | 15.0 | 5 |
80,000 | 20.0 | 6 |
100,000 | 25.0 | 6 |
120,000 | 30.0 | 7 |
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2.If combustion air is taken from outdoors through horizontal ducts, the openings and ducts MUST have at least 1 sq in. of free area per 2000 Btuh of the total input for all equipment within the confined space. (See Fig. 13.)
3.When ducts are used, they must be of the same cross- sectional area as the free area of the openings to which they connect. The minimum dimension of ducts must not be less than 3 in. (See Fig. 13.)
Ð14Ð
Fig. 13ÐConfined Space: Air for Combustion and
Ventilation from Outdoors
For Example:
COMBUSTION AIR FROM OUTDOORS THROUGH
HORIZONTAL DUCTS
345MAV Furnace | Free Area per Opening | Round Pipe |
Input Btuh | (Sq In.) | (In. Dia) |
40,000 | 20.0 | 6 |
60,000 | 30.0 | 7 |
80,000 | 40.0 | 8 |
100,000 | 50.0 | 8 |
120,000 | 60.0 | 9 |
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INSTALLATION
I.LEVELING LEGS (IF DESIRED)
When furnace is used in upflow position with side inlet(s), leveling legs may be desired. (See Fig. 14.) Install
NOTE: The maximum length of bolt should not exceed
1.Position furnace on its back. Locate and drill a
2.For each hole, install nut on bolt and then install bolt and nut in hole. (Install flat washer if desired.)