Roof Curb Installation
If a roof curb is used, follow the manufacturer’s Installation Instructions and be sure that all required clearances are observed (see following Clearances section).
Roof Curb Assembly
Figure 2
Clearances
All units require certain clearances for proper operation and service. Refer to Table 1 for the minimum clearances to combustibles as well as minimum clearances necessary for servicing and proper unit operation.
Minimum Clearance Requirements
| To | For | For | |
| Combustible | Proper | ||
| Service | |||
| Material | Operation | ||
|
| |||
|
|
|
| |
Front | 24" | 48" | 3" | |
|
|
|
| |
Rear | 0" | 24" | 3" | |
|
|
|
| |
Condenser | 0" | 24" | 3" | |
End | ||||
|
|
| ||
|
|
|
| |
Blower | 0" | 30" | 0" | |
End | ||||
|
|
| ||
|
|
|
| |
Top | 0" | 36" | 36" | |
|
|
|
|
Table 1
Figure 3 shows the minimum clearances to combustibles required above and below the vent hood. The minimum clearance in front of the vent hood is 24".
Do not permit overhanging structures or shrubs to obstruct condenser air discharge outlet or vent outlet.
Minimum Clearance to Combustibles
Above and Below the Vent Hood
Minimum Clearance Above Vent Hood: Distance from Top of Vent Hood to Top of Unit
Minimum Clearance Below Vent Hood: Distance from Bottom of Vent Hood to Base of Unit
Figure 3
In the U.S., units may be installed on combustible floors made from wood or classA, B, or C roof covering material. In Canada, units may be installed on combustible floors.
Service Access
Access to all serviceable components is provided by four removable panels: filter compartment, blower compartment, furnace compartment, and top panel.
Combustion Products Discharge
The unit must be positioned such that combustion products discharged at the vent outlet will not result in building degradation and must be consistent with the National Fuel Gas Code, Z223.1 or
The products of combustion are discharged through a screened opening in the front mullion. The horizontal vent system shall terminate at least 4' below, 4' horizontally from, or 1' above any door, window, or gravity air inlet into the building. The vent system shall terminate at least 3' above any forced air inlet located within 10'.
The unit shall be installed in a manner such that snow accumulation will not restrict the flow of flue products.
In addition to the above requirements, consideration must be given to prevent unwanted ice buildup from the vent condensate. The vent should not be located on the side of a building where the prevailing winter winds could trap the moisture, causing it to freeze on the walls or on overhangs (under eaves). The vent location should not discharge over
Page 4 | Issue 1008 |
