Procom MN180TPH Installation & Operation Instructions page 6

DETERMINING FRESH-AIR FLOW FOR HEATER LOCATION
Determining if You Have a Confined or Unconfined Space
Use this worksheet to determine if you have a confined or unconfined space.
Space: Includes the room in which you will install heater plus any adjoining rooms with doorless passageways
or ventilation grills between the rooms.
1. Determine the volume of the space
Length×Width×Height=
Example: Space size 20ft. (length)×16ft. (width)×8ft. (ceiling height) =2560cu. ft. (volume of space)
If additional ventilation to adjoining room is supplied with grills or openings, add the volume of these rooms
to the total volume of the space.
2. Divide the space volume by 50 cubic feet to determine the maximum Btu/Hr the space can support.
(volume of space)÷50 cu. ft.=(Maximum Btu/Hr the space can support)
3. Add the Btu/Hr of all fuel burning appliances in the space.
Vent-free heater
Gas water heater*
Gas furnace
Vented gas heater
Gas heater logs
Other gas appliances* +
Total
*Do not include direct-vent gas appliances. Direct-vent draws combustion air from the outdoors and vents to the outdoors.
4. Compare the maximum Btu/Hr the space can support with the actual amount of Btu/Hr used.
Btu/Hr (maximum the space can support)
Btu/Hr (actual amount of Btu/Hr used)
Example : 51,200 Btu/Hr(maximum the space can support)
56,000 Btu/Hr(actual amount of Btu/Hr used)
The space in the above example is a confined space because the actual Btu/Hr used is more than the maximum
Btu/Hr the space can support.
You must provide additional fresh air. Your options are as follows:
a) Rework worksheet, adding the space of an adjoining room. If the extra space provides an unconfined
space, remove door to adjoining room or add ventilation grills between rooms. See "Ventilation Air From
Inside Building".
b) Vent room directly to the outdoors. See "Ventilation Air From Outdoors".
c) Install a lower Btu/Hr heater if lower Btu/Hr size makes room unconfined.
WARNING: If the area in which the heater may be operated is smaller than that defined as an unconfined space
or if the building is of unusually tight construction, provide adequate combustion and ventilation air by one of the
methods described in the National Fuel Gas Code, ANSI Z223.1/NFPA 54, Air for Combustion and Ventilation, or
applicable local codes.
Ventilation Air From lnside Building
This fresh air would come from an adjoining unconfined space. When
ventilating to an adjoining unconfined space, you must provide two perma-
nent openings: one within 12 inches of the ceiling and one within 12 inches
of the floor on the wall connecting the two spaces (see options 1 and 2,
Figure 2). You can also remove the door into adjoining room (see option
3, Figure 2). Follow the National Fuel Gas Code. NFPA 5/ANSI Z.,
Section 5., Air for Combustion and Ventilation for required size of ventila-
tion grills or ducts.
cu.ft. (volume of space)
=
Btu/Hr
Example:
Btu/Hr
Gas water heater
Btu/Hr
Vent-free heater
Btu/Hr
Total
Btu/Hr
Btu/Hr
Btu/Hr
Figure 1 - Ventilation Air from Outdoors
 
30,000 Btu/Hr
+ 26,000 Btu/Hr
= 56,000 Btu/Hr