Mr. Heater MHVFGH30LPT Operating Instructions And Owner's Manual page 5

51.8 or 51,800 (maximum Btu/hr the space
can support)
WARNING: This heater shall not be installed in a
room or space unless the required volume of indoor
combustion air is provided by the method described
in the National Fuel Gas Code, ANSI Z223.1/NFPA 54,
the International Fuel Gas Code, or applicable local
codes.
Read the following instructions to insure proper fresh air
for this and other fuel-burning appliances in your home.
3. Add the Btu/hr of all the fuel-burning appliances in the
space such as, Vent–free heater, Gas water heater, Gas
furnace, Vented gas heater, Gas fireplace logs, and Other
gas appliances*
*Do not include direct-vent gas appliances. Direct-vent
draws combustion air from the outdoors and vents to
the outdoors.
Example:
Gas water heater 40,000 Btu/hr
Vent Free Heater + 20,000 Btu/hr
Total =60,000 Btu/hr
4. Compare the maximum Btu/hr the space can support
with the actual amount of Btu/hr used.
Example: 51,800 Btu/hr (maximum Btu/hr the
space can support)
60,000 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, and the space of an adjoining room.
If the extra space provides an unconfined space, remove
door to adjoining room or add ventilation grills between
the rooms. See Ventilation From Inside Building (Fig. 2)
B. Vent room directly to the outdoors. See Ventilation From
Outdoors (Fig. 3).
C. Install a lower Btu/hr heater if lower Btu/hr size makes
room unconfined.
If actual Btu/hr used is less than the maximum Btu/
hr the space can support, the space is an unconfined
space. You will need no additional fresh air ventilation.
VENTILATION AIR
Ventilation from Inside Building
This fresh air would come from an adjoining unconfined
space. When ventilation to an adjoining unconfined space,
you must provide two permanent openings: one within 12"
of the ceiling and one within 12" of the floor on the wall
connecting the two spaces (see options 1 & 2 of figure 2).
You can also remove door into adjoining room (see option3,
fig 2). Follow the National Fuel Gas Code NFPA 54/ ANSI
Z223.1, Section 5.3, Air for Combustion and Ventilation for
required size of ventilation grills or ducts.
Unvented Liquid Propane Fired Room Heater
WARNING: Rework worksheet, adding the space of
the adjoining unconfined space. The combined space
must have enough fresh air to supply all appliance in
both spaces.
Ventilation from Outdoors
If necessary provide extra fresh air by using ventilation grills
or ducts. Connect these items directly to the outdoors or
spaces open to the outdoors. These include attics* and
crawl spaces. Follow the National Fuel Gas Code NFPA
54/ ANSI Z223.1, Section 5.3, Air for Combustion and
Ventilation for required size of ventilation grills or ducts.
Or remove
Ventilation
door into
Gills into
Adjoining
Adjoining
Room -
Room -
Option 3
Option 1
*IMPORTANT: Do not provide openings for inlet or
outlet into attic. If attic has a thermostat-controlled power
vent, heated air entering the attic will activate the power
vent.
OUTLET AIR
OUTLET
AIR
INLET
AIR
IMPORTANT: Vent-free heaters add moisture to the
air. Although this is beneficial, installing heater in rooms
without enough ventilation air may cause mildew to form
from too much moisture. See Fresh Air for Combustion
and Ventilation, pages 4 through 5.
5
Installation Instructions and Owner's Manual
(30.5 cm)12"
Ventilation Gills into
Adjoining Room - Option 2
12" (30.5 cm)
Figure 2
VENTILATION AIR
VENTILATED
ATTIC
TO ATTIC
TO CRAWL
SPACE
VENTILATION CRAWL SPACE
Figure 3.