Installation - Mr. Heater MHVFRD10NG Operating Instructions And Owner's Manual

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.
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.
Unvented Natural Gas Fired Room Heater
Or remove
Ventilation
door into
Gills into
Adjoining
Adjoining
Room -
Room -
Option 3
Option 1
OUTLET AIR
OUTLET
AIR
INLET
AIR
*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.
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.

INSTALLATION

WARNING: Any change to this heater or its controls
can be dangerous.
NOTICE: This heater is intended for the use as
supplemental heat. Use this heater along with your
primary heating system. Do not install this heater as your
primary heat source. If you have a central heating system,
you may run system's circulating blower while using heater.
This will help circulate the heat throughout the house. In
the event of a power outage, you can use this heater as
your primary heat source for the duration of the outage.
WARNING: A qualified service person must install
heater. Follow all local codes.
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.