MrHeater MHVFDF20BFT Operating Instructions And Owner'S Manual Download Page 4

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Installation Instructions and Owner’s Manual

Universal Unvented Room Heater

ESTABLISHING ADEQUATE VENTILATION

The following are excerpts from National Fuel Gas Code, 

NFPA 54/ ANSI Z223.1, Section 5.3, Air for Combustion 

and Ventilation. All spaces in homes fall into one of the 
three following ventilation classifications:

1.  Unusually Tight Construction

2.  Unconfined Space

3.  Confined Space

This heater must not be installed in a confined space 
or unusually tight construction unless provisions are 
provided for adequate combustion and ventilation air. The 
information on pages 4 and 5 will help you classify your 
space and provide adequate ventilation.

Unusually Tight Construction 

If your home meets all of the three following criteria you 
must provide additional fresh air. See Ventilation from 
Outdoors, page 5.
Unusually tight construction is defined as construction 
where:
a.  Walls and ceilings exposed to the outside atmosphere 

have a continuous water vapor retarder with a rating 
of one perm (6 x 10

-11

 kg per pa-sec-m

2

) or less with 

openings gasketed or sealed and

b.  Whether stripping has been added on operable 

windows and doors, and 

c.  Caulking or sealants are applied to areas such as joints 

around windows and door frames, between wall-

ceiling joints, between wall panels, at penetrations 
for plumbing, electrical, and gas lines, and at other 
openings. 

If you home does not meet all of the three criteria above, 
see Determining the Type of Heater Location Space, below.

Confined Space and Unconfined Space

The National Fuel Gas Code, NFPA 54/ ANSI Z223.1

 

defines a confined space as a space whose volume is less 

than 50 cubic feet per 1,000 Btu per hour (4.8 m

3

 per kW) 

of the aggregate input rating of all appliances installed in 
that space, and an unconfined space as a space whose 

volume is not less than 50 cubic feet per 1,000 Btu per 
hour (4.8 m

3

 per kW) of the aggregate input rating of all 

appliances installed in that space. Rooms communicating 

directly with the space in which the appliances are 
installed*, through openings not furnished with doors, are 
considered a part of the unconfined space.

*Adjoining rooms are communication only if there are 
odorless passageways or ventilation grills between 
them.

DETERMINING THE TYPE OF HEATER LOCATION 
SPACE:

Use this method to determine if you have a confined or 
unconfined space.

Product Features

Figure 1

Control Knob

Grill

Front Panel

Burners

Igniter Button

Heater 
Cabinet

SAFETY DEVICE

This heater has a pilot with an Oxygen Depletion Sensor 
(ODS) safety shut off system. The ODS/pilot shuts off the 
heater if there is not enough fresh air.

IGNITION SYSTEM / BATTERY INSTALLATION

The heater is equipped with an electronic manual igniter. 
This system requires no matches, batteries, or other source 
to light heater but does require one AA battery to operate 
igniter. 
To install or replace battery unscrew the igniter cap (red 
button), insert battery positive (+) terminal up and replace 

cap. (AA Battery included)

THERMOSTATIC CONTROL

These heaters have a control valve with a thermostat 
sensing bulb. This results in the greatest heater comfort 
and may result in lower fuel bills.

LOCAL CODES

Install and use heater with care. 
Installation must conform to local codes or in the absences 
of local codes, use the latest edition of National Fuel Gas 

Code ANSI Z223.1/NFPA 54.

UNPACKING

1.  Remove heater from carton.
2.  Remove all protective packaging applied to heater 

for shipment.

3.  Check heater for any shipping damage. If heater 

is damaged, promptly inform dealer where you 
bought heater.

FRESH AIR FOR COMBUSTION AND VENTILATION

WARNING: 

This heater shall not be installed in a confined 

space or unusually tight construction unless provisions are 

provided for adequate combustion and ventilation air. Read 

the following instructions to insure proper fresh air for this 

and other fuel-burning appliances in your home. 

Summary of Contents for MHVFDF20BFT

Page 1: ...our gas supplier call the fire department Installation and service must be performed by a qualified installer service agency or the gas supplier This is an unvented gas fired heater It uses air oxygen...

Page 2: ...including benzene which is known to the state of California to cause cancer and cause birth defects or other reproductive harm for more information go to www P65Warnings ca gov Due to high temperature...

Page 3: ...ilation page 4 3 Keep all air openings in heater clear free of debris or any blockage This will ensure that enough air for proper combustion enters the heater 4 If heater shuts off do not relight unti...

Page 4: ...1 000 Btu per hour 4 8 m3 per kW of the aggregate input rating of all appliances installed in that space Rooms communicating directly with the space in which the appliances are installed through openi...

Page 5: ...g 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...

Page 6: ...l by using the floor mounting stands included with the heater If installed on combustible flooring such as carpeting tile or other combustible material other than wood flooring the heater must be plac...

Page 7: ...s at marked locations using 9 64 drill bit 2 Place mounting bracket onto wall Line up holes on each end of bracket with hole drilled in wall 3 Insert mounting screws through bracket and into wall stud...

Page 8: ...line Gas line pressure must be no greater than 10 5 inches of water If gas line pressure is higher heater regulator damage could occur PROPANE LP CAUTION Never connect heater directly to the Propane s...

Page 9: ...equal to or less than psi 3 5 kPa 2 Cap off open end of gas pipe where equipment shutoff valve was connected 3 Pressurize supply piping system by either using compressed air or opening main gas valve...

Page 10: ...seconds Note The first time that the heater is operated after connecting the gas supply the control knob should be depressed for about 30 seconds This will allow air to bleed from the gas system 6 Wi...

Page 11: ...ease follow the directions on the can If you don t follow directions on the can you could damage the burner or pilot assembly In addition the directions below should also be followed 1 Shut off the un...

Page 12: ...allows thermocouple to cool causing pilot flame to go out This problem could be caused by one or both of the following a Low gas Pressure b Dirty or Partially clogged ODS pilot a Contact local gas co...

Page 13: ...or replace burner orifice White powder residue forming within burner box or on adjacent walls or furniture When heated vapors from furniture polish wax carpet cleaners etc turn into white powder resid...

Page 14: ...ssories may be purchased at any Mr Heater Products local dealer or direct from the factory FOR INFORMATION REGARDING SERVICE Please call Toll Free 866 447 2194 WWW HEATSTARBYENERCO COM Our office hour...

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