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4

Installation Instructions and Owner’s Manual

Unvented Natural Gas Vent Free Room Heaters

Product Features

Figure 1

SAFETY DEVICE

This heater has a pilot with an Oxygen Depletion Sen

-

sor (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 ig

-

nitor. This system requires no matches, or other source 

to light heater, but does require one AA battery to oper

-

ate ignitor. 

(AA Battery included)

.

To install or replace battery unscrew the ignitor 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 bills.

BLOWER FAN CONTROL SWITCH OPERATION

On models equipped with an electrical blower. The blower 

switch has three positions: MANUAL, OFF and AUTO. In 

AUTO, the blower will turn on and off as the heater cycles 

on and off. On MANUAL, the blower will run continuously. 

To turn blower off, use the OFF position.

LOCAL CODES

Install and use heater with care. 
Installation must conform to local codes or in the ab

-

sences 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 un

-

less provisions are provided for adequate combus

-

tion and ventilation air. Read the following instruc

-

tions to insure proper fresh air for this and other 

fuel-burning appliances in your home. 

ESTABLISHING ADEQUATE VENTILATION

The following are excerpts from 

National Fuel Gas 

Code, NFPA 54/ ANSI Z223.1, Section 5.3, Air for Com-

bustion 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 pro

-

vided for adequate combustion and ventilation air. The 

information on pages 4 through 6 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 Air 

from Outdoors

, page 6.

Unusually tight construction is defined as construction 

where:

a. Walls and ceilings exposed to the outside atmo

-

sphere 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. Weather stripping has been added on operable win

-

dows 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 penetra

-

tions for plumbing, electrical, and gas lines, and at 

other openings. 

If your home does not meet all of the three criteria 

above, see 

Determine the Type of Heater Location 

Space

, page 5.

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 fur

-

nished with doors, are considered a part of the uncon

-

fined space.

Ignitor Button

Control Knob

Grill

Front Panel

Burners

Heater 

Cabinet

Fan Blower 

Switch

(located on back of 

heater)

*

Blower not included on all units

Summary of Contents for MHVFB20T NG

Page 1: ...on air must be provided Refer to Fresh Air for Combustion and Ventilation section on page 4 of this manual WARNING Improper installation adjustment alteration service or maintenance can cause injury o...

Page 2: ...able material on or near the appliance Never place any objects on the heater Due to high temperatures heater should be kept out of traffic and away from furniture and draperies Surface of heater becom...

Page 3: ...air openings in heater clear free of debris or any blockage This will insure that enough air for proper combustion enters the heater 4 If heater shuts off do not relight until you provide fresh outsi...

Page 4: ...om National Fuel Gas Code NFPA 54 ANSI Z223 1 Section 5 3 Air for Com bustion and Ventilation All spaces in homes fall into one of the three following ventilation classifications 1 Unusually Tight Con...

Page 5: ...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 suppor...

Page 6: ...sible provide greater clearances from the floor ceil ing and joining walls WARNING Rework worksheet adding the space of the adjoining unconfined space The combined space must have enough fresh air to...

Page 7: ...ter will be located Make sure mounting bracket is level For wall stud mounting locate one end of the mounting bracket over a wall stud WARNING Maintain minimum clearances shown in figure 7 If you can...

Page 8: ...ng bottom mounting screw into wall stud drill holes at marked locations using 9 64 drill bit 5 Re place heater onto mounting bracket 6 Place spacers between bottom mounting holes and wall anchor or dr...

Page 9: ...From Gas Meter 4 W C to 10 5 W C Pressure Tee Joint 1 8 NPT Plug Tap Cap Pipe Nipple Tee Joint 3 8 NPT Pipe Nipple Sediment Trap Test Gauge Connection Reducer Bushing to 1 8 NPT 3 Minimum cleaning A...

Page 10: ...our gas supplier call the fire department C Use only your hand to push in or turn the gas control knob Never use tools If knob will not push in or turn by hand don t try to repair it call a qualified...

Page 11: ...Heater may need more frequent cleaning due to excess lent from carpeting bedding material pet hair etc Make sure grille guard is in place before running heater If screen or grille guard is removed fo...

Page 12: ...acuum cleaner pressurized air or small soft bristled brush to clean CLEANING BURNER PILOT AIR HOLE INLET We recommend that you clean the unit ever 2 500 hours of operation or every three months We als...

Page 13: ...13 Installation Instructions and Owner s Manual Unvented Natural Gas Vent Free Room Heaters This page intentionally left blank...

Page 14: ...as regulator 6 Turn Control knob to pilot position When ignitor button is pressed in there is a spark at the ODS pilot but no ignition 1 Control knob not fully pressed in 2 Control knob not pressed in...

Page 15: ...ances see Figure 4 page 7 4 Clean burner orifice see Cleaning and Maintenance on pages 11 and 12 or replace burner orifice White powder residue forming within burner box or on adjacent walls or furni...

Page 16: ...B NG BF20T NG BF30TB NG BF30T NG 7 2 36 39 38 35 16 21 16 1 16 2 6 26 29 24 22 3 13 23 18 3 11 1 2 1 4 22 2 33 1 22 1 25 9 5 1 3 1 1 27 1 28 1 4 44 42 45 8 20 10 15 14 42 9 7 26 22 3 22 1 33 1 1 4 3 6...

Page 17: ...641 70641 Ignitor Module Mounting Bracket 1 10 70682 70682 70682 70682 High Limit Switch 1 11 70644 70644 70644 70644 Ignitor Module Battery powered 1 12 13 70338 70338 70356 70338 Pressure regulator...

Page 18: ...70692 Right Burner Gas Tube 1 70690 70693 Right Middle Gas Burner Tube 1 70598 Left Middle Gas Burner Tube 1 70691 70694 Left Burner Gas Tube 1 70695 70695 70696 70696 ODS Gas Tube Assembly 1 70697 7...

Page 19: ...19 Installation Instructions and Owner s Manual Unvented Natural Gas Vent Free Room Heaters This page intentionally left blank...

Page 20: ...escription of problem in all communication LIMITED WARRANTY Mr Heater Inc warrants its heaters and accessories to be free from defects in material and workmanship for a period of 1 year from date of p...

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