Mr. Heater MHVFRD20NGBT

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MR. HEATER, INC., 4560 W. 160

ST., CLEVELAND, OHIO 44135 · 800-251-0001

2016 - CB

UNVENTED NATURAL GAS FIRED ROOM HEATER

OPERATING INSTRUCTIONS

AND OWNER’S MANUAL

READ INSTRUCTIONS CAREFULLY: Read and follow all instructions. Place instructions in a safe

place for future reference. Do not allow anyone who has not read these instructions to assemble,

light, adjust or operate the heater.

Blue Flame Heaters

MHVFBF20NGBT

(BLOWER INCLUDED)

MHVFBF20NGT

(BLOWER SOLD SEPARATE)

MHVFBF30NGBT

(BLOWER INCLUDED)

MHVFBF30NGT

(BLOWER SOLD SEPARATE)

Plaque Heaters

MHVFRD20NGBT

(BLOWER INCLUDED)

MHVFRD20NGT

(BLOWER SOLD SEPARATE)

MHVFRD30NGBT

(BLOWER INCLUDED)

MHVFRD30NGT

(BLOWER SOLD SEPARATE)

WARNING: If the information in this manual is not followed exactly, a ﬁ re or explosion may result causing

property damage, personal injury, or loss of life.

- Do not store or use gasoline or other ﬂ ammable vapors and liquids in the vicinity of this or any other appliance.

- WHAT TO DO IF YOU SMELL GAS

• Shut off gas supply

• Do not try to light any appliance

• Do not touch an electrical switch; do not use any phone in your building.

• Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions.

• If you cannot reach your gas supplier, call the ﬁ re department.

- Installation and service must be performed by a qualiﬁ ed installer, service agency, or the gas supplier.

WARNING: This is an unvented gas-ﬁ red heater. It uses air (oxygen) from the room in which it is installed.

Provisions for adequate combustion and ventilation 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 or property

damage. Refer to this manual for correct installation and operational procedures. For assistance or additional

information consult a qualiﬁ ed installer, service agency, or gas supplier.

This appliance may be installed in an aftermarket permanently manufactured (mobile) home, where not prohibited

by local codes. This appliance is only for use with the type of gas indicated on the rating plate. This appliance is not

convertible for use with any other gas.

INSTALLER: Leave this manual with the appliance. CONSUMER: Retain this manual for future reference.

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This document provides comprehensive operating instructions and an owner's manual for Mr. Heater's unvented natural gas-fired room heaters, including both plaque and blue flame models. It emphasizes safety, proper installation, and maintenance to ensure efficient and long-lasting operation.

Function Description

The Mr. Heater unvented natural gas-fired room heater is designed to provide supplemental heating for residential spaces. These heaters utilize natural gas as fuel and operate without a vent, meaning they draw combustion air from the room and release combustion products directly into the room. To ensure safety, all models are equipped with an Oxygen Depletion Sensor (ODS) safety shutoff system, which automatically turns off the heater if there isn't enough fresh air available for proper combustion.

The heaters are available in two main types: plaque heaters and blue flame heaters. Plaque heaters, such as the MHVFRD20NGBT and MHVFRD30NGBT models, typically use ceramic plaques that glow red hot to radiate heat. Blue flame heaters, including the MHVFBF20NGBT and MHVFBF30NGBT models, produce a visible blue flame that heats the air directly through convection. Both types are offered with or without an integrated blower, which helps circulate the warm air throughout the room.

The heater's operation is controlled by a thermostat sensing bulb, allowing users to set a desired room temperature. This thermostatic control helps maintain a consistent comfort level and can contribute to lower energy bills by preventing overheating. For models equipped with a blower, a fan control switch allows users to select between MANUAL (continuous operation), OFF, or AUTO (blower cycles with the heater's on/off operation).

Usage Features

The manual stresses the importance of careful and complete reading of all instructions before assembly, operation, or servicing. It highlights several key usage features and safety precautions:

Ignition System: The heaters feature an electronic manual ignitor that requires one AA battery (included) for operation. This system eliminates the need for matches or other external ignition sources, simplifying the lighting process. Users simply push in and turn the control knob to the PILOT position, then press the ignitor button to light the pilot.
Thermostatic Control: The thermostatic control allows users to set the desired heat level, typically from 1 to 5. For plaque heaters, the thermostat simply turns the burner on and off. For blue flame heaters, the thermostat modulates the flame size as the temperature approaches the set point, then turns off the burner when the temperature is reached. The burner will cycle back on as the room temperature drops.
Blower Fan Control (on equipped models): The blower switch has three positions: MANUAL, OFF, and AUTO. In AUTO mode, the blower turns on and off in sync with the heater's cycling. In MANUAL mode, the blower runs continuously, providing constant air circulation.
Gas Type: The appliance is designed for use only with natural gas, as indicated on the rating plate. Field conversion to other gas types is not permitted.
Installation Flexibility: The heater can be mounted on a wall or placed on a non-combustible floor using included floor mounting stands. Clearances from combustible materials (front, top, sides) must be strictly maintained as specified in the manual.
Safety Shutoff System (ODS): The integrated Oxygen Depletion Sensor (ODS) system is a critical safety feature. If the oxygen level in the room drops below a safe threshold, the ODS will automatically shut down the heater, preventing the accumulation of harmful combustion byproducts.
Gas Leak Detection: Raw natural gas is odorless, but an odor-making agent is added to aid in leak detection. The manual provides clear instructions on what to do if a gas smell is detected, emphasizing immediate action such as shutting off the gas supply and contacting the gas supplier or fire department.
Supplemental Heating: These heaters are intended for supplemental heating and should be used in conjunction with a primary heating system. They can also serve as a primary heat source during power outages.
Air Quality Considerations: Users are warned that operating the heater where impurities like tobacco smoke, cleaning fluids, or paint fumes exist in the air may cause odors or discoloration of walls and ceilings. Vent-free heaters also add moisture to the air, and adequate ventilation is necessary to prevent mildew.

Maintenance Features

Regular cleaning and maintenance are crucial for the safe and efficient operation of the Mr. Heater unvented gas-fired room heater. The manual outlines several key maintenance procedures:

General Cleaning: Before servicing, the heater must be turned off and allowed to cool. Control areas, burner, and circulation air passageways must be kept clean. A vacuum cleaner, pressurized air, or a small soft-bristled brush can be used for cleaning. The exterior cabinet can be wiped with a soft cloth dampened with a mild soap and water mixture.
ODS/Pilot and Burner Cleaning: The ODS/pilot assembly and burner tube should be inspected and cleaned every 2,500 hours of operation or every three months. This involves blowing air through the port/slots and holes in the burner using compressed air (no greater than 30 psig) or a vacuum cleaner in the blow position. A yellow tip on the pilot flame indicates dust or dirt in the pilot assembly, requiring cleaning of the small pilot air inlet hole.
Annual Inspection: The heater should be inspected yearly by a qualified service person to ensure proper functioning and address any potential issues. More frequent cleaning may be necessary in homes with excessive lint from carpeting, bedding material, or pet hair.
Grille Guard: The grille guard must always be in place when the heater is running. If removed for servicing, it must be replaced before operating the heater again.
Troubleshooting Guide: The manual includes a detailed troubleshooting section that lists common symptoms, possible causes, and corresponding remedies. This guide helps users identify and resolve minor issues, such as no spark at the pilot, pilot lighting but going out, or burner not lighting. It also advises contacting a qualified service person or gas supplier for more complex problems or if issues persist.
Gas Connection Checks: After installation or servicing, all gas piping and connections must be tested for leaks using a liquid soap and water mixture. Any bubbles indicate a leak, which must be corrected immediately. The manual provides specific instructions for pressure testing the gas supply piping system.
Sediment Trap: Installation of a sediment trap in the supply line is recommended to prevent moisture and contaminants from entering the heater's fuel train, ensuring correct operation.

By adhering to these instructions, users can ensure the safe, efficient, and long-lasting performance of their Mr. Heater unvented natural gas-fired room heater.