MrHeater MH42T Assembly instructions

06/03 Revision L1 #73744MR. HEATER INC., 4560 W. 160TH ST., CLEVELAND, OHIO 44135 • 216-881-5500
GAS-FIRED INFRA-RED
PORTABLE 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.
MH42T
Model #
If the information in this manual is not followed exactly, a fire or explo-
sion may result causing property damage, personal injury or loss of life.
WARNING:
— Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any
other appliance.
— An LP cylinder not connected for use shall not be stored in the vicinity of this or any other appli-
ance.
— WHAT TO DO IF YOU SMELL GAS
• Do not try to light appliance.
• Extinguish any open flame.
• Shut off gas to appliance.
— Service must be performed by a qualified service agency.
— DO NOT LEAVE HEATER UNATTENDED OR IN OPERATION WHILE SLEEPING
This is an unvented gas-fired portable heater. It uses air (oxygen) from the area in which it is used.
Adequate combustion and ventilation air must be provided. Refer to page 3.
CYLINDER NOT INCLUDED
MODEL MH42T

2
Mr. Heater | Gas-Fired Infra-Red Portable Heater Operating Instructions and Owner’s Manual
GENERAL HAZARD WARNING:
FAILURE TO COMPLY WITH THE PRECAUTIONS AND
INSTRUCTIONS PROVIDED WITH THIS HEATER, CAN
RESULT IN DEATH, SERIOUS BODILY INJURY AND
PROPERTY LOSS OR DAMAGE FROM HAZARDS OF FIRE,
EXPLOSION, BURN, ASPHYXIATION, CARBON MONOX-
IDE POISONING, AND/OR ELECTRICAL SHOCK.
ONLY PERSONS WHO CAN UNDERSTAND AND FOLLOW
THE INSTRUCTIONS SHOULD USE OR SERVICE THIS
HEATER.
IF YOU NEED ASSISTANCE OR HEATER INFORMATION
SUCH AS AN INSTRUCTIONS MANUAL, LABELS, ETC.
CONTACT THE MANUFACTURER.
WARNING:
FIRE, BURN, INHALATION, AND EXPLOSION HAZARD.
KEEP SOLID COMBUSTIBLES, SUCH AS BUILDING
MATERIALS, PAPER OR CARDBOARD, A SAFE DIS-
TANCE AWAY FROM THE HEATER AS RECOMMENDED
BY THE INSTRUCTIONS NEVER USE THE HEATER IN
SPACES WHICH DO OR MAY CONTAIN VOLATILE OR
AIRBORNE COMBUSTIBLES, OR PRODUCTS SUCH AS
GASOLINE, SOLVENTS, PAINT THINNER, DUST PAR-
TICLES OR UNKNOWN CHEMICALS.
WARNING:
COMBUSTION BY-PRODUCTS PRODUCED WHEN
USING THIS PRODUCT CONTAIN CARBON MONOXIDE,
A CHEMICAL KNOWN TO THE STATE OF CALIFORNIA
TO CAUSE CANCER AND BIRTH DEFECTS (OR OTHER
REPRODUCTIVE HARM).
WARNING:
NOT FOR HOME OR RECREATIONAL VEHICLE USE
WARNING:
YOUR SAFETY IS IMPORTANT TO YOU AND TO OTHERS,
SO PLEASE READ THESE INSTRUCTIONS BEFORE YOU
OPERATE THIS HEATER.
CONTENTS
WARNINGS ................................................................................... 2
HOOK-UP INFORMATION .............................................................. 3
GENERAL INFORMATION .............................................................. 4
ODOR FADE WARNING ................................................................. 4
FOR SAFE OPERATION .................................................................. 4
VENTILATION ................................................................................ 5
MINIMUM CLEARANCE FROM COMBUSTIBLE MATERIALS ........... 5
ASSEMBLY PROCEDURE ................................................................ 5
LIGHTING INSTRUCTIONS ............................................................. 5
REPLACEMENT PARTS LIST ............................................................ 6
SHUT DOWN AND STORAGE ........................................................ 7
TROUBLE SHOOTING .................................................................... 7
WARRANTY .................................................................................. 8
INSTRUCTIONS FOR ORDERING PARTS ......................................... 8
The State of California requires the following warning:
WARNING:
CARBON MONOXIDE CAN KILL YOU
USING A PORTABLE GAS CAMPING HEATER INSIDE A
TENT, RV, CAMPER, VEHICLE, SHELTER OR OTHER
ENCLOSED AREAS CAN PRODUCE DEADLY CARBON
MONOXIDE

3Operating Instructions and Owner’s ManualMr. Heater | Gas-Fired Infra-Red Portable Heater
HOOK-UP INFORMATION
1.1 Heater model MH42T is packaged completely assembled.
Propane cylinders are not included with heater models.
1.2 Remove heater assembly from carton.
1.3 Place the slots of the black collar mounting bracket assembly
onto the collar of the bulk tank (see Fig. 1)
CAUTION:
BE SURE THE LOCKING KNOB ON THE COLLAR MOUNT-
ING BRACKET ASSEMBLY IS OUTSIDE THE COLLAR ON
THE BULK TANK. Tighten the black knob against the collar
of tank.
1.4 Check reflector of the heater (See Fig. 1) and the collar
mounting bracket assembly with the three #6-32 x ½ screws
and #6-32 Keps hex nuts. Be sure screws and nuts are secure
and tight.
1.5 Make sure tank valve is in “OFF” position (clockwise).
1.6 Make sure regulator knob is in “OFF” position by turning knob
clockwise to off.
1.7 Carefully screw POL nut directly into bulk tank valve finger-
tight, turning counterclockwise; then with a 7/8” open end
wrench tighten the POL fitting, hard.
1.8 Always connect the heater to bulk tank in the outdoors or in a
well ventilated area. NEVER connect heater to bulk tank near
an open flame.
1.9 Use only LP-gas cylinders constructed for use with propane
only (HD-5) and marked in accordance with specifications for
LP-gas cylinders of the U. S. Department of Transportation
(DOT Spec. 39).
1.10 Read pages 3 and 4 before lighting heater.
WARNING
Never touch heater while in operation to avoid injury.
Move heater by grasping the propane cylinder carefully.
MODEL MH42T
Figure 1
LP CYLINDER
POL NUT
TIGHTEN
REGULATOR KNOB
HOSE ASSEMBLY
REFLECTOR
COLLAR
MOUNTING
BRACKET
LOCKING KNOB

4
Mr. Heater | Gas-Fired Infra-Red Portable Heater Operating Instructions and Owner’s Manual
ODOR FADE WARNING
1. GENERAL INFORMATION
A. The Mr. Heater MH42T heaters are high pressure propane
appliances and are designed to be connected to a bulk
propane tank. Every unit is tested during manufacturing and
shipped fully
B. These heaters are equipped with three automatic Safety
Shutoff Valves. The gas flow will automatically stop the heater
burner if that heater burner fails to operate for any reason.
C. Maximum safety and convenience have been built into the Hi-
Med-Lo-Off Control Valve/Regulator. The following table lists
the approximate BTU’s consumed and the operating hours you
can reasonably expect from bulk propane cylinders.
2. FOR SAFE OPERATION
A. READ INSTRUCTIONS CAREFULLY: Read and adhere to these
instructions. Do not allow anyone who has not read the
instructions to assemble, light, adjust or operate the heater.
WARNING
KEEP THE HEATER OUT OF THE REACH OF CHILDREN
B. PROPANE IS VERY FLAMMABLE: In the event of a leak,
propane will accumulate and the possibility of a fire is present.
Propane gas is scented and its strong odor is readily detectable.
Never strike a match or bring any flame or create an electric
spark in an enclosure when you smell propane gas. Ventilate
the area thoroughly, move the heater outside, find and correct
the source of the leak before attempting to light any appliance.
If you are unsure of these instructions evacuate immediately
and call for help.
C. GAS LEAKAGE: If the leak cannot be corrected, do not tamper
with the heater; follow the shut down instructions and return
the heater to the dealer or address given on last page.
WARNING
DO NOT USE THIS HEATER ON BULK TANKS OF GREATER
CAPACITY THAN 100 POUNDS LPG
D. LEAK DETECTION: Before each use of the heater check all
fittings and connections with a soap solution to be sure there
are no leaks. Be sure the POL fitting is wrench (7/8”) tightened
into the On-Off valve on the propane cylinder. NEVER, NEVER
USE ANY FLAME FOR LEAK TEST.
E. CONNECTING HEATER TO PROPANE CYLINDER: Always
connect the heater to the bulk cylinder in the outdoors or in a
well ventilated area. Use a 7/8” open end wrench. NEVER
connect this heater to a cylinder near an open flame.
F. USE OF HEATER: Always operate the heater with the propane
cylinder in an upright position on a level noncombustible
surface. NEVER place the cylinder on its side when operating
the heater.
G. ATTEND HEATER: Do not leave heater unattended while it is in
operation.
H. ALWAYS USE A MATCH TO LIGHT HEATER: NEVER attempt
to light the heater with a spark lighter.
I. DO NOT TAMPER: Should the heater not perform properly,
such as little or no heat when operating in the “Hi” position, or
for any other reason, DO NOT ATTEMPT TO REPAIR OR TAMPER
with the heater. Any tampering could make the use of the
heater unsafe and dangerous. Return the heater to the dealer
or the address given on last page for repair or replacement.
J. FOR STORAGE: The heater Hi-Med-Lo-Off regulating valve
should always be turned to “Off” when the heater is not in use.
Allow at least 15 minutes for cooling before handling and
storing. Detach propane cylinder from heater before storing.
DO NOT store propane cylinders near open flame or heat.
K. DO NOT TRANSPORT OR MOVE APPLIANCE WHILE IN
OPERATION OR WHILE HEATER IS ATTACHED. FOLLOW
SHUTDOWN AND STORAGE INSTRUCTIONS TO
TRANSPORT OR MOVE THIS APPLIANCE.
WARNING
Asphyxiation Hazard
• Do not use this heater for heating human living
quarters.
• Do not use in unventilated areas.
• The flow of combustion and ventilation air must not
be obstructed.
• Proper ventilation air must be provided to support
the combustion air requirements of the heater
being used.
• Refer to the specification section of the heater’s
manual, heater dataplate, or contact the factory to
determine combustion air ventilation requirements
of the heater.
• Lack of proper ventilation air will lead to improper
combustion.
• Improper combustion can lead to carbon monoxide
poisoning leading to serious injury or death.
• Symptom of carbon monoxide poisoning can
include headaches dizziness and difficulty in
breathing.
1 Hi 14,000 31 157
1 Med 2,000 36 184
1 Lo 8,000 43 217
2 Hi 28,000 15 78
2 Med 24,000 18 92
2 Lo 16,000 21 108
3 Hi 42,000 10 52
3 Med 36,000 12 61
3 Lo 24,000 14 72
Burners Valve BTU Input Approximate Hours of Operation
Operating Position 20 Lb. Cylinder 100 Lb. Cylinder
Figure 2

5Operating Instructions and Owner’s ManualMr. Heater | Gas-Fired Infra-Red Portable Heater
3. VENTILATION
A. WARNING: This heater is an unvented appliance and
MUST be used ONLY in a well ventilated area. NEVER
attempt to operate the heater inside any vehicle, camper or
enclosure.
B. Any combustion process requires and consumes oxygen, and
will produce carbon monoxide. THIS HEATER MUST BE USED
WITH ADEQUATE VENTILATION. Do not use in a tightly
enclosed area. Two openings directly to the outdoors MUST be
provided. One HIGH and one LOW, preferably on opposite sides
of the enclosure. EACH OPENING SHALL HAVE A MINIMUM
FREE AREA OF 36 SQUARE INCHES (6” X 6”). Structures of
tight construction or tents using fire retardant materials will
require larger openings. If any additional fuel burning
appliances are operated ALWAYS provide additional ventilation.
Increase the area of each opening by at least 2 square inches
for each 1,000 BTU’s per hour of additional input rating.
C. WARNING: Provide ample ventilation. This heater consumes air
(oxygen). Do not use this heater in unventilated structures to
avoid endangering your life. Provide additional ventilation for
any additional fuel-burning appliances and additional
occupants.
4. MINIMUM CLEARANCE FROM
COMBUSTIBLE MATERIALS
A. WARNING: This heater is an unvented appliance and
MUST be used ONLY in a well ventilated area. NEVER
attempt to operate the heater inside any vehicle, camper or
enclosure.
B. WARNING: To avoid injury or property damage never allow
clothing, tents or other combustible material within 36” of the
heater. This heater must be located at least 32” above the floor
level when in use. Never operate the heater when sleeping.
C. WARNING: Never direct the heat output of this heater toward
any propane tank within 20 feet.
5. ASSEMBLY PROCEDURE
A. Make sure the regulator knob on the heater is “off” by turning
knob clockwise to the “OFF” position.
B. Carefully screw POL nut directly into bulk propane cylinder,
counterclockwise. REMEMBER – This is a left hand thread – see
Figure 1. Make sure the heater is in a vertical upright position
and directed away from the collar of the bulk tank. Use a 7/8”
open end wrench to tighten the POL fitting – left hand thread
– see Fig. 1.
6. LIGHTING INSTRUCTIONS
A. Before attempting to light the heater, check all fittings and
connections with a soap solution. NEVER USE A MATCH TO
CHECK FOR LEAKS. Should a gas leak occur, do not attempt
to repair or use heater. Return the heater to your dealer or the
address given on back page.
B. Fuel – This heater must be used only with a vapor withdrawal
LP gas bulk cylinder. THE BULK TANK MUST BE EQUIPPED WITH
A STANDARD POL VALVE.
WARNING:
USE HD.5 PROPANE GAS ONLY. DO NOT USE ANY OTHER
TYPE FUEL. SEE YOUR PROPANE DEALER IF YOU HAVE ANY
QUESTIONS REGARDING FUEL.
C. Turn the heater’s “Hi-Med-Lo-Off” regulator know to “Med”
(counterclockwise).
D. To light a burner, MH42T Model, place a lit match across the
mesh screen where you see “light here” on reflector. (See Fig.
4) THEN push in valve button on Safety Shutoff Valve. After the
burner is lit, continue to hold valve button in for 30 seconds,
then release the button slowly. CAUTION: DO NOT PUSH IN
VALVE BUTTON BEFORE INSERTING LIT MATCH. Repeat step “D”
for each burner.
E. Adjust heat output by turning knob to desired position.
F. If burner does not light within 30 seconds, turn the heater’s
regulator knob to “off” (clockwise) and allow at least five
minutes for gas to dissipate before attempting to relight.
G. NOTE: Should the orifice become clogged as indicated by low
volume of gas when operating on “Hi” with a full cylinder, or
should the heater fail to operate properly for any reason, return
the heater to the dealer or the address given on back page for
repair or replacement. DO NOT ATTEMPT TO REPAIR OR
TAMPER WITH HEATER.
H. COOKING: DO NOT USE THIS HEATER FOR COOKING.
Figure 3
MH42T 42,000 Vertical 32” 36" 36" 48”
MODEL
NO.
GAS
PROPANE
BTU/HR. RATING NORMAL
OPERATING
PROCEDURE
CLEARANCES TO COMBUSTIBLES
FROM C.L. OF
HTR. TO FLOOR SIDES REAR CEILING
Figure 4

6
Mr. Heater | Gas-Fired Infra-Red Portable Heater Operating Instructions and Owner’s Manual
ALL WARRANTY CLAIMS REQUIRE PROOF OF PURCHASE
REF.# ITEM# DESCRIPTION
1 73960 Manifold with safety shutoffs and orifices
2 F273117 12 inch thermocouple lead
3 73122 Plenum Assembly, Complete
4 F273164 Screen Assembly
5 73941 Bolt set (#10-32 x ¼ Phillips HD Mach Screws)
6 F273606 Replacement Regulator with Soft Nose POL
7 73743 Reflector
8 73742 Wire Guard
9 75607 Metal Ring
10 73938 Collar Mounting Bracket Assembly
11 73658 Hose Assembly/Less Regulator (11” Long)
12 73213 Replacement Safety Shutoff with Orifice
13 75613 Locking Knob
14 73214 Bolt – ¼-20 with Seal Washer
15 73322 Plenum Assembly with Clip –Center Only
Mr. Heater • Gas-Fired Infra-Red Portable Heater • Model #MH42T
Figure 6
Figure 5
NOTE:
WHEN LIGHTING BURNER WITH A
MATCH OR TAPER, LIGHT AT
SCREEN. (NOT AT ORIFICE)
REPLACEMENT PARTS LIST FOR HEATER MODEL MH42T FULLY ASSEMBLED WITH METAL GAS MANIFOLD

7Operating Instructions and Owner’s ManualMr. Heater | Gas-Fired Infra-Red Portable Heater
7. SHUTDOWN AND STORAGE
INSTRUCTIONS
A. The bulk propane tank “on-off” valve should ALWAYS be
completely turned “OFF” when the heater is not in use.
B. When shutting off the heater, turn the regulator knob on the
heater to “OFF” (clockwise). (See Figure 4)
C. CAUTION: After turning unit off, heater will remain
extremely hot. Allow at least 15 minutes for cooling before
handling and storing. Detach heater from bulk tank before
handling and storage. REMEMBER – POL fitting is a left-hand
thread.
TROUBLE SHOOTING
MR. HEATER APPLIANCE
The chart assumes that the proper gas and gas pressure is available to the heater. The chart also assumes that the heater is used in
accordance with Mr. Heater installation and operating instructions.
If satisfactory results cannot be obtained after performing any of the above procedures,
Please call Mr. Heater’s Customer Care Center at 1-800-251-0001. Thank you.
D. HEATER STORAGE: Always remove the propane cylinder from
the heater when not in use. Always store propane cylinders in
a cool, well ventilated place away from any flame or heat and
in a location not used for habitation. DO NOT STORE PROPANE
TANK WITHIN 60 FT. OF OPEN FLAME OR HEAT.
E. See Figure 6 for spare parts list.
PROBLEM POSSIBLE CAUSE SOLUTION
Burners will not light Propane tank turned off Open tank valve
Propane tank empty Get tank filled
Heater regulator not turned on Turn valve to medium position
Safety Shutoff plunger not depressed Depress S/S valve while lighting
Air in manifold or hose or propane tank Purge air from unit
Hear gas but burners will Air in propane tank Return tank to dealer to purge air
not light (hissing) Defective regulator Replace
Partially plugged orifice Clean or replace
Burner lights, turns red but Thermocouple not secure Secure thermocouple
will not stay lit Thermocouple out of position Position tip 3/16” to 3/8” from screen
Defective thermocouple Replace thermocouple
Safety shutoff defective Replace safety shutoff
Blue flame at top of Out of storage Clean all openings with H.P. air
heater screen Defective regulator Replace regulator
Blue flame only – never gets red Something in Venturi Clean venturi tube with wire
Orifice partially plugged H.P. air clean out venturi/orifices
Screen plugged up
Connection at propane tank “O-Ring” on POL missing or defective Replace “O” ring or POL
leaking gas after securing Valve seat on cylinder worn Return to dealer
Heater emits high pitched sound Heater warming up No Danger – heater warming up.
Sound will stop in 1-3 minutes

8
Mr. Heater | Gas-Fired Infra-Red Portable Heater Operating Instructions and Owner’s Manual
WARNING:
USE ONLY MANUFACTURER’S REPLACEMENT PARTS. USE OF ANY OTHER PARTS
COULD CAUSE INJURY OR DEATH. REPLACEMENT PARTS ARE ONLY AVAILABLE
DIRECT FROM THE FACTORY AND MUST BE INSTALLED BY A QUALIFIED SERVICE
AGENCY.
PARTS ORDERING INFORMATION:
PURCHASING: Accessories may be purchased at any Mr. Heater local dealer or
direct from the factory
FOR INFORMATION REGARDING SERVICE
Please call Toll-Free 800-251-0001 • www.mrheater.com
Our office hours are 8:30 AM – 5:00 PM, EST, Monday through Friday.
Please include the model number, date of purchase, and description of problem in
all communication.
LIMITED WARRANTY
The company warrants this product to be free from imperfections in material or
workmanship, under normal and proper use in accordance with instructions of The
Company, for a period of one year from the date of delivery to the buyer. The Company, at
its option, will repair or replace products returned by the buyer to the factory,
transportation prepaid within said one year period and found by the Company to have
imperfections in material or workmanship.
If a part is damaged or missing, call our Technical Support Department at 800-251-0001.
Address any Warranty Claims to the Service Department, MR. HEATER INC., 4560 W. 160TH
ST., CLEVELAND, OHIO 44135. Include your name, address and telephone number and
include details concerning the claim. Also, supply us with the purchase date and the name
and address of the dealer from whom you purchased our product.
The foregoing is the full extent of the responsibility of the Company. There are no other
warranties, express or implied. Specifically there is no warranty of fitness for a particular
purpose and there is no warranty of merchantability. In no event shall the Company be
liable for delay caused by imperfections, for consequential damages, or for any charges of
the expense of any nature incurred without its written consent. The cost of repair or
replacement shall be the exclusive remedy for any breach of warranty. There is no warranty
against infringement of the like and no implied warranty arising from course of dealing or
usage of trade. This warranty will not apply to any product which has been repaired or
altered outside of the factory in any respect which in our judgment affects its condition or
operation.
Some states do not allow the exclusion or limitation of incidental or consequential
damages, so the above limitation or exclusion may not apply to you. This Warranty gives you
specific legal rights, and you may have other rights which vary from state to state.
OPERATING INSTRUCTIONS
AND OWNER’S MANUAL MH42T
Model #
MR. HEATER INC., 4560 W. 160TH ST., CLEVELAND, OHIO 44135 • 216-881-5500
Mr. Heater and Portable Buddy are registered trademarks of Enerco Group, Inc.
© 2003, Enerco/Mr. Heater. All rights reserved
Mr. Heater Inc. reserves the right to make changes at any time, without notice or
obligation, in colors, specifications, accessories, materials and models.