MrHeater MHU200NG Operating Instructions And Owner'S Manual Download Page 4

Large Unit Heater

4

Operating Instructions and Owner’s Manual

SHIPPING

The heater is completely assembled. Installation instructions, two 
mounting brackets (shipped loose), and a flue transition are included. 
Check the unit for shipping damage. The receiving party should 
contact the last carrier immediately if any shipping damage is found.

APPLICATIONS

This is 

not

 an explosion proof heater. This heater may not be used 

in a Class 1 or Class 2 Explosive Environment. Consult your local fire 
marshal, insurance carrier, and other authorities for approval if the 
proposed installation is in question.

COMMERCIAL/INDUSTRIAL

The heater is designed and certified for use in industrial and 
commercial buildings, such as warehouses, manufacturing plants, 
aircraft hangars, and vehicle maintenance shops. For maximum safety, 
the building must be evaluated for potential problems before installing 
the heater system. This unit is certified for use as furnished by the 
manufacturer. Do not alter the fan or operate motors at a reduced 
speed.

 

CAUTION: Installation of restrictive devices to the inlet or 

outlet of the fan motor may result in premature failure of the 
exchanger pipe, overheating of the appliance, or damage to 
the components. Do not attach ductwork, air filters, or poly-
tubes to any Mr. Heater unit heater.

STANDARDS, CERTIFICATIONS, AND 
GOVERNMENT REGULATIONS

Installation of this gas-fired heater must conform with all applicable 
local, state, and national specifications, regulations, and building 
codes. Contact the local building inspector and/or fire marshal for 
guidance.

In the absence of local codes, the installation must conform to the 
latest edition of:

CSA IN USA

Installation of gas unit heaters must conform with local building codes 
or, in the absence of local codes, with the current National Fuel Gas 
Code ANSI Z223.1. 

Installation in aircraft hangars must be in accordance with the current 
Standard for Aircraft Hangars ANSI/NFPA No. 409.

Installation in parking structures must be in accordance with the 
current Standard for Parking Structures ANSI/NFPA No. 88A. 

For installation in a residential garage these units must be installed so 
that the bottom of the heater is located no less than 8 feet (2.438m) 
above floor. Heater must be located or protected to avoid physical 
damage by vehicles. Refer to the National Fuel Gas Code, ANSI Z223.1, 
current edition.

Authorities having jurisdiction should be consulted before NFPA 
installation. Air for combustion and ventilation must conform to the 
methods outlined in ANSI Z223.1, section 5.3, Air for Combustion 
and Ventilation, or applicable provisions of local building codes. ANS 
Z83.8 / CSA 2.6 is the standard for Gas Unit Heater Construction. The 
National Fuel Gas Code is available from:

American National Standard Institute Inc.
11 West 42nd Street
New York, NY 10036

These units are CSA International design certified. These unit heaters 
are certified for installation to combustible material as listed in 

Table 

3

 and on unit rating plate. Accessibility and service clearances must be 

observed in addition to fire protection clearances.

All electrical wiring and ground for unit must be in accordance with 
the regulations of the current National Electric Code ANSI/No. 70. 

The National Electric Code is available from:

National Fire Protection Association 
1 Batterymarch Park
PO Box 9101
Quincy, MA 02269-9101

CSA IN CANADA

The instructions are intended only as a general guide and do not 
supersede local codes in any way. Authorities having jurisdiction 
should be consulted before installation. The installation must conform 
with local building codes or in the absence of local codes, with the 
current CSA B149.1, Natural Gas and Propane Installation Code. All 
electrical wiring and grounding for the unit must also comply with the 
Canadian Electrical Code CSA C22.1, current edition.

These heaters are CSA International certified for the clearances to 
combustible material listed on the rating plate and 

Table 3

. Provide 

adequate clearance around air openings into the combustion 
chamber, clearances from combustible material, and provisions for 
accessibility and for combustion and ventilation air supply. Provision 
shall be made for service accessibility to the heater. Note that fire 
protection clearances may be exceeded to provide additional space for 
service and accessibility. CAN/CGA B149.1-10 is the code for Natural 
Gas and Propane Installation.

Copies of these Standards can be viewed or purchased at www.nfpa.
org or www.scc.ca.

GARAGE INSTALLATIONS

Installation in parking structures must be in accordance with the 
current Standard for Parking Structures ANSI/NFPA No. 88A. 

Installation in repair garages must be in accordance with the current 
Standard for Repair Garages ANSI/NFPA No. 88B.

1. In a storage area, clearance from heaters to combustible materials 

must be such that the material shall not attain a temperature above 
160��F by continuous operation of the unit.

2. Eight foot minimum clearance from the floor to the bottom of the 

heater must be maintained. Refer to the CSA B149.1, Natural Gas 
and Propane Installation Code.

Canada

: Refer to CAN/CGA B149.1: Installation Codes for Gas Burning 

Appliances and applicable Standards for Public Garages.

Guidelines:

• Heaters must not be installed less than 8 ft. (2.4 m) above the 
floor. Minimum clearances to combustibles must be maintained from 
vehicles parked below the heater.

• When installed over hoists, minimum clearances to combustibles 
must be maintained from the upper most point of objects on the 
hoist.

AIRCRAFT HANGAR INSTALLATIONS

Installation of gas unit heaters must conform with local building codes 
or, in the absence of local codes, with the current National Fuel Gas 
Code ANSI Z223.1. 

Summary of Contents for MHU200NG

Page 1: ...o this manual For assistance or additional information consult a qualified installer service agency or the gas supplier WHAT TO DO IF YOU SMELL GAS DO NOT try to light appliance DO NOT touch any elect...

Page 2: ...E INSTRUCTIONS BEFORE YOU OPERATE THIS HEATER WARNING FIRE OR EXPLOSION HAZARD Failure to follow safety warnings exactly could result in serious injury death or property damage Be sure to read and und...

Page 3: ...perly Set ________________________________ Furnace BTU input _____________________________________ Level ___________________________________________________ Line Pressure _____________________________...

Page 4: ...al Standard Institute Inc 11 West 42nd Street New York NY 10036 These units are CSA International design certified These unit heaters are certified for installation to combustible material as listed i...

Page 5: ...nual is to provide information regarding safety design guidelines installation operation and maintenance of the this gas fired unit heater You must read and understand the instructions and all safety...

Page 6: ...tion of these units must comply with the National Fuel Gas Code ANSI Z223 1 NFPA 54 latest edition and other applicable local building codes In Canada the installation of these units must comply with...

Page 7: ...ontal pitch as directed in these instructions and the latest edition of the National Fuel Gas Code ANSI Z223 1 NFPA 54 or CSA B149 1 Installation Code Determine that there is not blockage restriction...

Page 8: ...h a diameter 4 inches greater than the vent pipe diameter must be used If there is 6 feet or more of vent pipe prior to passing through the combustible wall or floor then the metal thimble need only b...

Page 9: ...than any part of a building within a horizontal distance of 10 3 05m unless otherwise specified by the American National Fuel Gas Code ANSI Z223 1 or Canada CAN CGA B149 Installation Code The vent mu...

Page 10: ...ombustion which can result in the production of excessive carbon monoxide Follow these guidelines and all applicable codes for all models prior to installing the combustion air duct work WARNING Suffi...

Page 11: ...drip leg should be installed in the vertical pipe run to the unit In some localities codes may require that a manual main shutoff valve and union furnished by installer be installed external to the un...

Page 12: ...putting into service For leak testing on pressures below 20 inches W C Before leak testing close the field installed manual shut off valve shown on Figure 9 on the supply line to isolate the gas valve...

Page 13: ...ssure Input Rating W C kPa BTU Hr W W C kPa BTU Hr W MHU200NG 7 23 1 8 200 000 58 614 6 66 1 66 192 000 56 269 MHU250NG 7 23 1 8 250 000 73 268 6 66 1 66 240 000 70 337 MHU300NG 3 81 0 95 300 000 87 9...

Page 14: ...the side access control compartment of the unit The low voltage thermostat and accessory control devices can be wired to the terminals in the side access control compartment Refer to the wiring diagra...

Page 15: ...Large Unit Heater 15 Operating Instructions and Owner s Manual Main Components FIGURE 10 Line Voltage Thermostat Wiring Connector on Heater S1 S4 M1 VG MC FS S2 S3 S2 CB SE T1 RFC CFC...

Page 16: ...Large Unit Heater 16 Operating Instructions and Owner s Manual Internal Wiring Diagram FIGURE 11...

Page 17: ...field supplied power wires so that they do not come in contact with the flue wrapper or venter housing These hot surfaces may damage the wire s insulation resulting in damage to the unit THERMOSTAT LO...

Page 18: ...puts set it to the maximum rating 7 Observe the pressure rating on the pressure gauge Verify maximum inlet gas supply pressure 8 Turn off all other gas appliances on the same supply line 9 Observe the...

Page 19: ...manifold pressure hose connector using a soap solution or equivalent method as described in ANSI Z223 1 NFPA 54 Prior to Leaving Job Site Prior to leaving the job site verify that Service access door...

Page 20: ...hts burner DO NOT attempt to light the burners manually 5 There is a main shut off valve upstream of the unit Open it See Figure 9 on Page 11 6 Wait five minutes to clear out any gas If you then smell...

Page 21: ...upply Follow lighting instructions to light unit Check burner flame FLUE PASSAGEWAY AND FLUE BOX The flue passages and flue box should be inspected and cleaned prior to each heating season The sequenc...

Page 22: ...old Screws FUEL CONVERSION INSTRUCTIONS FIGURE 15 Rotation of the Valve Manifold Assembly ROTATE valve manifold assembly The heater is standard manufactured for operation with natural gas In case of u...

Page 23: ...NOT FOLLOWED EXACTLY A FIRE EXPLOSION OR PRODUCTION OF CARBON MONOXIDE MAY RESULT CAUSING PROPERTY DAMAGE PERSONAL INJURY OR LOSS OF LIFE THE QUALIFIED SERVICE AGENCY PERFORMING THIS WORK ASSUMES RES...

Page 24: ...space tightly sealed building 1 Remove obstruction or correct vent lengths 2 Replace wiring or hose connections 3 Replace pressure switch The control board does not send spark to the electrode 1 The e...

Page 25: ...ontrol board does not send 120 VAC to the air movement fan after approx 30 seconds after ignition and if contact relay fan control is open and there isn t 24VAC on relay fan control 3 The control boar...

Page 26: ...er listed on the unit rating plate Mr Heater Large Unit Heater Model MHU200NG MHU250NG MHU300NG MHU400NG Liquid Propane to Natural Gas Conversion Kit MHU200NG F260165 MHU250NG F260166 MHU300NG F260167...

Page 27: ...60291 60291 60291 60291 20 BLOWER DRIVE RELAY 60292 60292 60292 60292 21 PRESSURE SWITCH 60293 60294 60294 60294 22 DETECTION ELECTRODE 60295 60295 60295 60295 23 MANUAL RESET SAFETY THERMOSTAT 140 C...

Page 28: ...001 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 de tails concerning the claim Al...

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