MrHeater MHU200NG Operating Instructions And Owner'S Manual Download Page 23

Large Unit Heater

23

Operating Instructions and Owner’s Manual

The electrode and sensor are not adjustable. DO 
NOT change location or position as part of this 
conversion kit.

Step 1

 

CAUTION: THE UNIT MUST NOT BE CONNECTED TO EITHER 

THE GAS SUPPLY OR THE ELECTRICAL POWER SUPPLY, 
BEFORE PROCEEDING WITH CONVERSION.

Step 2

Remove and retain the four screws holding the manifold on to the 
burner box (Figure 14). Rotate the valve/ manifold assembly, away from 
the burners (Figure 15). The valve/manifold assembly holds the orifices. 
This will allow access to the orifices on the manifold.

Step 3

Remove and discard the adjustment spring cap from gas valve/
regulator with a flat blade screw driver by turning the screw counter-
clockwise.

Step 4

Remove and discard the orifices from the manifold with using a ½ “ 
open end wrench.  Turn them counter-clockwise to remove. Take the 
new orifices from the conversion kit and before installing, confirm that 
the number stamped on the side of the orifice matches as indicated 
in 

Table 1

. If it does not, immediately contact Mr. Heater, Inc. for the 

correct kit.  If they are the correct orifices, install them in the manifold 
using caution not to cross thread.

WARNING

THIS CONVERSION KIT SHALL BE INSTALLED BY A 
QUALIFIED SERVICE AGENCY IN ACCORDANCE WITH THE 
MANUFACTURER’S INSTRUCTIONS AND ALL APPLICABLE 
CODES AND REQUIREMENTS OF THE AUTHORITY 
HAVING JURISDICTION. IF THE INFORMATION IN THESE 
INSTRUCTIONS IS 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 RESPONSIBILITY FOR 
THE PROPER CONVERSION OF THIS APPLIANCE WITH THIS 
KIT.

 

WARNING: Electrical Shock Hazard

UNPLUG THE ELECTRICAL CORD FROM THE OUT-
LET BEFORE PERFORMING ANY SERVICE MAINTE-
NANCE. 

FAILURE TO FOLLOW THESE INSTRUCTIONS WILL 
RESULT IN DEATH, INJURY OR PROPERTY DAM-
AGE.

 

WARNING: Explosion Hazard

TURN OFF THE GAS SUPPLY TO THE HEATER 
BEFORE PERFORMING ANY SERVICE OR MAINTE-
NANCE.

FAILURE TO FOLLOW THESE INSTRUCTIONS WILL 
RESULT IN DEATH, INJURY OR PROPERTY DAM-
AGE.

Step 5

Rotate the valve/ manifold assembly back up into the burner box, 
making sure that all the orifices are indexed into the burners and are 
not caught on the locating ring on the back of each burner.  Secure the 
manifold to the burner box with the four screws removed in step 2.

Step 6 

Following the instructions Electrical Requirements and Gas Connections 
Sections (making sure to leak check all connections with soapy water) 
to reinstall the heater.

Step 7 

Take the rate tag from the kit and stick it over the existing portion of 
the rate label. This tag is preprinted with all the correct information for 
the converted heater. See Figure 16.

FIGURE 16

Position Of The Rate Tag

Step 8 

Remove the converted information tag from the kit and fill in the 
information.  Then place this tag below the updated rating tag on the 
unit.

Step 9 

Replace any panels and operate heater following all warnings/cautions 
and instructions in the operator’s manual and labels.

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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