FUEL CONVERSION MANUAL
READ INSTRUCTIONS CAREFULLY: YOUR SAFETY
IS IMPORTANT TO YOU AND TO OTHERS. Read and
follow all instructions. Place instructions in a safe place
Model #
HSU50
HSU80
HSU125
COMPACT UNIT HEATER FOR COMMERCIAL APPLICATIONS
COMPACT UTILITY HEATER FOR RESIDENTIAL APPLICATIONS
for future reference. Do not allow anyone who has
not read these instructions to assemble, light, adjust or
operate the heater.
For Big Maxx Heaters using
Honeywell VR8205M valves.
Model #
MHU50
MHU80
MHU125
WARNING:
Instructions are for
Honeywell VR8205M
valves.
WARNING: Improper installation, adjustment, alteration, service or maintenance can cause
injury or property damage. Refer to this manual. For assistance or additional information
consult a qualified installer, service agency or the gas supplier.
- WHAT TO DO IF YOU SMELL GAS
Ǟ Open Windows
Ǟ DO NOT try to light appliance.
Ǟ DO NOT touch any electrical switch
Ǟ DO NOT use any telephone in your house. Immediately call your local gas supplier from a neighbor’s
telephone. Follow the gas supplier’s instructions.
Ǟ DO NOT touch any electrical switch; do not use any phone in your building.
Ǟ If you cannot reach your gas supplier, call the Fire Department.
- Installation and service must be performed by a qualified installer, service agency or the gas supplier.
FOR YOUR SAFETY:
Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance.
WARNING: If the information in these instructions are not followed exactly, a fire or explosion may result causing
property damage, personal injury or loss of life.
Enerco Group Inc., 4560 W. 160TH ST., CLEVELAND, OHIO 44135 •1 - (800) - 251 - 0001
60187
WARNING: YOUR SAFETY IS IMPORTANT
TO YOU AND TO OTHERS, SO PLEASE READ THESE
INSTRUCTIONS BEFORE YOU OPERATE THIS HEATER.
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
MONOXIDE 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: THIS PRODUCT CAN EXPOSE
YOU TO CHEMICALS INCLUDING LEAD AND LEAD
COMPOUNDS, WHICH ARE KNOWN TO THE STATE
OF CALIFORNIA TO CAUSE CANCER AND BIRTH
DEFECTS OR OTHER REPRODUCTIVE HARM. FOR MORE
INFORMATION VISIT WWW.P65WARNINGS.CA.GOV
WARNING: FIRE, BURN, INHALATION, AND
EXPLOSION HAZARD. KEEP SOLID COMBUSTIBLES,
SUCH AS BUILDING MATERIALS, PAPER, OR
CARDBOARD, A SAFE DISTANCE 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 PARTICLES OR
UNKNOWN CHEMICALS.
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: Fuels used in liquefied propane gas appliances, and the products of combustion of such fuel,
can expose you to chemicals including benzene, which is known to the state of California to cause cancer and cause birth
defects or other reproductive harm, for more information go to www.P65Warnings.ca.gov
CONTENTS
Fuel Conversion Kits ...................................................... E3
Fuel Conversion Instructions ......................................... E4
Rating Tag Conversion .................................................. E6
Warranty ...................................................................... E8
LANGUAGES
ENGLISH .................................................................E1 - E8
SPANISH .................................................................S1 - S8
FRENCH .................................................................. F1 - F8
GENERAL INFORMATION
RETAIN THIS MANUAL FOR FUTURE REFERENCE.
FOR QUESTIONS, PROBLEMS, MISSING PARTS BEFORE
RETURNING TO RETAILER PLEASE CALL WITH MODEL NUMBER
AND SERIAL NUMBER OF HEATER:
1 - (800) - 251 - 0001
MONDAY-FRIDAY 8-5 EASTERN TIME
OR E-MAIL USING THE ENERCO WEBSITE:
WWW.ENERCO.COM/
In order to provide the best service possible Enerco is now
giving you more ways to get in touch with us:
YouTube: youtube.com/mrheaterTV
Facebook: www.facebook.com/mrheaterproducts/
Twitter: https://twitter.com/MrHeater
Compact Unit Heater
Fuel Conversion Manual
E-2
FUEL CONVERSION
FUEL CONVERSION INSTRUCTIONS
FUEL CONVERSION Section 1: FUEL CONVERSION KITS
For Converting from Natural Gas to L.P. Gas
HONEYWELL KIT #393691
Gas Conversion Labels
Control Conversion Labels
Orifice
(See P/N Table Below)
Part Number Description
13575 Gas conversion label
60232 Converted Rating tag
60233 Converted Rating tag
60234 Converted Rating tag
11727 Spring - gas valve (label inc.)
60156 L.P. Orifice
13576 Control Conversion Label
Fuel Conversion Part Numbers
Model # BTU/HR
HSU50/MHU50 50,000
HSU80/MHU80 80,000
HSU125/HSU125 125,000
50 80 125
1 1 1
1
1
1 1 1
3 5 8
1 1 1
Natural - To - LP
F260163
1
For Converting from L.P. Gas to Natural Gas
HONEYWELL KIT #393691
Gas Conversion Labels
Control Conversion Labels
Part Number Description
13575 Gas conversion label
60235 Converted Rating tag
60236 Converted Rating tag
60237 Converted Rating tag
11727 Spring - gas valve (label inc.)
60049 L.P. Orifice
13576 Control Conversion Label
Orifice
(See P/N Table Below)
Fuel Conversion Part Numbers
Model # BTU/HR
HSU50/MHU50 50,000
HSU80/MHU80 80,000
HSU125/HSU125 125,000
50 80 125
1 1 1
1
1
1 1 1
3 5 8
1 1 1
LP - To - Natural
F260164
1
Compact Unit Heater
Fuel Conversion Manual
E-3
FUEL CONVERSION Section 2: FUEL CONVERSION INSTRUCTIONS
4 screws
FIGURE 10 FIGURE 11
R
o
t
a
t
e
V
a
l
v
e
/
M
a
n
i
f
o
l
d
A
s
s
e
m
b
l
y
WARNING: Explosion Hazard
Turn off the gas supply to the heater before performing any service or maintenance.
Failure to follow these instructions will result in death,
injury or property damage.
WARNING: Electrical Shock Hazard
Unplug the electrical cord from the outlet before
performing any service maintenance.
Failure to follow these instructions will result in death,
injury or property damage.
The electrode and sensor are not adjustable. DO
NOT change location or position as part of this
conversion kit.
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.
Compact Unit Heater
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 10). Rotate the valve/ manifold assembly, away
from the burners (Figure 11). The valve/manifold assembly holds the
orifices (3 orifices on unit HSU50/MHU50, 5 orifices on unit HSU80/
MHU80, 8 orifices on unit HSU125/MHU125). This will allow access
to the orifices on the manifold, and also the adjustment spring in the
valve/regulator.
Step 3
Remove and discard the adjustment spring cap from gas valve/
regulator with a flat blade screw driver by turning the screw counterclockwise. Remove and discard the regulator adjustment screw found
under the cap. Remove and discard the spring that is located under
the adjustment screw. Take the spring kit from the conversion kit,
and compare the part number of the kit to the parts list on page 3. If
it does not match, immediately contact Heatstar, Inc. for the correct
kit. After confirming the spring kit is correct for the heater model you
are converting, install the new spring and adjustment screw. Turn
spring adjustment screw clockwise (in) until the screw stops, then turn
it counter-clockwise (back) 1 ½ turns. Place conversion label supplied
with the spring kit on the valve near the adjustment screw cover
opening.
Step 4
Remove and discard the orifices (3 orifices on unit HSU50/MHU50,
5 orifices on unit HSU80/MHU80, 8 orifices on unit HSU125/
MHU125) 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 the number for the kit being
installed. If it does not, immediately contact Heatstar, Inc. for the
correct kit. If they are the correct orifices, install them in the manifold
using caution not to cross thread.
Fuel Conversion Manual
E-4
6
5
4
3
2
1
4”
0
1
2
3
4
5
6
6
5
4
3
2
1
0
1
2
3
4
5
6
N.G. L.P.
FIGURE 12
10”
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 in the unit heaters operations manual
mount the heater and connect the gas supply (making sure to leak
check all connections with soapy water).
Step 7
Remove valve pressure test plug and retain for later use. Connect a
water-filled U-tube manometer to the test port. See Figure 12. Use a
manometer because test gauges are not reliable and may give a false
reading.
Step 8
Connect main electrical power supply, and turn main gas supply on.
Step 9
Turn up the thermostat to call for heat, thereby starting the ignition
sequence for the heater.
Step 10
When the burners light, set the manifold gas pressure by turning the
adjustment screw to the regulator spring that was replaced in step 6.
Once the pressure has been adjusted, replace the adjustment screw
cover with a new one from the conversion kit.
Decrease Pressure
Counter-Clockwise
Refer to Table 6 for inlet pressure requirements, and set manifold
pressures according to gas type and altitude(See Table 4 and Table 5).
The manometer illustration (See Figure 12) shows each of the pressure
readings.
Increase Pressure
Clockwise
Step 11
Turn down the thermostat and allow the heater to complete a cool
down cycle. Then disconnect main electrical power, and turn the main
gas supply off to appliance.
Step 12
Disconnect the manometer from appliance and replace the test plug
on valve removed in step 6.
Compact Unit Heater
Fuel Conversion Manual
E-5
FUEL CONVERSION Section 3: RATE TAG CONVERSION INSTRUCTIONS
FIGURE 13
Step 13
Connect main electrical power, and turn main gas supply back on.
Turn up thermostat to call for heat. When the main burners light
using soapy water check all connections thoroughly for gas leaks.
Remembering to also check the pressure test plug replaced in step
12. Allow the heater to operate for at least 5 minutes, then observe
the main burner flame. A hard blue flame extending into the tube is
normal. Slight yellow tipping is acceptable. There is no air adjustment
to the burner.
Step 14
See figure 13. Remove the data tag for their respective gases. Remove
label and place over the existing portion of the tag. This tag is
preprinted with all the correct information for the converted heater.
Step 15
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 16
Replace any panels and operate heater following all warnings/cautions
and instructions in the operator’s manual and labels.
Table 4
NATURAL GAS MANIFOLD PRESSURES - IN. W.C.. (KPA)
MHU50/80/125
HSU50/80/125
50/80/125 4.0”WC (0.99 KPA)* 3.6”WC (0.89 KPA)
0-2000 (0-610) 2000-4500 (610-1370)
*NO ADJUSTMENT REQUIRED
ALTITUDE FT. (M)
Table 5
LP/PROPANE GAS MANIFOLD PRESSURES - IN.W.C.. (KPA)
MHU50/80/125
HSU50/80/125
50/80/125 10”WC (2.49 KPA)* 8.5”WC (2.12KPA)
0-2000 (0-610) 2000-4500 (610-1370)
*NO ADJUSTMENT REQUIRED
ALTITUDE FT. (M)
Table 6
INLET PRESSURES:
Natural Gas
MAX - 14” WC (3.49 kPa)
MIN - 5”WC (1.25 kPa)
Propane
MAX - 14” WC (3.49 kPa)
MIN - 11”WC (2.74 kPa)
Compact Unit Heater
Fuel Conversion Manual
E-6
THIS PAGE INTENTIONALLY LEFT BLANK
ESTA PÁGINA SE DEJÓ INTENCIONALMENTE EN BLANCO
CETTE PAGE A ÉTÉ INTENTIONNELLEMENT LAISSÉE VIERGE
Compact Unit Heater
Fuel Conversion Manual
E-7
FUEL CONVERSION MANUAL
READ INSTRUCTIONS CAREFULLY: YOUR SAFETY
IS IMPORTANT TO YOU AND TO OTHERS. Read and
follow all instructions. Place instructions in a safe place
Model #
HSU50
HSU80
HSU125
for future reference. Do not allow anyone who has
not read these instructions to assemble, light, adjust or
operate the heater.
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 HEATSTAR LOCAL DEALER,
Mr. HEATER LOCAL DEALER, OR DIRECT FROM THE FACTORY
FOR INFORMATION REGARDING SERVICE:
Please call Toll-Free 1 - (800) - 251 - 0001
Our office hours are 8:00 AM – 5:00 PM, EST, Monday through Friday.
Or contact us using an enerco website:
www.enerco.com • www.heatstarbyenerco.com • www.mrheater.com
Please include the model number, date of purchase, and description of problem in all
communication.
For Big Maxx Heaters using
Honeywell VR8205M valves.
Model #
MHU50
MHU80
MHU125
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 1-888-849-1899.
Address any Warranty Claims to the Service Department, Enerco Group, 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.
Enerco Group, Inc. reserves the right to make changes at any time, without notice or obligation,
in colors, specifications, accessories, materials and models.
Enerco Group, Inc., 4560 W. 160TH ST., CLEVELAND, OHIO 44135 • 1 - (800) - 251 - 0001
Heatstar is a registered trademark of Enerco, Inc.
Mr. Heater is a registered trademark of Enerco, Inc.
© 2018, Enerco. All rights reserved
Compact Unit Heater
Fuel Conversion Manual
E-8