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28

Removing The Burner Orifices

1. Adjust the thermostat to the OFF position, or its lowest 

temperature setting.

2. Turn the main gas supply valve (on the outside of the 

unit) to the OFF position.

3. Turn off all electrical power to the furnace.
4. Remove the door from the burner compartment. See 

Figure 37 (page 29)

.

5. Turn the gas valve ON/OFF knob (1) to the OFF position.

 CAUTION:

It  is  good  practice  to  label  all  wires  prior 

to disconnection. Wiring errors can cause 

improper and dangerous operation.

6. Disconnect the wires from the terminals (2).
7. Remove the supply gas piping from the gas valve inlet 

(3).

8. Remove four screws (4) securing the gas manifold 

assembly (5) to the burner assembly (6).

9. Set aside the screws (4) and remove the gas manifold 

assembly (5) from the burner assembly.

 WARNING:

Do not attempt to drill the gas orifices. Use only 

factory  supplied  orifices.  Improperly  drilled 

orifices  may  cause  fire,  explosion,  carbon 

monoxide poisoning, personal injury or death.

10. Carefully remove the burner orifices (7) from the gas 

manifold assembly (5).

11. 

Read the rating plate affixed to the appliance to 
determine its rated input (Btu/hr) and the size of the 
factory installed orifices. NOTE: Natural Gas furnaces 
may be equipped with one of three orifices.

 WARNING:

Do not use Teflon tape or pipe joint compound 

on the orifice threads. The hole in the orifice 

may become blocked and cause fire, explosion, 

property damage, carbon monoxide poisoning, 

personal injury, or death.

IMPORTANT NOTES:

•  Before installing an orifice, check the face or side 

of the orifice for the drill number to ensure that it 
is the appropriate size.

•  To prevent cross threading, screw the orifices (7) 

into the gas manifold assembly (5) by hand until 
snug, then tighten with a wrench.

12. Install the appropriate LP/Propane orifices (7) into the 

gas manifold assembly (5).

13. Remove the pressure regulator cap (

Figure 36

) from 

the gas valve.

Conversion to LP/Propane

 WARNING:

This  furnace  was  shipped  from  the  factory 

equipped to operate on natural gas. Conversion 

to  LP/propane  gas  must  be  performed  by 

qualified  service  personnel  using  factory 

supplied conversion parts. Failure to use the 

proper conversion kit can cause fire, explosion, 

property damage, carbon monoxide poisoning, 

personal injury, or death.

This furnace can be converted from factory-equipped 
natural gas to Liquid Propane gas. Conversion of this 
valve requires replacement of the burner orifices on the 
manifold assembly and flipping the regulator cap to the 
side marked LP. See 

Figure 36

 below. The orifices required 

for conversion are supplied with the furnace.

For altitudes between 0 and 1,999 feet, only the orifice is 
changed. Altitudes between 2,000 and 10,000 feet require 
both the orifice and regulator pressure to be changed. 
See 

Table 13 (page 41)

 to determine the correct orifice 

size and manifold pressure to use at different altitudes.

 WARNING:

Shut off the gas supply at the manual gas shutoff 

valve, before disconnecting the electrical power. 

A fire or explosion may result causing property 

damage, personal injury or loss of life. Failure to 

follow the safety warnings exactly could result 

in serious injury, death or property damage.

 WARNING:

To avoid electric shock, personal injury, or death, 

turn  off  the  electric  power  at  the  disconnect 

or the main service panel before making any 

electrical connections.

Figure 36

ON

OFF

IN

N

A

T N

A

T

L

P

L

P

Other side 

of cap

Pressure Regulator

Cap

Manifold 

Pressure Plug

Inlet Pressure 

Plug

ON/OFF 

Knob

OR

Figure 36. 

Gas Valve - Top View

Summary of Contents for M4RC-072D-35C

Page 1: ...department RISQUE D INCENDIE OU D EXPLOSION Le non respect des avertissements de s curit pourrait entra ner des blessures graves la mort ou des dommages mat riels L installation et l entretien doivent...

Page 2: ...loor Openings 16 Installing Finger Tabbed Duct Connectors 16 Narrow Duct Attachment Option 1 17 Narrow Duct Attachment Option 2 17 Installing Screw Down Duct Connectors 18 Installing the Downflow Furn...

Page 3: ...rovide adequate combustion and ventilation air to the furnace space as specified on pages 6 9 Provide adequate clearances around the vent air intake terminal as specified in Figure 7 page 11 Figure 8...

Page 4: ...mestic hot water equipment where the bottom of the vent terminal and the air intake is installed above four feet above grade the following requirements must be satisfied a A CO detector and alarm shal...

Page 5: ...Electrical Code NEC ANSI NFPA 70 CANADA Canadian Electrical Code CSA C22 1 Gas Piping Gas Pipe Pressure Testing Current edition of the NFGC and the NFPA 90B For copies contact the National Fire Prote...

Page 6: ...QUE D EMPOISONNEMENT AU MONOXYDE DE CARBONED Le non respect des consignes suivantes portant sur chacun des appareils raccord s au syst me d vacuation mis en service pourrait entra ner l empoisennement...

Page 7: ...htly sealed to the furnace The required sizing of these openings is determined by whetherinsideoroutsideairisusedtosupportcombustion the method by which the air is brought to the space and by the tota...

Page 8: ...ustion Air Drawn from Inside Total Input Rating Btuh Minimum Free Area Each Opening Round Duct Diameter 40 000 100 sq In 12 inches 60 000 100 sq In 12 inches 80 000 100 sq In 12 inches 100 000 100 sq...

Page 9: ...ntly adopted by the NFGC uses one opening within 12 inches of the top of the space This method may be used if it is acceptable to the local codes The following conditions must be met 1 The opening mus...

Page 10: ...onofthefurnacecombustionsystem See list of substances on page 4 Route piping as direct as possible between the furnace and the outdoors Horizontal piping from inducer to the flue pipe must be sloped 1...

Page 11: ...rotection see page 12 Figure 7 12 min to maximum expected snow level both pipes 90 Elbow Exhaust vent option B Exhaust vent option A Mounting kit faceplate secured to wall with screws both pipes Combu...

Page 12: ...exposed to temperatures below freezing i e when it passes through unheated spaces chimneys etc the pipe must be insulated with 1 2 inch thick sponge rubber insulation Armaflex type insulation or equiv...

Page 13: ...ponsible for water leakage which occurs due to loose hose connections or improperly sealed drain line pipes CIRCULATING AIR REQUIREMENTS WARNING Do not allow combustion products to enter the circulati...

Page 14: ...in2 The total free area of openings in the floor or ceiling registers serving the return air duct system must be at least 352 in2 At least one register should be located where it is not likely to be c...

Page 15: ...and other documents supplied with the furnace and or optional air conditioningequipment Unlessitisnoteddifferentlyinthis manual onlyusefactoryauthorizedkitsandaccessorieson thisappliance Refertolocala...

Page 16: ...4 210 901991A 904012 10 1 4 260 901992A 904013 12 1 4 311 901993A 904014 NOTE Dimensions shown as Inches Millimeter Table 3 Duct Connector Sizes X FLOOR OPENING FLOOR CAVITY SUPPLY AIR DUCT Locating...

Page 17: ...form an opening for the duct connector applies to Options A or B 3 Installtheductconnectorwiththebottomtabsextending into the supply air duct 4 Bend the tabs on the bottom of the duct connector upward...

Page 18: ...y Air Duct Hole for Gas Line Wood Floor Bend tabs up 90 Figure 18 Screw Down Duct Connector Figure 20 Figure 20 A C Coil Box Installation D O N O T I N S T A L L S C R E W S I N T H I S S U R F A C E...

Page 19: ...f drilling screws secure the bracket to the A C coil box and the furnace Repeat for other side of furnace 5 Position the plenum on top of the coil box and secure together with sheet metal screws The s...

Page 20: ...have two switches one connected to the static tap on the inducer assembly and the other to the collector box Downflow M4RLSeries furnacesrequireonlyoneswitchconnected to the inducer s static tap as s...

Page 21: ...itch Accessories The components in Figure 27 Figure 28 page 22 Figure 29 Figure 30 are included in the extra parts bag that is supplied with the purchase of M4RC M4RL furnaces Depending on your partic...

Page 22: ...ield Supplied 2 PVC ELBOW Field Supplied PVC Trap 2 PVC Tee 2 x 1 2 PVC Reducer 1 2 x 1 2 Hose Barb 1 2 x 3 4 Hose Barb 2 PVC Pipe from Inline Drain Assembly Not Included 1 2 Tubing Formed into a Loop...

Page 23: ...to the finish flange or vent pipe with a hose clamp if using neoprene couplings Upflowfurnacesrequirethe3 neoprenecouplingclamps to be installed above the coil box Upflow Furnaces Combustion air and...

Page 24: ...secondary heat exchanger A drain must always be at the lowest point of the venting system NOTE Ifusingacondensatepump thefurnace drain line must be installed above the pumps water line Exceptions clar...

Page 25: ...ply with the latest edition of the National Fuel Gas Code ANSIZ223 1 or CAN CGAB149 1or 2 Installation Codes Some local regulations require the installation of a manual main shut off valve and ground...

Page 26: ...t t une solution savonneuse commerciale fabriqu esp cifiquementpurlad tectiondes fuites de gaz Un incendie ou une explosion peut entra ner des dommages mat riels des blessures ou la mort AVERTISSEMENT...

Page 27: ...Shut Off Valve location requirements NOTE B Inducer assembly omitted for clarity of pipe installation Figure 35 Typical Gas Connections 4 7 5 3 6 UPFLOW MODELS DOWNFLOW MODELS 9 2 See Note B 1 3 See...

Page 28: ...screw the orifices 7 into the gas manifold assembly 5 by hand until snug then tighten with a wrench 12 Install the appropriate LP Propane orifices 7 into the gas manifold assembly 5 13 Remove the pre...

Page 29: ...vent cross threading hand tighten the plug first then tighten with 3 16 Allen wrench Measuring the Manifold Pressure The manifold pressure must be measured by installing a pressure gauge Manometer Mag...

Page 30: ...t 105 F 40 C For electrical specifications refer to the furnace nameplate or Table 5 page 32 2 Check all gas connections for leaks with a soap and water solution If the solution bubbles there is a gas...

Page 31: ...s or 2 Measure the current flow on the thermostat R W circuit after the circulating blower motor has started The six pin terminal marked Expansion Port is not used in the single stage furnace as shipp...

Page 32: ...MOTOR CONNECTION FIELD WIRING LOW VOLTAGE CONNECTION R C Y G W NOTE The Y terminal on the control board must be connected to the thermostat for proper cooling mode operation Connect R W For Heating O...

Page 33: ...t gas per hr Local heating value of the gas obtained from gas supplier 1 040 Btu per cubic ft Input rate 1 040 x 90 93 600 Btuh Verifying Adjusting Input Rate IMPORTANT NOTE The input rate must not ex...

Page 34: ...l for cooling the contactorintheoutdoorcondensingunitisde energized and the control continues to run the fan for a period of 60 seconds Fan Mode When the thermostat energizes the G terminal for contin...

Page 35: ...rned open Is the gas turned on Are any manual reset switches open Is the filter dirty or plugged Is the flame sensor coated Remove and clean with steel wool Do not use emery cloth or sandpaper Is ther...

Page 36: ...ter s An air filter is supplied with the furnace as shipped from the factory It is recommended that filters be cleaned or replaced monthly during the heating season WARNING Never operate the furnace w...

Page 37: ...ng Bottom Return Opening RC Upflow Furnace Model s Dim A Dim B Dim C 054D 24B 17 1 2 15 7 8 16 1 8 072D 35C 21 19 3 8 19 5 8 090D 35C 108D 45D 24 1 2 22 7 8 23 1 8 NOTE Dimensions shown in inches A 34...

Page 38: ...1590 48 1555 49 1495 51 1435 53 1340 57 Low 1410 54 1390 55 1365 56 1330 58 1310 59 1275 60 1235 62 1210 63 RC090D 35C Side Return 90 000 High 2240 2175 35 2100 37 2040 38 1985 39 1910 40 1825 42 172...

Page 39: ...agnostic Description Low Flame Sensor Signal Flame Present FAULT CONDITIONS Yellow LED Continuous Flash On Alternating Flash Replaces 710915B IGNITOR INDUCER FLAME SENSOR C BLOWER LIMIT DOOR SWITCH R...

Page 40: ...44 220 439 84 43 214 429 86 42 209 419 88 41 205 409 90 40 200 400 92 39 196 391 94 38 191 383 96 38 188 375 98 37 184 367 100 36 180 360 102 35 176 353 104 35 173 346 106 34 170 340 108 33 167 333 11...

Page 41: ...3 0 Manifold Pressure 9 000 to 9 999 FT 49 49 49 49 Orifice Size 2 8 2 8 2 8 2 8 Manifold Pressure Table 12 Table 12 High Altitude Deration Chart for Natural Gas Low Heating Value NATURAL GAS LOW HEAT...

Page 42: ...air supply inlet to building or the combustion air inlet to any other appliance 6 inches 15cm for appliances 10 000 Btuh 3kW 6 inches 15cm for appliances 10 000 Btuh 3kW 4 ft 1 2m below or to side of...

Page 43: ...Close to Furnace as Possible 2 x 3 Neoprene Couplings with 2 Hose Clamps Upward Pitch 1 4 Per Foot Exhaust Vent 5 3 Combustion Air Vent Pipe 7 3 x 90 Elbows 3 x 90 Elbow Exhaust Vent 3 Exhaust Vent St...

Page 44: ...STION AIR X See NOTE 5 X See NOTE 5 PVC Tee PVC Trap X See NOTE 5 X See NOTE 5 PVC Tee PVC Trap Collector Box Drain Factory Equipped See NOTE 2 Inline Drain Field Supplied See NOTES 2 3 Drain Line Att...

Page 45: ...PE Inline Drain Factory Supplied See NOTE 4 Collector Box Drain Factory Equipped See NOTE 2 Inline Drain Factory Supplied See NOTE 4 Collector Box Drain Factory Equipped See NOTE 2 Drain Line Attached...

Page 46: ...controls the flow of gas to the burners When the gas valve is energized it automatically opens and regulates the gas pressure in the manifold Inducer Assembly The inducer assembly vents products of co...

Page 47: ...47...

Page 48: ...nstructions to the customer s package for future reference ELECTRICAL SYSTEM Electrical connections tight YES NO Line voltage polarity correct YES NO Supply Voltage _________________________________ V...

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