Lennox ML18007036A-EC Installation Instructions Manual

Brand: Lennox

Model: ML18007036A-EC

Category: Water heaters & boilers

Type: Installation Instructions Manual

This manual is also suitable for

INSTALLATION INSTRUCTIONS

THIS MANUAL MUST BE LEFT WITH THE

HOMEOWNER FOR FUTURE REFERENCE

LENNOX MERIT SERIES™ GAS FURNACE

506998-01

08/2013 Supersedes 06/2012

Improper installation, adjustment, alteration,

service or maintenance can cause property

damage, personal injury or loss of life.

Installation and service must be performed

by a licensed professional installer (or

equivalent), service agency or the gas

supplier.

WARNING

As with any mechanical equipment, personal

injury can result from contact with sharp

sheet metal edges. Be careful when you

handle this equipment.

CAUTION

TABLE OF CONTENTS

Lennox Merit Series™ Furnace Specications ........... 2

Lennox Merit Series™ Gas Furnace ............................ 3

Shipping and Packing List........................................... 3

Requirements ............................................................... 3

General ......................................................................... 4

Shipping and Packing List........................................... 4

General ......................................................................... 4

Location/Placement ..................................................... 4

Duct System ................................................................. 5

Installing Optional Cooling Coil ................................... 5

Venting ......................................................................... 6

General Lennox Merit Series™ E or EC Series ......... 17

Gas Piping .................................................................. 17

Electrical .................................................................... 18

Filters ......................................................................... 19

Duct System ............................................................... 19

Venting ....................................................................... 19

Gas Piping .................................................................. 19

Electrical .................................................................... 21

Integrated Control ...................................................... 22

Lennox Merit Series™ Schematic wiring diagram ... 23

Unit Start-Up .............................................................. 24

Gas Pressure Adjustment .......................................... 25

Proper Combustion .................................................... 26

High Altitude .............................................................. 26

Other Unit Adjustments ............................................. 27

Service ....................................................................... 28

Repair Parts ............................................................... 31

This is a safety alert symbol and should never be ignored.

When you see this symbol on labels or in manuals, be alert to

the potential for personal injury or death.

MODEL DIMENSIONS mm

A B C D

ML18007036A-E 456 512 80 -

ML18007036A-EC 456 512 80 533

ML18011060C-E 544 600 123 -

ML18011060C-EC 544 600 123 438

ML18013560D-E 633 690 167 -

ML18013560D-EC 633 690 167 438

LENNOX MERIT SERIES™ FURNACE SPECIFICATIONS

NOTE: DUCT CONNECTIONS ARE INTERCHANGEABLE FROM SIDE TO SIDE

LENNOX MERIT SERIES™ GAS FURNACE

SHIPPING AND PACKING LIST

REQUIREMENTS

The Lennox Merit Series™ unit is shipped ready for

installation for external applications.

Package 1 of 1 contains:

1 x Assembled Lennox Merit Series™ unit

1 x Bag assembly containing the following:

2 x Screws

1 x Snap bushing

1 x Snap plug

1 x Wire tie

1 x Vent warning label

1 x Owner’s manual

1 x Bag assembly containing the following:

1 x 2.5m Power cord

The following items may be ordered separately:

1 x Thermostat

1 x Propane/LP changeover kit

1 x High altitude kit

Check equipment for shipping damage. If you nd any

damage, immediately contact the last carrier.

The Lennox Merit Series™ furnace is approved for

installation for outside of building, with clearances as listed

in Figure 6. (Accessibility and service clearances must take

precedence over re protection clearances). Installation of

Lennox forced air central furnaces must be in accordance

with these instructions, local gas tting regulations,

municipal building codes, electrical wiring regulations and

the current edition of the Australian Gas Installation Code

(AS5601).

Adequate clearance must be made around the air openings

into the vestibule area. Provisions shall be made for proper

operation and for combustion air and ventilation air supply

according to the current edition of the Australian Gas

Installation Code (AS5601).

NOTE: For installation on combustible oors, the furnace

shall not be installed directly on carpeting, tile, or other

combustible material other than wood ooring.

For installation in a residential garage, the furnace must be

installed so that the burner(s) and the ignition source are

located no less than 457 mm (18 in) above the oor.

The furnace must be located or protected to avoid physical

damage by vehicles. When a furnace is installed in a public

garage, hangar, or other building that has a hazardous

atmosphere, the furnace must be installed according to

recommended good practice requirements and current

edition of the Australian Gas Installation Code (AS5601).

Unit must be adjusted to obtain a temperature rise within

the range specied on appliance rating plate. This Lennox

Merit Series™ furnace must be installed so that its electrical

components are protected from water.

When this furnace is used with cooling units, it shall be

installed in parallel with, or on the upstream side of, cooling

units to avoid condensation in the heating compartment.

With a parallel ow arrangement, a damper (or other means

to control the ow of air) must adequately prevent chilled

air from entering the furnace. If the damper is manually

operated, it must be equipped to prevent operation of either

the heating or the cooling unit, unless it is in the full HEAT or

COOL setting.

When installed, this furnace must be electrically

grounded according to local codes.

All eld wiring must comply with the current edition

of Australian Standard AS3000.

The blower access panel must be securely

in place when the blower and burners are

operating. Gas fumes, which could contain

carbon monoxide, can be drawn into living

space resulting in personal injury or death.

WARNING

GENERAL GENERAL

LOCATION / PLACEMENT

These instructions are intended as a general guide and do

not supersede local codes in any way. Consult authorities

having jurisdiction before installation.

In addition to the requirements outlined previously, the

following general recommendations must be considered

when installing a Lennox Merit Series™ furnace:

Place the furnace as close to the center of the air

distribution system as possible.

Do not block the furnace combustion air openings with

clothing, boxes, doors, etc. Air is needed for proper

combustion and safe unit operation.

These instructions are intended as a general guide and

do not supersede local codes in any way. Consult AGA.

AG-601 INSTALLATION CODE or authorities having

jurisdiction before installation.

The Lennox Merit Series™ furnace is approved for

installation outside the building only with clearances as listed

in Table 1.

Installation of Lennox outdoor central furnaces must be

in accordance with these instructions, local gas tting

regulations, municipal building codes, electrical wiring

regulations and the current edition of the Australian Gas

Installation Code (AG 601).

The following general recommendations should be considered

when installing the Lennox Merit Series™ Gas Furnace.

The Lennox Merit Series™ Gas Furnace can be installed in

either right or left hand mode.

NOTE: On some models - 1/3 and 1/2 hp blower motors

are equipped with either four exible mounting legs or three

exible legs and one rigid leg. The rigid leg is equipped with

a shipping bolt and a at white plastic washer (rather than

the rubber mounting grommet used with a exible mounting

leg). This shipping bolt and at washer must be removed

before the furnace is put into operation. Once the shipping

bolt and washer are removed, the rigid leg will not touch the

fan housing.

Select a unit location that will allow for required clearances

per local AG 601 codes and in Table 1.

Also consider gas supply connections, electrical supply, vent

termination and installation and service clearances (600mm

front).

Accessibility and service clearances must not take

precedence over re protection clearances.

The Lennox Merit Series™ Gas Furnace furnace should be

set on a eld-provided platform to keep the unit base out

of water. The unit is equipped with base rails, which lift the

bottom of the unit off of the platform. Unit must be levelled

using shims or levelling bolts. Knock-outs are provided in

unit base to install eld-provided levelling bolts.

Do not install the furnace in a corrosive

or contaminated atmosphere. Meet all

combustion and ventilation air requirements,

as well as all local codes.

CAUTION

SHIPPING AND PACKING LIST

Package 1 of 1 contains:

1 x Assembled unit

1 x Flue adapter/cowl eld–installed

2 x Starting collars

The following additional items may be ordered separately,

if required:

1 x Cooling coil

1 x Thermostat

1 x LP Changeover kit

Check unit for shipping damage. Receiving party should

contact last carrier immediately if any shipping damage is

found.

DUCT SYSTEM INSTALLING OPTIONAL

COOLING COIL

The unit is provided with knock-outs for either right or left-

side connection of the supply and return air plenums.

Refer to the dimensioned drawing on page 2 to locate and

size the plenum entry into the side of the building.

Cover plates are provided to seal the unused knock-outs and

these become convenient access ports for regular service

and maintenance.

Size and install supply and return air duct system using

industry-approved standards that result in a quiet and

low-static system with uniform air distribution. The furnace

access panel must always be in place when the unit is in

operation and it must not allow leaks into the duct system.

Construct a protective covering made of suitable materials to

shield the plenum connections from rain. Rain shield should

be attached to the side of the unit cabinet above the plenum

connections and span the distance to the building wall above

the plenum entry into the structure. Rain shield connections

must be caulked so that they are weather-tight.

If optional cooling coil is to be used, install coil according to

the steps indicated below:

1. Remove Lennox Merit Series™ Gas Furnace unit rear

panel.

NOTE: Installation of larger evaporator coils may require

removal of unit top panel as well.

2. Place cooling coil on unit coil deck in cooling

compartment.

3. Using template provided with the coil, cut holes for

refrigeration and drain piping. Align coil with piping holes

in panel. Seal holes around piping.

4. Reinstall Lennox Merit Series™ panel.

5. Make refrigerant piping connections to condensing unit

per local codes and sound plumbing practices.

Ref. Item Minimum clearances mm

Natural draft Fan assisted

A Below eaves, balconies and other projections:

• Appliances up to 50 Mj/h input

• Appliances over 50 Mj/h input

300

500

200

300

B From the ground, above a balcony or other surface* 300 300

C From a return wall or external corner* 500 300

D From a gas meter (M) (see 4.7.11 for vent terminal location of regulator) 1000 1000

E From an electricity meter or fuse box (P) 500 500

F From a drain pipe or soil pipe 150 75

G Horizontally from any building structure* or obstruction facing a terminal 500 500

H From any other ue terminal, cowl, or combustion air intake* 500 300

J Horizontally from an openable window, door, non-mechanical air inlet, or any other

opening into a building with the exception of sub-oor ventilation:

• Appliances up to 150 Mj/h input

• Appliances over 150 Mj/h input up to 200 Mj/h input

• Appliances over 200 Mj/h input

• All fan-assisted ue appliances, in the direction of discharge

500

1500

300

500

1500

K From a mechanical air inlet, including a spa blower 1500 1000

N Vertically below an openable window, non-mechanical air inlet, or any other opening

into a building with the exception of sub-oor ventilation:

• Space heaters up to 50 Mj/h input

• Other appliances up to 50 Mj/h input

• Appliances over 50 Mj/h input and up to 150 Mj/h input

• Appliances over 150Mj/h input

150

500

1000

1500

150

500

1000

1500

*Unless appliance is approved for closer installation

NOTES:

1. All distances are measured to the nearest part of the terminal.

2. Prohibited area below electricity meter or fuse box extends to

ground level.

3. See Clause 5.13.6.6 for restrictions on a ue terminal under a

covered area.

4. See Appendix J, Figures J2(a) and J3(a), for clearances required from a

ue terminal to an LP Gas cylinder. A ue terminal is considered to be a

source of ignition.

5. For appliances not addressed above, approval shall be obtained from

the Authority.

Figure 1

VENTING

The Lennox Merit Series™ unit is shipped standard for top ue discharge. A ue adapter is supplied with the furnace. It must

be installed on the outside of the furnace.

FLUE TERMINATION

CLEARANCES

VENTING

A 4−inch diameter ue transition is factory-inst

alled on the

combustion

air inducer outlet of all models. Figure 3

shows

the combustion air inducer as shipped from the

factor

FIGURE 2

Mounting Screws Location

Mounting Screws

Flue Transition

Upow Position

FIGURE 3

UPFLOW POSITION

Top Vent Discharge

FLOW

AIR

Collector Box

Vent Pipe

Flue

Transition

Pressure

Switch

Make−Up

Box

IMPORTANT

The unit will not vent properly with the ue transition

pointed down in the 6 o’clock position.

The combustion air inducer may be rotated clock-

wise or counterclockwise by 90° to allow for top or

side vent discharge in all applications. When the unit

is installed, the ue transition must be in the 9

o’clock, 12 o’clock or 3 o’clock position.

necessary, reposition the combustion air inducer, pres-

sure

switch and/or make−up box as needed per the follow-

ing

steps. See gures 3 through 9.

1 − Remove the four mounting screws (gure 2) which

secure the combustion air inducer / pressure switch

assembly to the orice plate. Lift the assembly and ro-

tate it 90 degrees clockwise or counterclockwise to ei-

ther the 3 o’clock position or to 9 o’clock position. Re−

secure with four screws. Gasket should be left in place.

2 − Use tin snips to cut preferred opening on the cabinet

for repositioning the ue outlet. Use the cut−out piece

as a cover plate to patch unused opening on cabinet.

UPFLOW POSITION

Left Side Vent Discharge

FIGURE 4

Cut combustion air inducer tubing from 225mm to 125mm

to avoid interference with inducer motor

Remove make−up box assembly (2 screws) and cut wire tie to

free make−up box wires. Re−install make−up box on other side

of cabinet.

Re−secure make−up box wires: Either pull excess wires

through the blower compartment and secure using supplied

wire tie, or coil excess wire and secure to the gas manifold.

FLOW

AIR

Make−Up

Box

Pressure

Switch

Flue

Transition

Vent Pipe

Collector Box

Gas supply piping must be brought into the unit from the right

side in order to accommodate the ue pipe.

UPFLOW POSITION

Right Side Vent Discharge

FIGURE 5

FLOW

AIR

Cover Plate Flue Transition

Vent Pipe

Pressure

Switch

Make−Up

Box

Collector Box

Cut combustion air inducer tubing from 225mm to 125mm

to avoid interference with inducer motor

VENTING

HORIZONTAL LEFT POSITION

Top Vent Discharge

FIGURE 6

Disconnect pressure switch hose from barbed tting on the

pressure switch assembly. Remove pressure switch assembly

(1 screw) and cut wire tie to free pressure switch wires.

Re−install pressure switch on the other side of orice plate and

re−connect pressure switch hose.

Re−secure pressure switch wires: Either pull excess wires

through the blower compartment and secure using supplied

wire tie, or coil excess wire and secure to the gas manifold.

Pressure

Switch

Vent Pipe

Flue

Transition

Cover Plate

Make−Up Box Collector Box

FLOW

AIR

FIGURE 7

Make−Up Box Collector Box

Vent Pipe

Pressure Switch

HORIZONTAL LEFT POSITION

Side Vent Discharge

Disconnect pressure switch hose from barbed tting on the

pressure switch assembly. Remove pressure switch assembly

(1 screw) and cut wire tie to free pressure switch wires. Re−

install pressure switch on the other side of orice plate and re−

connect pressure switch hose.

Re−secure pressure switch wires: Either pull excess wires

through the blower compartment and secure using supplied

wire tie, or coil excess wire and secure to the gas manifold.

FLOW

AIR

Cut combustion air inducer tubing from 225mm to 125mm

to avoid interference with inducer motor

HORIZONTAL RIGHT POSITION

Top Vent Discharge

FIGURE 8

Remove make−up box assembly (2 screws) and cut wire tie to

free make−up box wires. Re−install make−up box on other side

of cabinet.

Re−secure make−up box wires: Either pull excess wires through

the blower compartment and secure using supplied wire tie, or

coil excess wire and secure to the gas manifold.

FLOW

AIR

Flue

Transition

Vent Pipe

Pressure Switch

Cover Plate

Make−Up Box

Collector Box

Gas supply piping must be brought into the unit from the bot-

tom in order to accommodate the ue pipe.

Cut combustion air inducer tubing from 225mm to 125mm

to avoid interference with inducer motor

HORIZONTAL RIGHT POSITION

Side Vent Discharge

FIGURE 9

FLOW

AIR

Pressure Switch

Flue Transition

Collector Box

Make−Up Box

VENTING

The Lennox Merit Series

Gas Furnace units

are classied as fan−assisted

Category I furnaces

when vertically vented according to the latest edition

of National Fuel Gas Code (NFPA 54 / ANSI Z223.1)

in the USA. A fan−assisted Category I furnace is an

appliance equipped with an integral mechanical means

to either draw or force combustion products through the

combustion chamber and/or heat exchanger. The internal

unit is not approved for use with horizontal venting.

NOTE −

Use these instructions as a guide. They do not su-

persede local codes. This furnace must be vented accord-

ing to all local codes these installation instructions, and the

provided venting tables in these instructions

The venting tables in this manual were extracted from the

National Fuel Gas Code (NFPA 54 / ANSI Z223.1) and are

provided as a guide for proper vent installation. Proper ap-

plication, termination, construction and location of vents

must conform to local codes having jurisdiction.

of local codes, the NFGC serves as the

dening document.

Refer to the tables and the venting information contained in

these instructions to properly size and install the venting

system.

Use self−drilling sheet metal screws or a mechanical fas-

tener to rmly secure the vent pipe to the round collar of the

ue transition. If self−drilling screws are used to attach the

vent pipe, it is recommended that three be used. Drive one

self−drilling screw through the front and one through each

side of the vent pipe and collar. See gure 10.

Install the rst vent connector elbow at a minimum of six

inches (152 mm) from the furnace vent outlet. See gure

10.

Venting Using a Masonry Chimney

The following additional requirements apply when a lined

masonry chimney is used to vent this furnace.

Masonry chimneys used to vent Category I central fur-

naces must be either tile-lined or lined with a listed metal

lining system or dedicated gas vent. Unlined masonry

chimneys are prohibited. See gures 11 and 12 for com-

mon venting.

A chimney with one or more sides exposed to the outside of

the structure is considered to be an exterior chimney.

An exterior masonry chimney that is not tile−lined must be

lined with B1 vent or a listed insulated exible metal vent.

An exterior tile−lined chimney that is sealed and

capped

may be lined with a listed uninsulated exible metal vent.

If the existing chimney will not accommodate a listed metal

liner, either the chimney must be rebuilt to accommodate

one of these liners or an alternate approved venting meth-

od must be found.

Insulation for the exible vent pipe must be an encapsu-

lated berglass sleeve recommended by the exible vent

pipe manufacturer. See gure 11.

IMPORTANT

Once the venting system is installed, attach

connected Vent" warning sticker to a visible area of

the plenum near the vent pipe. See gure 10. The

warning sticker is provided in the bag assembly. Or-

der kit 66W04 for additional stickers.

WARNING

Asphyxiation hazard. The exhaust vent for this fur-

nace must be securely connected to the furnace ue

transition at all times.

FIGURE 10

FLUE TRANSITION

COLLAR

VENT PIPE

(min. 150mm length)

“DISCONNECTED VENT”

WARNING

STICKER

FLUE

TRANSITION

COLLAR

VENT CONNECTION UPFLOW AND HORIZONTAL POSITION

VENT PIPE

(min. 150mm length)

“DISCONNECTED VENT”

WARNING

STICKER

In the absence

VENTING

FIGURE 11

Common Venting Using Metal−Lined Masonry Chimney

4 in. (102 mm)

minimum

MIN. LENGTH −− AS

SHORT AS PRACTICAL

MAX. LENGTH

−− SEE NOTE 1

BELOW.

SEALED

PERMANENTLY

SEALED FIREPLACE

OPENING

EXTERIOR

CHIMNEY WITH

METAL

LINER

VENT CONNECTOR

NOTE 1 − Refer to the provided venting tables for installations. Refer

to the capacity requirements shown in the provided venting tables.

OTHER

APPLIANCE

FURNACE

5 ft. (1.5 m)

minimum

NOT insulate the space between the liner and the

chimne

y wall with puffed mica or any other loose gran-

ular insulating material.

IMPORTANT

SINGLE appliance venting of a fan-assisted furnace

into a tile-lined masonry chimney (interior or outside

wall) is PROHIBITED. The chimney must rst be lined

with either type B1 vent or an insulated single wall

exible vent lining system which has been sized ac-

cording to the provided venting tables and the vent

pipe manufacturer’s instructions.

fan−assisted furnace may be commonly vented into an

existing

lined masonry chimney if the following conditions

are met:

The chimney is currently serving at least one drafthood−

equipped appliance;

The vent connectors and chimney are sized according

to the provided venting tables.

type B1 double-wall vent is used inside a chimney, no oth-

er appliance can be vented into the chimney

. The outer wall

of type B1 vent pipe must not be exposed to ue product

type B1 vent or masonry chimney liner shall terminate

above the

roof surface with a listed cap or a listed roof as-

sembly

according to the terms of their respective listings

and the vent manufacturer’s instructions.

When inspection reveals that an existing chimney is not

safe for the intended purpose, it shall be rebuilt to conform

to nationally recognised standards, lined or relined with

suitable materials, or replaced with a gas vent or chimney

suitable for venting the units. The chimney

passageway

must be checked periodically to ensure that it is clear and

free of obstructions.

Do not install a manual damper, barometric draft regulator,

or ue restrictor between the furnace and the chimney.

Never connect a Category I appliance to a chimney that is

servicing a solid−fuel appliance. If a replace chimney ue

is used to vent this appliance, the replace opening must

be permanently sealed.

A type B or listed chimney lining system that passes

through an unused masonry chimney ue is not considered

to be exposed to the outdoors.

General Venting Requirements

Vent all internal furnaces according to these instructions:

1 −Vent diameter recommendations and maximum allow-

able piping runs are found in the provided venting

tables.

2 −In no case should the vent or vent connector diameter

be less than the diameter specied in the provided

venting tables.

3 −The minimum vent capacity determined by the sizing

tables must be less than the low re input rating and the

maximum vent capacity must be greater than the high

re input rating.

4 −Single appliance vents − If the vertical vent or tile-lined

chimney has a larger diameter or ow area than the

vent connector, use the vertical vent diameter to de-

termine the minimum vent capacity and the vent

connector diameter to determine the maximum vent

capacity. The ow area of the vertical vent, however,

shall not exceed 7 times the ow area of the listed ap-

pliance categorized vent area, drafthood outlet area or

ue collar area unless designed according to approved

engineering methods.

5 −Multiple appliance vents − The ow area of the largest

section of vertical vent or chimney shall not exceed 7

times the smallest listed appliance categorized vent

area, drafthood outlet area or ue collar area unless de-

signed according to approved engineering methods.

VENTING

FIGURE 12

Common Venting Using Tile−Lined Interior Masonry Chimney and Combined Vent Connector

MINIMUM LENGTH = AS SHORT AS PRACTICAL.

FOR MAXIMUM LENGTH SEE NOTE TO LEFT

INTERIOR TILE−LINED

MASONRY CHIMNEY

NOTE − the chimney must be properly

sized per provided venting tables or

lined with listed metal lining system.

PERMANENTLY

SEALED FIREPLACE

OPENING

VENT

CONNECTOR

NOTE− Refer to provided venting

tables for installations.

FURNACE

OTHER

APPLIANCE

6 −

The entire length of single wall metal vent connector

shall be readily accessible for inspection, cleaning,

and replacement.

7 −

Single appliance venting congurations with zero lateral

lengths are assumed to have no elbows in the vent

system. For all other vent congurations, the vent

system is assumed to have two 90° elbows. For each

additional 90° elbow or equivalent (for example two

45° elbows equal one 90° elbow) beyond two, the

maximum capacity listed in the venting table should

be reduced by 10% (0.90 x maximum listed capacity).

8 −

The common venting tables (5, 6, 7, and 8) were gen-

erated using a maximum horizontal vent connector

length of 1−1/2 feet (.46 m) for each inch (25 mm) of

connector diameter as follows:

Connector Diameter

inches (mm)

Maximum Horizontal

Connector Length feet (m)

3 (76) 4−1/2 (1.37)

4 (102) 6 (1.83)

5 (127) 7−1/2 (2.29)

6 (152) 9 (2.74)

7 (178) 10−1/2 (3.20)

9 −

If the common vertical vent is offset, the maximum

common vent capacity listed in the common venting

tables should be reduced by 20%, the equivalent of two

90° elbows (0.80 x maximum common vent capacity).

The horizontal length of the offset shall not exceed

1-1/2 feet (.46 m) for each inch (25 mm) of common

vent diameter.

10 − The vent pipe should be as short as possible with the

least number of elbows and angles required to com-

plete the job. Route the vent connector to the vent us-

ing the shortest possible route.

11 − A vent connector shall be supported without any di

or sags and shall slope a minimum of 1/4 inch (6.4 mm)

per linear foot (305 mm) of connector, back toward the

appliance.

12 − Vent connectors shall be rmly attached to the furnace

ue collar by self−drilling screws or other approved

means, except vent connectors of listed type B vent

material which shall be assembled according to the

manufacturer’s instructions. Joints between sections

of single wall connector piping shall be fastened by

screws or other approved means.

13 − When the vent connector used for Category I ap-

pliances must be located in or pass through a crawl-

space, attic or other areas which may be cold, that por-

tion of the vent connector shall be constructed of listed

double-wall type B vent material or material having

equivalent insulation qualities.

14 − All venting pipe passing through oors, walls, and ceil-

ings must be installed with the listed clearance to com-

bustible materials and be re stopped according to lo-

cal codes. In absence of local codes, refer to NFGC

(Z223.1).

15 − No portion of the venting system can extend into, or pas

through any circulation air duct or plenum.

VENTING

16 −Vent connectors serving Category I appliances shall

not be connected to any portion of mechanical draft

systems operating under positive pressure such as

Category III or IV venting systems.

7 − If vent connectors are combined prior to entering the

common vent, the maximum common vent capacity

listed in the common venting tables must be reduced by

10%, the equivalent of one 90° elbow (0.90 x maximum

common vent capacity).

18 −

The common vent diameter must always be at least as

large as the largest vent connector diameter.

19 −

In no case, shall the vent connector be sized more than

two consecutive table size diameters over the size of

the draft hood outlet or ue collar outlet.

20 − Do not install a manual damper,

barometric draft regu-

lator or ue restrictor between the furnace and the

chimney.

21 − When connecting this appliance to an existing dedi

cated or common venting system, you must inspect the

venting system’s general condition and look for signs

of corrosion. The existing vent pipe size must conform

to these instructions and the provided venting tables. If

the existing venting system does not meet these re-

quirements, it must be resized.

Capacity of Type B Double−Wall Vents with Type B Double−Wall Connectors

Serving a Single Category I Appliance

Height

(m) (m)

Lateral

Vent and Connector Diameter − D (mm)

76mm 100mm 125mm 150mm

Appliance Input Rating in Thousands of Btu Per Hour

MIN MAX MIN MAX MIN MAX MIN MAX

1.8

2.4

4.5

3.0

6.0

9.0

0 0 78 0 152 0 251 0 375

0.6 13 51 18 97 27 157 32 232

1.2 21 49 30 94 39 153 50 227

1.8 25 46 36 91 47 149 59 223

0 0 84 0 165 0 276 0 415

0.6 12 57 16 109 25 178 28 263

1.5 23 53 32 103 42 171 53 255

2.4 28 49 39 98 51 164 64 247

00 88 0 175 0 295 0 447

0.6 12 61 17 118 23 194 26 289

1.5 23 57 32 113 41 187 52 280

3.0 30 51 41 104 54 176 67 267

00 94 0 191 0 327 0 502

0.6 11 69 15 136 20 226 22 339

1.5 22 65 30 130 39 219 49 330

3.0 29 59 40 121 51 206 64 315

4.5 35 53 48 112 61 195 76 301

00 97 0 202 0 349 0 540

0.6 10 75 14 149 18 250 20 377

1.5 21 71 29 143 38 242 47 367

3.0 28 64 38 133 50 229 62 351

4.5 34 58 46 124 59 217 73 337

6.0 48 52 55 116 69 206 84 322

00 100 0 213 0 374 0 587

0.6 9 81 13 166 14 283 18 432

1.5 21 77 28 160 36 275 45 421

3.0 27 70 37 150 48 262 59 405

4.5 33 64 44 141 57 249 70 389

6.0 56 58 53 132 66 237 80 374

9.0 NA NA 73 113 88 214 104 346

NOTE − Single appliance venting congurations with zero lateral lengths are assumed to have no elbows in the vent system. For all other

vent congurations, the vent system is assumed to have two 90° elbows. For each additional 90° elbow or equivalent (for example two 45°

elbows equal one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maxi-

mum listed capacity).

VENTING

Capacity of Type B Double−Wall Vents with Single−Wall Metal Connectors

Serving a Single Category I Appliance

Height

(m)(m)

Lateral

Vent and Connector Diameter − D (mm)

76mm 100mm 125mm 150mm

Appliance Input Rating in Thousands of Btu Per Hour

MIN MAX MIN MAX MIN MAX MIN MAX

1.8

2.4

6.0

9.0

4.5

3.0

0 38 77 59 151 85 249 126 373

0.6 39 51 60 96 85 156 123 231

1.2 NA NA 74 92 102 152 146 225

1.8

0.6

1.5

2.4

0.6

1.5

3.0

0.6

1.5

3.0

4.5

0.6

1.5

3.0

4.5

6.0

0.6

1.5

3.0

4.5

6.0

9.0

NA NA 83 89 114 147 163 220

37 83 58 164 83 273 123 412

39 56 59 108 83 176 121 261

NA NA 77 102 107 168 151 252

NA NA 90 95 122 161 175 243

37 87 57 174 82 293 120 444

39 61 59 117 82 193 119 287

52 56 76 111 105 185 148 277

NA NA 97 100 132 171 188 261

36 93 56 190 80 325 116 499

38 69 57 136 80 225 115 337

51 63 75 128 102 216 144 326

NA NA 95 116 128 201 182 308

NA NA NA NA 158 186 220 290

35 96 54 200 78 346 114 537

37 74 56 148 78 248 113 375

50 68 73 140 100 239 141 363

NA NA 93 129 125 223 177 344

NA NA NA NA 155 208 216 325

NA NA NA NA 186 192 254 306

34 99 53 211 76 372 110 584

37 80 55 164 76 281 109 429

49 74 72 157 98 271 136 417

NA NA 91 144 122 255 171 397

NA NA 115 131 151 239 208 377

NA NA NA NA 181 223 246 357

NA NA NA NA NA NA NA NA

NOTE − S

ingle appliance venting congurations with zero lateral lengths are assumed to have no elbows in the vent system. For all other

vent congurations, the vent system is assumed to have two 90° elbows. For each additional 90° elbow or equivalent (for example two 45°

elbows equal one 90° elbow) beyond two, the maximum capacity listed in the venting ta

ble should be reduced by 10 percent (0.90 x maxi-

mum listed capacity).

VENTING

Vent Connector Capacity

Type B Double−Wall Vents with Type B Double−Wall Connectors

Serving Two or More Category I Appliances

Vent

Height

(m)

Connector

Rise

(m)

Vent and Connector Diameter − D (mm)

25mm 50mm 125mm 150mm

Appliance Input Rating in Thousands of Btu Per Hour

MIN MAX MIN MAX MIN MAX MIN MAX

1.8

122 37 35 66 46 106 58 164

0.6 23 41 37 75 48 121 60 183

0.9 24 44 38 81 49 132 62 199

2.4

22 40 35 72 49 114 64 176

23 44 36 80 51 128 66 195

24 47 37 87 53 139 67 210

3.0

22 43 34 78 49 123 65 189

23 47 36 86 51 136 67 206

24 50 37 92 52 146 69 220

4.5

21 50 33 89 47 142 64 220

22 53 35 96 49 153 66 235

24 55 36 102 51 163 68 248

6.0

21 54 33 99 46 157 62 246

22 57 34 105 48 167 64 259

23 60 35 110 50 176 66 271

9.0

20 62 31 113 45 181 60 288

21 64 33 118 47 190 62 299

22 66 34 123 48 198 64 309

Common Vent Capacity

Type B Double−Wall Vents with Type B Double−Wall Connectors

Serving Two or More Category I Appliances

Vent

Height

(m)

Common Vent Diameter − D (mm)

100mm 125mm 150mm 175mm

Appliance Input Rating in Thousands of Btu Per Hour

FAN + FANFAN + NAT FAN + FANFAN + NATFAN + FANFAN + NATFAN + FAN FAN + NAT

1.8 92 81 140 116 204 161 309 248

2.4 101 90 155 129 224 178 339 275

3.0 110 97 169 141 243 194 367 299

4.5 125 112 195 164 283 228 427 352

6.0 136 123 215 183 314 255 475 394

9.0 152 138 244 210 361 297 547 459

0.6

0.9

0.6

0.9

0.6

0.9

0.6

0.9

0.6

0.9

VENTING

Vent Connector Capacity

Type B Double−Wall Vents with Single−Wall Metal Connectors

Serving Two or More Category I Appliances

Height

(m)

Lateral

(m)

Vent and Connector Diameter − D (mm)

76mm 100mm 125mm 150mm

Appliance Input Rating in Thousands of Btu Per Hour

MIN MAX MIN MAX MIN MAX MIN MAX

1.8

1 NA NA NA NA NA NA NA NA

0.6 NA NA NA NA NA NA 168 182

0.9 NA NA NA NA 121 131 175 198

2.4

1NA NA NA NA NA NA NA NA

0.6 NA NA NA NA 125 126 184 193

0.9 NA NA NA NA 130 138 191 208

3.0

1NA NA NA NA 119 121 182 186

0.6 NA NA 84 85 124 134 189 203

0.9 NA NA 89 91 129 144 197 217

4.5

1NA NA 79 87 116 138 177 214

0.6 NA NA 83 94 121 150 185 230

0.9 NA NA 87 100 127 160 193 243

6.0

149 56 78 97 115 152 175 238

0.6 52 59 82 103 120 163 182 252

0.9 55 62 87 107 125 172 190 264

9.0

147 60 77 110112 175 169 278

0.6 51 62 81 115117 185 177 290

0.9 54 64 85 119 122 193 185 300

NOTE − Single appliance venting congurations with zero lateral lengths

are assumed to have no elbows in the vent system. For all other

vent congurations, the vent system is assumed to have two 90° elbows. For each additional 90° elbow or equivalent (for example two 45°

elbows equal one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maxi

mum listed capacity).

Common Vent Capacity

Type B Double−Wall Vents with Single−Wall Metal Connectors

Serving Two or More Category I Appliances

Vent

Height

(m)

Common Vent Diameter − D (mm)

100mm 125mm 150mm 175mm

Appliance Input Rating in Thousands of Btu Per Hour

FAN + FANFAN + NAT FAN + FANFAN + NATFAN + FANFAN + NATFAN + FAN FAN + NAT

1.8 NA 78 NA 113 200 158 304 244

2.4 NA 87 NA 126 218 173 331 269

3.0 NA 94 163 137 237 189 357 292

4.5 121 108 189 159 275 221 416 343

6.0 131 118 208 177 305 247 463 383

9.0 145 132 236 202 350 286 533 446

VENTING

Removal of the Furnace from Common Vent

In the event that an existing furnace is removed from a

venting system commonly run with separate gas ap-

pliances, the venting system is likely to be too large to

properly vent the remaining attached appliances.

Conduct the following test while each appliance is operat-

ing and the other appliances (which are not operating) re-

main connected to the common venting system. If the

venting system has been installed improperly, you must

correct the system as indicated in the general venting re-

quirements section.

WARNING

CARBON MONOXIDE POISONING HAZARD

Failure to follow the steps outlined below for each

appliance connected to the venting system being

placed into operation could result in carbon mon-

oxide poisoning or death.

The following steps shall be followed for each ap-

pliance connected to the venting system being

placed into operation, while all other appliances

connected to the venting system are not in

operation:

1 −

Seal any unused openings in the common venting sys-

tem.

−Inspect the venting system for proper size and horizontal

pitch. Determine that there is no blockage, restriction,

leakage, corrosion, or other deciencies which could

cause an unsafe condition.

3 − Close all building doors and windows and all doors be-

tween the space in which the appliances remaining

connected to the common venting system are located

and other spaces of the building. Turn on clothes dry-

ers and any appliances not connected to the common

venting system. Turn on any exhaust fans, such as

range hoods and bathroom exhausts, so they will oper-

ate at maximum speed. Do not operate a summer ex-

haust fan. Close replace dampers.

4 −Follow the lighting instructions. Turn on the appliance

that is being inspected. Adjust the thermostat so that

the appliance operates continuously.

5 −After the burner have operated for 5 minutes, test for

leaks of ue gases at the draft hood relief opening. Use

the ame of a match or candle.

6 −After determining that each appliance connected to th

common venting system is venting properly, (step 3)

return all doors, widows, exhaust fans, replace damp-

ers, and any other gas−burning appliances to their pre-

vious mode of operation.

7 −If a venting problem is found during any of the preced-

ing tests, the common venting system must be modi-

ed to correct the problem.

Resize the common venting system to the minimum

vent pipe size determined by using the appropriate

tables in Appendix G. (These are in the current stan-

dards of the National Fuel Gas Code ANSI Z223.1.

GENERAL E OR EC SERIES

GAS PIPING

THERMOSTAT INSTALLATION

Install a room thermostat according to the instructions

furnished with it. Select a location on an inside wall and not

subject to drafts, direct sunshine or other heat sources. The

initial heat anticipator setting should be equal to the total

current draw of the control circuit.

FURNACE CHECK-OUT

Before leaving, the installer should make the following

checks to ensure that the controls are functioning properly.

CHECKING AND ADJUSTING GAS INPUT

The minimum permissible gas supply pressure for the purpose

of input adjustment is listed on table 4 of this manual.

GAS PRESSURE REGULATOR

Gas input must never exceed the value shown on the

furnace rating plate.

The manifold pressure can be measured by connecting

a water manometer or gauge to the pressure tap in the

downstream side of the gas valve.

Only small variations in gas input may be made by adjusting

the regulator. In no case should the nal manifold pressure

vary more than 0.3 in. W.C. (0.07kPa) from the above

specied pressures.

TEMPERATURE RISE

Check the temperature rise and, if necessary, adjust blower

speed to maintain temperature rise within the range shown

on the unit rating plate.

GAS SUPPLY

This unit is to be installed by a licensed gas

plumber fully in accordance with AG601 installation

regulations.

1. This unit is shipped standard for centre installation of gas

piping. Piping can be converted for right-side connection.

Simply connect gas supply to piping assembly.

2. When connecting gas supply, factors such as length

of run, number of ttings and furnace rating must

be considered to avoid excessive pressure drop. Unit

connection at gas manifold is 1/2 in. (12mm). Size piping

according to gas regulations.

3. Gas piping must not run in or through air ducts, clothes

chutes, chimneys or gas vents, dumb waiters or elevator

shafts.

4. Piping should be sloped 6mm per 380mm upward toward

the meter from the furnace. The piping must be supported

at proper intervals (2m) using suitable hangers or straps.

5. In some localities, codes may require installation of a

manual main shut-off valve and union (furnished by

installer) external to the unit. Union must be of the ground

joint type.

Compounds used on threaded joints of gas

piping must be resistant to the actions of

liquied petroleum gases.

IMPORTANT

Some soaps used for leak detection are

corrosive to certain metals. Carefully rinse piping

thoroughly after leak test has been completed.

Do not use matches, candles, ame or other

sources of ignition to check for gas leaks.

CAUTION

NOTE: Installer must provide a 3mm N.P.T. plugged tap in

the eld piping upstream of the gas supply connection to the

unit. Tap must be accessible for test gauge connection. This

requirement is negated if the gas valve in the unit is tted

with an integral pressure tapping point.

NOTE: If emergency shut-off is required, shut off main

manual gas valve and disconnect main power to unit. These

devices should be properly labelled by the installer.

LEAK CHECK

After gas piping has been completed, carefully check all

piping connections (factory and eld) for gas leaks. Use a

leak detecting solution or other preferred means.

The furnace must be isolated from the gas supply system

by closing its individual manual shut-off valve during any

pressure testing of the gas supply system at pressures equal

to or less than 1/2 psig (3.48 kPa).

4. Install a separate disconnect switch (protected by either

fuse or circuit breaker) near the unit so power can be

turned off for servicing.

5. Before connecting thermostat or power wiring, check

to make sure wires will be long enough to facilitate

servicing at a later date. Remove blower access panel

and swing panel to check wire length for access.

6. Complete wiring connections to equipment using wiring

diagrams provided with unit and in eld wiring diagrams

shown in gures 5. Use 18 gauge wire or larger for

thermostat connections.

7. Electrically ground unit in accordance with local codes.

8. Three 240 volt accessory terminals are provided on the

control board. Two are energised with the indoor blower

and one is energised with the combustion air blower. Any

accessory rated up to one amp can be connected to the

accessory terminals with the neutral leg of the circuit

connected to the 240 volt neutral wires.

9. This unit is equipped with an integrated control board

that controls blower operation, fan off timings (EGC Board

0nly) and ignition. The board includes a terminal strip for

thermostat connections and two diagnostic LEDs. See

gure 6 for control board conguration. Diagnostic codes

are given in a chart at the back of this manual.

The red diagnostic button can be used to view the last

failure code. (EGC Ignition Board Only)

10.Refer to blower speed chart on wiring diagrams for

factory set cooling, heating and continuous fan speeds.

Systems using a cooling thermostat sub-base may

operate the blower continuously (factory set at low speed)

through the thermostat “FAN ON” switch. Systems, which

do not include a cooling sub-base require a toggle switch

which must be wired between terminals “R” and “G” on

the thermostat connection terminal strip. The blower

motor will operate at the designated speed during cooling

or heating demand; however, when demand is satised,

blower speed will revert to selected continuous speed.

When testing pressure of gas lines, gas valve

must be disconnected and isolated. See Figure 13.

Gas valves can be damaged if subjected to more

than 1/2 psig (3.48 kPa).

IMPORTANT

Electrostatic discharge can affect electronic

components. Take precautions during

furnace installation and service to protect the

furnace’s electronic controls. Precautions will

help to avoid control exposure to electrostatic

discharge by putting the furnace, the control

and the technician at the same electrostatic

potential. Neutralise electrostatic charge by

touching hand and all tools on an unpainted

unit surface, such as the gas valve or

blower deck, before performing any service

procedure.

CAUTION

MANUAL MAIN

SHUT-OFF VALV

WILL NOT HOLD

NORMAL TEST

PRESSURE

CAP

GAS VALVE

FURNACE

Figure 13

ELECTRICAL

ELECTROSTATIC DISCHARGE (ESD)

Precautions and Procedures

These units operate on 240 volt, single phase, 50Hz

electrical power. Refer to gure 14 for eld wiring and

Figure 16 for schematic wiring diagram and troubleshooting.

1. Select circuit protection and wire size according to

requirements listed on unit rating plate.

2. Snap-hole plugs are provided on both sides of cabinet to

facilitate wiring.

3. Install room thermostat according to instructions provided

with thermostat.

The blower access panel must be securely

in place when the blower and burners are

operating. Gas fumes, which could contain

carbon monoxide, can be drawn into living

space resulting in personal injury or death.

WARNING

If a exible gas connector is required or

allowed by the authority that has jurisdiction,

black iron pipe shall be installed at the gas

valve and extend outside the furnace cabinet.

The exible connector can then be added

between the black iron pipe and the gas

supply line.

CAUTION

FILTERS

DUCT SYSTEM

GAS PIPING

VENTING

This unit is not equipped with a lter or rack. A eld-provided

high-velocity lter is required for the unit to operate properly.

Table 2 lists recommended lter sizes. A lter must be in

place any time the unit is operating.

TABLE 2

Furnace

Cabinet Width

Filter Size mm (in) and Quantity

Side Return Bottom Return

A - 338

(14-1/2”)

406 X 635 X 25 1

(16 X 25 X 1)

356 X 635 X 25 1

(14 X 25 X 1)

B- 446

(17-1/2”)

406 X 635 X 25 1

(16 X 25 X 1)

406 X 635 X 25 1

(16 X 25 X 1)

C - 533

( 21”)

405 X 635 X 25 1

(16 X 25 X 1)

508 X 635 X 25 1

(20 X 25 X 1)

D - 622

(24-1/2”)

405 X 635 X 25 2

(16 X 25 X 1)

610 X 635 X 25 1

(24 X 25 X 1)

Use industry approved standards (such as those published

by Air Conditioning Contractors of America or American

Society of Heating, Refrigerating and Air Conditioning

Engineers) to size and install the supply and return air duct

system. This will result in a quiet and low static system that

has uniform air distribution.

Refer to the current edition of the Australian Gas

Installation Code (AG601, ES5601) for gas piping

requirements and gas pipe sizing tables.

Gas supply piping should not allow more than 125 Pa

(0.5”W.C.) drop in pressure between gas meter and unit.

Supply gas pipe must not be smaller than unit gas

connection.

The Lennox Merit Series™ Gas Furnace is a fan-assisted

furnace equipped with an integral mechanical means to

either draw or force products of combustion through the

combustion chamber and/or heat exchanger. When installed

in the vertical position and vented vertically, the furnace

operates with a non-positive vent stack pressure. When

installed in the horizontal position and vented vertically, the

furnace operates with a positive stack pressure.

GAS SUPPLY

1. This unit is shipped standard for left or right side

installation of gas piping (or top entry in horizontal

applications). Connect the gas supply to the piping

assembly.

2. When connecting the gas supply piping, consider factors

such as length of run, number of ttings, and furnace

rating to avoid excessive pressure drop.

3. The gas piping must not run in or through air ducts,

clothes chutes, gas vents or chimneys, dumb waiters, or

elevator shafts.

4. The piping should be sloped 6.4mm (1/4 in) per 4.57m

(15 ft.) upward toward the meter from the furnace. The

piping must be supported at proper intervals every 2.44

to 3.01m (8 to 10ft) with suitable hangers or straps.

Install a drip leg in vertical pipe runs to the unit.

5. A 3 mm (1/8”) N.P.T. plugged tap or pressure port is

located on the gas valve to facilitate test gauge connection.

6. In some localities, codes may require the installation of a

manual main shut off valve and union (furnished by the

installer) external to the unit. The union must be of the

ground joint type.

Compounds used on threaded joints of gas

piping must be resistant to the actions of

liquied petroleum gases.

IMPORTANT

NOTE: If emergency shut-off is necessary, shut off the main

manual gas valve and disconnect main power to the furnace.

The installer should properly label these devices.

GROUND

JOINT

UNION

AUTOMATIC

GAS VALVE

FIELD

PROVIDED

AND INSTALLED

GROUND

JOINT

UNION

Left Side Piping

(Standard)

Right Side Piping

(Alternate)

AUTOMATIC

GAS VALVE

DRIP LEG

MANUAL

MAIN SHUT-OFF

VALVE

(With 3mm NPT

Plugged Tap Shown)

MANUAL

MAIN SHUT-OFF

VALVE

(With 3mm NPT

Plugged Tap

Shown)

NOTE - BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET

GROUND

JOINT

UNION

DRIP LEG

MANUAL

MAIN SHUT-OFF

VALVE

GROUND

JOINT

UNION

DRIP LEG

MANUAL

MAIN

SHUT-OFF

VALVE

GROUND

JOINT

UNION

DRIP LEG

MANUAL

MAIN SHUT-OFF

VALVE

Horizontal Application

Left-Side Air Discharge

Horizontal Application

Right-Side Air Discharge NOTE - BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET

FIELD

PROVIDED

AND INSTALLED

Figure 14

Figure 15

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Model: ML18007036A-EC

Category: Water heaters & boilers

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