Installation Guide

ManualsBrandsMRCOOL ManualsForced Air Furnaces93% AFUE 100,000 BTU Multi-Position 2-Stage Multi-Speed Gas Furnace with LP Kit

I&O manual

IMPORTANT

The “VENT SYSTEM” must be installed as specified in these

instructions for Residential and Non HUD Modular Homes. The

direct vent system is the only configuration that can be installed

in a Non HUD Modular Home.

WARNING

This furnace may not be common vented with any other appliance,

since it requires separate, properly sized air intake and vent lines.

The furnace shall not be connected to any type of B, BW or L vent

or vent connector, and not connected to any portion of a factory-

built or masonry chimney

The furnace shall not be connected to a chimney flue serving a

separate appliance designed to burn solid fuel.

CAUTION

7.2 Combustion Air/Vent Pipe Sizing

TABLE 4: Maximum Equivalent Pipe Length

Model Input

BTUH (kW)

Pipe Size

Inches (cm)

Maximum Equivalent

length feet (m)

60（17.6）

2（5.1） 60（18.2）

90（27.4）

60（18.2）

90（27.4）

30（9.1）

90（27.4）

N/A

90（27.4）

3 (7.6)

2（5.1）

3 (7.6)

2（5.1）

3 (7.6)

2（5.1）

3 (7.6)

80（23.4）

100 (29.3)

120（35.1）

When combustion air pipe is installed above a suspended ceiling

or when it passes through a warm and humid space, the pipe must

be insulated with 1/2” Armaflex or other heat resistant type insula-

tion if two feet or more of pipe is exposed.

Vent piping must be insulated if it will be subjected to freezing

temperatures such as routing through unheated areas or through

an unused chimney.

The size of pipe required will be determined by the furnace model,

the total length of pipe required and the number of elbows required.

Table 4, "Maximum Equivalent Pipe Length" lists the maximum

equivalent length of pipe allowed for each model of furnace. The

equivalent length of elbows is shown in Table 6, "Equivalent Length

of Fittings".

The equivalent length of the vent system is the total length of straight

pipe PLUS the equivalent length of all of the elbows.

The following rules must also be followed:

1. Long radius (sweep) elbows are recommended. Standard elbows

may be used, but since they have a longer equivalent length, they

will reduce the total length of pipe that will be allowed. Short

radius (plumbing vent) elbows are not allowed. The standard

dimensions of the acceptable elbows are shown below.

NOTE: For single pipe systems it is recommended to install the

combustion air coupling provided and install approximately

18” of PVC pipe on the furnace.In addition to the vent/flue

pipe, a single 90° elbow should be secured to the

combustion air intake to prevent inadvertent blockage.

The maximum equivalent length listed in Table 4, "Maximum

Equivalent Pipe Length" is for the vent piping and the air intake

piping separately. For example, if the table allows 60 equivalent

feet for a particular model, then the vent can have 60 equivalent

feet of pipe, AND the combustion air intake can have another 60

equivalent feet of pipe.

Three vent terminal elbows (two for the vent and one for the

combustion air intake) are already accounted for and need not

be included in the equivalent length calculation.

All combustion air and vent pipe must conform to American

National Standards Institute (ANSI) and American Society for

Testing and Materials (ASTM) standards D1785 (Schedule 40

PVC), D2665 (PVC-DWV), F891 (PVC-DWV Cellular Core),

D2261 (ABS-DWV) or F628 (Schedule 40 ABS). Pipe cement

and primer must conform to ASTM Standard D2546 (PVC) or

D2235 (ABS). If ABS pipe is to be used, any joint where ABS

pipe is joined to PVC pipe must be glued with cement that is

approved for use with BOTH materials. Metallic materials must

not be used for venting or air intake.

If a flexible connector is used in the vent system, it must be

made of a material that is resistant to acidic exposure and to at

least 225° F temperature. Flexible connectors are also allowed

in the combustion air pipe.

All models are supplied with 2" vent connections. When the pipe

must be increased to 3" diameter, the transition from 2" to 3"

must be done as close to the furnace as possible. For upflow

models, the transition from 2" to 3" should be done immediately

above the furnace. For downflow or horizontal models, the

transition from 2 "to 3" pipe should be done immediately after

exiting the furnace.

In Canada, vents shall be certified to ULC S636, Standard for

Type BH Gas Venting Systems. IPEX System 636 PVC is

certified to this standard.

In Canada, the first three feet (900 mm) of the vent must be

readily accessible for inspection.

Minimum vent length for all models is 5 feet.

7. COMBUSTION AIR AND VENT SYSTEM

7.1 Combustion Air And Vent Safety

This Category IV, dual certified direct vent furnace is designed for

residential application. It may be installed without modification to the

condensate system in a basement, garage, equipment room, alcove,

attic or any other indoor location where all required clearance to

combustibles and other restrictions are met. The combustion air and

the venting system must be installed in accordance with Section 5.3,

Air for Combustion and Ventilation, of the National Fuel Gas Code

Z223.1/NFPA 54 (latest edition), or Sections 7.2, 7.3 or 7.4 of CSA

B149.1, National Gas and Propane Codes (latest edition) or

applicable provisions of the local building code and these

instructions.