Heatilator NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual

Installation Manual

Installation and Appliance Setup

CAUTION! Risk of Fire! DO NOT store instruction manuals inside replace cavity.
High temperatures could cause a re.

INSTALLER: Leave this manual with the appliance, not inside the appliance.
CONSUMER: Retain this manual for future reference. Do not store inside the appliance.
Contact your dealer with questions regarding installation, operation or service.

NOTICE: DO NOT discard this manual!

Models:

NNXT33-IFT
NNXT33L-IFT
NNXT36-IFT
NNXT36L-IFT

WARNING:
FIRE OR EXPLOSION HAZARD
Failure to follow safety warnings exactly
could result in serious injury, death, or
property damage.

• DO NOT store or use gasoline or other am-

mable vapors and liquids in the vicinity of this
or any other appliance.

• What to do if you smell gas

- DO NOT try to light any appliance.

- DO NOT touch any electrical switch. DO
NOT use any phone in your building.

- Leave the building immediately.

- Immediately call your gas supplier from
a neighbor’s phone. Follow the gas sup­plier’s instructions.

- If you cannot reach your gas supplier, call

the re department.

• Installation and service must be performed

by a qualied installer, service agency, or the

gas supplier.

This appliance may be installed as an OEM
installation in manufactured home (USA
only) or mobile home and must be installed
in accordance with the manufacturer’s
instructions and the Manufactured Home

Construction and Safety Standard, Title 24
CFR, Part 3280 in the United States, or the
Standard for Installation in Mobile Homes,
CAN/CSA Z240 MH Series, in Canada.

This appliance is only for use with the type(s)
of gas indicated on the rating plate. This
appliance is not convertible for use with other

gases, unless a certied kit is used.

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

DANGER

HOT GLASS WILL

CAUSE BURNS.

DO NOT TOUCH GLASS

UNTIL COOLED.

NEVER ALLOW CHILDREN

TO TOUCH GLASS.

A barrier designed to reduce the risk of

burns from the hot viewing glass is provided
with this appliance and must be installed for

the protection of children and other at-risk

individuals.

Decorative barrier front must be ordered separately at
time of appliance purchase. See Section 3.A.

1

Safety Alert Key:

• DANGER! Indicates a hazardous situation which, if not avoided will result in death or serious injury.

• WARNING! Indicates a hazardous situation which, if not avoided could result in death or serious injury.

• CAUTION! Indicates a hazardous situation which, if not avoided, could result in minor or moderate injury.

• NOTICE: Used to address practices not related to personal injury.
Note: The term “recommend” or “recommended” does not indicate a requirement. It is a best practice suggested by Hearth

& Home Technologies®. Failure to perform the recommended task will not result in a safety concern.

Table of Contents

Installation Standard Work Checklist .................... 3

1 Product Specic and Important Safety Information

A. Appliance Certication ............................4

B. Glass Specications ..............................4

C. BTU Specications ............................... 4

D. High Altitude Installations .......................... 4

E. Non-Combustible Materials Specication. . . . . . . . . . . . . . 4

F. Combustible Materials Specication .................4

G. Electrical Codes .................................4

H. California ...................................... 4

I. Requirements for the Commonwealth of Massachusetts .. 5

2 Getting Started

A. Design and Installation Considerations ............... 6

B. Good Faith Wall Surface ..........................6

C. Tools and Supplies Needed ........................6

D. Inspect Appliance and Components .................. 7

3 Framing and Clearances

A. Appliance/Decorative Front Dimension Diagrams .......8

B. Appliance Location and Clearances to Combustibles ... 12

C. Constructing the Appliance Chase .................. 14



4 Termination Location and Vent Information

A. Approved Pipe .................................15

B. Vent Termination Minimum Clearances .............. 15

C. Vent Terminal Clearances ........................16

D. Use of Elbows .................................17

E. Vent Diagrams .................................18



5 Vent Clearances and Framing

A. Pipe Clearances to Combustibles ..................31

B. Wall Penetration Framing/Firestops ................. 32

C. Ceiling Firestop/Floor Penetration Framing ........... 33

D. Install Attic Insulation Shield ....................... 33

6 Appliance Preparation

A. Top Vent ......................................34

B. Prepare For Heat Management ....................36

C. Securing and Leveling the Appliance ................ 36

7 Venting and Chimneys

A. Assemble Vent Sections (DVP Pipe Only) ...........37

B. Assemble Slip Sections ..........................39

C. Secure the Vent Sections ......................... 39

D. Disassemble Vent Sections ....................... 40

E. Vertical Termination Requirements .................. 40

F. Horizontal Termination Requirements ............... 41

G. Shrouds ......................................43

8 Electrical Information

A. General Information .............................44

B. Wiring Requirements ............................45

9 Gas Information

A. Fuel Conversion ................................47

B. Gas Pressure ..................................47

C. Gas Connection ................................ 47

D. High Altitude Installations ......................... 47

E. Air Shutter Setting ..............................48

10 Finishing

A. Facing Material .................................49

B. Mantel and Wall Projections ....................... 49

C. Non-combustible Mantel and Wall Projections for use with

Simon Fronts ..................................50

D. Non-combustible Mantel and Wall Projections for use with

Demi / Tres Fronts ..............................50

11 Appliance Setup

A. Remove the Shipping Materials ....................51

B. Clean the Appliance .............................51

C. Install Burner Media / Embers ..................... 51

D. Install Control Heat Shield ........................52

E. Install Fixed Glass Assembly ...................... 52

F. Install Decorative Barrier Front. . . . . . . . . . . . . . . . . . . . . 52

G. Install Logs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

12 Reference Materials

A. Vent Components Diagrams ......................55

B. Optional Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

C. Accessories ...................................67

 = Contains updated information.

2

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

Installation Standard Work Checklist

2628-982 2/20

ATTENTION INSTALLER:

Follow this Standard Work Checklist

This standard work checklist is to be used by the installer in conjunction with, not instead of, the instructions contained in this

installation manual.

Customer:
Lot/Address:

Model (circle one):

NNXT36-IFT, NNXT36L-IFT

NNXT33-IFT, NNXT33L-IFT

WARNING! Risk of Fire or Explosion! Failure to install appliance according to these instructions could lead

to a re or explosion. Install ONLY components and accessories approved by Hearth & Home Technologies.
Unapproved components and accessories could cause replace to overheat.

Appliance Install YES IF NO, WHY?

Veried that the chase is insulated and sealed. (Pg. 14) ___________________________
Veried clearances to combustibles. (Pg. 12-13) ___________________________
Fireplace is leveled and secured. (Pg. 36) ___________________________

Venting/Chimney Section 7 (Pg 37-43)

Venting conguration complies to vent diagrams. ___________________________
Venting installed, locked and secured in place with proper clearance. ___________________________

Firestops installed. ___________________________
Attic insulation shield installed. ___________________________

Exterior wall/Roof ashing installed and sealed. ___________________________

Terminations installed and sealed. ___________________________

Date Installed:
Location of Fireplace:
Installer:
Dealer/Distributor Phone #

Serial #:

Electrical Section 8 (Pg 44-46)

Unswitched power (110-120 VAC) provided to the appliance. ___________________________
Switch wires properly installed. ___________________________

Gas Section 9 (Pg 47-48)

Proper appliance for fuel type. ___________________________

Was a conversion performed? ___________________________

Leak check performed and inlet pressure veried. ___________________________
Veried proper air shutter setting for installation type. ___________________________

Finishing Section 10 (Pg 49-50)

Combustible materials not installed in non-combustible areas. ___________________________
Veried all clearances meet installation manual requirements. ___________________________
Mantels and wall projections comply with installation manual requirements. ___________________________

Appliance Setup Section 11 (Pg 51-54)

All packaging and protective materials removed (inside & outside of appliance). ___________________________
Refractories, logs, mineral wool, lava rock and vermiculite installed correctly. ___________________________

Glass assembly installed and secured. ___________________________
Accessories installed properly. ___________________________
Decorative barrier front properly installed. ___________________________

Manual bag and all of its contents are removed from inside/under
the appliance and given to party responsible for use and operation. ___________________________
Started appliance and veried no gas leaks exist. ___________________________

Hearth & Home Technologies recommends the following:

• Photographing the installation and copying this checklist for your le.

• That this checklist remain visible at all times on the appliance until the installation is complete.

Comments: Further description of the issues, who is responsible (Installer/ Builder/ Other Trades, etc) and corrective
action needed _____________________________________________________________________________________
_________________________________________________________________________________________________
_________________________________________________________________________________________________
Comments Communicated to party responsible ____________________ by ______________________on ___________
(Builder / Gen. Contractor/) (Installer) (Date)

 = Contains updated information.

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

3

1 1

Product Specic and Important Safety Information

A. Appliance Certication

MODELS: NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT,

NNXT36L-IFT

LABORATORY: Underwriters Laboratories, Inc. (UL)

TYPE: Direct Vent Heater

STANDARD: CSA / ANSI Z21.88:19 • CSA 2.33:19

This product is listed to ANSI standards for “Vented Gas
Fireplace Heaters” and applicable sections of “Gas Burn­ing Heating Appliances for Manufactured Homes and
Recreational Vehicles”, and “Gas Fired Appliances for
Use at High Altitudes”.

NOTICE: This installation must conform with local codes.
In the absence of local codes you must comply with the
National Fuel Gas Code, ANSI Z223.1-latest edition in
the U.S.A. and the CAN/CGA B149 Installation Codes in
Canada.

NOT INTENDED FOR USE AS A PRIMARY HEAT SOURCE.

This appliance is tested and approved as either supplemen­tal room heat or as a decorative appliance. It should not be
factored as primary heat in residential heating calculations.

D. High Altitude Installations

NOTICE: If the heating value of the gas has been reduced,
these rules do not apply. Check with your local gas utility
or authorities having jurisdiction.

When installing above 2000 feet elevation:

• In the USA: Reduce input rate 4% for each 1000 feet
above 2000 feet.

• In CANADA: Input ratings are certied without a

reduction of input rate for elevations up to 4500 feet
(1370 m)above sea level. Please consult provincial and/
or local authorities having jurisdiction for installations at
elevations above 4500 feet (1370 m).

Check with your local gas utility to determine proper
orice size.

E. Non-Combustible Materials Specication

Material which will not ignite and burn. Such materials are

those consisting entirely of steel, iron, brick, tile, concrete,

slate, glass or plasters, or any combination thereof.

Materials that are reported as passing ASTM E 136,

Standard Test Method for Behavior of Materials in
a Vertical Tube Furnace at 750 ºC shall be considered

non-combustible materials.

B. Glass Specications

This appliance is equipped with 5 mm ceramic glass. Re­place glass only with 5 mm ceramic glass. Please contact
your dealer for replacement glass.

C. BTU Specications

Models

(U.S. or Canada)

NNXT33-IFT

(NG)

NNXT33L-IFT

(Propane)

NNXT36-IFT

(NG)

NNXT36L-IFT

(Propane)

Maximum

Input BTU/h

(0-2000 FT) 29,000 16,000 #39

(0-2000 FT) 28,000 15,750 1.55 mm

(0-2000 FT) 31,000 18,500 #37

(0-2000 FT) 29,000 15,500 #52

Minimum

Input

BTU/h

Orice

Size

F. Combustible Materials Specication

Materials made of or surfaced with wood, compressed pa-

per, plant bers, plastics, or other material that can ignite
and burn, whether ame proofed or not, or plastered or

unplastered shall be considered combustible materials.

G. Electrical Codes

NOTICE: This appliance must be electrically wired

and grounded in accordance with local codes or, in the
absence of local codes, with National Electric Code

ANSI/NFPA 70-latest edition or the Canadian Electric
Code CSA C22.1.

• A 110-120 VAC circuit for this product must be pro­tected with ground-fault circuit-interrupter protection,
in compliance with the applicable electrical codes,
when it is installed in locations such as in bathrooms

or near sinks.

H. California

WARNING: This product and the fuels used to

operate this product (liquid propane or natural
gas), and the products of combustion of such fuels, can
expose you to chemicals including benzene, which is

known to the State of California to cause cancer and

reproductive harm. For more information go to: www.
P65Warnings.ca.gov.

4

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

Note: The following requirements reference various
Massachusetts and national codes not contained in this
document.

I. Requirements for the Commonwealth of

Massachusetts

For all side wall horizontally vented gas fueled equipment
installed in every dwelling, building or structure used in
whole or in part for residential purposes, including those
owned or operated by the Commonwealth and where the
side wall exhaust vent termination is less than seven (7)

feet above nished grade in the area of the venting, in­cluding but not limited to decks and porches, the following
requirements shall be satised:

Installation of Carbon Monoxide Detectors

At the time of installation of the side wall horizontal vented

gas fueled equipment, the installing plumber or gas tter

shall observe that a hard wired carbon monoxide detector

with an alarm and battery back-up is installed on the oor

level where the gas equipment is to be installed. In addi-

tion, the installing plumber or gas tter shall observe that

a battery operated or hard wired carbon monoxide detec­tor with an alarm is installed on each additional level of
the dwelling, building or structure served by the side wall
horizontal vented gas fueled equipment. It shall be the
responsibility of the property owner to secure the services

of qualied licensed professionals for the installation of

hard wired carbon monoxide detectors.

In the event that the side wall horizontally vented gas fu­eled equipment is installed in a crawl space or an attic,
the hard wired carbon monoxide detector with alarm and

battery back-up may be installed on the next adjacent
oor level.

In the event that the requirements of this subdivision can
not be met at the time of completion of installation, the
owner shall have a period of thirty (30) days to comply
with the above requirements; provided, however, that dur­ing said thirty (30) day period, a battery operated carbon
monoxide detector with an alarm shall be installed.

Inspection

The state or local gas inspector of the side wall horizon­tally vented gas fueled equipment shall not approve the
installation unless, upon inspection, the inspector ob­serves carbon monoxide detectors and signage installed
in accordance with the provisions of 248 CMR 5.08(2)(a)1
through 4.

Exemptions

The following equipment is exempt from 248 CMR 5.08(2)
(a)1 through 4:

• The equipment listed in Chapter 10 entitled “Equipment
Not Required To Be Vented” in the most current edition
of NFPA 54 as adopted by the Board; and

• Product Approved side wall horizontally vented gas fu­eled equipment installed in a room or structure separate
from the dwelling, building or structure used in whole or
in part for residential purposes.

MANUFACTURER REQUIREMENTS

Gas Equipment Venting System Provided

When the manufacturer of Product Approved side wall
horizontally vented gas equipment provides a venting
system design or venting system components with the
equipment, the instructions provided by the manufacturer
for installation of the equipment and the venting system
shall include:

• Detailed instructions for the installation of the venting
system design or the venting system components; and

• A complete parts list for the venting system design or
venting system.

Gas Equipment Venting System NOT Provided

When the manufacturer of a Product Approved side wall
horizontally vented gas fueled equipment does not pro-

vide the parts for venting the ue gases, but identies

“special venting systems”, the following requirements

shall be satised by the manufacturer:

Approved Carbon Monoxide Detectors

Each carbon monoxide detector as required in accor­dance with the above provisions shall comply with NFPA

720 and be ANSI/UL 2034 listed and IAS certied.

Signage

A metal or plastic identication plate shall be permanent­ly mounted to the exterior of the building at a minimum
height of eight (8) feet above grade directly in line with the
exhaust vent terminal for the horizontally vented gas fu­eled heating appliance or equipment. The sign shall read,
in print size no less than one-half (1/2) in. in size, “GAS

VENT DIRECTLY BELOW. KEEP CLEAR OF ALL OB­STRUCTIONS”.

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

• The referenced “special venting system” instructions
shall be included with the appliance or equipment in­stallation instructions; and

• The “special venting systems” shall be Product Ap­proved by the Board, and the instructions for that sys­tem shall include a parts list and detailed installation
instructions.

A copy of all installation instructions for all Product Ap­proved side wall horizontally vented gas fueled equip­ment, all venting instructions, all parts lists for venting
instructions, and/or all venting design instructions shall
remain with the appliance or equipment at the completion
of the installation.

See Gas Connection section for additional Common­wealth of Massachusetts requirements.

5

2 2

Getting Started

A. Design and Installation Considerations

WARNING! Risk of Fire or Explosion! Read all instruc­tions before starting the installation.

Heatilator direct vent gas appliances are designed to op­erate with all combustion air siphoned from outside of the
building and all exhaust gases expelled to the outside. No
additional outside air source is required.

Installation MUST comply with local, regional, state and
national codes and regulations. Consult insurance carrier,

local building inspector, re ofcials or authorities having

jurisdiction over restrictions, installation inspection and
permits.

Before installing, determine the following:

• Where the appliance is to be installed.

• The vent system conguration to be used.

• Gas supply piping requirements.

• Provisions for optional heat management system.

• Electrical wiring requirements.

• Framing and nishing details.

• Whether optional accessories—devices such as a fan,
wall switch, or remote control—are desired.

B. Good Faith Wall Surface

TO CEILIN G

110°F

115°F

APPLIANCE OPENIN G

145°F

170°F

180°F

Figure 2.1 Good Faith Wall Surface Temperatures Above Appliance

18 in.

12 in.

6 in.

MEASU REMENTS FROM

TOP EDGE O F THE OPENI NG

APPLIA NCE FRONT

If installing a television (TV) above the appliance, see
Section 3 of the appliance Owner’s Manual.

132°F

24 in.

123°F

120°F

48 in.

42 in.

36 in.

30 in.

Installation and service of this appliance should be performed by

qualied personnel. Hearth & Home Technologies recommends
HHT Factory Trained or NFI certied professionals.

Improper installation, adjustment, alteration, service or
maintenance can cause injury or property damage. For

assistance or additional information, consult a qualied

service technician, service agency or your dealer.

NOTICE: Surface temperatures listed above are taken with
a temperature measuring probe as prescribed by the test
standard used for appliance certication. Temperatures
on walls or mantels taken with an infrared thermometer
may yield increased temperatures of up to 30 °F (17 °C) or
more depending on the thermometer settings and material
characteristics being measured. Use appropriate nishing
materials that are able to withstand these conditions. For
additional nishing guidelines, see Section 10.

C. Tools and Supplies Needed

Before beginning the installation be sure that the following
tools and building supplies are available.

Hand Tools Tape measure
Level Framing material
Manometer Framing square
Voltmeter Electric drill and bits (1/4 in.)
Plumb line Safety glasses/Gloves
Wrenches Reciprocating saw
1/4 in. nut driver

Non-corrosive leak check solution

1/2 - 3/4 in. length, #6 or #8 Self-drilling screws
1/4 in. length, #6 or #8 Self-drilling screws (B-Vent only)

Caulking material (300 ºF minimum continuous exposure

rating)

6

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

D. Inspect Appliance and Components

WARNING! Risk of Fire or Explosion! Damaged parts
could impair safe operation. DO NOT install damaged, in­complete or substitute components. Keep appliance dry.

WARNING! Risk of Fire, Explosion or Electric Shock!
DO NOT use this appliance if any part has been under

water. Call a qualied service technician to inspect the
appliance and to replace any part of the control system
and/or gas control which has been under water.

• Carefully remove the appliance and components from

the packaging.

• The vent system components and decorative barrier

fronts may be shipped in separate packages.

• If packaged separately, the log set and appliance grate

must be installed.

• Report to your dealer any parts damaged in shipment.

• This product is factory-equipped with an IntelliFire Touch
remote control, which was paired to the appliance at the

factory. This specic remote control needs to remain with

the contents of the manual bag. Do not install batteries

in the remote control until performing the nal appliance
setup and checklist.

Hearth & Home Technologies disclaims any responsibility

for, and the warranty will be voided by, the following actions:

• Installation and use of any damaged appliance or vent
system component.

• Modication of the appliance or vent system.

• Installation other than as instructed by Hearth & Home

Technologies.

• Improper positioning of the logs/media (as applicable) or
the glass assembly.

• Installation and/or use of any component part not approved

by Hearth & Home Technologies.

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

7

3 3

P

O

Q

R

K

I

J

H

T

S

ALTERNATE
GAS ACCESS

C

D

B

A

E

F

G

M

L

GAS LINE
ACCESS

N

ELECTRICAL
ACCESS

MEASURE TO TOP OF STANDOFF

C VENT
OPENING

L

C VENT OPENING
L

C VENT
OPENING

L

HEAT MANAGEMENT
ACCESS (BOTH SIDES)

Framing and Clearances

A. Appliance/Decorative Front Dimension Diagrams

Dimensions are actual appliance dimensions. Use for reference only. For framing dimensions and clearances refer to Section 5.

Appliance Dimensions Table

Location Inches Millimeters Inches Millimeters

A 38 965 41 1041
B 33 838 36 916
C 6-3/8 162 6-3/8 162
D 19-7/8 505 19-7/8 505
E 29-5/8 752 32-5/8 829
F 31-1/2 800 31-1/2 800
G 35-1/4 896 35-1/4 896

Figure 3.1 Appliance Dimensions - NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT

8

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

H 15-3/4 400 15-3/4 400

I 1-3/4 44 1-3/4 44
J 23-1/2 597 23-1/2 597
K 39-1/2 1003 39-1/2 1003
L 3 76 3 76
M 6-1/2 165 6-1/2 165
N 34-1/2 876 34-1/2 876
O 11-5/8 295 14-5/8 371
P 5-7/8 148 7-3/8 186
Q 11-1/2 292 11-1/2 292
R 19-1/8 486 19-1/8 486
S 2-3/8 60 2-3/8 60
T 8 203 8 203

NNXT33-IFT/NNXT33L-IFT NNXT36-IFT/NNXT36L-IFT

DEMI-B DECORATIVE BARRIER FRONTS

IMPORTANT! This replace requires an installed decorative barrier front to prevent direct contact with the
hot viewing glass. DO NOT operate the replace with the barrier removed.

Decorative barrier front must be ordered at time of replace purchase. If decorative barrier front is not
present, contact dealer.

Note: See Section 10 for hearth, mantel and

nishing requirements.

A

G

B

F

DEMI33-B

DEMI36-B

E

D

C

A B C D E F G

in. 29-7/8 20-3/8 32-7/8 1-7/8 6-3/4 30 31-5/8

mm 759 518 835 48 171 762 803

in. 32-7/8 20-3/8 35-7/8 1-7/8 6-3/4 30 31-5/8

mm 835 518 911 48 171 762 803

Figure 3.2 Decorative Barrier Front Dimensions - DEMI-B

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

9

TRES-B DECORATIVE BARRIER FRONTS

A

B

C

D

E

F

G

IMPORTANT! This replace requires an installed decorative barrier front to prevent direct contact with the
hot viewing glass. DO NOT operate the replace with the barrier removed.

Decorative barrier front must be ordered at time of replace purchase. If decorative barrier front is not
present, contact dealer.

Note: See Section 10 for hearth, mantel and

nishing requirements.

A B C D E F G

TRES33-B

TRES36-B

in. 29-7/8 21 32-7/8 1-7/8 6-3/4 30 31-5/8

mm 759 533 835 48 171 762 803

in. 32-7/8 21 35-7/8 1-7/8 6-3/4 30 31-5/8

mm 835 533 911 48 171 762 803

Figure 3.3 Decorative Barrier Front Dimensions - TRES-B

10

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

SIMON DECORATIVE BARRIER FRONTS

IMPORTANT! This replace requires an installed decorative barrier front to prevent direct contact with the
hot viewing glass. DO NOT operate the replace with the barrier removed.

Decorative barrier front must be ordered at time of replace purchase. If decorative barrier front is not
present, contact dealer.

Note: See Section 10 for hearth, mantel and

nishing requirements.

A

SIM-3933

SIM-4236

G

B

E

F

D

C

A B C D E F G

in. 31-3/8 21 32-7/8 1-5/8 2-3/8 30 31-1/2

mm 797 533 835 41 60 762 800

in. 34-3/8 21 35-7/8 1-5/8 2-3/8 30 31-1/2

mm 873 533 911 41 60 762 800

Figure 3.4 Decorative Barrier Front Dimensions - SIMON-B

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

11

B. Appliance Location and Clearances to

NOTICE: Allow 18 inches minimum clearance
on side(s) of appliance for venting of heat
management system.

18 IN. MIN.

Combustibles

When selecting a location for the appliance it is important

to consider the required clearances to walls and allow suf-

cient clearance for heat management systems venting.

See Figure 3.5 and Figure 3.6.

WARNING! Risk of Fire or Burns! Provide adequate
clearance around air openings and for service access.
Due to high temperatures, the appliance should be lo­cated out of trafc and away from furniture and draperies.

NOTICE: Illustrations reect typical installations and are
FOR DESIGN PURPOSES ONLY. Illustrations/diagrams
are not drawn to scale. Actual installation may vary due to
individual design preference.

* As B increases, J increases accordingly.

J*

Figure 3.5 Clearance for Heat Management System

1/2 in. (13 mm)

min. appliance

to combustibles

B

Drywall

A

C

48 in.

F

B

D

A

G

H

A

Top Vent

One 90° elbow

Horiz Term

In addition to these framing dimensions, also reference
the following sections:

• Clearances and Mantel Projections

• Vent Clearances and Framing

Rear Vent

One 90° elbow

Vert Term

Alcove

Installation

A

(1219 mm)

maximum

Rear Vent

Two 90° elbows

Horiz Term

C

I

A

E

1 in. (25 mm)

min. pipe to

combustibles

NNXT33-IFT

NNXT36-IFT

Figure 3.6 Appliance Locations

12

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

D

in 39 35-1/2 19-5/8 47 53-1/4 40 50-1/4 66-1/2 75-3/8 9-1/2

mm 991 902 498 1194 1353 1016 1276 1689 1915 241

in 42 37-5/8 19-5/8 47 53-1/4 43 53-1/4 66-1/2 75-3/8 10-5/8

mm 1067 956 498 1194 1353 1092 1353 1689 1915 270

E

A B C D E F G H I J

Note: If the inside of the framed cavity is to be nished,

the framing dimensions must include the finished
surface. If drywall is to be attached to the rear wall,
the depth must be measured from the drywall surface.

NO COMBUSTIBLE MATERIALS
IN SHADED AREA.

CLEARANCES TO COMBUSTIBLES:
1 INCH - BOTTOM & SIDES OF VENT PIPE
3 INCHES- TOP OF VENT PIPE

NO COMBUSTIBLE MATERIALS ALLOWED
BELOW TOP OF STANDOFFS.

2 X 4 OR 2 X 6 FRAMING

FINISH WALL
COMBUSTIBLE

COMBUSTIBLE
FRAMING

FOR MANTEL AND WALL
PROJECTIONS SEE SECTION 10.B

1/2 in.

(13 mm)

Combustible flooring may be installed next
to the front of the appliance.

Clearance to Ceiling

30 in. (762 mm)

0 in. to level
of standoffs

1/2 in.

(13 mm)

Drywall

0 in.

NNXT MODEL

(NG/PROPANE)

NNXT33-IFT

NNXT36-IFT

TOP OF FIREPLACE OPENING

36 in.

(914 mm)

Combustible Object

B

C

A

*MINIMUM FRAMING DIMENSIONS

A B C** D D

Rough

Opening

(Width)

in. 39 34-7/8 19-5/8 10 9

mm 991 886 498 254 229

in. 42 34-7/8 19-5/8 10 9

mm 1067 886 498 254 229

Rough
Opening
(Height)

Rough

Opening

(Depth)

Rough

Opening

(DVP Pipe)

Rough

Opening

(SLP Pipe)

0 in.

D

* Adjust framing dimensions for interior sheathing (such as sheetrock)

C** Add 11-1/2 inches for rear vented elbow vented directly off the rear of the appliance.

Figure 3.7 Clearances to Combustibles

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

13

C. Constructing the Appliance Chase

NOTICE: Install appliance on hard metal or wood surfaces
extending full width and depth. DO NOT install directly on
carpeting, vinyl, or any combustible material other than
wood.

WARNING! Risk of Fire! Maintain specied air space
clearances to appliance and vent pipe:

• Insulation and other materials must be secured to prevent
accidental contact.

• The chase must be properly blocked to prevent blown

insulation or other combustibles from entering and

making contact with replace or chimney.

• Failure to maintain airspace may cause overheating and
a re.

A chase is a vertical box-like structure built to enclose the

gas appliance and/or its vent system. In cooler climates
the vent should be enclosed inside the chase.

NOTICE: Treatment of ceiling restops and wall shield
restops and construction of the chase may vary with the
type of building. These instructions are not substitutes
for the requirements of local building codes. Therefore,
you MUST check local building codes to determine the
requirements to these steps.

NOTICE: Where required by code, install only sprinkler
heads with a sprinkler activation temperature classied
as Extra High.

• Sprinklers inside of chase: Keep sprinkler head away
from vent and chimney.

• Heat Management applications: Maintain 36 inches of
clearance to openings from which heat is discharged
such as convection slots, heat zone registers, etc. Refer
to Section 6.B for Heat Management options allowed
for this appliance.

Chases should be constructed and insulated in the same
manner as the thermal envelope of the home based on
the code requirements for that climate zone to prevent air

leakage and draft problems. The chase is an extension of

the building thermal envelope.

To further prevent drafts and air leakage, the wall shield
and ceiling restops should be sealed with caulk with
a minimum of 300 ºF continuous exposure rating to

seal gaps. Gas line holes and other openings should
be sealed with caulk with a minimum of 300 ºF continu­ous exposure rating or stuffed with unfaced insulation. If the
appliance is being installed on a cement surface, a layer of
plywood may be placed underneath to prevent conducting
cold up into the room.

Minimum height requirements for an exterior chase on a top­vented appliance are shown in Figure 3.9. Reference Figure

4.4 for additional clearances.

A

B

3 IN. MIN.

*

46-1/2 IN.

56-1/2 IN. INVENT SOFFITS

*

60-1/2 IN. VENT SOFFITS
74-1/2 IN. VINYL SOFFITS

NOTE: THESE DIMENSIONS ARE DERIVED
USING DIMENSION C FROM 4.4.

NOTE: If overhang (Dim. A) is less than 2 inches, clearance from top of termination
cap to bottom of overhang (Dim. B) may be 0 inches.

Dimension A is measured from the edge of the overhang to the surface the
termination cap is mounted to.

Figure 3.8 Exterior Chase - Minimum Height Requirements



14

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

H (MIN.) - MINIMUM HEIGHT FROM ROOF

Termination Location and Vent Information

.

A B

6 in. (minimum) up to 20 in.

152 mm/508 mm

18 in. minimum

457 mm

20 in. and over 0 in. minimum

CLEARANCE

= 6 IN.

H

V

V

H=Measure Horizontal Distances from H
V=Measure Vertical Distances from V

H

4 4

A. Approved Pipe

WARNING! Risk of Fire, Delayed Ignition or Asphyxi­ation. This appliance requires a separate vent. DO NOT

vent to a pipe serving any other appliance.

This appliance is only approved for use with Hearth & Home

Technologies DVP or SLP venting systems. Refer to Sec­tion 12.A for vent component information and dimensions.
Only use listed decorative termination caps/shrouds with

Hearth & Home Technologies approved venting systems
DO NOT mix pipe, ttings or joining methods from different

manufacturers.
The pipe is tested to be run inside an enclosed wall. There

is no requirement for inspection openings at each joint with­in the wall.

B. Vent Termination Minimum Clearances

WARNING

Fire Risk.

Maintain vent clearance to combustibles as

specied.

• DO NOT pack air space with insulation or other

materials.

Failure to keep insulation or other materials away
from vent pipe could cause overheating and re.

Wood or Fuel Oil

Termination Cap

B

A *

**Gas

Termination

Cap

* If using decorative cap cover(s), this distance may need to be increased.
Refer to the installation instructions supplied with the decorative cap cover

** If two gas terminations are present, they may be level (B = 0 inches)
provided A is a minimum of 6 inches.

2 FT.
MIN.

GAS DIRECT VENT
TERMINATION CAP

Roof Pitch H (Min.) Ft

Flat to 6/12...........................................................1.0*

Over 6/12 to 7/12 .................................................1.25*

Over 7/12 to 8/12 .................................................1.5*

Over 8/12 to 9/12 .................................................2.0*

Over 9/12 to 10/12 ...............................................2.5*

Over 10/12 to 11/12 .............................................3.25

Over 11/12 to 12/12 .............................................4.0

Over 12/12 to 14/12 .............................................5.0

Over 14/12 to 16/12 .............................................6.0

Over 16/12 to 18/12 .............................................7.0

Over 18/12 to 20/12 .............................................7.5

Over 20/12 to 21/12 .............................................8.0

* H minimum may vary depending on regional snowfall.

Refer to local codes.

HORIZONTAL

OVERHANG

20 INCHES MIN.

LOWEST

DISCHARGE

OPENING

X

12

ROOF PITCH

IS X/ 12

TO LOWEST DISCHARGE OPENING

VERTICAL

WALL

Figure 4.2 Staggered Termination Caps

CAUTION! Risk of Burns! Termination caps are HOT,
consider proximity to doors, trafc areas or where people

may pass or gather (sidewalk, deck, patio, etc.). Listed

cap shields available. Contact your dealer.

• Local codes or regulations may require different
clearances.

• Hearth & Home Technologies assumes no responsibility

for the improper performance of the appliance when the
venting system does not meet these requirements.

• Vinyl protection kits are suggested for use with vinyl siding.

• Measure horizontal and vertical termination cap clearances
as noted in Figure 4.3.

Figure 4.1 Minimum Height From Roof to Lowest Discharge
Opening

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

Figure 4.3

15

C. Vent Terminal Clearances

= AREA WHERE TERMINAL IS NOT PERMITTED

X

= AIR SUPPLY INLET

K

V

L

Electrical

Service

C

V

K

C

V

B

J

V

B

D

V

V

V

F

B

A

G

M

V

= VENT TERMINAL

H or i

V

X

V

V

V

H

H

E

V

V

A

U.S.A. Installations: In accordance with the current ANSI Z223.1/NFPA 54, National Fuel Gas Code.
Canadian Installations: In accordance with the current CSA B149.1, Natural Gas and Propane Installation Code.

U.S.A. CANADA

A Clearance above grade,veranda, porch, deck, or balcony 12 in. (305 mm) 12 in. (305 mm)

B Clearance to window or door that may be opened, or to permanently closed window 9 in. (229 mm) 12 in. (305 mm)

clearance below unventilated soft 12 in. (305 mm) 12 in. (305 mm)

C

clearance below ventilated soft 18 in. (457 mm) 18 in. (457 mm)

V

clearance below any vinyl softs and electrical service 30 in. (762 mm) 30 in. (762 mm)

D clearance to outside corner 6 in. (152 mm) 6 in. (152 mm)

E clearance to inside corner 6 in. (152 mm) 6 in. (152 mm)

not to be installed above a gas meter/regulator assembly within 3 feet horizontally from

F

the center-line of the regulator

3 ft (914 mm) 3 ft (914 mm)

G clearance to gas service regulator vent outlet 3 ft (914 mm) 3 ft (914 mm)

clearance to non-mechanical air supply inlet to building or the combustion air inlet to

H

any other appliance termination (mechanical or non-mechanical)

9 in. (228 mm) 12 in. (305 mm)

clearance to a mechanical (powered) air supply inlet

I

***(All mechanical air intakes within 10 feet of a horizontal termination cap must be

3 ft (914 mm)*** 6 ft (1.8 m)

a minimum of 3 feet below termination.)

On public property: clearance above paved sidewalk or a paved driveway.

7 ft (2.1 m) 7 ft (2.1 m)**

J

**(A vent shall not terminate directly above a sidewalk or paved driveway which is located between two single family dwellings

and serves both dwellings.)

clearance from sides of electrical service 6 in. (152 mm) 6 in. (152 mm)

K

Location of the vent termination must not interfere with access to the electrical service.

clearance above electrical service 12 in. (305 mm) 12 in. (305 mm)

L

Location of the vent termination must not interfere with access to the electrical service.

clearance under veranda, porch, deck, balcony or overhang

*(Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of

M

two sides beneath the oor.)

vinyl or composite overhang 30 in. (762 mm) 30 in. (762 mm)

Figure 4.4 Minimum Clearances for Termination

16

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

12 in. (305 mm) 12 in. (305 mm)*

D. Use of Elbows

Diagonal runs have both vertical and horizontal vent as­pects when calculating the effects. Use the rise for the
vertical aspect and the run for the horizontal aspect. See
Figure 4.5.

Two 45º elbows may be used in place of one 90º elbow.
On 45º runs, one foot of diagonal is equal to 8-1/2 in. (216

mm) horizontal run and 8-1/2 in. (216 mm) vertical run. A

length of straight pipe is allowed between two 45º elbows.

See Figure 4.5.

Figure 4.6 shows the vertical and horizontal offsets for
DVP or SLP elbows.

Y

X

VERTICAL

EFFECTIVE

LENGTH

RUN

HORIZONTAL

SLP

Pipe

SLP4 4 102 2-3/4 70

SLP6 6 152 4-1/4 108

SLP12 12 305 8-1/2 216

SLP24 24 610 17 432

SLP36 36 914 25-1/2 648

SLP48 48 1219 34 864

SLP6A 3 to 6 76 to 152

SLP12A 3 to 12 76 to 305

Effective Length Rise/Run

Inches Millimeters Inches Millimeters

2-1/8-4-1/4 54-108

2-1/8-8-1/2 54-216

RISE

Vent

Type

DVP 4-1/2 114 17 432

SLP 5 127 11-3/4 298

Inches Millimeters Inches Millimeters

X Y

X

X

Vent Type

DVP 16-1/4 413

SLP 11-1/4 286

Figure 4.6 Vertical and Horizontal Offset for DVP and SLP Elbows

Inches Millimeters

X

DVP
Pipe

DVP4 4 102 2-3/4 70

DVP6 6 152 4-1/4 108

DVP12 12 305 8-1/2 216

DVP24 24 610 17 432

DVP36 36 914 25-1/2 648

DVP48 48 1219 34 864

DVP6A 3 to 6 76 to 152

DVP12A 3 to 12 76 to 305

Figure 4.5

Effective Length Rise/Run

Inches Millimeters Inches Millimeters

2-1/8-4-1/4 54-108

2-1/8-8-1/2 54-216

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

Note: Back to back 45 degree or 90 degree elbows have

no additional vertical or horizontal value and are not in­cluded in determining maximum vent run lengths.

17

E. Vent Diagrams

A

3 IN. MIN.

* NOTE: If overhang (A) is less than 12 inches
and there is no gutter present, the TRAP-VSS
is required to prevent direct roof runoff from
entering the horizontal termination cap.

General Rules:

• A maximum of three 90º elbows (or six 45º elbows) may
be used in any vent conguration. Some elbows may be

installed horizontally. See Figure 4.15.

• A maximum of three 90º elbows (or six 45º elbows)

may be used in a top vented, vertically terminated vent

conguration. See Figure 4.24.

• Elbows may be placed back to back anywhere in the

system.

• Any 90º elbow may be replaced with two back to back

45º elbows.

• When penetrating a combustible wall, a wall shield

restop must be installed.

• When penetrating a combustible ceiling, a ceiling restop

must be installed.

• Horizontal runs of vent do not require vertical rise;
horizontal runs may be level.

• When the horizontal termination cap is exposed to high
precipitation, the cap should have a 1/4 inch downward
slant to allow any moisture in cap to be released. See

Figure 4.7. See Figure 4.8 for additional water inltration



prevention.

WALL

1/4 in. max.

(6 mm)

Figure 4.7 Water Inltration Prevention

18

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

Figure 4.8 Exterior Chase - Water Inltration Prevention



Measuring Standards

Vertical and horizontal measurements listed in the vent
diagrams were made using the following standards:

• Pipe measurements are shown using the effective length
of pipe. See Section 12.A (Figure 12.1 for DVP, Figure

12.7 for SLP) for information on effective length of pipe
components.

• Horizontal terminations are measured to the outside

mounting surface (ange of termination cap) (see Figure

4.9).

• Vertical terminations are measured to top of last section
of pipe. See Figure 4.10.

• Horizontal pipe installed level with no rise.

OVERHANG

C

WALL

MEASURE TO SHADED SURFACE
(OUTSIDE MOUNTING SURFACE)

Figure 4.9 Measure to Outside Mounting Surface

E

C and E dimensions are dened in Figure 4.4.

Figure 4.11 Measure Horizontal and Vertical Termination

Clearance to Trapezoid Portion of Cap

Figure 4.10. Measure to Top of Last Section of Pipe

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

19

Note: The Novus series appliances can adapt to SLP
series vent pipe when venting off the top of the appliance.
You must use a DVP-SLP24 adapter or a DVP-2SL and
two feet of SLP pipe which can only be attached to the
appliance starting collar.

When looking at horizontal termination diagrams, neither

adapter is counted as part of the minimum vertical (V1 min.)
requirements.

All venting rules for the vent run must still be followed.

Top Vent - Horizontal Termination

Top Vent—Horizontal Termination—Two 45º Elbows
Installation requirements to replace the rst 90º elbow

with two 45º elbows:

4 ft min.

(1.22 m)

(IDENTICAL VENT RUNS USING DVP AND SLP PIPE)

DVP PIPE

SLP PIPE

HORIZONTAL EXAMPLE

H1 = 11 ft.

max.

H1 = 11 ft.

max.

V1 = 1 ft.

V

= 1 ft.

1

WALL

25 ft max.

(7.62 m)

Figure 4.12 Minimum Installation Requirements for Two 45 De­gree Elbows - Top Vent - Horizontal Termination

(IDENTICAL VENT RUNS USING DVP AND SLP PIPE)

*Minimum vertical dimension includes

*6 ft (1.83 m) min.

60 ft (18.29 m) max.

2 ft. SLP

AND

DVP-2SL

VERTICAL EXAMPLE

vertically oriented 45 degree elbows.

OR

*6 ft (1.83 m) min.

60 ft (18.29 m) max.

DVP-SLP24

DVP-SLP24

Adapter

OR

2 ft. SLP

AND

DVP-2SL

20

DVP

Figure 4.13

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

SLP

Top Vent - Horizontal Termination

One Elbow

V1 Minimum H1 Maximum

0* 0* 18 in. 457 mm

4 in. 102 mm 4 ft. 1.22 m

6 in. 152 mm 6 ft. 1.83 m

12 in. 305 mm 11 ft. 3.35 m

18 in. 457 mm 17 ft. 5.2 m

24 in. 610 mm 17 ft. 5.2 m

V1 + H1 = 50 ft. (15.24 m) Maximum

* You may install the elbow directly on top of the

NOTE: A minimum venting scenario consists of a 90 degree elbow
off the top of the appliance with a DVP-TRAP2 horizontal termination
cap.

appliance (DVP only).

H

V

1

1

Figure 4.14

Heatilator • NNXT33-IFT, NNXT33L-IFT, NNXT36-IFT, NNXT36L-IFT Installation Manual • 2628-980 Rev. E • 2/21

21