Desa Tech CMH2800TNB, VMH2800TNB Owner's Manual

VENT-FREE NATURAL

GAS HEATER

OWNER’S OPERATION AND INSTALLATION MANUAL

®

Shown with Optional

Hearth Base and Mantel

14,000 to 28,000 Btu/Hr with Thermostat “B” Models

WARNING: If the information in this manual is not
followed exactly, a fire or explosion may result caus­ing property damage, personal injury, or loss of life.

— Do not store or use gasoline or other flammable
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.

• 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
fire department.

— Installation and service must be performed by a
qualified installer, service agency, or the gas supplier.

This appliance may be installed in an aftermarket* manufactured (mobile) home, where not
prohibited by state or local codes.

*Aftermarket: Completion of sale, not for purpose of resale, from the manufacturer. (I.E. Installation of this
product is permitted after the manufactured (mobile) home is sited)

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

WARNING: Improper installation,
adjustment, alteration, service,
or maintenance can cause injury
or property damage. Refer to this
manual for correct installation
and operational procedures. For
assistance or additional infor­mation consult a qualified in­staller, service agency, or the
gas supplier.

WARNING: This is an unvented
gas-fired heater. It uses air (oxy­gen) from the room in which it is
installed. Provisions for adequate
combustion and ventilation air
must be provided. Refer to

Combustion and Ventilation

tion in this manual.

Air for

sec-

Save this manual for future reference.

CONTENTS

SECTION PAGE

Safety Information....................................................................................2

Product Identification ...............................................................................4

Local Codes .............................................................................................. 4

Product Features .......................................................................................4

Unpacking.................................................................................................4

Assembly ..................................................................................................5

Air for Combustion and Ventilation.........................................................8

Installation ................................................................................................12

Connecting to Gas Supply ........................................................................ 20

Checking Gas Connections.......................................................................21

Operating Heater ......................................................................................23

Inspecting Burner .....................................................................................26

Cleaning and Maintenance ....................................................................... 28

Troubleshooting........................................................................................ 28

Technical Service ..................................................................................... 32

Specifications ...........................................................................................32

Service Hints ............................................................................................32

Replacement Parts .................................................................................... 32

Parts Centrals............................................................................................33

Accessories ............................................................................................... 34

Illustrated Parts List.................................................................................. 36, 37

SAFETY

INFORMATION

WARNINGS

IMPORTANT: Read this owner’s manual carefully and completely
before trying to assemble, operate, or service this heater. Improper
use of this heater can cause serious injury or death from burns, fire,
explosion, electrical shock, and carbon monoxide poisoning.

DANGER

Carbon monoxide poisoning may lead to death!

Carbon Monoxide Poisoning: Early signs of carbon monoxide poisoning

resemble the flu, with headaches, dizziness, or nausea. If you have these signs,
the heater may not be working properly. Get fresh air at once! Have heater
serviced. Some people are more affected by carbon monoxide than others. These
include pregnant women, people with heart or lung disease or anemia, those
under the influence of alcohol, and those at high altitudes.

Natural Gas: Natural gas is odorless. An odor-making agent is added to natural
gas. The odor helps you detect a natural gas leak. However, the odor added to
natural gas can fade. Natural gas may be present even though no odor exists.

Make certain you read and understand all warnings. Keep this manual for
reference. It is your guide to safe and proper operation of this heater.

2

Safety Information continues on next page

101812

SAFETY

INFORMATION

Continued

WARNINGS

WARNING: Any change to this heater or its controls can be dangerous.

1. This appliance is only for use with the type of gas indicated on the rating
plate. This appliance is not convertible for use with other gases.

2. If you smell gas

• shut off gas supply

• do not try to light any appliance

• do not touch any electrical switch; do not use any phone in your building.

• 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 fire department

3. This heater shall not be installed in a bedroom or bathroom.

4. Never install the heater

• in a recreational vehicle

• where curtains, furniture, clothing, or other flammable objects are less than
36 inches from the front, top, or sides of the heater

• as a fireplace insert

• in high traffic areas

• in windy or drafty areas

Continued

5. This heater needs fresh, outside air ventilation to run properly. This heater has
an oxygen depletion sensor (ODS) pilot light safety system. The ODS shuts
down the heater if not enough fresh air is available. See Air for Combustion
and Ventilation, pages 8 through 11.

6. If heater shuts off, do not relight until you provide fresh, outside air. If heater
keeps shutting off, have it serviced.

7. Do not run heater

• where flammable liquids or vapors are used or stored.

• under dusty conditions.

8. Never place any objects on the heater.

9. Surface of heater becomes very hot when running heater. Keep children and
adults away from hot surface to avoid burns or clothing ignition. Heater will
remain hot for a time after shutdown. Allow surface to cool before touching.

10.Carefully supervise young children when they are in same room with heater.

11.Make sure screen is in place before running heater.

12.Do not use heater if any part has been under water. Immediately call a quali­fied service technician to inspect the room heater and to replace any part of the
control system and any gas control which has been under water.

101812

13.Turn off and unplug heater and let cool before servicing. Only a qualified
service person should service and repair heater.

14.Operating heater above elevations of 4,500 feet could cause pilot outage.

15. WARNING: Do not use a blower insert, heat exchanger insert, or other
accessory not approved for use with this heater.

3

PRODUCT

IDENTIFICATION

Ignitor Button

Control Knob

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Lighting and
Warning
Plates

LOCAL CODES

Heater
Cabinet

Screen

Front
Panel

Log

Figure 1 - Vent-Free Gas Log Natural Gas Space Heater

Install and use heater with care. Follow all local codes. In the absence of local
codes, use the latest edition of The National Fuel Gas Code ANSI Z223, also
known as NFPA 54*.

*Available from:

American National Standards Institute, Inc.

1430 Broadway

New York, NY 10018

PRODUCT

FEATURES

UNPACKING

4

National Fire Protection Association, Inc.

Batterymarch Park

Quincy, MA 02269

Safety Device

This heater has a pilot with an Oxygen Depletion Sensor Shutoff System (ODS).
The ODS/pilot is a required feature for vent-free room heaters. The ODS/pilot shuts
off the heater if there is not enough fresh air.

Piezo Ignition System

This heater has a piezo ignitor. This system requires no matches, batteries, or other
sources to light heater.

Thermostatic Heat Control

This heater has a thermostat sensing bulb and a control valve. This results in the
greatest heater comfort. This can also result in lower gas bills.

1. Remove heater from carton.

2. Remove all protective packaging applied to heater for shipment.

3. Make sure your heater includes two hardware packets.

4. Check heater for any shipping damage. If heater is damaged, promptly inform
dealer where you bought heater.

101812

ASSEMBLY

ASSEMBLING HEATER

Tools Required: Phillips screwdriver, 5/16" hex wrench, and slotted screwdriver

Removing Front Panel Of Heater

1. Remove two screws near bottom corners of front panel with Phillips screwdriver.

2. Pull bottom of front panel forward, then down (see Figure 2) .

Figure 2 - Removing Front Panel of Heater

Installing Log

Note:

For easier installation, lay heater on its back.

1. Remove log from inside top of heater. Discard protective packaging.

2. Attach ignitor cable to piezo ignitor (see Figure 3).

Piezo Ignitor

Ignitor Cable

101812

Figure 3 - Attaching Ignitor Cable to Piezo Ignitor

3. With Phillips screwdriver, remove four screws holding screen in place. Re­move screen.

4. Gently slide log between log retaining brackets on deflector assembly (see Figure
4, page 6). The log should fit firmly against bottom of log retaining brackets.

5. Reattach screen using four screws removed in step 3.

Continued

5

WARNING ICON G 001

ASSEMBLY

Continued

WARNING

Always have burner shield and screen in place before operating
heater. This prevents excessive temperatures on heater surfaces.

Failure to position the parts in accordance with these diagrams or
failure to use only parts specifically approved with this heater may
result in property damage or personal injury.

Front Panel

Truss­Head
Screw

Brass
Front
Trim

Screen

Nut

Log

Screw

Heater Cabinet

Screw

Deflector

Log
Retaining
Brackets

Burner Shield

Figure 4 - Assembling Heater

Attaching Brass Front Trim to Front Panel

1. Locate brass front trim in brass trim package.

2. Slide the head of two truss-head screws from hardware packet into each end of
brass front trim (see Figure 5).

3. Line up screws with holes in front panel (see Figure 4). Insert screws in holes.
Attach nuts from inside of front panel. Tighten with wrench.

Front Panel

Brass Front
Trim

Truss-Head Screw

Figure 5 - Attaching Brass Front Trim to Front Panel

Nut

6

101812

ASSEMBLY

Continued

Assembling and Attaching Brass Trim

1. Remove packaging from remaining three pieces of brass trim.

2. Locate four brass screws, two adjusting plates with set screws, and two shims in
the hardware packet.

3. Align shim under adjusting plate as shown in Figure 6.

4. Slide one end of adjusting plate/shim in slot on mitered edge of top brass trim
(see Figure 6).

5. Slide other end of adjusting plate/shim in slot on mitered edge of side brass trim
(see Figure 6).

6. While firmly holding edges of brass trim together, tighten both set screws on the
adjusting plate with slotted screwdriver.

Top Brass Trim

Side Brass Trim

Set Screws

Adjusting
Plate

Shim

Mitered Edge

Slot

Figure 6 - Assembling Brass Trim

Slot

7. Repeat steps 1 through 6 for other side.

8. Place the assembled trim on front of heater cabinet. Attach on top and sides
with four brass screws included in hardware package (see Figure 7).

Screws

Assembled
Brass Trim

101812

Figure 7 - Attaching Brass Trim to Heater

9. Reattach front panel to heater if you are going to mount the heater to the base. Do
not reattach front panel at this time if you are going to mount heater to wall.

7

AIR FOR

WARNING

COMBUSTION

AND

VENTILATION

This heater shall not be installed in a confined space unless
provisions are provided for adequate combustion and ventilation
air. Read the following instructions to insure proper fresh air for
this and other fuel-burning appliances in your home.

Today’s homes are built more energy efficient than ever. New materials, increased
insulation, and new construction methods help reduce heat loss in homes. Home
owners weather strip and caulk around windows and doors to keep the cold air out
and the warm air in. During heating months, home owners want their homes as
airtight as possible.

While it is good to make your home energy efficient, your home needs to breathe.
Fresh air must enter your home. All fuel-burning appliances need fresh air for
proper combustion and ventilation.

Exhaust fans, fireplaces, clothes dryers, and fuel burning appliances draw air from
the house to operate. You must provide adequate fresh air for these appliances.
This will insure proper venting of vented fuel-burning appliances.

PROVIDING ADEQUATE VENTILATION

The following is exerpts from National Fuel Gas Code. NFPA 54/ANSI Z223.1,
Section 5.3, Air for Combustion and Ventilation.

All spaces in homes fall into one of the three following ventilation classifications:

1. Unusually Tight Construction; 2. Unconfined Space; 3. Confined Space.
The information on pages 9 through 11 will help you classify your space and provide
adequate ventilation.

Unusually Tight Construction

The air that leaks around doors and windows may provide enough fresh air for
combustion and ventilation. However, in buildings of unusually tight construction,
you must provide additional fresh air.

Unusually tight construction is defined as construction where:
a. walls and ceilings exposed to the outside atmosphere have a continu-

ous water vapor retarder with a rating of one perm or less with open-

ings gasketed or sealed
b. weather stripping has been added on openable windows and doors
c. caulking or sealants are applied to areas such as joints around window

and door frames, between sole plates and floors, between wall-ceiling

joints, between wall panels, at penetrations for plumbing, electrical, and

gas lines, and at other openings.

If your home meets all of the three criteria above, you must provide addi­tional fresh air. See

If your home does not meet all of the three criteria above, proceed to page 9.

Ventilation Air From Outdoors

and

, page 11

and

.

Unconfined Space

The National Fuel Gas Code, ANSIZ223.1, 1992, Section 5.3 defines uncon-
fined space as a space whose volume is not less than 50 cubic feet per 1000 Btu
per hour (4.8 cubic m per kw) of the aggregate input rating of all appliances
installed in that space. Rooms communicating directly with the space in which
the appliances are installed, through openings not furnished with doors, are
considered a part of the unconfined space.

Confined Space

The National Fuel Gas Code, ANSIZ223.1, 1992, Section 5.3 defines confined
space as a space whose volume is less than 50 cubic feet per 1000 Btu per hour
(4.8 cubic m per kw) of aggregate input rating of all appliances installed in that

8

space.

101812

AIR FOR

COMBUSTION

AND

VENTILATION

Continued

DETERMINING AIR FLOW FOR HEATER LOCATION

Determining if You Have a Confined or Unconfined Space

Use this worksheet to determine if you have a confined or unconfined space.
Space: Includes the room in which you will install heater plus any adjoining rooms with

doorless passageways or ventilation grills between the rooms.

1. Determine the volume of the space (length x width x height).
Length x Width x Height = ___________________ cu. ft. (volume of space)

Example:

If additional ventilation to adjoining room is supplied with grills or openings, add the
volume of these rooms to the total volume of the space.

2. Divide the space volume by 50 cubic feet to determine the maximum Btu/Hr the space
can support.

____________ (volume of space) ÷ 50 cu. ft. = (Maximum Btu/Hr

the space can support)

Example:

Btu/Hr the space can support)

3. Add the Btu/Hr of all fuel burning appliances in the space.

Example:

* Do not include direct-vent gas appliances. Direct-vent draws combustion air from the
outdoors and vents to the outdoors.

4. Compare the maximum Btu/Hr the space can support with the actual amount of Btu/Hr
used.

_________________ Btu/Hr (maximum the space can support)
_________________ Btu/Hr (actual amount of Btu/Hr used)

Example:

The space in the above example is a confined space because the actual Btu/Hr used is more
than the maximum Btu/Hr the space can support. You must provide additional fresh air.
Your options are as follows:

A. Rework worksheet, adding the space of an adjoining room. If the extra space provides

an unconfined space, remove door to adjoining room or add ventilation grills between

rooms. See Ventilation Air From Inside Building, page 10.
B. Vent room directly to the outdoors. See Ventilation Air From Outdoors, page 11.
C. Install a lower Btu/Hr heater, if lower Btu/Hr size makes room unconfined.

If the actual Btu/Hr used is less than the maximum Btu/Hr the space can support, the space
is an unconfined space. You will need no additional fresh air ventilation.

Space size 20 ft. (length) x 16 ft. (width) x 8 ft. (ceiling height) =

2560 cu. ft. (volume of space)

2560 cu. ft. (volume of space) ÷ 50 cu. ft. = 51.2 or 51,200 (maximum

Vent-free heater ___________________ Btu/Hr
Gas water heater* ___________________ Btu/Hr
Gas furnace ___________________ Btu/Hr
Vented gas heater ___________________ Btu/Hr
Gas fireplace logs ___________________ Btu/Hr
Other gas appliances* + ___________________ Btu/Hr
Total = ___________________ Btu/Hr

Gas water heater 30,000 Btu/Hr
Vent-free heater + 28,000 Btu/Hr
Total = 58,000 Btu/Hr

51,200 Btu/Hr (maximum the space can support)
58,000 Btu/Hr (actual amount of Btu/Hr used)

101812

Continued

9

AIR FOR

COMBUSTION

AND

VENTILATION

Continued

WARNING

If the area in which the heater may be operated is smaller than
that defined as an unconfined space, provide adequate combus­tion and ventilation air by one of the methods described in the

National Fuel Gas Code, ANSI Z223.1, 1992, Section 5.3.

VENTILATION AIR

Ventilation Air From Inside Building

This fresh air would come from an adjoining unconfined space. When ventilating to
an adjoining unconfined space, you must provide two permanent openings: one within
12" of the ceiling and one within 12" of the floor on the wall connecting the two spaces
(see options 1 and 2, Figure 8). You can also remove door into adjoining room (see
option 3, Figure 8). Follow the National Fuel Gas Code NFPA 54/ANSI Z223.1,
Section 5.3, Air for Combustion and Ventilation for required size of ventilation grills
or ducts.

WARNING

Rework worksheet, adding the space of the adjoining unconfined
space.
appliances in both spaces.

The combined spaces must have enough fresh air to supply all

Ventilation

Grills

into Adjoining

Room,

Option 1

12"

Ventilation Grills

Into Adjoining Room,

Option 2

Or

Remove
Door into
Adjoining

Room,

Option 3

12"

10

Figure 8 - Ventilation Air from Inside Building

101812

AIR FOR

COMBUSTION

AND

VENTILATION

Continued

Ventilation Air From Outdoors

Provide extra fresh air by using ventilation grills or ducts. You must provide two
permanent openings: one within 12" of the ceiling and one within 12" of the floor.
Connect these items directly to the outdoors or spaces open to the outdoors. These
spaces include attics and crawl spaces.

IMPORTANT:

a thermostat-controlled power vent. Heated air entering the attic will activate the
power vent.

Do not provide openings for inlet or outlet air into attic if attic has

Outlet
Air

Inlet
Air

Outlet
Air

Inlet Air

Figure 9 - Ventilation Air from Outdoors

Ventilated
Attic

Ventilated

Crawl Space

To Attic

To

Crawl

Space

101812

11

INSTALLATION

NOTICE

A qualified service person must install heater. Follow all local codes.

CHECK GAS TYPE

Use only natural gas. If your gas supply is not natural gas, do not install heater. Call
dealer where you bought heater for proper type heater.

INSTALLATION ITEMS

Before installing heater, make sure you have the items listed below.

• piping (check local codes)

• sealant (resistant to propane/LP gas)

• manual shutoff valve *

• ground joint union

• test gauge connection *
(see Figure 24, page 21)

• sediment trap

• tee joint

• pipe wrench

* An A.G.A. design-certified manual shutoff valve with 1/8" NPT tap is an acceptable
alternative to test gauge connection. Purchase the optional A.G.A. design-certified
manual shutoff valve from your dealer. See Accessories, page 34.

LOCATING HEATER

WARNING

WARNING ICON G 001

Maintain the minimum clearances shown in Figure 10 (page 13). If
you can, provide greater clearances from floor, ceiling, and join­ing wall.

You can locate heater on floor. The optional hearth base is needed. You can also
install the optional decorative mantel on the heater when using the optional hearth
base.

IMPORTANT:

manual. Purchase the optional mantel and hearth base from your dealer. See
Accessories, pages 34 and 35.

The heater may also be mounted on a wall. You cannot use optional mantel if
mounting heater on a wall.

Only use optional mantel and hearth base specified in this

12

WARNING

WARNING ICON G 001

Never install the heater

• in a bedroom or bathroom

• in a recreational vehicle

• where curtains, furniture, clothing, or other flammable objects are
less than 36 inches from the front, top, or sides of the heater

• as a fireplace insert

• in high traffic areas

• in windy or drafty areas

CAUTION

WARNING ICON G 001

This heater creates warm air currents. These currents move heat
to wall surfaces next to heater. Installing heater next to vinyl or
cloth wall coverings or operating heater where impurities in the air
(such as tobacco smoke) exist, may discolor walls.

IMPORTANT:

Vent-free heaters add moisture to the air. Although this is beneficial, in­stalling heater in rooms without enough ventilation air may cause mildew to form from
too much moisture. See Fresh Air for Combustion and Ventilation, pages 8 through 11.

101812