26 | Installation instructions
Attention residents of the Commonwealth of Massachusetts:
In the Commonwealth of Massachusetts the following regulation went
into effect on 12/30/2005:
(a)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 finished grade in the area of the venting,
including but not limited to decks and porches, the following
requirements shall be satisfied:
1. INSTALLATION OF CARBON MONOXIDE DETECTORS. At the time of
installation of the side wall horizontal vented gas fueled equipment, the
installing plumber or gas fitter shall observe that a hard wired carbon
monoxide detector with an alarm and battery back-up is installed on the
floor level where the gas equipment is to be installed. In addition, the
installing plumber or gas fitter 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 qualified
licensed professionals for the installation of hard wired carbon
a.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 floor level.
b. 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.
2.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
3. SIGNAGE. A metal or plastic identification 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) inch in size, "GAS
VENT DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUCTIONS".
4. 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.(b)
EXEMPTIONS: The following equipment is exempt from 248 CMR
5.08(2)(a)1 through 4:
1. 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
2. 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.
(c) MANUFACTURERS REQUIREMENTS - GAS EQUIPMENT VENTING
SYSTEM REQUIRED. When the manufacturer of Product Approved side
wall horizontally mounted gas equipment provides a venting system
design or venting system components with the equipment, the
instructions provided by the manufacturer for the installation of the
equipment and the venting shall include:
1. Detailed instructions for the installation of the venting system or the
venting system components: and
2. A complete parts list for the venting system design or venting system.
(d)MANUFACTURER REQUIREMENTS - GAS EQUIPMENT VENTING
SYSTEM NOT PROVIDED. When the manufacturer of a product approved
side wall horizontally vented gas fueled equipment does not provide the
parts for the venting of flue gases, but identifies "special venting
6 720 805 440 (2014/11)
systems," the following requirements shall be satisfied by the
1. The referenced "special venting system" instructions shall be included
with the appliance or equipment installation instructions; and
2. 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.
(e) A copy of all installation instructions for all products 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.
Combustion air requirements
▶ In areas where outside temperatures routinely come
close to freezing, sealed combustion operation is
required. Use a concentric termination or separate
terminations for combustion and vent, which must
be installed on the same wall or roof surface,
however never facing the direction of prevailing
winds. Failure to do so may result in heat exchanger
freezing up and leaking. This failure is not covered
under the manufacturer's warranty.
▶ When installed in an environment where corrosive
chemicals or dirty air (e.g. hair salons, car washes)
are present the twin pipe system is required.
Twin pipe and Concentric pipe
The water heater is designed as a sealed combustion appliance. It is
recommended that the combustion air be provided by a dedicated 2", 3"
or 4" pipe from the outside (twin pipe) or by connecting to the
Concentric vent kit (see Fig.9). The combustion air pipe may be PVC or
any other rigid sealed 2", 3" or 4" pipe. The combustion air piping must
pitch down 1/4 inch per foot towards termination to prevent rain water
from entering the appliance. In twin pipe penetrations, the combustion
air inlet, whether terminating vertically or horizontally, must be located
in such a manner as to provide a minimum 3 foot clearance from the
exhaust vent termination. See Fig.10 and 11 Letter I, page 15.
For the maximum length of the combustion air pipe, see tables 8, 9 &10.
▶ Terminations must prevent rain and debris from
entering the combustion air and exhaust vent piping.
Note: These appliances require substantial combustion air to operate.
The C950 requires 8750 cubic feet, or 1094 square feet with and 8 foot
ceiling. The C1050 requires 9950 cubic feet, or 1243 square feet an 8
foot ceiling. If the large amount of air space, which equates to about half
of most average sized homes, is not available, the appliance must pull air
from the outside (see twin pipe above).
Although it is permissible to draw combustion air from the inside, it is not
the manufacturer's recommended installation method. Always install a 3
inch 90° elbow on the top of the combustion air inlet adaptor to prevent
foreign objects from falling into the unit.
If a single pipe installation is utilized, follow guidelines below for
providing adequate combustion air for the water heater as well as any
other appliances that may consume air in the same space. Always follow
local codes if they are more stringent and regulations.
• Appliances located in unconfined spaces: