Provide For Adequate Ventilation - Vermont Castings UVL18RN Installation And Operation Instructions Manual

Fresh Air Requirements for
Combustion and Ventilation
WARNING
This heater must have fresh air for proper
operation. If it does not, poor fuel combustion
could result. Read the following instructions to
ensure proper fresh air supply for this and
other fuel-burning appliances in your home.
Modern construction standards have resulted in
homes that are highly energy-efficient and that
allow little heat loss. Your home needs to breathe,
however, and all fuel-burning appliances need fresh
air to function properly and safely. Exhaust fans,
clothes dryers, fireplaces, and other fuel burning
appliances all use the air inside the building. If the
available fresh air supply is insufficient to meet the
demands of these appliances, problems can result.
The vent-free logsets have specific fresh air require-
ments. You must determine that these requirements
will be met within the space where the appliance will
be installed. The following information will help you
ensure that adequate fresh air is available for the
heater to function properly.

Provide for Adequate Ventilation

Any space within a home can be classified in these
categories:
1) Unusually tight construction
2) Confined space
3) Unconfined space.
First, determine which classification defines the
intended installation space.
Unusually Tight Construction
You must provide additional fresh air if the space
falls into this classification. Unusually Tight Con-
struction is defined as construction wherein:
a. Walls and ceilings exposed to the outside atmo-
sphere have a continuous water vapor barrier with a
rating of one perm or less, with openings gasketed
or sealed, and
b. weather stripping has been added on openable
windows and doors and
c. caulking or sealants are applied to areas such as
joints around windows and door frames, between
sole plates and floors, between wall and ceiling
joints, between wall panels, at penetrations for
plumbing, electrical, and gas lines, and at all other
openings.
UVL Series
Installation Requirements
If your home meets all of the above criteria, you
must provide additional fresh air for the appliance as
detailed on Page 6.
If your home does not meet the above criteria, follow
the procedure below.
Use the following formula to determine if you have a
confined or unconfined space.
Space is defined as the room in which you will install
the heater, plus any adjoining rooms with doorless
passageways or ventilation grilles between the
rooms. The National Fuel Gas Code defines a
confined space as a space whose volume is less
than 50 cubic feet per 1,000 BTU per hour input
rating (4.8m
rating of all appliances installed in that space and an
unconfined space as a space whose volume is not
less than 50 cubic feet per 1,000 BTU per hour
(4.8m
appliances installed in that space. Rooms communi-
cating directly with the space in which the appliances
are installed, through openings not furnished with
doors, are considered a part of the unconfined
space.
1. Determine the volume of space (length x width x
height). Include adjoining rooms connected by
doorless passageways or ventilating grilles.
Example: A room that is 18' x 12' x 8' has a volume
of 1728 cubic feet. An adjoining open kitchen that is
10' x 12' x 8' has a volume of 960 cubic feet. An
adjoining open dining room is 12' x 12' x 8' with a
volume of 1152 cubic feet. The total volume is 3840
cubic feet.
2. Divide the volume of space by 50 cubic feet. The
result is the maximum BTU/hour the space can
support.
Example: 3840 cubic feet divided by 50 = 76.8 or
76,800 BTU/hour.
3. Add the BTU/hour ratings of all fuel-burning
appliances installed in the same space, including the
following:
Gas Water Heater
Gas Fireplace Logs
Vented Gas Heater*
* Do not include Direct-vent appliances as these use
outdoor air for combustion and vent to the outdoors.
Determine If You Have a Confined or
Unconfined Space
3
per Kw) of the aggregate (total) input
3 per Kw) of the aggregate input rating of all
Gas Furnace
Vent-free Gas Heater
Other Gas Appliances*
5