Natco VW Installation And Operating Instructions Manual Download Page 6

Page: 6 / 24

12 inches of the ceiling, and the other within 12
inches of the floor. Each opening should
have a minimum free area of one square inch per
4,000 BTUH input of the total input rating of all
appliances in the enclosed area. See Table II for
recommended air supply for each model. An

improperly ventilated equipment room can get

excessively hot and cause accelerated
deterioration of controls and electrical
components.

IMPORTANT: In beauty shops, barber shops,
cleaning establishments and self-service laundries
with dry cleaning equipment, it is important that the
water heater be installed in a location where
combustion and ventilation air is received from a
source outside the building. Please refer to the most
recent edition of the National Fuel Gas Code, ANSI

* When the ceiling height exceeds 8 feet, you are only allowed to consider 8
feet when calculating the total volume of the enclosure.

Z223.1, or in Canada, CGA requirements.

Exhaust Fans or Vents: Any equipment which
exhausts air from the heater room can deplete
the combustion air supply or reverse the natural
draft action of the venting system. This could
cause flue products to accumulate in the heater
room. Additional air must be supplied to
compensate for such exhaust. The information in
Table II is not applicable in installations where
exhaust fans or blowers of any type are used.
Such installations must be designed by

qualified engineers.

If a blower or fan is used to supply air to the
heater room, the installer should make sure it
does not create drafts which could cause
nuisance shutdowns of the pilot. If a blower is
necessary to provide adequate combustion air to
the heater, a suitable switch or equivalent must
be wired into the heater control circuit to prevent
the heater from firing unless the blower is
operating.

The heater must be completely isolated and
protected from any source of corrosive chemical
fumes such as trichlorethylene, perchlorethylene,
chlorine, etc.

Table II. Minimum Recommended

Air Supply to Heater

Heater

Each Opening*

Model

(Square Inches)

500

125

600

150

715

179

850

213

1010

253

1200

300

1430

358

1670

418

1825

457

*Net Free Area in Square Inches

Area indicated is for one of two openings; one at

floor level and one at the ceiling, so the total net free
area could be double the figures indicated. For
special conditions refer to the latest edition of ANSI
Z223.1 or, in Canada, CAN1-B149.1 and .2.

Consult factory if not communicating directly through
the walls with the outdoors.

Note: Check with louver manufacturers for net free
area of louvers. Correct for screen resistance to the
net free area if a screen is installed. Check all local
codes applicable to combustion air.

2B-2. Venting

Natco heaters have built-in draft diverters for
natural draft operation and must not be
connected to any portion of a mechanical
draft system under positive pressure. The flue
outlet must be connected to a clear, unobstructed
vent of adequate capacity ending above the

12345678901234567890

Water

Heater

12345678901234567890

CLOSET INSTALLATION

(UNACCEPTABLE)

A closet is any 4 sided enclosure
which is less than 16* times the total
volume of all the gas fired appliances
within the enclosure.

ROOM INSTALLATION

(ACCEPTABLE)

A room is any enclosure which is at
least 16* times greater than the total
volume of all the gas fired appliances
within the enclosure.

12345678901234567890

Water

Heater

Figure 6 – Alcove Installation

ALCOVE INSTALLATION

(ACCEPTABLE)

An alcove suitable for the installation
of a water heater is a restricted section
of a room not separated from the
room by a door or partition and which
meets the minimum clearances for
the specific model water heater listed
below.