Combined Air Inlet Points; Vent System Options; Barometric Damper Location - Lochinvar 399 Installation And Service Manual

If the air inlet cap is within a 10-foot (3.05m) radius of the flue
outlet, the point of termination for the combustion air inlet cap
must be at least 3 feet (0.91m) below the point of flue gas
termination (vent cap).
Do not install the combustion air inlet cap closer than 10 feet
(3.05m) from an inside corner of an L-shaped structure.

Combined Air Inlet Points

The air inlet pipes from multiple boilers can be combined to a
single common connection if the common air inlet pipe has a
cross sectional area equal to or larger than the total area of all
air inlet pipes connected to the common air inlet pipe.
: Two 10" air inlet pipes (78.5 in
total area of 157 in 2 and will require a 15" (176.7 in
common air inlet pipe.
The air inlet point for multiple boiler air inlets must be
provided with an exterior opening which has a free area equal
to or greater than the total area of all air inlet pipes connected
to the common air inlet. This exterior opening for combustion
air must connect directly to the outdoors. The total length of
the combined air inlet pipe must not exceed a maximum of 50
(15.2m) equivalent feet. Subtract 5 feet (1.5m) for each 90°
elbow in the air inlet pipe. You must deduct the restriction in
area provided by any screens, grills or louvers installed in the
common air inlet point. These are common on the sidewall air
inlet openings. Screens, grills or louvers installed in the
common air inlet can reduce the free area of the opening from
25% to 75% based on the materials used.

Vent System Options

This unit has six venting options.
1. Conventional Negative Draft Venting
This option uses a vertical rooftop flue termination.
Combustion air is supplied from the mechanical room. See
column 2 for detailed information.
2. Vertical DirectAire™ Venting
This option uses a vertical conventional vent for flue products.
Combustion air is supplied by a pipe from the sidewall or
rooftop. See page 17 for venting details.
3. Sidewall Venting
This option uses a powered vent assembly to exhaust the flue
products out a sidewall vent termination. Combustion air is
supplied from the mechanical room. See page 19 for venting
details.
4. Horizontal DirectAire™ Venting
This option uses a powered vent assembly to exhaust the flue
products out a sidewall. Combustion air is supplied by a pipe
from the sidewall. See page 21 for venting details.
5. Direct Venting
This option uses a sealed AL29-4C flue and a separate
combustion air pipe to the outdoors. This system terminates
both the flue and combustion air inlet in the same pressure
zone. The flue outlet and combustion air intake may terminate
at either a sidewall (horizontal) or the rooftop (vertical). See
page 22 for venting details.
6. Outdoor Installation Venting
This option uses the installation of a special air inlet/vent cap
2 area each) have a
on top of the unit. See page 26 for venting details.
2 area)
All units are shipped from the factory equipped for
conventional negative draft venting. All other optional vent
systems require the installation of specific vent kits and
venting materials. The following is a detailed explanation of
the installation requirements for each venting system,
components used and part numbers of vent kits for each model.

Barometric Damper Location

Any venting system option that requires a barometric damper
must adhere to the following directions for optimum
performance.
The preferred location for the barometric damper is in a tee or
collar installed in the vertical pipe rising from the unit's flue
outlet. The barometric damper MUST NOT be installed in a bull
head tee installed on the unit's flue outlet. The tee or collar
containing the barometric damper should be approximately three
feet vertically above the connection to the unit's flue outlet. This
location ensures that any positive velocity pressure from the
unit's internal combustion fan is dissipated and the flue products
are rising due to buoyancy generated from the temperature of the
flue products. Adjust the weights on the damper to ensure that
draft is maintained within the specified range.
15
Installation and
Service Manual