LAARS U.H.E. - Installation Manual - Manual (Page 18)

CAUTION
Check to make sure flue gases do not recirculate into the air intake terminal when using direct venting. If the water
heater is having service issues, flue recirculation may be a contributing factor. Even when the minimum vent terminal
separation distances are followed, recirculation may still occur depending upon the location outside the building, the
distance from other buildings, proximity to corners, weather conditions, wind patterns, and snow depth. Periodically
check to make sure that flue recirculation is not occurring. Signs of flue gas recirculation include frosted or frozen
intake terminals, condensate in the intake terminal and venting system, oxidation or white chalk material on the flame
sensor or igniter shield. Correction to flue recirculation may involve angling the intake and exhaust away from each
other, increasing the distance between them, relocating the air intake to another side of the building, or using inside air
for combustion.
Check to be sure the intake and exhaust terminals are not obstructed, especially during periods of below freezing
weather.
All intake and exhaust venting components must have the same diameter size. Do not use a different size on the intake
and exhaust venting. For 4” venting, use the supplied 3” vent terminals.
Be sure the condensate runs freely to a drain and does not accumulate inside the water heater. In cold climates,
precautions may need to be taken to insure that the condensate drain does not freeze. Make sure the condensate trap or
drain loop is installed to prevent flue gases from being discharged into the room. Refer to the Venting section of the
Installation and Operating Instructions Manual for complete instructions on venting and condensate drainage.
CAUTION
The vent shall terminate a minimum of 12 inches above expected snowfall level to prevent blockage of vent termination.
The horizontal centerline of the exhaust vent terminal (if applicable) must not be located lower than the horizontal
centerline of the air intake terminal if vented through the same wall.
A service drain loop must be installed in the drain tubing to serve as a condensate trap to prevent flue gases from
escaping into the room.
DO NOT position the air intake above the exhaust terminal.
NEVER locate the air intake where exhaust gases can be introduced.
NOTICE
Before beginning installation of any vent pipe, read the vent pipe manufacturer’s installation instructions.
Do not install the water heater in any location where the ambient temperature may fall below freezing. Water heater
must be protected from freezing downdrafts during shutdown periods.
Provide protection of the building materials from degradation by flue gases from the exhaust vent terminal.
VENTING
The venting instructions must be followed to avoid restricted combustion or recirculation of flue gases. Such conditions
cause sooting or risks of fire and asphyxiation.
This water heater can be installed as either a direct vent system or power vent (air from inside) system. If it is installed
as a direct vent system, then the air intake and the exhaust vent are piped to the outside. If a power vented system is
used, then air is drawn from inside and only the exhaust is piped to the outside. Determine which system is best for
your application and install as described in the following sections.
DIRECT VENT INSTALLATION
Venting may be run horizontally through an outside wall or vertically through a roof through using either 3 inch (7.6
cm) or 4 inch (10.2 cm) diameter PVC, ABS or CPVC pipe. This water heater is supplied with a screened intake and
exhaust 90° elbow referred to as the exhaust vent terminal and the air intake terminal.
NOTICE
If 4 inch PVC, ABS, or CPVC pipe is used, then a use a 4 “ to 3” reducer fitting before exiting the wall or roof to
use the supplied screened intake and exhaust 90° elbows.
Direct Vent Terminal Location
Plan the vent system layout so that proper clearances are maintained from plumbing and wiring. Before the vent is
installed, determine the vent pipe termination location as shown in Figure 12.
18