Direct Intake Vent System - A.O. Smith 910 Installation Manual And Owner's Manual

On-demand gas tankless water heater

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Troubleshooting manual (37 pages)

Table Of Contents

Table of Contents

Combustible air supplied by mechanical fan or make up air device

The water heater is equipped with a combustible air sensor that will shut off the unit when inadequate com-

bustible air supply to unit is detected.

If a mechanical fan or make up air device is used to supply air to the water heater or utility room, the

installer should make sure it does not create drafts which could cause nuisance shutdowns.

If a blower is necessary to provide adequate combustion air to the water heater, the blower and water

heater must be set up so that the water heater cannot fire unless the blower is operating. Possible

methods include the use of the water heater internal fan control port or the use of external flow sensors/

transmitters and relays.

This water heater may be converted to a direct-vent (sealed combustion) appliance by installing an adapt-

er 100112186 (TM-DV50) which will bring all required combustible air from outside the building. When

installing the direct-vent conversion kit, please follow all instructions included with the kit.

The water heater must be installed in a location where the proper amount of combustible air will be

available to it at all times without obstructions.

If used as a direct-vent appliance, the water heater

requires a 5" (127 mm) combustible air supply pipe. The

intake pipe must be sealed airtight.

Air supply pipe can be made of ABS, PVC (solid core),

CPVC (solid core), galvanized steel, corrugated aluminum,

corrugated stainless steel or Category III stainless steel.

Use of cellular core PVC (ASTM F891), cellular core CPVC,

or Radel® (polyphenylsulfone) in non-metallic venting

systems is prohibited. Covering non-metallic vent pipe

and fittings with thermal insulation is prohibited.

Change the DIP switch settings to the direct-vent system.

(See diagram below.)

Sidewall venting is recommended for the direct-vent

system.

The manufacturer recommends running the exhaust vent

and the intake pipe parallel.

For the venting instructions for direct intake vent installa-

tions, refer to pp. 15 to 20.

To change the DIP switch settings for direct vent installation, locate the lower bank of

DIP switches at the bottom of the center computer board as shown below.

Only adjust the appropriate DIP switches as shwon below.

Turn off the power supply to the water heater before changing the DIP switch settings.

WARNING

Failure to observe this warning could result in carbon monoxide poisoning or death.

The lower bank of DIP switches