A.O. Smith BTP(V)-540A warranty Vertical Venting for BTP Models, Barometric Draft Control Assembly

Heater must be protected from freezing downdrafts during shutdown periods.

The BTP 540A, 650A and 750A water heater are classified as a category I appliance (non-positive vent pressure, non- condensing) when installed with the supplied barometric draft control assembly in a vertical vent installation.

The BTPV 540A through 740A heater is classified as a category

IIIappliance (positive vent pressure, non-condensing) when installed with supplied sidewall vent kits or direct vent kit.

All regulations pertaining to the venting of these heaters must be followed.

The following vent installation instructions cover vertical, horizontal, and direct vent applications.

NOTE: A NEGATIVE DRAFT MUST BE MAINTAINED IN VENTING.

A negative draft of 0.02” to 0.04” w.c. Must be maintained in venting system. Measure draft at the location illustrated in Figure 4. Adjust the control counter-weights if necessary as shown in the MAINTENANCE portion of this manual.

Where an existing chimney or vent is to be used, be sure that the chimney or vent has adequate capacity for the number and sizes of gas appliances being vented through it. Inspect the chimney or vent and remove all soot or other obstructions, which will retard free draft.

Vent connectors making horizontal runs must have a minimum upward slope toward the chimney or vent of ¼ inch per foot. Vent connector length should be kept as short as possible. Be sure that the vent pipe does not extend beyond the inside wall of a chimney, see Figure 4.

VERTICAL VENTING - FOR BTP MODELS

BAROMETRIC DRAFT CONTROL ASSEMBLY

Adouble-acting barometric draft control assembly is provided with any unit intended for chimney venting. The purpose of this draft control is twofold. During downdrafts it acts as a pressure relief control to prevent the downdraft from blowing into the heater. It also allows for makeup air to enter the chimney without being drawn through the heater. In both cases the control prevents the heater performance from being adversely affected by conditions within the chimney.

The draft control assembly must be installed without alteration. This assembly is factory adjusted for horizontal application only and must be attached to the heater as shown in Figure 4. The direction in which the outlet to the draft controls assembly faces is arbitrary. The assembly must be fitted to the jacket cover such that it is plumb and level to the ground. Fasten the draft control assembly to the top cover using sheet metal screws at three locations, or more, as required.

Damper or other obstructions must not be installed between the heater and the barometric draft control assembly.

Do not adjust settings on gate.

When installed, the damper gate must pivot freely in the ring guides. This gate will automatically adjust to regulate the chimney draft imposed on the heater.

VENT CONNECTIONS

Vent connections must be made to an adequate stack or chimney. Refer to the National Fuel Gas Code or to the vent pipe manufacturer’s gas vent and chimney sizing table to properly design and size the venting system. Refer to Table 1 for the vent pipe size required for installation to the barometric draft control assembly outlet.

	TABLE 1.
Model		Flue Outlet
BTP-540A		9” (228.6 mm)
BTP-650A		9” (228.6 mm)
BTP-740A		9” (228.6 mm)

Single-wall or type B venting may be used with these heaters in vertical vent installations. All local and utility regulations on venting must be followed.

FIGURE 4.

In venting systems where a continuous or intermittent back (positive) draft is found to exist, the cause must be determined and corrected. In some cases, a special vent cap may be required.

WARNING

Failure to correct back drafts may cause air contamination and unsafe conditions.

Do not connect the heater to a common vent or chimney with solid fuel burning equipment. This practice is prohibited by many local building codes as is the practice of venting gas fired equipment to the ductwork of ventilation systems.

Connectors shall not be connected to a chimney, vent or venting system served by a power exhauster, unless the connection is made on the negative pressure side of the exhauster.

Do not connect any heater vented by natural draft to any vent serving mechanical draft equipment operating under positive vent pressure such as category III or category IV appliances.

HORIZONTAL (SIDE-WALL) VENTING -

FOR BTPV MODELS

An exhaust vent hood, vent hood and a flue reducer are supplied with any unit intended for through-the-wall horizontal venting. These parts must be installed without alteration. The vent hood adapter is designed for use with Selkirk Metalbestos Model PS or Model G venting, see Figure 7 on page 10.

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