ASHLAND CITY, TENN. — A. O. Smith Water Heater Co. has introduced its Vertex 90% efficient condensing residential water heater that the company said can produce "endless hot water." The 50- gal., 76,000 Btuh power vented unit was produced in cooperation with the U.S. Department of Energy and engineering consulting firm TIAX LLC, Cambridge, Mass.

Simplified installation gives plumbing contractors a solution for applications where an existing 40- or 50-gal. tank type unit is already installed and needs replacing. The height, diameter and placement of water and gas connections on the Vertex unit are the same as standard gas units. The power-vent design allows vertical or sidewall venting using 2-in., 3-in. or 4-in. PVC pipe, depending upon the distance. The unit can be vented 127 equivalent feet with 4-in. pipe, said Brand Manager David Chisholm.

A. O. Smith was selected by DOE and TIAX because the firm can manufacture a glass-lined, steel helical coil, which is at the heart of the water heater's heat exchange. The company had been making a similar heat exchanger for its Cyclone commercial water heater at its McBee, S. C., plant, Chisholm said.

The 90% efficient Vertex will save on operating costs compared to standard 78% efficient water heaters. First hour deliver is estimated at 127-gal. with a recovery rate of 93-GPH, similar to a 75-gal. power vented water heater. The unit can produce more than 3-GPM at a 45°F temperature rise, and slightly more than 1.5-GPM at a 90°F rise.

At the heart of the unit's 90% efficient design is an internal 11/2-in. helical coil heat exchanger with more surface area exposed to water in the tank than a standard straight vertical flue tube. The increased surface area of the helical coil has been proven to provide improved thermal efficiency in commercial products manufactured by A. O. Smith. The increased heat transfer surface area, combined with the 350-in. length of the coil, enables Vertex to accept 76,000 Btuh input while keeping heat energy inside the tank longer.

The water heater fires with a bottom-mounted burner with combustion air also entering through the bottom, Chisholm explained. A top-mounted blower blows combustion gasses down through the helical coil heat exchanger, which passes through the sidewall at the bottom to a condensate terminal. Exhaust gasses are then pulled up a PVC pipe back to the blower, which handles double duty and exhausts the combustion products out of the house.

Side-mounted hot and cold recirculating taps allow Vertex to be installed as part of a combination space heating/water heating application, radiant floor heating system or any system requiring a recirculating hot water loop.

"Today's homeowner demands more hot water than ever before," said Cliff Deidiker, residential product manager for A. O. Smith. "Vertex is a tank-type unit in a class by itself. Under the right conditions, it will deliver enough hot water to meet the increasing demands of consumers who expect an endless supply of hot water. For any customer who needs more hot water, and particularly for the homeowner who wants the very best, Vertex is made-to-order for them and for the contractor."

Any wholesaler that stocks A. O. Smith products has access to the Vertex now, although whether they keep it in inventory is up to them, Chisholm said. He noted that each distributor sets its own prices, but the wholesale price should be at about a slight premium to a 75-gal. powervented water heater.

The technology that drives Vertex is the result of a partnership between A. O. Smith and TIAX LLC, Cambridge, Mass., an engineering product development firm that's a spinoff from Arthur D. Little's Technology & Innovation business.