Tank Type ~ Gas Water Heaters

American ProLine Series

More and more, tankless on-demand water heaters are becoming the “norm” for radiant heat and domestic hot water applications. But, if your BTU requirements are moderate, it may not be practical to spend $1,300 on Takagi’s  smallest on-demand heater, or, needless to say, $2,300 to $4,000 dollars on a high-efficiency water/space heater like the Polaris or the Bock.

All the above units may be oversized for your application and you’d end up with lots of expensive, highly efficient heating capacity sitting around doing nothing much of the time. This is especially true if your system utilizes a heat source such as solar panels in a region where enough solar tubes or flat plates can actually do most of the water heating (Arizona, New Mexico, and Colorado, for example, and many other lower latitude western and eastern states) or with systems using an outdoor wood boiler as a primary heat source. In these two cases, the back-up is mainly a tank of hot water sitting around waiting to do something and it rarely makes sense to own a four thousand dollar storage tank.

On the other hand, design and spacial considerations must also come into play.

If you’re using a dual heat exchanger solar storage tank (lower heat exchanger coil for the solar, upper coil for the back-up), for example, it’s very clunky to use some low cost 30 gallon water heater to send “back-up” water to your upper heat exchanger coil — from an efficiency standpoint, a plumbing and venting standpoint, and a cluttering up your utility room with another tank of water standpoint — especially if the “back-up” will be used frequently in less than ideal solar regions.

A small, easy to install, efficient, and well designed on-demand unit is normally best for dual coil solar storage tanks.

But, for a small “closed system”, or for an equally small “open” system with very modest domestic hot water requirements, this kind of tank-type heater can make sense.


The American Water Heater Proline Series units come in a wide range of storage capacities (30 to 75 gallons), heating capacities (between 40,000 and 75,000 BTU’s/hr) and are available in either gas or electric models.

American even offers Direct Vent and Power Vent models, and some have extra side taps for easy installation of a heat exchanger loop when secondary heat sources are part of the heating system. Quality wise, they are a level above most “standard” water heaters. Their efficiency rating, at 78%, isn’t great, but the up-front cost is pretty low.


The Polaris is a “tank-type” water heater. It heats water at 96% efficiency, slightly better than the Takagi on-demand unit. But because the Polaris stores 50 gallons of hot water, it suffers from “stand-by heat loss” and that fact lowers its overall efficiency.

Polaris Water Heater

Polaris Water Heater

The upfront cost of a Polaris is also high due to its stainless steel tank. However, the Polaris has proved to be a consistently reliable machine and if your heating requirements approach 100,000 BTU’s or greater, the Polaris will start to pay for itself with fuel savings from the moment you fire it up.

Its many excellent features include, as mentioned, an all stainless steel tank, an igniter instead of a wasteful pilot light, a rating of 130,000 BTUs (or up to 199,000 on some models) and, of course, its amazing efficiency. The Polaris is a high recovery water heater, making over 160 gallons of hot water per hour! In most homes, one Polaris can heat plenty of water for all domestic needs AND provide 100% of the home’s heating. The Polaris comes with a 10 year warranty on the stainless steel tank and shipping is free.

If you’re considering a tank-type water, the Polaris can’t be beat.