Very few water heaters use oil as a fuel source. One of the best is the Bock water heater. If oil is your only or preferred fuel option, check out the Bock line at www.bockwaterheaters.com.
Fuel oil contains more BTU’s than either natural gas or propane and with a well engineered unit like a Bock, oil can be an excellent fuel source.
Bock also manufactures a variety of gas water heaters, all with great recovery rates, good efficiency, power venting capabilities, and some models with BTU/hr. ratings of up to 600,000!
A note about alternate fuels
This information doesn’t apply to oil-fired Bock water heaters, but Biodiesel, a product made from virgin soy or waste vegetable oil, is now commonly processed into a fuel that in many cases can outperform petroleum products. Biodiesel is cleaner, renewable, contains no sulphur and would be well worth investigating for use in a heating appliance.
In fact, as a real world example of how effective even pure vegetable oil can be, our web designer collects used fryer grease from restaurants, filters it, and then pours the straight oil directly into the fuel tank of her diesel Volkswagen Jetta! She estimates her fuel costs at $.10 per gallon (the filters cost a few pennies each).
Actual biodiesel is vegetable oil processed to more closely resemble the No.2 heating oil used in oil-fired water heaters and boilers and could very well serve as an alternative to a petroleum based fuel source. Several “waste oil” boilers currently on the market would happily burn biodiesel and so would many conventional oil-fired boilers and water heaters.
But needlessly to say, always check with the manufacturer of your chosen heat source before using biodiesel and, should you go that route, always use a biodiesel blend that carries the ASTM certification.
For more details about biodiesel, follow this biodiesel link.
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.