Beware of Tankless Water Heaters


The availability of relatively inexpensive tankless hot water heaters has apparently convinced some owners of older boats (and some newer ones) that going tankless is a smart way to save space and money. Theyd be wrong. The least expensive versions are designed for outdoor use, and even those designed for indoor use are not intended for use on a boat.

Tankless propane water heaters carry serious risk of causing carbon-monoxide poisoning or oxygen depletion when mounted in a tight or sealed space. Because a boat is more tightly sealed than a shoreside home, the carbon monoxide is more likely to become trapped. Boater deaths have been attributed to tankless water heaters, and several brands have been recalled over the years-among them Wolter Water Heater, Paloma, and Rheem-Rudd-because they posed a carbon-monoxide poisoning hazard.

That said, you will find tankless propane water heaters on some production boats, but it is buyer beware, in our opinion. Where you mount the heater, how it is installed, and how it is vented are of critical importance. Weve heard of boat owners mounting them successfully in vented spaces such as cockpit lazarettes, galleys, and anchor lockers, and many install them with heat shields. For extra precaution, you could run the water heater on a propane system separate from your stove, and rig it with a water solenoid that opens when the propane solenoid opens so the propane won't flow unless there is water flowing.

If you decide to install the tankless water heater despite the risks, you should first be sure that your heater hasnt been recalled. We also recommend investing in a quality carbon monoxide detector like the Fireboy/Xintex, (PS, December 2005), and always keeping a hatch open in the shower when using the heater. Also, check out our recent blog on inspecting marine systems for propane leaks. It wouldn't hurt to look into your other water-heating options as well; youll find a good sampling of whats available on the marine market in our December 2013 water-heater test.

Darrell Nicholson, editor of Practical Sailor, grew up boating on Miami’s Biscayne Bay on everything from prams to Morgan ketches. Two years out of Emory University, after a brief stint as a sportswriter, he set out from Miami aboard a 60-year-old wooden William Atkin ketch named Tosca. For 10 years, he and writer-photographer Theresa Gibbons explored the Caribbean, crossed the Pacific, and cruised Southeast Asia aboard Tosca, working along the way as journalists and documenting their adventures for various travel and sailing publications, including Cruising World, Sail, Sailing, Cruising Helmsman, and Sailing World. Upon his return to land life, Darrell became the associate editor, then senior editor at Cruising World magazine, where he worked for five years. Before taking on the editor’s position at Practical Sailor, Darrell was the editor of Offshore magazine, a boating-lifestyle magazine serving the New England area. Darrell has won multiple awards from Boating Writer’s International, including the Monk Farnham award for editorial excellence. He holds a U.S. Coast Guard 100-ton Master license and has worked as a harbor pilot and skippered a variety of commercial charter boats.


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