In serious hot water

Ocean Navigator|July/August 2020

In serious hot water
Devising a multiple-input system for producing hot water
Rebecca Childress

Tierra del Fuego, Land of Fire, might have a warm name, but the images of glaciers and penguins give me the chills. We are sailing our way toward the southern tip of South America, and while my husband, Patrick Childress, sees this as a great adventure, I am more practical and first require heat and hot water on our Valiant 40, Brick House.

To warm the air, we have installed a radiator “car heater,” which transfers heat from the diesel engine cooling system and blows warm air in the main saloon when the engine is running. A wood-burning stove from Cubic Mini Wood Stoves (cubicminiwoodstoves. com) was also installed in the main saloon for heat at anchor.

Coldwater showers in the equatorial tropics are quite a different sensation than those near Antarctica. Our original water heater got very hot when the diesel engine ran for a long time, or when plugged into 120volt AC shore power. But going forward, it will be very rare to have any shore power, and it is unreasonable to run the engine just to heat up water. Nearly any original component still on our 44-year-old sailboat has long outlived its expiration date; with every passing day, we felt our original water heater was one day closer to a bursting disaster.

It was time to update our water heating capabilities. Traditionally, marine water heaters work by either heating an element with electricity, or by circulating hot engine coolant through heat exchanger coils inside the water heater. But why not have the ability to heat water from the cooling system of the diesel engine, shore power, and also multiple ways from our 12-volt system? Why not utilize free excess energy from our wind generator and solar panels to heat water? We had just installed a new Freedom Won lithium battery bank, which gave us more usable energy due to more efficient charging.

When I contacted various water heater companies, the only one that was receptive to a 12-volt element being installed in their heater was Torrid Marine ( They were keen to assist with an off-grid water heating solution and were already making hybrid water heaters — the Explorer Series. The Explorer can have dual electrical elements, and can even be used in combination with a hydronic diesel heater or stove equipped with heating coils, passively capturing heat without any additional power being consumed.

Torrid Marine set to work with, which supplied a 12-volt DC/120volt AC element and built us a custom water heater with it. The Torrid Marine heaters are glass-lined and foam insulated with a stainless steel outer casing, and that’s the durability we required. With more research, and by talking to other owners of Torrid Marine heaters, we knew working with this highly responsive company would be worthwhile.

Going down in capacity

Our old water heater was 11 gallons, but we purposely bought Torrid Marine’s smallest unit, simply because we practice water conservation anyway; six gallons gives us at least three showers. In addition, six gallons would be much more efficient to heat using the off-grid methods we had planned. Torrid Marine also explained that hot water rises — just like hot air — and since the outlet is at the top, the first bit of hot water effectively floats to the top and flows out of the outlet first while the rest of the water heater is still heating up.

After going through many details with Torrid Marine, the water heater was shipped to us in Africa as quickly as if we were in a marina in the U.S. We received it just three days after it was built, which is unusual in Africa.

The first step was removing the old water heater and installing the new one in its place. Not wanting to buy a propane torch and soldering supplies for a small one-time job, we hired a plumber for an hour to make fast work of connecting one pipe and supplying the one needed hose adapter. Everything else, we did ourselves; improvisation like this is a mandatory skill for cruising the world.


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July/August 2020