A marine water heater is a heating device used in boats and ships for heating water as well as spaces. Powered by either electricity or propane, a marine water heater is a way to provide instant and required amount of hot water for tasks such as washing-up, personal hygiene, and shower, besides cooking etc. There are some marine water heaters that can utilize the wasted heat generated by the boat’s engine to heat up the water, at no extra cost!

Designed for small and compact areas, a marine hot water heater is an excellent appliance with economical operation costs despite working in extremely humid conditions and with salty, fresh water. That’s why marine water heaters are required to be manufactured with very high quality materials.

How Does A Marine Water Heater Work?

As mentioned above, since a marine water heater is constantly exposed to intense humidity and salty water, the marine hot water heater manufacturers designed these devices with anti-corrosion casing like aluminum and stainless steel or high gauge stainless steel or any other such material water tank. These appliances are available in different sizes as well and start from as small as 6 gallons to as large as 20 gallon capacities.

Marine heaters are designed to heat water quickly and effectively. That’s why the heating element is positioned at the lowest point of the water tank, as water is the coldest there. The position of water inlets and water outlets is also given special attention so that both types of water don’t get mixed. The marine hot water heater can use energy generated from AC generator or engine’s cooling water, or to some power source at the shore and they work on 110V power output.

Propane run marine water heaters are especially designed for the marine environment. These appliances don’t require electricity and rely only on the boat/yacht’s engine’s power. Since they work on closed combustion principle, these heaters are reliable and can be installed just about anywhere.

It’s important to understand that a low quality marine water heater will have low quality parts, which can easily get corroded and rusted over a period of use. Higher quality water heaters have an enclosed heating element, a heavy-duty heat-exchanger, thick insulation, and good usage time and recovery rate. The thermostat in all marine water heaters is calibrated at the manufacturing site and needs to be approved by the Coast Guard for ‘spark ignition’ protection.

Top Marine Water Heater Manufacturers

1)    Atwood
2)    Torrid
3)    Superstor
4)    Isotemp
5)    Webasto

Marine Water Heater Buying & Maintenance Tips

If you love the open waters and enjoy occasional boat or yacht rides frequently, you can’t do without a marine water heater. There is nothing like a hot shower when sailing to get off the sweat and the grime. A marine hot water heater is also handy when you need to clean and wash in cold areas. However, while such a device is an essential accessory, you’ll need to maintain it for better performance and longer life.

Here are some tips for buy marine water heaters:

1)    Buy a marine water heater based on the size of boat you own
2)    A big boat requires a big marine water heater to fulfill all the needs.
3)    Buying a solar power energized water heater can be a good idea; however they may be expensive and bulky
4)    Check insulation quality

Replacing parts are expensive, so you should take good care of your heater. Here are some tips for maintaining marine water heaters:

1)    Periodic inspections
2)    Quick fix of defects
3)    Check insulation from time to time to minimize heat loss and save money
4)    Replace any damaged or spoiled insulation material
5)    Inspect the anode periodically; immediately repair any damaged or defective anode to prevent accidents.

Top 2 Marine Water Heater Models

Atwood 6 Gallon Marine Water Heater

Price:  $349.01


1)    Best marine water heater manufacturer
2)    120 VAC electric heater
3)    6.12 gallon/hour recovery rate
4)    1500 watt heat exchanger
5)    Quick hot water production
6)    High quality casing for heating element
7)    SS water tank
8)    Meets UL specifications

Atwood EHM 11 Water Heater With Heat Exchanger 11 Gallon 110 V

Price: $426.99


1)    Very safe
2)    Highly efficient heat exchanger
3)    Superb installation flexibility
4)    Lightweight and easy to use
5)    Ignition protected electrical system
6)    Adheres to Coast Guard specs
7)    High-corrosion resistant aluminum casing

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One Response to “Marine Water Heater”

  1. Sam Clemens says:

    I bought a Atwood and was disappointed, it worked fine on electric but the heat exchanger didn’t work as well as the seaward that I took out. The Atwood lasted about 2 years and I had tank leaks. I replaced it with a seaward that had a better heat exchanger so the engine heated it better. The Seawork lasted about 3 years and the tanks leaked. I replaced that with a Raridan with a glass lined tank that was a more exspensive unit but it had a therostate so I could set the tempeture, the heat exchanger worked the best and I sold the boat after 5 years and the heater was still working good. I guess you get what you pay for.

    Captain Sam Clemens

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