Hot Water Tank vs tankless heater

[650Guy]

Hey All,

I think my hot water tank has come to the end of its service life. Considering replacing my 11 gal tank with one of those inline tankless heaters. Has anyone done it? the tankless ones seem to be cheaper and would THINK they are more efficient?

Just wondering if anyone has done it and had any thoughts/advise?

[Midnightsun]

Problem with those is they need a lot of power to heat the water as it comes out of the faucet, probably at least 30 amps 220v.

[650Guy]

Great point. I didn’t even look. Do ya happen to know what the tank draw is?

[Midnightsun]

A standard tank ranges from 750 to 1500 watts or the equivalent of a hair dryer so not that much not to mention more suited for the boats electrical supply.

[buster53]

A boat’s electrical system was designed to power your basic 120v water heater. It was not designed for a tankless system. For that you need way more amps than your boat can provide or you need gas

[bud37]

The other issue to consider is what triggers the tankless system.......the boat water pressure and the more important is the flow for lets say a shower may not control well.....something to consider and check out.....they may have improved some in the last while.

[tomschauer]

Your 120v 11 gallon water heater should draw 12.5 amps at 120 volts. Lower voltage at the dock, higher amperage.
The on demand will draw more unless you get a single point of use unit, which may not give you the hot water needed for a shower, but would work for hand washing, dish washing etc. Also, you would miss the "free heat" you get from the engine heating coil in the water heater ( unless someone changed out the original).

Soooo, keep in mind, your water heater is most likely on a the house 30 amp breaker, along with your batter charger, microwave, stove, receptacles etc. If you install a 120v instantaneous 25 amp heater, you will need to turn off everything else to use it. Or be in the dark with cold water!

[km1125]

Source of the post Your 120v 11 gallon water heater should draw 12.5 amps at 120 volts. Lower voltage at the dock, higher amperage.
The on demand will draw more unless you get a single point of use unit, which may not give you the hot water needed for a shower, but would work for hand washing, dish washing etc. Also, you would miss the "free heat" you get from the engine heating coil in the water heater ( unless someone changed out the original).

Soooo, keep in mind, your water heater is most likely on a the house 30 amp breaker, along with your batter charger, microwave, stove, receptacles etc. If you install a 120v instantaneous 25 amp heater, you will need to turn off everything else to use it. Or be in the dark with cold water!

Agree with all that except the "Lower voltage at the dock, higher amperage". If the shore power voltage drops, then the amperage drops as well on the water heater, as it's just a resistive load. That also means less heating power, so if you have low voltage at the dock it will take longer to heat the tank.

Even if you could install a 120v 25 A "instant" heater, it would take 15 minutes to heat 6 gallons of water from 60F to 120F, so it might be a long shower or a pretty cool shower (if you're using both hot and cold water).

[Midnightsun]

We boat in clean water which makes for a giant bath tub. Many here use one like this on the swim platform from a wash down pump. Works well but does require propane. https://www.ebay.com/itm/5GPM-LPG-Propa ... 0005.m1851

[andreww]

I am using Rinnai Indoor Tankless and I am very satisfied with it, it is great to have instant hot water! This device is easy to install with tools. Overall I enjoyed it very much and would recommend it to everyone.