2-stage water heater

[KnotConnected]

Hey!

I've got a two stage water heater on my boat. While roughing it the other weekend we fired up the engine, and it seemed to warm the onboard water system well enough to shower in. While I was at the slip with shore power and city water plumbed into the boat, I turned on the electric heater and the water didn't seem to warm up at all. It's possible that I didn't run it long enough, as I didn't want to burn the heater out, but should the heater work with the plumed water inlet as well as on-board water, or will I need to shut off the city water supply to use the water heater?

 

[smokeonthewater]

The water heater will work the same with city or onboard water.

As long as there is water in the heater you won't burn the element... It can be turned on 24 hrs a day and has a thermostat to regulate it.... I would expect it to take a couple hours to heat up on electricity.

If you need hot water faster it doesn't hurt a thing to idle the engine and run the electric element at the same time.

 

[gm280]

Have you verified that the electric water heater element is indeed good and not open? It easily could be the heating element is not conducting electricity and that could be the reason the water didn't heat up... :noidea:

 

[shrew]

The water heater fills and displaces from the top. If you run the water tank empty, the waterheater is still full. Make sure you're getting 110V to the water heater when the breaker is turned on. These are just like residential water heaters in that they need to be replaced periodically.

 

[JoLin]

would expect it to take a couple hours to heat up on electricity.

If you need hot water faster it doesn't hurt a thing to idle the engine and run the electric element at the same time.

A boat the size of the OP's likely has a 6-gallon water heater (like my last 3 boats), so figure about 30 minutes on shore power to heat it up. The boats I've had that are equipped with shore power have an ammeter next to the breakers. When you turn on the breaker for the heater, you should see an immediate spike of about 10 amps on the meter until the water is hot and the heater shuts off. If no amps reading, either the heating element or thermostat are shot.

If you ever turned the heater on when it was dry, you can bet that the heating element burned out, so keep that in mind. I did it once, too.

 

[cptrick3]

Switch your water heater on and off. Does the voltage meter indicate a draw?

 

[MTboatguy]

They are pretty easy to test the element with a multi meter, turn the electricity off at the breaker panel and measure the ohms across the terminals, no reading, the element is bad, leave one lead touching a screw on the element, then touch the other lead to any metal on the heater body, if you get a reading, the element is grounded out and needs to be replaced. So to recap, if you get an ohm reading by touching the two screws on the element, it is most likely good. The ohms reading will vary depending on the wattage of the element.

 

[KnotConnected]

Thanks for the help! I'll check it this weekend and see if the ammeter fluctuates when flipping the water heater breaker, then give it 30-60 minutes and see what she does.

 

[gm280]

Some times the heat elements get covered over with scale. And that can cause it to not heat properly. However, you can remove it and clean that scale off or even sandblast it and it will work like new again. I actually don't that before and it worked for years. And before going to the effort to clean it. Verify it is indeed good with a Ohm reading first. If it reads a very low resistance, it is still good...

 

[smokeonthewater]

I can't imagine myself ever trying to save $15 by sandblasting and reusing a water heater element.... If you pull it out just put a new one in JMHO

 

[MTboatguy]

The elements are to inexpensive to ever worry about it, if it does not test out correctly, replace it, come on, we are talking less than $15 dollars! Yikes!