Marine vs House electric water heaters

[Franziska]

It may be illogic, I agree, and I'd really would want this to be different, but, that's what the standart over here say.
I do not make that rule.

Guess the reasoning is that a stove is fully supervised...

Originally Posted by GinTonic

If vent free is prohibited in Europe , than does this mean you cannot have a gas range / stove in your boat in Europe ? As far as I know the burning chamber of a gas stove has openings towards the interior of the boat...and these water heaters are 38,000 Btu , very similar power to a gas range.

[Shrew]

I like a marine water heaters that can be connected via hoses to the heat exchanger. Just chugging into and out of harbors is enough to heat the water. One less thing to have to run the generator for. Admittedly, I'm a coastal cruiser.

Plus parts are available at most marine chandlers. Once your in the harbor, it might be a trek to get residential parts. Most residential consumer parts aren't always 'marinized'. It's not the water heater itself, but the access panels, screws, bolts, etc. that end up rusting very quickly.

[boatpoker]

Originally Posted by GinTonic

If vent free is prohibited in Europe , than does this mean you cannot have a gas range / stove in your boat in Europe ? As far as I know the burning chamber of a gas stove has openings towards the interior of the boat...and these water heaters are 38,000 Btu , very similar power to a gas range.

Not sure about Europe but is the US, underwriters usually require ABYC Standards. These standards are different for "attended" appliances (stoves) and "unattended" appliances (propane water heaters). under these standards, all unattended propane appliances but not draw combustion air from inside the boat and all exhaust systems must terminate outside the interior of the vessel.

Fun fact .. Many of these older units, including Paloma had a statement in their manuals saying not to install them in a boat. Apparently there was an issue in that the valves did not work unless level

[capt jgw]

Originally Posted by RigBig

What hasn't been mentioned yet is the AC wiring of a non marine hot water heater. A box store unit will more than likely have the ground and neutral wires connected at the hot water unit. You don't want that on a boat. The ground and neutral wire should only be connected at the dock pedestal and NOT anywhere on a boat.

No, in a building the N and G circuits are connected at the main panel only, never in a device or appliance. Same as on a boat if you consider the main panel to be ashore.

[Franziska]

Are you sure that's the same in Europe (OP is in Greece) as in the US?

Originally Posted by capt jgw

No, in a building the N and G circuits are connected at the main panel only, never in a device or appliance. Same as on a boat if you consider the main panel to be ashore.

[capalfie]

Hi, I am a bit lost with your answer. I ve just bought a Raritan water heater 110v and now is bolted to my hot water tank expansion...how would you connect it to avoid being exposed to a electrical shock then?
Thanks...
Cap Alfie

[boatpoker]

Originally Posted by capalfie

Hi, I am a bit lost with your answer. I ve just bought a Raritan water heater 110v and now is bolted to my hot water tank expansion...how would you connect it to avoid being exposed to a electrical shock then?
Thanks...
Cap Alfie

With the safety ground !
Connecting N/G at the water heater introduces current to the safety ground and it will trip GFCI's due to the imbalance.

Also if your boat is properly wired with the AC ground and DC negative bonded you are introducing AC current ito the DC grounding system which greatly increases the chances of electrocution and ESD.


Of course this only makes sense if I'm interpreting your unclear statement correctly

[alaskanviking]

Electrically there isn't much difference between a house and marine electric only water heater. In a house the ground is connected via the water pipes, so you have to make sure you connect the boat ground likewise or whichever the appropriate place is in the manual. Electric house water heaters are typically vastly cheaper. There may be something about the valve not working at certain angles,. But from what I've seen they're the same valve from the same supplier. Possibly swap out for the marine version and be money ahead if this is the case.

Propane/Nat gas tank water heaters including RV propane water heaters shouldn't be used. It's dangerous. Boats move more, sail boats heel specifically. Insurance is unlikely to support it.

A marine specific water heater or calorifier (outside us term) is different in a few important aspects. First the obvious is you can connect to the engine and heat the water with engine heat. This lets you disconnect from the dock. You get a lot of heat from the engine. the hot water from my 7 gallon will burn me after 30 min run at load, which was about what it took to go into the marina. You will also find some of the new marine water heaters that have a combo 120v and 12v element, so you can heat from the DC bus or use as a dump load for solar. As an alternative instead of connecting to the engine you can connect to a diesel hydronics heater for heating water anytime you want. For extra cost you can get some marine water heaters with 2 heater coils inside, 1 for engine, and 1 for hydronics or generator. House water heaters have no need for either of those functions. Lastly The materials for a marine water heater are usually more corrosion resistance. Stainless hardware, bronze fittings ect. Tanks tend to be thicker as well because the engine or dc element are not generally temp controlled. That means they build up more heat and pressure than a house or electric only marine water heater. Some marine water heater tanks are made of steel or glass lined steel. Not sure if those are the cheaper ones or not, the one on my boat is made from stainless.

I've noticed that UK or european marine calorifiers may be much better than US marine water heaters. It appears they have better insulation, bronze tanks, easy to get with one or two exchanger coils, can install higher pressure valves, have more dual 120v/12v elements built in, and come in a better range of smaller sizes. I was looking into a smaller 2-3gal with engine coil to install for the shower as a heat exchanger connected to a hydronic system. Couldn't find such an appropriate beast in the US.