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Old 09-10-2014, 12:33   #1
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On-demand freshwater heaters

There are small AC water heaters, especially popular in Asia, which heat water as it flows through it, without the use of a large tank. You just turn it on and you have hot water.

They would be perfect for boats, save a load of space, but I have been unable to find a marine version. Do you know of one?
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Old 09-10-2014, 12:53   #2
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re: On-demand freshwater heaters

I don't know about the Asian ones, but the ones we had 30 years ago in Germany were 3-phase and used upwards of 3kW. Be prepared to install a very large inverter. Let us know when you find the Asian version. Forget about a marine version. The regular one will work just as well.


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Old 09-10-2014, 12:57   #3
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re: On-demand freshwater heaters

I just checked on a German site and found the the new electronic versions consume between 18 and 30 kW. That's why you need 3-phase. 18kW requires over 1000A on 12V.


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Old 09-10-2014, 13:07   #4
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re: On-demand freshwater heaters

An under shower sump that recirculates the shower water on a yacht would be a good idea. Sure it would get dirtier as you wash and peeing in the shower not such a great idea, but you could have a long hot shower for just using a few litres..
Still waiting on quick to get back to me about a 500w filiment to replace the 1200w so I can heat with the solar...
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Old 09-10-2014, 13:11   #5
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re: On-demand freshwater heaters

Take a look at the propane equivalent which is meant for camping. It would have to be vented.

http://www.amazon.com/Eccotemp-L5-Po...xp_grid_pt_0_0
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Old 09-10-2014, 13:16   #6
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re: On-demand freshwater heaters

Quote:
Originally Posted by roetter View Post
I just checked on a German site and found the the new electronic versions consume between 18 and 30 kW. That's why you need 3-phase. 18kW requires over 1000A on 12V.
Thanks Rolf,
Perhaps I should have researched them a little better before asking the question. I have found a few since reading your first reply which draw less power than 18kW, but still a bit much for my 30A AC and 500 ah DC systems.
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Old 09-10-2014, 13:29   #7
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re: On-demand freshwater heaters

Quote:
Originally Posted by monte View Post
An under shower sump that recirculates the shower water on a yacht would be a good idea. Sure it would get dirtier as you wash and peeing in the shower not such a great idea, but you could have a long hot shower for just using a few litres..
Still waiting on quick to get back to me about a 500w filiment to replace the 1200w so I can heat with the solar...
Makes sense. Now if I could get my wife to buy into it.
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Old 09-10-2014, 14:43   #8
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re: On-demand freshwater heaters

Install a diesel hydronic system with an Everhot. Paloma makes propane marine versions, but they are generally regarded as unsafe. Love my Everhot!
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Old 09-10-2014, 16:03   #9
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re: On-demand freshwater heaters

Quote:
Originally Posted by savoir View Post
Take a look at the propane equivalent which is meant for camping. It would have to be vented.

http://www.amazon.com/Eccotemp-L5-Po...xp_grid_pt_0_0
We used one of these propane versions on a hot dog cart. They work great and do give instant hot water.

Unfortunately, you cannot drink the water. This stuff comes from china, possible lead solder, etc. etc. We were advised to use it for washing up only.

I have often wondered why I have not heard of folks on boats using these before. Perhaps in salt water environment they do not hold up well? I cannot say but would be interested if someone has used one on a boat before.

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Old 09-10-2014, 16:52   #10
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re: On-demand freshwater heaters

A floating hot dog cart. Hmmmmmm - might work.

I've seen a floating coffee bar. The guy was flat out busy.
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Old 09-10-2014, 17:42   #11
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re: On-demand freshwater heaters

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A floating hot dog cart. Hmmmmmm - might work.

I've seen a floating coffee bar. The guy was flat out busy.
Actually....hummmm
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Old 09-10-2014, 18:41   #12
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re: On-demand freshwater heaters

Excellent idea...A floating roach coach! Good coffee, good food what's not to like? Throw in garbage pick up and holding tank Pump out and your in business!
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Old 10-10-2014, 07:39   #13
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on-demand freshwater heaters

There are no marine versions and no need for them. Household ones work fine. The Titan 220 v ones work well for baths or showers and there are many 110v ones that will work great for low flow like a galley sink or lavatory. Heating water fast takes power. You have to work around the power you have available. I use some Stiebel Eltron units, about $179. Not really high flow but the water is hotter than I can touch.
I need hot water only two times a day. When I take a shower and when I wash the dishes. No need to keep the water hot the other 23 1/2 hours of the day.


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Old 10-10-2014, 08:11   #14
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re: On-demand freshwater heaters

See ➥ Propane Water Heater

And ➥ ShowerMate M-550 ‚Äď Marine Tankless Water Heater - PrecisionTemp

And ➥ Sure Marine Service, Inc. | Everhot Tankless On Demand Copper Water Heater
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Old 10-10-2014, 08:19   #15
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re: On-demand freshwater heaters

I have one in my house that heats using natural gas. I vaguely remember a thread on this a while ago but don't remember where to find it. There are definite options for your boat. The only down side I can remember is if you happen to be running your engine then it will no longer heat the water. You will have to dedicate a system just for heating instead of being able to use the engine and or the generator.
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