Recommendations for water heater

David M

New Member
Hey everyone! I am brand new to the sight as well as being a brand new owner of a 1983 E-381 :D I'm looking to install a water heater and would love some recommendations. It's just me and my dog living aboard and am in a marina that has shower facilities, but would love the option of taking a shower when I take her out.
I briefly considered a tankless system, but after looking at the power requirements it just didn't make sense for the available power I currently have onboard. Unless there's a brand new special low power consumption one out there that someone knows about??? So, pretty much only looking at the standard type water heater. (Electric or combo with engine) I only have the CNG tank for the stove and don't think I'd consider any gas type heater.
I've attached a photo of the platform where there supposedly was one previously. It's wired and plumbed to the area as well. The platform is 20"w /17"d/ 20"h.

Looking forward to seeing your suggestions! Thanks!
 

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Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
A friend put an IsoTemp water heater into their E-33, and has been happy with it for many years. Lots of different dimension and gallonage configurations.
We put in an Atlantic brand SS tank in the 90's and it's still working like new. Unfortunately they are no longer manufactured.
Other owners should have some suggestions.
One great thing is that modern heaters have superior insulation compared to the ones from 30+ years ago.
When spec-ing one out, be sure that the wiring and the water and coolant connections are where you can get at them, and that the high temp. pressure release has an easy way to route the hose to the bilge. This will vary from boat to boat.
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Hi,
Our boat came with a 6 gallon Seaward water heater that worked well for almost 20 years. I recently replaced it with a 6 gallon Kuuma water heater. They look almost identical, but the Kuuuma was less expensive and had equally good reviews. Both of them produced hot water from the engine running and having coolant routed through them, or with AC power when at shore power.
Frank
 

toddster

Curator of Broken Parts
Blogs Author
I’ve been happy with the 6-gallon Seaward. On my boat, I had to nibble about 1/2 inch out of the lip of the cockpit locker to get it in. Now there’s a subtle Seaward-shaped key-way there. If the boat previously had one, it ought to be all set. One possible problem (you can’t see what isn’t there) is if the heater is higher than the engine, you may need a header tank at that location, to bleed air out of the loop. I simply relocated the heat exchanger to be next to the water heater, so it is the header. There wasn’t really room for it in the engine compartment anyway. In case it’s not obvious, you also need a check valve where feed line branches off from the pressurized cold water line.
 

Stuphoto

New Member
Hi,
Our boat came with a 6 gallon Seaward water heater that worked well for almost 20 years. I recently replaced it with a 6 gallon Kuuma water heater. They look almost identical, but the Kuuuma was less expensive and had equally good reviews. Both of them produced hot water from the engine running and having coolant routed through them, or with AC power when at shore power.
Frank
I am a newbie here, so please treat this question as such.

In a former life I drove trucks for a living in Canada.
We often used Webasto Diesel heaters to warm up the coolant rather than running the motor during some insanely cold -40 days.
It was enough to keep us toasty inside the bunk while sleeping.

Is there any reason why we couldn't use such a system at times in our boats rather than running the motor?
I should point out, these systems are compact, efficient, and built tough.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Is there any reason why we couldn't use such a system at times in our boats rather than running the motor?
I should point out, these systems are compact, efficient, and built tough.
These are called "hydronic" systems and are often installed on larger boats. Expensive. They can, if plumbed for it, warm an engine, the coil in your hot water tank, and route hot water thru several little heater units inside the boat. I have a friend that put one in a 37-ish boat, and said that while it works OK, it can use significant amps for the little fan-driven heaters and considering the complication he would generally not advise it.

He's not mad at it, but rather acknologing that it's a complex system with some failure points that can potentially halt the main engine if a hose leaks somewhere.
Also, since you are heating air inside the boat condensation can build up, unlike a forced air furnace that draws in outside air, heats it, and therefore lowers the relative humidity.

No wrong answers, just choices and options, as the old saying goes.
 
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Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
Here's the Isotherm on my 381, which fits nicely on a platform behind the engine.

diesel isotherm wide.jpg

I installed a smaller water heater unit on the 32-3, which served well and was only about $400 at the time.

 

Stuphoto

New Member
Thank you Loren,
I still have a lot to learn in this new world.
I am grateful that everyone here seems to be understanding with newbies.

I like that tank Christian,
I think I actually have room for it on my 25mk1, right in front of the factory h2o tank.
The sad part is it would increase my water capacity by 66%
 

toddster

Curator of Broken Parts
Blogs Author
Friends had a hydronic system on a 26-foot (IIRC) cabin cruiser that we used to take out in the San Juans in the winter. It worked OK as long as the boat was moving, but nothing like a diesel heater. And that was with big twin inboards. I suppose the system was under-sized.

I've thought about adding a hydronic blower, but I wonder if the little impeller pump on my atomic 4 could really support another serial heat exchanger.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
I've thought about adding a hydronic blower, but I wonder if the little impeller pump on my atomic 4 could really support another serial heat exchanger.
I installed a "HeaterCraft" cabin heater over a decade ago. Our old closed-cooling pump did not seem to mind. The coolant circuit then went from engine > to hot water tank coil > to heater , and back to engine. Due to heat loss at idle, I did have to put some split foam wrap around those lines.
I found one example on the web: https://www.boatid.com/heater-craft...ROz0dz_-7QeXfJhEQwF1ePAdHinBY5lxoC7wEQAvD_BwE
 

David M

New Member
Here's the Isotherm on my 381, which fits nicely on a platform behind the engine.

View attachment 41417

I installed a smaller water heater unit on the 32-3, which served well and was only about $400 at the time.

Christian,

What model/size is that tank? It looks as if you have the same platform behind the main engine that I do.

Thanks,

David
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
Looks like it's called Isotemp now, and they have sizes in the 6-gallon range, slim fit. And there are less expensive options at West Marine --Kuuma, etc.

A note: it is tempting to use pvc elbows to connect to boat water plumbing, but not recommended. My former owner had continuous leaks, apparently because heat expands the pvc. I replaced with brass rated for drinking water.

Also: the heat exchanger is involved in this setup, since hot coolant is routed through the heater. You can hook up direct from the heat exchanger, or from the front of the engine, which I prefer. There are threads on that if you're interested.

Anyhow, good time to service (boil out) the heat exchanger as part of the project. How-to threads available.
 
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