Hot Water Heater Recommendations Please

[michaeld]

I have spent quite some time Googling for a hot water heater. I'm confused, so I'm hoping collective knowledge/expertise will help point me in the right direction. Assume only two aboard, water conservative showers. Engine heat exchanger and 115VAC required. No more than 5-6 gallon size.

Experience & advice solicited... Make/Model Good/Bad/Ugly

Thanks!

[PippaB]

Out boat came with an Isotemp, I believe the "Spa" series (or its predecessor). Our is 5.5 gallons/25 liters. We have never run it on the electrical circuit, so can't comment on that side of things, but we do have it connected to the engine. Keeps water hot for 24-48 hours in the tropics, warm for another day. 24 hours only in more temperate climes. Easily enough water for two of us to shower without reaching the end of the tank.

With engine heat driving the water temperature to 75-80C the tempering valve is a must. Ours did stop working at 10-12 years old, simply replaced with a standard device from the plumbing store.

If I were installing from scratch I might consider one of the diesel-fired heaters designed for space heating, but we also frequently sail in areas where heat is more necessary than FL.

[rbk]

I’ve been looking as well and isotemp looks good but I’ve been seeing too many horror stories recently and they all seem to be similar stories. They really look like a quality product, good insulation, decent price and mixing valve (most don’t) but rusty failed welds keep popping up in reviews. If isotemp would acknowledge this and correct it I wouldn’t hesitate, until then I’m sceptical. While warranty does seem to be honoured it’s still the inconvenience of replacing seals, or swapping the tank, purging the cooling system etc every year or two.

[Nord Sal]

Why would you need to heat hot water?

[malbert73]

Originally Posted by Nord Sal

Why would you need to heat hot water?

Hot showers?

[steve77]

Originally Posted by malbert73

Hot showers?

He's referring to the seemingly redundant term "Hot Water Heater". Some people think it should just be a "Water Heater".

We installed an Isotemp Slimline about 4 years ago and have had absolutely no issues with it. Like others have said, it keeps hot water available for a long time and is easily adequate for two of us on board. We regularly use the unit powered by AC (genset or shore power) as well as from the auxiliary.

We are very happy with the Isotemp. Cheers!

Steve

[rwidman]

Originally Posted by Nord Sal

Why would you need to heat hot water?

That one had me scratching my head as well!

[svfinlandia]

Originally Posted by Nord Sal

Why would you need to heat hot water?

You beat me to it!
Like me, I’m sure you just couldn’t resist.
It’s kind of always been one of my pet peeves - calling a water heater a “Hot” water heater. Like you, I always have to ask “if the water is already hot why do you want to heat it”

Al, S/V Finlandia

[Wildcats]

We had a Whale Seaward aluminum 11 gallon tank on our Ranger Tug. It had a 1500 watt heating element. We noticed that the screens on the faucets were becoming clogged with aluminum oxide (the tank is aluminum). We decided to replace the tank. We purchased an 11 gallon Isotemp stainless tank with a 750 watt element. We wondered if the 750 watt element would be adequate for the two of us. It is not an issue though, and we have plenty of hot water for the two of us to shower. Initially, the water temp was too low for our liking even with the unit turned to maximum. I contacted Isotemp and they told me that the proportioning valve could be loosened and the temp adjusted to a higher temperature. That worked like a charm. Our potable water tank in the Pacific Northwest (San Juan Islands) gets cold so that may be the reason. The mixing valve added very cold water to the output. One comment about installing the Isotemp. It works well but beware that it comes with British pipe threads (BSP) while the U.S. and Canada use American pipe threads (NPT= National Pipe thread). The difference is the angulation of the thread, British being 55 degrees while the American/Canadian pipe is 60 degrees angulation. I thought it wouldn't be a consequential difference but boy was I wrong. I finally had to get a BSP to NPT connector. Without this it was a heck of a time getting the connections to stop leaking. The threads didn't match up well without the connector.

[Capt. Ray]

Indeed. A cold water heater would be far preferable.

Originally Posted by Nord Sal

Why would you need to heat hot water?

[Boatyarddog]

Originally Posted by rbk

I’ve been looking as well and isotemp looks good but I’ve been seeing too many horror stories recently and they all seem to be similar stories. They really look like a quality product, good insulation, decent price and mixing valve (most don’t) but rusty failed welds keep popping up in reviews. If isotemp would acknowledge this and correct it I wouldn’t hesitate, until then I’m sceptical. While warranty does seem to be honoured it’s still the inconvenience of replacing seals, or swapping the tank, purging the cooling system etc every year or two.

Why do you purge the cooling system every year or two.
Air pockets? Or ?
Never have a problem with mine.
Boatyarddog

[rbk]

Originally Posted by Boatyarddog

Why do you purge the cooling system every year or two.
Air pockets? Or ?
Never have a problem with mine.
Boatyarddog

If you’re having to remove the water heater due to warranty issues ie full replacement every other year.

[more]

Originally Posted by michaeld

I have spent quite some time Googling for a hot water heater. I'm confused, so I'm hoping collective knowledge/expertise will help point me in the right direction. Assume only two aboard, water conservative showers. Engine heat exchanger and 115VAC required. No more than 5-6 gallon size.

Experience & advice solicited... Make/Model Good/Bad/Ugly

Thanks!

https://www.svb24.com/en/quick-warm-...boiler-b3.html
USA shop
https://www.mauriprosailing.com/us/p...05S000A00.html

https://www.quickusastore.com/boat-s...-water-heater/

this is a working horse 20-30 year usually without problem

[dlj]

I have an Isotemp Slim B 25 liter. It came with the boat and runs very well. Has both heat from engine and electric when I have shore power. I can run it off my inverter but typically don't. Keeps water hot a long time, like a couple days.

dj

[Marathon1150]

I replaced a Raritan 10gal tank that was more than 30 years old and was still working fine, more or less. I replaced it on the advice of Raritan because they could not provide a new thermostat for the tank and in their view, it was time to retire it. Other than the thermostat, the tank had no other issues.

I replaced the above with a new Raritan that was the same physical size but only holds 6 gallons (US). Over the years, Raritan has added a lot of insulation to their tanks. The tank is under the V berth and during the colder months, provided a warm bed. The new tank doesn't leak enough heat to accomplish this desirable outcome but we aren't wasting power either.

Our second boat also has a Raritan tank that is now about 25 years old. Still going strong and no issues during the 3 years that we have owned this boat.

Both are connected to the engine cooling system and both are wired to the 120V panel when we are connected to shore power. I wouldn't hesitate to buy another Raritan despite the price.