Gotta get a new water heater

[mitiempo]

Kuuma is the lowest quality water heater you can buy. It is a cheap copy of the Seaward which is a budget unit itself but better made. The Seaward has an option for an anode which the Kuuma does not have. Aluminum tanks make for lousy water heaters with short lives. A Kuuma is a very short lived water heater.

IsoTherm would be my choice - stainless tank and good insulation and very well made.

Other good brands are Torrid and Raritan with glass lined steel tanks.

[gamayun]

Originally Posted by wrwakefield

I am preparing to do the same thing. After researching I went with an IsoTemp SPA Model [Polypropylene outer jacket vs stainle$$] for several reasons:

• Built-in mixing valve [Prevent scalding when engine heats it to 180F.]
• Super insulated [hot tank purported to last 24+ hours by other owners]
• SS tank and heat exchanger [no zincs...]
• 750 watt [1200w available] 115 or 230VAC electric element [half of the usual 1500 watt]
  True, slower to heat from electric, but less load on shore power/generator... And you can set thermostat much higher than usual e.g., 160F to take advantage of that mixing valve and get more usable hot water per charge
• Mounts Horizontally or vertically

I'll post a blog entry when I complete that project in early May.

Here is a link to Defender's listings FYI.

I hope this is helpful.

Yep, this is what I got. Mounted it against the side wall and freed up some space so it's not so crowded. They're about twice as expensive as the cheaper brands, but if I never have rusty water in the bilge again, it was well worth the extra $$....

[HopCar]

I'm partial to the Raritan water heaters because of their glass lined tanks. I avoid water heaters with aluminum tanks. They just don't last.

[mitiempo]

Originally Posted by HopCar

I'm partial to the Raritan water heaters because of their glass lined tanks. I avoid water heaters with aluminum tanks. They just don't last.

I agree glass lined is better than aluminum but stainless tanks (IsoTherm and Quick) are much better again.

[MarkSF]

Originally Posted by Cheechako

The cheaper water heaters seem to work fine. I don't think I've had any that lasted less than 8 years (on the boat when I got it) and actually only ever had one fail... no idea how old it was...but it looked ancient.
I've never been sold on SS being worth it. Not even sure it's a good application for stainless...

Cutlery. Thats all stainless is good for!

[Found at Sea]

Hi Bill,
I have a CT 41 probably built by the same folks at some point. Last weekend I had the same issue with my pump cycling and hot water in the bilge. I'm not sure of the original manufacturer of my failed H2O heater but what I do know is that it's located next to the mizzen mast in what appears to be a fairly inaccessible location (port of the mizzen mast under the cockpit deck). Access can be had by cutting out a section of the bulk head behind the galley sink. Not sure of the effect that may have on the structural integrity of the boat. Any help with the extent of demo required to R&R these old tanks would be appreciated. Thanks in advance.

Found at Sea

[Terra Nova]

Originally Posted by Found at Sea

...Access can be had by cutting out a section of the bulk head behind the galley sink. Not sure of the effect that may have on the structural integrity of the boat...

You could start your own thread with some photos and sketches to describe your installation. Post a link here.

[Cheechako]

Originally Posted by Found at Sea

Hi Bill,
I have a CT 41 probably built by the same folks at some point. Last weekend I had the same issue with my pump cycling and hot water in the bilge. I'm not sure of the original manufacturer of my failed H2O heater but what I do know is that it's located next to the mizzen mast in what appears to be a fairly inaccessible location (port of the mizzen mast under the cockpit deck). Access can be had by cutting out a section of the bulk head behind the galley sink. Not sure of the effect that may have on the structural integrity of the boat. Any help with the extent of demo required to R&R these old tanks would be appreciated. Thanks in advance.

Found at Sea

Are you sure there isn't other access? I would be surprised.....

[Found at Sea]

The second and larger of the two H2O heaters (20 gal.) is the easiest to access and it's the only one that has recirc. lines to the engine. It's located under the forward galley cabinet, port side. I don't know why but it was abandoned some years ago. Original plumbing schematics show one heater for the galley and the other for the head/shower. I believe the lines have been altered to draw everything from the aft heater that died. I haven't started the demo process but obviously have been thinking about it quite a bit. Wish me luck.

[Sonosailor]

I replaced a 1996 Isotemp 25 litre with an Isotemp Spa 15 litre just last fall, and In both cases, I never hooked up the electrical - just the glycol lines from the engine. Small, fast to warm up, and still enough water for you.

[Admiral Nelson]

I just installed an Isotemp SPA water heater 8 gallons and found that the water does not stay warm for more than 12 hours. Isotemp claim to be 24 hours which has been my experience so far. I was wondering what was everyone's experience with their tank. You have hot water for how long?

[wrwakefield]

Originally Posted by Admiral Nelson

I just installed an Isotemp SPA water heater 8 gallons and found that the water does not stay warm for more than 12 hours. Isotemp claim to be 24 hours which has been my experience so far. I was wondering what was everyone's experience with their tank. You have hot water for how long?

Hi Admiral,

We recently completed the installation of the IsoTemp 40 liter Spa water heater I mentioned earlier in this thread. My Admiral is very pleased with the results [It replaced a 6 gallon perfectly functional Raritan unit...]

[For those researching new water heaters: We paid US$520 - including USPS shipping to Alaska- for the IsoTemp Spa water heater from Fisheries Supply. This seems to be much more in line with other water heater pricing than I see discussed in this thread...]

You didn't mention the specifics of how hot the water is [or isn't] before and after your 12 hour period of heat retention, nor your usage once the heating source is off. You also didn't mention some of the other environmental factors that will influence your results.

For example, on our boat the engine heats the water to 180° - 190°F and I have the mixing valve [the one that comes installed on the IsoTemp] adjusted to 120°F [the temp of the water you get at the taps.] This mixing of 'superheated' water with cold to achieve the desired temperature at the tap yields 2 to maybe 3 times the tank volume of usable hot water (meaning pleasant showers...)

These are our results, which are likely lower than those of you with warmer 'cold' water per the following:

Note: The ambient water temp of our tanks- which lie against the hull- approach the ambient water temp we boat in- currently mid 40's F or cooler in winter and Mid 50's F in summer... If we're lucky... Mixing warmer cold water will yield even better results... [e.g., 70°F+ cold water would yield 3- possibly 4 times the mixed hot water volume vs. the 2-3 we currently enjoy...]

Regarding heat retention as relates to insulation: Our water and space heaters are installed in the enclosed engine room (which averages 110°F ambient temp while motoring.) When we anchor, we still have hot water 48 hours later if little has been used. If more is used (i.e., if more cold is mixed with the superheated tank of water- say a couple of showers) then of course it doesn't last as long- perhaps 24-36 hours- but we are still gathering data... We find it plenty for 4+ hot showers [2 adults; pausing water flow while bathing; still having to mix in some cold water to get desired temperature...] over a 3 day period, and dishes, etc.

To maximize our hot water retention at anchor, when possible we shower, etc, while motoring so the water heater has enough time to reach maximum temp before shutting down the engine.

One aspect of our install regarding longevity of hot water is our engine room also warms up to 80°F+ when we run the Espar heater, which is also installed there... The engine room rarely cools off below 60°F [even in 20° to 30°F ambient outdoor temperatures] and then only after days at anchor with no or little heat demand [e.g., sunny days in winter- below ~60°N- in our pilothouse reduce the run time for the Espar during those periods...]

This 'warm' engine room environment reduces the burden on the IsoTemp insulation.

If yours is cooling off prematurely without you using any or little hot water, try insulating the hot lines immediately adjacent to the heater, as some conductive heat loss occurs there... You could also further insulate the tank itself if it resides in a cool environment.

You may also want to check the cold water line into the heater after an hour or so of no water being run. If it is warm or hot a small distance from the water heater, you may have a thermal siphon situation and need to install a check-valve or re-route the water line(s).

I also recommend you do some temperature measurements and track hot water usage after the heat source is off so you can estimate the heat loss factors.

An IR thermometer (or IR camera) will reveal any insulation deficiencies in the IsoTemp insulation layer.

I hope this is helpful.

[Terra Nova]

wr--good post.

[Found at Sea]

I've had good luck with the 9 gal Kuuma although I've only had it in the boat for 6 months at this time. When off shore we have hot to warm H2O for a minimum of 24 hours.

[TacomaSailor]

WRWakefield hit all the details very well. Just to add our specific experience:

I installed a new Isotherm in Oct last year to replace the Isotherm that lasted 14-years. The heat retention of the new unit seems equal to the old. We use AC shore power to heat the tank for 2-hours in the morning when we wake up. The tank water is still plenty hot for taking a shower the next morning if we do not turn the shore heat back on.

I imagine the answer to your question (how long does it stay hot) depends on:
- how hot do you allow the tank to get while being heated
- what is your sensual definition of HOT
- does the temperature of the cold being mixed at the tank hot outlet vary