Water Tank Service-Maintenance

This is a general hot-water tank question: my boat is coming up on 19 years old, and the hot-water tank is original. Is there an expected usable life? Am I already past that? It’s a pretty common unit that heats off the engine coolant and off a 110 element.

Suggestions? Thanks!

Spinner said:

This is a general hot-water tank question: my boat is coming up on 19 years old, and the hot-water tank is original. Is there an expected usable life? Am I already past that? It’s a pretty common unit that heats off the engine coolant and off a 110 element.

Suggestions? Thanks!

Click to expand...

If it has an anode, change it.

Spinner said:

This is a general hot-water tank question: my boat is coming up on 19 years old, and the hot-water tank is original. Is there an expected usable life? Am I already past that? It’s a pretty common unit that heats off the engine coolant and off a 110 element.

Suggestions? Thanks!

Click to expand...

Nineteen years is a long time for any water heater, land or water.

Spinner said:

This is a general hot-water tank question: my boat is coming up on 19 years old, and the hot-water tank is original. Is there an expected usable life? Am I already past that? It’s a pretty common unit that heats off the engine coolant and off a 110 element.

Suggestions? Thanks!

Click to expand...

Sue,

Mine was 13 years old when I replaced it. While it still worked and wasn't rusted, I rationalized that the next one would probably exceed my boat ownership. As such, it was very easy to change it when I did as the engine, generator, and saloon floor were out of the boat.

Another motivating factor is the heat exchanger in the water heater. I have 2 friends who each have had the heat exchanger fail. When it happens, if the engine cooling system is directly coupled to the water heater, your domestic water system (30+ PSI) pushes water back through your engine coolant system. If you're lucky, the expansion (radiator) cap vents your engine coolant into the overflow bottle and then into the bilge. If you're unlikely, well the engine coolant system is designed for around 10 PSI. All sorts of bad things could happen.

Ted

O C Diver said:

Sue,

Mine was 13 years old when I replaced it. While it still worked and wasn't rusted, I rationalized that the next one would probably exceed my boat ownership. As such, it was very easy to change it when I did as the engine, generator, and saloon floor were out of the boat.

Another motivating factor is the heat exchanger in the water heater. I have 2 friends who each have had the heat exchanger fail. When it happens, if the engine cooling system is directly coupled to the water heater, your domestic water system (30+ PSI) pushes water back through your engine coolant system. If you're lucky, the expansion (radiator) cap vents your engine coolant into the overflow bottle and then into the bilge. If you're unlikely, well the engine coolant system is designed for around 10 PSI. All sorts of bad things could happen.

Ted

Click to expand...

Good tip. As mentioned in my first post above, ours was hidden in a cabinet aft. It's relatively new (from previous owner) and it runs solely on electric, though I did discover it has heat exchanger plumbing. I was thinking of putting it in the engine compartment near the engine, a Lehman 120, and hooking it up to the engine heat exhanger. Maybe not such good idea? I think I found the heat exchanger ports on the engine. Not sure if the Lehman engine has a separate heat exchanger system, or is it plumbed into the freshwater cooling system? Anyone know?

Also, I am considering switching to tankless instant hot water. Has anyone done this and how well does it work?

Max1 said:

Good tip. As mentioned in my first post above, ours was hidden in a cabinet aft. It's relatively new (from previous owner) and it runs solely on electric, though I did discover it has heat exchanger plumbing. I was thinking of putting it in the engine compartment near the engine, a Lehman 120, and hooking it up to the engine heat exhanger. Maybe not such good idea? I think I found the heat exchanger ports on the engine. Not sure if the Lehman engine has a separate heat exchanger system, or is it plumbed into the freshwater cooling system? Anyone know?

Also, I am considering switching to tankless instant hot water. Has anyone done this and how well does it work?

Click to expand...

This is another thread currently running on tankless water heaters:

https://www.trawlerforum.com/forums/s31/tankless-hot-water-heater-60471.html

Unless your generator is running all the time, I don't see it working well.

I'm currently considering running engine coolant to an external heat exchanger, then plumbing the water heater and cabin heat from there.

Ted

Thanks for the info! I will add it the list….btw, my boat with 450 Cummins Diamond engine came without shut offs for the coolant lines to the red dot heater and hot water tank. When the heater core failed, that’s when it was noticed!

Spinner said:

This is a general hot-water tank question: my boat is coming up on 19 years old, and the hot-water tank is original. Is there an expected usable life?

Click to expand...

It depends on the brand...some are longer lived than others. Raritan water heaters have glass lined tanks with replaceable anodes and can easily last at least 25 years. Water heaters that have anodized metal tanks don't have replaceable anodes and rarely last more than 10 years before the anodizing wears off and the hot water begins smelling like rotten eggs. A new water is the only cure. Some brands including Raritan have replaceable heating elements and thermostats, others don't.

My advice: if it ain't broke yet, don't worry about it...it'll let you know if/when you need to replace it.

--Peggie

Hi Sue,
Our NT 37 came with a Kuuma all aluminum water heater. We replaced the original at about the 16-17 year old mark with same. They are not that expensive, and I replaced it myself (not a difficult job for someone with reasonable "hands on" skills). Mine did not have an anode, but it is possible to remove the drain spigot and install one. On my new tank the plastic spigot was in way too tight and I did not want to risk damaging the new tank so I left "well enough" alone (it had lasted over 16 years after all). I do recommend that you also install shutoff valves between the engine's cooling system and the water heater as well as the "red dot" if you haven't already and are draining the coolant anyway. In that way should you have an off engine failure in those systems, they can be isolated and the engine will still operate. I agree with Ted (OC), change it out (soon) on your timetable rather than risk a potential failure at the worst time. They don't last forever and if it were me, I would not want to risk causing an engine issue. "Penny wise and Pound foolish" possibly?
Best,
Tom

HeadMistress said:

My advice: if it ain't broke yet, don't worry about it...it'll let you know if/when you need to replace it.

--Peggie

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Peggie

While I don't normally disagree with you, waiting for the coffee pot to die is one thing. Being in the PNW on a summer cruise and loosing your water heater is decidedly different. While marine water heaters aren't cheap, loosing part of your summer vacation waiting for a water heater to be shipped in (if they're not on backorder) could be significantly more expensive.

Ted

Spinner said:

This is a general hot-water tank question: my boat is coming up on 19 years old, and the hot-water tank is original. Is there an expected usable life? Am I already past that? It’s a pretty common unit that heats off the engine coolant and off a 110 element.

Suggestions? Thanks!

Click to expand...

I'm going to jump on the band wagon to replace proactively. If I recall you are a full time live aboard? That puts more stress on everything and it is more than an inconvenience when an important system fails. Were it me I'd replace with like kind if it is still available. That way you will have minimal work to fit the replacement. If you have to go with a different make I've had great sucess with Isotemp. I buy their Sap version with the plastic external cover. Cheaper than the stainless external cover and works just as well. Most include a heat exchanger for engine loop or hydronic loop. The larger ones come with two loops so you can use both engine and hydronic heat source without valving.

We are replacing our failing 9yr old Raritan water heater. We are experiencing the issue OC Diver described.

When researching new units, we wanted a replacement that wasn't very difficult to replace the anode like the Raritan is.

I ordered a new torrid water heater today. https://torridwaterheaters.com They seem like a great company with a good product.

The only downside is the build time is 16 weeks.

Good luck,

Jeremiah