Replacing Water Heater

Can I replace my 12 gallon electric water heater with house type unit or should I use the Raritan marine unit? Does not have engine heat exchanger .

I would use a marine unit and add a heat exchanger. There are a lot of good water heaters that don’t cost anywhere near as much as a Raritan. Theirs are very dear.

Beware of those made with Al tanks. Cheap they are. Rot out too quickly. I replaced an Al Seaward with a Glass lined Torrid.

I replaced an aging Raritan with an Isotemp. Engine heating loop, mixing valve and only 750 watts. Full time liveaboard.

I also replaced a Raritan with an Isotemp. 100% satisfied with it.

I also recommend the Isotemp SPA water heaters. They have a stainless tank, good insulation, engine heat exchanger, and mixing valve.
The mixing valve allows you to heat the water to a high temperature but when it comes out of the heater it is mixed with cold water to make it safe. This effectively gives you much more safe hot water than the tank size.
Isotherm SPA Water Heaters

All the Raritans are available with heat exchanger. They're expensive but comparably priced to Torrid and Isotherm Raritan tanks can easily last 25 years or longer because they have glass lined tanks with a replaceable anode and for at least the last 20 years have had a polymer shell that can never rust . Cheaper water heaters have metal shells and anodized metal tanks. When the anodizing on a metal tank tank wears off, replacing the water heater is the only option. If/when a replacement anode for a Raritan is needed, it's about $50 part and a 30 minute job.

Has anybody converted to an instant on propane powered hot water heater, sounds like a perfect filling solution for a live-aboard

There is a report in my insurers quarterly mag about an externally mounted propane heater, and a nearby gas fuel container with a vented cap.
Vented gas vapour and pilot flame got together, with a very negative outcome.

Yup, hate it when that happens.

I installed a Torrid 20 gallon tank about 10 years ago and it has run fine. I put two heat exchangers in it, one for engine heat and one for the hydronic heating system. If you're in the PNW, Sure Marine in Seattle is a good resource.

Most HW heaters die from the inside rotting out.

For folks with a big enough boat the Rheem Marathon is made in a 30-40 and 50 gallon size , and has a lifetime

Its plastic inside and outside and larger as it is super insulated.

Expensive as a home unit , but the usual boat stuff markup makes it seem fine.

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motion30 said:

Has anybody converted to an instant on propane powered hot water heater, sounds like a perfect filling solution for a live-aboard

Click to expand...

I would not install a propane powered appliance on my boat unless it was designed and ABYC approved for the purpose. I doubt you will find one that is.

kartracer said:

Can I replace my 12 gallon electric water heater with house type unit or should I use the Raritan marine unit? Does not have engine heat exchanger .

Click to expand...

Your boat water heater most likely runs on 120 volts. Residential water heaters typically run on 240 volts. You might be able to order a 120 volt water heater or replace the heating element but you're better off buying a marine water heater with a heat exchanger.

When we cruise and anchor, we have no way to power our water heater but we still have hot water the next morning from having the heat exchanger.

Comodave said:

Yup, hate it when that happens.

Click to expand...

And rightly so. Gasoline vapor and naked flame yield potential disaster; in this case the explosion destroyed the boat,but the occupants escaped ashore.
With a naked propane heater pilot light onboard, you may be able to mitigate your risks, but there can be adjacent risks you cannot control, or even know about.
Safer with the conventional method, heating a cylinder with engine coolant,and if you can, using a generator.

a lot of new propane appliances do not use open pilot lights but electronic ignition on demand.

probably could make ABYC compliant with just a brain cell or two.

Replaced our Kouma 1500 watt, 11 gal heater with a 6 gal, 750 watt Isotemp unit. wanted to be able to get hot water via our Honda generator after a couple of days at anchor. Gen would not drive previous unit. Still wsorking on wiring, but new unit has been great.