is there a diesel water heater that works with electricity and engine coolant ?

[Brann-]

Hi,
I'm considering buying a diesel water heater to replace my current one, which produce hot water using either shore power or engine coolant, depending on what's available. Obviously, this means I don't have hot water while anchored.

I'd like to retain the capacity to get hot water without using diesel when the engine is running and when I've got shore power

Is there a model that does what I want, or do I need to install a diesel water heater on top of the existing installation and find a way to make both systems work together (maybe with a valve to choose where to pump the hot water from ?)

Thanks a lot !
Brann

[chris95040]

There are hydronic cabin heaters, tiny diesel burners that heat up coolant and pump it to radiators. You could plumb that coolant loop through your water heater. I believe there are water heaters with two heat exchangers and an electric element, so you could have all 3 sources available, engine, tiny diesel burner, and shore power. Or you could have this new coolant loop heated by either the diesel burner or an electric element. etc etc.

But I dont understand why you need it, or why you say about your current setup 'this means i dont have hot water while anchored'. Just run your engine for a few minutes and you've got hot water at anchor. And since it sounds like you dont have a generator, dont you do that daily anyways to top off the batteries?

[Pete7]

Brian, how many circuits does your calorifier have?

If its single circuit then you are looking at combining a diesel water heater with the engine cooling circuit with some interesting plumbing. This assumes the engine is fresh water cooled.

Webasto would be a good solution.

If you have a double circuit calorifier then you could have both engine and water heater on different circuits.

Surejust > 30 litre vertical twin coil Surecal calorifier

The other option would be a adding a water heating kit to the reflecks or dickinson type stove heaters.

Pete

[Brann-]

Originally Posted by chris95040

There are hydronic cabin heaters, tiny diesel burners that heat up coolant and pump it to radiators. You could plumb that coolant loop through your water heater. I believe there are water heaters with two heat exchangers and an electric element, so you could have all 3 sources available, engine, tiny diesel burner, and shore power. Or you could have this new coolant loop heated by either the diesel burner or an electric element. etc etc.

But I dont understand why you need it, or why you say about your current setup 'this means i dont have hot water while anchored'. Just run your engine for a few minutes and you've got hot water at anchor. And since it sounds like you dont have a generator, dont you do that daily anyways to top off the batteries?

I have indeed seen that kind of dual exchanger water heater, that's a good idea, thanks!

Running the engine to warm up a water tank sounds to me as a very inefficient use of diesel, but I haven't look at actual figures. In my case, solar panels and a wind generator usually keep the battery bank fully charged, so running the engine would be solely to warm up water. Also, it usually takes more than a few minutes to get hot water, and there's the noise issue ...

[MartinR]

Combine a Webasto heater with a heat exchanger.
[URL="https://www.butlertechnik.com/installation-accessories-c63/water-heater-matrices-c116/webasto-motor-home-plate-heat-exchanger-with-mixer-valve-4111209a-p1516"/URL]

Install in reverse, so that the primary circuit coolant flow goes through Webasto heat exchanger first, and then through the calorifier. instant (almost) hot water.

[travellerw]

Originally Posted by Brann-

I have indeed seen that kind of dual exchanger water heater, that's a good idea, thanks!

Running the engine to warm up a water tank sounds to me as a very inefficient use of diesel, but I haven't look at actual figures. In my case, solar panels and a wind generator usually keep the battery bank fully charged, so running the engine would be solely to warm up water. Also, it usually takes more than a few minutes to get hot water, and there's the noise issue ...

We heat water through our inverter once our solar has filled the batts.

We had a 2000W 220V water heater element installed. Since our inverter is 110V, the element only draws 1/4 wattage (500W). While running it draws about 36-38A. A half hour of running the water heater gives us enough hot water for 2 showers (nice warm showers).

[Brann-]

Originally Posted by Pete7

Brian, how many circuits does your calorifier have?

If its single circuit then you are looking at combining a diesel water heater with the engine cooling circuit with some interesting plumbing. This assumes the engine is fresh water cooled.

Webasto would be a good solution.

If you have a double circuit calorifier then you could have both engine and water heater on different circuits.

Surejust > 30 litre vertical twin coil Surecal calorifier

The other option would be a adding a water heating kit to the reflecks or dickinson type stove heaters.

Pete

Only one circuit, currently linked to the engine directly. But I could definitely buy a new water heater with two circuits.

If I go for a Webasto, I'm a bit confused with how this works: I'm assuming that the webasto is heating some coolant in a closed circuit, and that I lead this closed circuit to go wherever I want, including through my water heater calorifier, is this correct?

[De.windhoos]

Maybe this is a solution?

[Dockhead]

Originally Posted by Brann-

Only one circuit, currently linked to the engine directly. But I could definitely buy a new water heater with two circuits.

If I go for a Webasto, I'm a bit confused with how this works: I'm assuming that the webasto is heating some coolant in a closed circuit, and that I lead this closed circuit to go wherever I want, including through my water heater calorifier, is this correct?

Yes, you are right. And you can lead the coolant through fan coils or radiators as well and get cabin heat

[Pete7]

Originally Posted by Brann-

If I go for a Webasto, I'm a bit confused with how this works: I'm assuming that the webasto is heating some coolant in a closed circuit, and that I lead this closed circuit to go wherever I want, including through my water heater calorifier, is this correct?

Yes, actually Webasto were popular on some cars in the UK for a while. Range Rovers and the like, possibly BMW as well. they used the cars heating circuit to heat the car before you got in. Lots of bits on UK ebay for them.

Pete

[Pete7]

Originally Posted by De.windhoos

Maybe this is a solution?

You would be better off heating the water with those water heating vacuum tubes rather than convert sunlight to electricity and then to heat.

[MartinR]

I recently bought a Webasto heater for both hot water and cabin heating. It will be connected to the calorifier for hot water and to fan heat exchangers for cabin heating. I see no need to have the engine connected to the calorifier also. Of course, you get some free hot water, but on the other hand it makes the engine coolant installation more vulnerable.

[Dean Sutherland]

We have an Espar diesel hydronic furnace that heats glycol from engine, diesel furnace and/or electricity. It will also use diesel and/electric to pre-heat the engine. It also has a “hot water” only function that heats only the potable water “on-demand.” It’s an “all-in-one” box that you run hoses and wires to/from. It works fantastic. We’ve cruised thousands of miles using engine heat to heat the boat, used diesel to heat and used shore and generator to heat electrical (takes a lot of electricity—we have two 2,000 watt 120volt elements ; we can use neither, one or both). I installed it. I recommend you investigate Espar systems as well as Webasto and others.

[skipgundlach]

I guess I missed something. I had the impression OP was speaking of hot water - as in, for washing or anything else.

Virtually any marine water heater will have both AC element and heat-transfer coils for engine coolant. But there are also dual voltage elements which have 12VDC input; wind generator controllers generally have a load diverter which would feed that element when the batteries are full.

So, if you had ample solar and wind, you could make hot water any of those three ways - dockside power, excess wind power, and engine coolant circulation.

OTOH, if what you're wanting is cabin heat, there are diesel fired hot-water circulating, fan spread hot air heating systems. A good cruising buddy just bought one for installation on his previously sub or full tropical cruising boat, for when it arrives in Vancouver for what is expected to be many years...

[Scott Berg]

Torrid makes water heaters with multiple elements and multiple heat exchanger circuits
They work perfectly with a webasto hydronic heater like the 90 or 2010.