Water Heater Placement on a 36 Footer

[Rustic Charm]

Originally Posted by seasick

On a 36' boat I would place it directly behind the gear box and high enough to avoid obstructing access to the stuffing box. This keeps the weight centered and the engine coolant lines short. Insulate the HW plumbing to distant sink and showers etc.

I have room in the same spot i think? i'd have to check, ive got a little more width than the width of the engine.

[Rustic Charm]

Originally Posted by captain mitch

Yup, I go with the closer to the engine.
One point though, stay away from West Marine water heaters, go with a brand name in heaters. We replaced a Seaward unit with a West (we were leaving for the islands and in a rush) now we await the Seaward replacement to arrive.
the West unit heats slow on electric power and is so poorly insulated that it barely holds a showers worth overnite. It looks just like a Seaward, but sure is a terrible performer.

cheers.i'll stick with the Isotherm spa units. They have a good reputation.

[daletournier]

I've only been just researching today in regards to going the other way. Wouldn't it be easier to improve ventilation in your current setup ?

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[Rustic Charm]

Originally Posted by daletournier

I've only been just researching today in regards to going the other way. Wouldn't it be easier to improve ventilation in your current setup ?

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You mean flue the LPG unit to the outside?

Firstly, i wouldnt trust the unit to be flued to the outside. It's not designed for that. It's an outdoors unit only.

Secondly, to appropriately set up the gas and make it legal is a big undertaking on my boat. The whole system has to be redone.

[wrwakefield]

Originally Posted by Rustic Charm

Someone suggested to me to resolve the lost water problem, to set up a return valve to the water tank so that when i run the tap, it all runs back to the water tank until it's hot enough for a shower then switch back to the shower.

Hi Rustic,

I did this on a previous boat. It definitely conserves a bit of water.

The trade-off is sometimes the water in the water heater tank gets funky tasting and mineral rich- and if you are putting that back into your potable water tank...

Lessons learned...

Cheers!

Bill

[Dockhead]

The killer solution is a calorifier with two loops in it, one with engine coolant and the other powered by a hydronic heater.

If you have only one heads, then I would be contrary to other posters and say put the calorifier there, not next to the engine. Add a booster pump to circulate the coolant from the engine. Then you solve the lost water problem. The idea is that you don't care about lost engine waste heat, but you care a lot about lost water and lost heat in your domestic hot water.

And at the same time, you can plumb in a radiator or bus heater in the heads to heat the space as well as the water. There's nothing like getting out of the shower into a really nice warm dry space. If you've added a booster pump, then the engine coolant can do more than one job. Dry out your heads and towels every time you motor.

Those cruising warm tropical waters have no idea what we're talking about here.

[wrwakefield]

Originally Posted by Rustic Charm

Brilliant. That's the model i was looking at. The manafacturuer has given me the supplier in Australia.

I want it to run on 'power' as well when 'out'. So i'd have to link it to a battery thingy is a 110 or 240 better for this purpose?

Hi Rustic,

The IsoTemp models I had access to had several AC heating options, but, in my opinion, none of them are conducive to use through an inverter.

From memory the heating element options included:
110VAC [cycles don't matter since this is an (was induction; corrected to resistive) load... Thanks Dockhead for clarifying my double-think error...]
750 watts or 1500 watts

I chose 750 to reduce load on shore power line- even though it takes longer to heat a tank... once heated, however, it is difficult to run out of hot water...

220VAC I didn't want this so didn't pay attention, but I believe it also offered the low and higher wattage elements as an option.

RE: Using the electric elements when away from shore power:

We turn it on whenever the generator is run. [And, while I haven't tried it, the 750 watt (~7 amps @ 110VAC) element should be easily powered by a 2k Honda/Yahama portable generator...]

I don't think it would be advisable to run it off of an inverter. [I inadvertently did that once with our 110VAC 750 watt unit. I noticed a sudden high amp load on the battery monitor and thankfully (quickly) realized the errors of my ways...] I noticed because, since we select the incoming AC source [vs. have the inverter auto-activate if the primary AC source is unavailable] I have a habit of checking battery load whenever the inverter is first switched on...

This water heater does heat up very quickly from the engine coolant loop... A 30 minute run will keep us in hot water for a day or two. As you know, this is because it is designed to hold high temp water [our engine runs at 185°F, so that is the tank temp...] and the hot water goes a lot further since it is mixed after the tank to the desired tap hot water temp. [More details in the blog post I referenced in my first response in this thread...]

Did I cover your questions?

Best wishes with your project.

Cheers!

Bill

[Dockhead]

Originally Posted by wrwakefield

Hi Rustic,

The IsoTemp models I had access to had several AC heating options, but, in my opinion, none of them are conducive to use through an inverter.

From memory the heating element options included:
110VAC [cycles don't matter since this is an induction load...]
750 watts or 1500 watts

I chose 750 to reduce load on shore power line- even though it takes longer to heat a tank... once heated, however, it is difficult to run out of hot water...

220VAC I didn't want this so didn't pay attention, but I believe it also offered the low and higher wattage elements as an option.

RE: Using the electric elements when away from shore power:

We turn it on whenever the generator is run. [And, while I haven't tried it, the 750 watt (~7 amps @ 110VAC) element should be easily powered by a 2k Honda/Yahama portable generator...]

I don't think it would be advisable to run it off of an inverter. [I inadvertently did that once with our 110VAC 750 watt unit. I noticed a sudden high amp load on the battery monitor and thankfully (quickly) realized the errors of my ways...] I noticed because, since we select the incoming AC source [vs. have the inverter auto-activate if the primary AC source is unavailable] I have a habit of checking battery load whenever the inverter is first switched on...

This water heater does heat up very quickly from the engine coolant loop... A 30 minute run will keep us in hot water for a day or two. As you know, this is because it is designed to hold high temp water [our engine runs at 185°F, so that is the tank temp...] and the hot water goes a lot further since it is mixed after the tank to the desired tap hot water temp. [More details in the blog post I referenced in my first response in this thread...]

Did I cover your questions?

Best wishes with your project.

Cheers!

Bill

Immersion heaters run fine from inverters as long as everything is sized and loaded correctly. They are pure resistance loads, which are pleasant for the electronics.

Do you have that much solar?

Not much point running them from an alternator, since you will be getting all the waste heat you can use from the coolant loop, whenever the engine is running. You also have to be very careful not to overload the alternator this way (don't ask me how I know).

[wrwakefield]

Originally Posted by Dockhead

The killer solution is a calorifier with two loops in it, one with engine coolant and the other powered by a hydronic heater.

If you have only one heads, then I would be contrary to other posters and say put the calorifier there, not next to the engine. Add a booster pump to circulate the coolant from the engine. Then you solve the lost water problem. The idea is that you don't care about lost engine waste heat, but you care a lot about lost water and lost heat in your domestic hot water.

And at the same time, you can plumb in a radiator or bus heater in the heads to heat the space as well as the water. There's nothing like getting out of the shower into a really nice warm dry space. If you've added a booster pump, then the engine coolant can do more than one job. Dry out your heads and towels every time you motor.

Those cruising warm tropical waters have no idea what we're talking about here.

You are right, DH; that is one of the more ideal set-ups in cooler climes!

Cheers!

Bill

[GILow]

Originally Posted by wrwakefield

Hi Rustic,

I did this on a previous boat. It definitely conserves a bit of water.

The trade-off is sometimes the water in the water heater tank gets funky tasting and mineral rich- and if you are putting that back into your potable water tank...

Lessons learned...

Cheers!

Bill

This sounds lethal. Have a look at the breeding conditions for Legeionellosis. They are practically this setup.

Matt

[Rustic Charm]

Originally Posted by GILow

This sounds lethal. Have a look at the breeding conditions for Legeionellosis. They are practically this setup.

Matt

I don't believe that's correct Matt. Well, not a concern anyway. The water tanks themselves can be a breeding ground if permitted to breed the bacteria. That is if they are never cleaned.

The circulating of a small amount of water from a cold water heater back to a cold water receptical will not in itself contribute to the over breeding of the bacteria.

And let's keep in mind the Legionairs bacterium is already in many water supplies.

[Rustic Charm]

Originally Posted by Dockhead

Immersion heaters run fine from inverters as long as everything is sized and loaded correctly. They are pure resistance loads, which are pleasant for the electronics.

Do you have that much solar?

Not much point running them from an alternator, since you will be getting all the waste heat you can use from the coolant loop, whenever the engine is running. You also have to be very careful not to overload the alternator this way (don't ask me how I know).

I currently have 240 watts of solar panels, 2 x 120w ( I think).

I'm a bit worried the heat from my engine won't be enough. I've currently got a Glind on it and it's useless to shower with. Just doesn't heat the water fast enough travelling through it.

[GILow]

Originally Posted by Rustic Charm

I don't believe that's correct Matt. Well, not a concern anyway. The water tanks themselves can be a breeding ground if permitted to breed the bacteria. That is if they are never cleaned.

The circulating of a small amount of water from a cold water heater back to a cold water receptical will not in itself contribute to the over breeding of the bacteria.

And let's keep in mind the Legionairs bacterium is already in many water supplies.

I built a solar hot water for this house from scratch a few years back, spent a lot of time doing the research and talking to the experts. My system uses an enclosed loop of coolant from the evacuated tubes to a heat exchanger in the house holding tank. If the house holding tank does not reach 65 degrees C in a 24 hour period the gas booster switches on and brings the tank up to temperature to kill off any bugs. Not often a problem in sunny Adelaide but I hear the gas booster and circulation pump switch on every few days in the bad bits of winter.

The risk areas were around water transitioning the range of 40 degrees or thereabouts, from memory. When you return the warmed water to your main tank it has transitioned this temperature range and now there is nothing in the holding tank to kill off any increased levels of bacteria in the returned water. Any residual chlorine from the mains water will be long gone from the holding tank.

Seriously I would not dare try what is being suggested. Either that or the experts in the area are wrong and the government regs around this stuff is also being paranoid. To my mind, for the sake of a few litres of water, I would not return the heated water.

Matt


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[Rustic Charm]

Originally Posted by GILow

I built a solar hot water for this house from scratch a few years back, spent a lot of time doing the research and talking to the experts. My system uses an enclosed loop of coolant from the evacuated tubes to a heat exchanger in the house holding tank. If the house holding tank does not reach 65 degrees C in a 24 hour period the gas booster switches on and brings the tank up to temperature to kill off any bugs. Not often a problem in sunny Adelaide but I hear the gas booster and circulation pump switch on every few days in the bad bits of winter.

The risk areas were around water transitioning the range of 40 degrees or thereabouts, from memory. When you return the warmed water to your main tank it has transitioned this temperature range and now there is nothing in the holding tank to kill off any increased levels of bacteria in the returned water. Any residual chlorine from the mains water will be long gone from the holding tank.

Seriously I would not dare try what is being suggested. Either that or the experts in the area are wrong and the government regs around this stuff is also being paranoid. To my mind, for the sake of a few litres of water, I would not return the heated water.

Matt

I don't doubt whatever the experts on solar hot water systems say. But I'm not raising building a solar hot system. I'm suggesting nothing more than returning 'cold water' that's sitting in the pipes to the water tank it's come from, rather than emptying it down the drain, or in this case out into the sea.

I'm aware there are significant problems with 'evapourative air conditioners' re legionaires disease on the mainland and further up North too. But we don't even have them here for domestic use.

[Dockhead]

Originally Posted by Rustic Charm

I currently have 240 watts of solar panels, 2 x 120w ( I think).

I'm a bit worried the heat from my engine won't be enough. I've currently got a Glind on it and it's useless to shower with. Just doesn't heat the water fast enough travelling through it.

The engine will be more than enough - many kilowatts. Just need to be sure the coolant is actually circulating. Eliminate air locks and add a boost pump if necessary.



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