Shower Hot Water Options

[lowey49er]

notice to Wotname, Lowey49er here, re my previous post, I'm not near the boat at the moment ,but one of the members has just shown my set up in the previous post, I cant have it inside the boat because I don,t have the room so I improvised for use in the cockpit. but for what its worth, I also have the same unit in my Mobile home mounted beside the sinkI have a 30ft Triaxle and the hot water cylinder is up the back end and I used too much water getting hot to the sink , So I permanenty mounted on the wall besides the sink and plumbed the exhaust out through the wall. This unit is plumbed to the caravan gas supply, instant hot water at the sink at any time three years of constant use, no dramas with the fumes, I also have internal gas space heating and a full gas oven and hot plates , never had a drama with gas at all for over four years.
My complete boat set-up was less than $350.00Australian.

[GILow]

Originally Posted by Snowpetrel

On the heating the boat issue, do you have much insulation? SNP1 was freezing before I insulated her, The diesel heater on full, and still cold, but with 45mm of foam insulation she was toasty. Had to keep the hatch open to stop from overheating. Even just cooking and body-heat warmed her up nicely in all but the worst tassie weather.

On this one.... SNP1 was steel if I remember correctly? I am wondering if there is a difference in heating steel vs fibreglass boats. Basic thermodynamics suggests that steel will conduct heat better, and therefore be harder to heat (let's please not start another steel vs fibreglass war, there have been plenty of those on CF). But in practice I wonder if the conductivity of the boat skin is academic in the great equation of heat flow that is a boat on the water?

Important to me because I have the whole heating system down on paper now, but I am yet to fire a $ in anger at the purchasing phase. At this stage I am basing my heat equations on observations from using an old oil column heater. That and managing to be on the boat at anchor on the coldest Adelaide winter night in 20 years, which I concede would be pretty darn mild in comparison to the higher latitude nights.

Matt

[Wotname]

Originally Posted by GILow

On this one....
But in practice I wonder if the conductivity of the boat skin is academic in the great equation of heat flow that is a boat on the water?
....

Matt

I would expect steel to conduct heat away faster than FG and certainly faster than plywood .
And
The temperature gradient is less between cabin and water than cabin and air...no?

[Rustic Charm]

Originally Posted by Snowpetrel

I am surprised by the fact that the Glind isn't working, the only one I saw was on a small boat with a diesel that could only have been 15-20 hp and he had boiling water from it in about 5 minutes. I don't know how his was hooked up, and I am not sure how I would hook one into my engine to get the maximum heat from it, but it seems tricky to fully bypass the heat exchanger on many yacht diesels?

Not sure what I'm going to do yet, for now just a kettle and solar shower. I had kind of hoped a glind would work, because it seems like a simple solution.. I do have a small LPG on demand unit in my shed, but now ive got a metho stove, it seems silly to add LPG. And since it's unflued I'd have to install it in a vented locker somewhere or have it as a portable unit in the cockpit.

I also like the idea of being able to reuse the wasted engine heat, rather than lugging around LPG tanks.

On the heating the boat issue, do you have much insulation? SNP1 was freezing before I insulated her, The diesel heater on full, and still cold, but with 45mm of foam insulation she was toasty. Had to keep the hatch open to stop from overheating. Even just cooking and body-heat warmed her up nicely in all but the worst tassie weather.

I will be interested to hear what ends up working for you. Those Kumaar force 10 hot water calorifiers look like good value, anybody know anything about them?

I doubt mine has much insulation. I've redone the roof and put 25mm foam in the roof. It had soggy insulation bats that had become wet and causing rust.

The sides may have some of the same. I'm not sure as they are covered up with wood which I havnt as yet renovated.

[Cowboy Sailer]

The review misused units. It said that it draws 25 amps at 12 volts. It should have said that it uses 10 to 12 amp-hours for about a half hour of use. (25 amp draw for 1/2 hour would be 12.5 amp-hours.)

[Snowpetrel]

To be fair, when she was very cold I had the lining out as well, so just bare steel overhead. Very cold! Grp is no where near as bad, but still some insulation has got to help a lot. The boat being in the water actually seems to help. Certainly at night. It's always much colder when you are on the slip. Cold floor syndrome is a problem as well, but that's because we like to walk around in socks or bare feet! I'm planning a cork Floor to keep my toes toasty.

Just another thought RC damp matress foam makes for a very cold bed. It condenses between the matress and the base.

Sent from my HTC_0PCV2 using Cruisers Sailing Forum mobile app

[Dockhead]

Originally Posted by Rustic Charm

That's all very well for sunny days, (as I have one) but doesn't work at all if there's no sun. So I'm after something a little more regular.

As others have said, the most efficient way to make domestic hot water is with engine waste heat. Diesel engines produce vast amounts of waste heat which is not hard to capture for heating water, and it's free. Forget propane, solar, and all those other methods.

I don't know the device you have, but it sounds like it might be a normal calorifier. This must work -- there are zero moving parts -- if there isn't a hole in it somewhere. Most common problem is an air lock somewhere in the coolant loop. Is there a high point in the coolant loop? Are the valves open? Is there a blockage somewhere? If everything checks out, then maybe the connections to your engine are not designed correctly to get flow, or maybe the calorifier is too far from the engine, or too high or low. A small DC circulation pump can solve many of these problems (inelegantly, but effectively).

If the calorifier has holes or some other problem, just replace it -- they're not that expensive.

It's really nice to have a 230v AC immersion heater in your calorifier for use on the dock.

And some calorifiers (like mine) have a second coolant loop for attaching to a central heating system. It doesn't sound like you have central heat, but if you ever consider installing it, it is dandy for making domestic hot water, and it's really not all that expensive. Can be worth its weight in gold if you cruise in the winter time, or if you ever wanted to.

All these secondary ways of making hot water -- DC power, solar, propane, etc. -- are ok if you don't have a diesel engine, or never run it, etc. But for 99% of cruisers, engine waste heat is the primary method of producing hot water.

DC power, by the way, is extremely inefficient, and will kill a car-type alternator in short order. I would cross that off the list first off. This is useful, as far as I can tell, only for cruisers with large photovoltaic banks who need somewhere to dump the waste electrical power after the batteries are charged.

[Cottontop]

Originally Posted by Cowboy Sailer

The review misused units. It said that it draws 25 amps at 12 volts. It should have said that it uses 10 to 12 amp-hours for about a half hour of use. (25 amp draw for 1/2 hour would be 12.5 amp-hours.)

Either way, about 0.3 kwh, enough to raise the temperature of 7 gallons about 20 degrees F. The link is to a page having about every conversion you could need when thinking about heating water. In "American" units.

Kilowatt hours of electricity needed to heat water

[El Pinguino]

Back to the 'Glint' ... everything I have read about them suggests - no storage of hot water and the engine needs to be running for them to heat water.... is this correct?

[GILow]

Originally Posted by Cowboy Sailer

The review misused units. It said that it draws 25 amps at 12 volts. It should have said that it uses 10 to 12 amp-hours for about a half hour of use. (25 amp draw for 1/2 hour would be 12.5 amp-hours.)

Well spotted. That sort of unit confusion seems to happen a lot.


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[DeepFrz]

The Glind looks to me, just looking at the web site, that its made for larger engines such as you would find in an off road vehicle. You really need a regular marine calorifier (insulated hot water tank). They work well when engine runs for about 20 minutes if they are hooked up properly.

[SVNeko]

Just a detail, but an owner of a sistership to ours has a nifty system for use with a calorifier located a distance from the shower. A separate valve and return line to the water tanks plumbed into the hot line allows him to run the hot water until its warm without wasting it. Turn on the valve and water is cycled from the water heater to the main tanks. Run it for several minutes and your water is warm and you haven't flushed precious H2O simply because its not warm.

Sent from my SM-T210R using Cruisers Sailing Forum mobile app

[Rustic Charm]

Originally Posted by Dockhead

As others have said, the most efficient way to make domestic hot water is with engine waste heat. Diesel engines produce vast amounts of waste heat which is not hard to capture for heating water, and it's free. Forget propane, solar, and all those other methods.

I don't know the device you have, but it sounds like it might be a normal calorifier. This must work -- there are zero moving parts -- if there isn't a hole in it somewhere. Most common problem is an air lock somewhere in the coolant loop. Is there a high point in the coolant loop? Are the valves open? Is there a blockage somewhere? If everything checks out, then maybe the connections to your engine are not designed correctly to get flow, or maybe the calorifier is too far from the engine, or too high or low. A small DC circulation pump can solve many of these problems (inelegantly, but effectively).

If the calorifier has holes or some other problem, just replace it -- they're not that expensive.

It's really nice to have a 230v AC immersion heater in your calorifier for use on the dock.

And some calorifiers (like mine) have a second coolant loop for attaching to a central heating system. It doesn't sound like you have central heat, but if you ever consider installing it, it is dandy for making domestic hot water, and it's really not all that expensive. Can be worth its weight in gold if you cruise in the winter time, or if you ever wanted to.

All these secondary ways of making hot water -- DC power, solar, propane, etc. -- are ok if you don't have a diesel engine, or never run it, etc. But for 99% of cruisers, engine waste heat is the primary method of producing hot water.

DC power, by the way, is extremely inefficient, and will kill a car-type alternator in short order. I would cross that off the list first off. This is useful, as far as I can tell, only for cruisers with large photovoltaic banks who need somewhere to dump the waste electrical power after the batteries are charged.

Thanks Dockhead. Yes, I'll stay well clear of the 12V electric unit.

[Rustic Charm]

Originally Posted by El Pinguino

Back to the 'Glint' ... everything I have read about them suggests - no storage of hot water and the engine needs to be running for them to heat water.... is this correct?

That's exactly right. And I was happy to run the engine and bring it up to speed to have a quick shower. But, mine does not run hot enough to keep the water running through the unit even mildly warm.

[Rustic Charm]

Originally Posted by SVNeko

Just a detail, but an owner of a sistership to ours has a nifty system for use with a calorifier located a distance from the shower. A separate valve and return line to the water tanks plumbed into the hot line allows him to run the hot water until its warm without wasting it. Turn on the valve and water is cycled from the water heater to the main tanks. Run it for several minutes and your water is warm and you haven't flushed precious H2O simply because its not warm.

Sent from my SM-T210R using Cruisers Sailing Forum mobile app

That there is a brilliant idea