Hot water, heaters, cookers.....

Helo, Duane. These devices are still very common in Brazil and they have an extra grounding wire, for prevention of electric hazards. They usually draw something around 5,000 watts (either 110 or 220 V). The problem is not only the high energy necessary to make them run, but worse than that, usually current inverters have only a bipole energy outlet, so grounding such a device is not effective.

 

Thanks Sam -- you answered all my questions. It's a pity they draw so much energy -- the idea still sounds simple enough. Like I said, perhaps some kind of different electric storage device like a capacitor instead of a battery might give better performance if the coil material was modified to take less energy to heat the flowing water. Is there a website that sells them?

 

If only it were that simple - the fact is that it takes a given amount of energy (about 1 calorie to raise 1 gram of water by 1 degree C between 0 & 100 C - interestingly it takes a further 540 calories to turn water at 100 into steam. Anyway, I digress....) What I'm trying to say is that to heat your water you can run your heater at 5 kW for 5 minutes or a 1kW heater for 25 minutes - the end result will be the same - hot water and flat batteries! But to heat flowing water quickly enough to produce 'hot' water, you simply can't get away from requiring lots of energy....
did that make sense...

 

Yes -- it makes sense. I guess I'm just trying to suggest the idea that if a different type of battery/capacitor storage device -- together with a new designed resistor heater element for the shower head portal would make a better hot shower water maker for small boats than having to make and store hot water aboard in some water tank.

Thanks for the quick overview of how current technology works -- perhaps some future technique in either making or storing onboard electric power can make a quick add-on device to the shower head be the better choice in our heating needs.

Until then -- we live in the present...

 

Hot Water on O-1

We use capacitors in Laser systems, which require high power over a short duration, to store energy between pulses and level out the power draw. It works well for loads where the duration is in milliseconds, but when the duration approaches tenths of seconds the weight and cost trade tends to favor batteries. Unless you intend to take very short showers I think your best bet would be to use AGM batteries because they can provide very high discharge rates. Since the electric water heaters you are referring to are resistance heaters they should run on either AC or DC power so you could eliminate the power inverter, but to maintain full capacity you would want to provide the same voltage, i.e. 120 VDC. You could achieve that by using 12 small AGM batteries in series but then you need a 120 VDC charger or some complicated switching to charge the batteries in parallel i.e. 12 VDC and then discharge in series for showering. All in all it sounds like a very complicated and heavy system to get a hot shower.

I think O-1 would be a good application for solar water heating. If you mounted a solar water heater panel on the roof and a hot water tank in the bilge you could collect solar heat and store it until you need it. You can also get hot water storage tanks with a capsule of wax for better heat storage. When the wax melts it stores about 100 BTU per pound, so you can store more heat per unit weight and/or volume.

Regards;
Mike Schooley

 

Hot water...

Thanks Mike -- you have provided some very interesting options for an onboard hot water heating system. The solar water option seems to be the easiest and most economical -- I like the wax capsule concept in keeping the water warmer longer.

Suffice to say, anybody trying to build a homemade device that uses electricity to heat a resistor for a hot water shower should be careful in designing it safely. Mixing water and electricity improperly can result in a jerky dance event for the bather -- and that's no fun.

Lately, I've been studying alternative electrical storage devices and I used to think some kind of light weight capacitor device could store as much -- if not more energy, than conventional electrochemical batteries, but after further review, the concept still needs more study. If I discover some new views on the matter, I'll post them here.

Again, thanks Mike!

 

Best Solution for an Outboard

Actually, the easiest and most economical solution is to use an inboard engine. However, if you insist on using an outboard, then I think the best option is solar.

Regards;
Mike Schooley

 

The most common form of heating hot water is the small powered oil furnace.
This and a high cap insulated tank can provide winter heat or almost "endless " hot water.At some cost with great safty.

For USCG pax boats the Way Wolf is the classic.
For a yacht the Hurricane, works well as the circ pumps are sized to the vessel.

Toe kick heaters can be used dockside or underway , but good old baseboard heaters work far better , as no noisy thirsty blowers are needed for air circulation.


These units require very little DC in operation and are suitable for mooring living aboard in northern climes. Or in marinas with "Iffy" electric service, most marinas "after THE storm".

Our choice was for a dickinson Antartic with internal copper heating coil and thermosyphon to heat the vessel , light it in Oct and turn off in May, no maint!
And the heat stays on when the electric goes off for a few weeks.

HW is from a engine coil in water tank and 120V for dockside.Good insulation lasts a couple of days.

TAKE the daily showers while underway , to begin overnight with hottest water.

FAST FRED

 

How much hot water do you need and at what temp? The hydraHot will provide a nearly endless supply of 120 degree water at about 1.5 gpm flow is fairly small 12 volt dc powered with 120v ac heating element for shore power also can be plumbed into a closed water cooling system to use engine heat to heat the boiler or runs a small deisel fired burner. Provides 3 zones of heat and hot water from 3 sources of power all of which I assume are allready on board your boat. The Aquahot is a slightly larger version which give a little more hot water and 5 zones of heating form a unit that is approx 18"x20"x36". I am not sure what it would take to make it usable on a boat but we use them all the time on luxury RV's only thing I can think of would be plumbing the exhaust and running the water lines to and from the unit it has it's own pumps and valves for the heating portion and has a tempering valve to control water temp which is adjustable. Do a search for Vehicle Systems Incorporated or for aquahot and you should find them.

 

heating options

I've stumbled on to the options thread and learned alittle more on what I have been researching.
I previously asked in another thead the pro's and con's of both electric and LP
comforts limited to heating, water,cooking, and perishable refrigeration.
any input from this thread would be helpfull.
I've attached a link to a water heating unit that has been designed for marine use and I surely like the LP format for all economic and efficiency
purpose for my boat project but still lack alot of first hand experience
on the safety and design for using LP in a marine environment.
Recently I have seen this unit or similar units in the home building industry
And since being in the trades for many years, for obvious reason I am comfortable with this type of system.
I just need to learn more about it for this application

Thank for any input
Donjames Bosch W125 waterheater http://www.go2marine.com

 

The problem with propane is its heavier than air, so any malfunction could fill the bilge with explosive gasses.

Yachts sometimes get around this with an electric valve switch , by the stove with an indicator lamp.

There are "bilge sniffers" that will claim to turn off the gas , but do you want to bet your LIFE on its working?

And do you want the batt drain of about 1ah (24ah daily) just to hold the valve open?

RV's and houses have leaky floors (not airtight) that drain any leaking gas away ,hopefully boats don't.

IF you could mount everything outside in a self draining cockpit , no problem.

We chose propane and the switch & sensor for the galley range below, as the only batt drain is when actually cooking.
We also chose a huge RV fridge , outside in the self draining cockpit , A pain when getting breakfast goodies on a rainy day before sunrise.
But far cheaper than Marine refridgeration as it only used 20 lbs of propane in 25 days , and is quite handy for salsa & brew at the end of the day.

FAST FRED

 

As a Master certified RV tech I can tell you there are some differences in the install of LP appliances in RV's but many of the princaples would also apply to boats first all LP appliances other than the cooktop are installed direct vented meaning the intake and combustion air must come from outside and they must be sealed from the interior of the coach. So we do not rely on leaky floors for gas safety the new generation LP cooktops have electronic igniction with thermicouple protection to prevent gas discharge when not lit. All appliances are at least double redundent in failure protection and it is allmost allways stupidity not componet failure which causes gas fires in a RV. Which could probably also be said of most boat fires. The LP detectors have a near zero failure rate and most of the ones sent in for warranty are in perfect working order we change them to give the customer peice of mind about the safety of their unit. We also try to educate them on how they work and what causes them to go off usually something they just did or cleaning solvent spills, Or hair spray which by the way usually contains propane as propellent. The PRE TELL LP detectors are combined with a LP shut off valve so when it detects a flamable vapor it shuts off the LP along with a audible alarm if I were going to use LP on a boat I would use this type of detector in my bildge area but I would wire it to a relay so that when it detected gas not only would it shut down the LP but it would turn on a blower to vent the bildge. I would also use alarms in the cooking and sleeping areas as a redundent protection. That being said the only thing I would consider using LP for on a boat would be for cooking and refridgeration and maybe for a nice big grill on deck. There are a large number of sizes and types of RV refridgerators that would work in a boat app properly installed and many offer 3 way power choose from 120vac 12vdc or LP. Since there are laws in the US about how much portable LP we can carry no more than 2 40lb bottles in most configurations using LP for heat or hot water would be to big of a pain in the butt to be usefull. For comfort heating and hot water I would look at the Aqua Hot Hydra Hot or the Hurricane deisel fired boiler systems as they are fairly effeicent and quite safe also all of them offer mutiple heat source ie 120vac electric heaters and also can be tied into your engine cooling system to draw engine heat to keep the boiler hot this would only work well on closed cooling systems but it is there .
Good Luck

 

boat experment

roamdeep

yes propane is bad , but remember when gas was the same way the new solar powered vent fans with hoses to the bottom of the bilge and then another to the propane box will keep you safe , we have been doing this for a grate many years in the amazon river , you can build your box out of a platic bucket put the hose out the small hose and then the pour spout your vacum hose to the stern of your boat near the water away from your exaust port

allen

 

The wood stove is a good solution
Cheers
Daniel
http://www.marinestove.com/index.htm

 

Daniel,
The stove shown on web site you exhibited today looks excellent. I shall keep it in mind for a later time.