12 volt heating element

[Fearnow]

Looking for a 12 volt heating element for my Quick 60l. I have seen some discussion, but nothing about where to buy and do they come with a thermostat.
It would be nice to have some hot water without running the engine or using 110v.

[john61ct]

Takes a lot of energy, sure you have that much excess solar?

Yes running your existing setup off an inverter will waste maybe 20-30% efficiency, but for a testing period will at least give a go/no-go on the overall concept.

Diesel or propane (if already in use) may be more practical.

[Adelie]

What’s a Quick 60l? Water heater?

http://www.cruisersforum.com/forums/...ml#post2856119

[MartinR]

You are talking serious Amps here, big cables. Inverter makes more sense.

[Fearnow]

I've read that these elements come in different wattage and you only turn them on for a short time before you want eg. a shower. Quick Boiler B-3 is the make, but they say you have to do some conversion and can't just put a 12 volt element in there and, of course change the voltage. Inverters are very wasteful and not sure it would handle my heater.

[Lancerbye]

A 1200 watt /120 volt element draws 10 amps from a 120 volt supply. A 1200 watt /12 volt element will draw 100 amps from the 12 volt supply. Are you sure you want to do this? Equivalent to starting motor current on a small diesel engine.

[MartinR]

A good sine inverter has 90 to 95% efficiency. The cheap MSW inverters maybe 75%.

[Fearnow]

After looking at all the stats, I will just keep on running the engine for a few minutes if I really need a warm shower. I don't have that kind of power.

[GordMay]

The “B3" 60l heater come with a 220V element. Don’t see a 12V option, anywhere on their site.
➥ B3 60L Round Water Heater


Perhaps, one of these might fit.
➥ http://mwands.com/store/dc-water-heating-elements

[CaptainJohn49]

I have a Flicka 20 with no hot water but I also have a Winnebago View (RV) that has a 6 gal (25 l.) hot water tank that works on propane or 110v. I can tell you from experience that the RV water heater produces hot water from full cold to shower temp in 5 minutes using propane. I actually turn the heater off before I take a shower and I have still have plenty of hot water. If the water starts to cool I know it's time to get out of the shower. The water situation isn't as severe on a RV as on a sailboat but it's still a big part of everyday life.


Now the RV heater wouldn't work on the sailboat but I'm certain a marine "dual heat" water heater could be found. 5 gal. of propane lasts a month or more on the RV for water heating and cooking. Here in Montana we pay only $0.99 per gallon. Pretty cheap and very efficient.


CaptainJohn49

[Scubaseas]

Google "300 Watt 12 Volt DC Submersible Water Heater Element"


But you need a huge battery bank or big power source. How much power depends on how much water and to what temperature. You need to look at amp/hours to BTUs.



Having said that I can get hot water from a wind generator if it's blowing 30 knots for a day or two. My set up has a shunt or dump to a water heating element and after the batteries are full all the energy goes to the water heater.

[john61ct]

And 300W, although a big load for solar/batteries, is **tiny** for a HWS.

Just getting a couple gallons up to shower temp would take a long time.

The Ah consumed is pretty constant anyway, so **if** you did have that much excess power, might as well get the job done more quickly, tank unit more can be compact less need for massive insulation.

Actual loss from inverters for this sort of load depends on several variables, but the published specs are always at the most optimistic combination of factors. Test with coulomb-counters, comparing actual watt-hour use from the bank compared to a mains socket, to get the number for your IRL scenario.

Most smaller boats just do not have that much excess power on average, so a moot point.

[john61ct]

But if you **do** have a kW of panels and an LFP bank that is full by noon every day,

**and** a big enough boat that carrying a big insulated water tank is NBD,

then this is not a bad idea for putting that "free" excess energy production to use.

[Davidhoy]

Has anyone ever used a 12VDC water heater element as a dump load for when you have excess amps? It would seem like a handy way to not let those amps go to waste. Assuming you have any excess amps, that is...

[mikedefieslife]

Originally Posted by MartinR

You are talking serious Amps here, big cables. Inverter makes more sense.

Not really, it's only going to be about 80 amps. Any decent sized house bank should be able to take that for an 30-45 mins or however long it takes to heat water.

That being said, I did run my 230v 1000w heating element from an inverter. Work well and drew around 88 amps max according to my clamp meter.