Heating water in silence (via inverter)

[yachtgemini]

Simply go to a 12-volt heater for your water tank..

Like https://www.amazon.co.uk/Aiicioo-Hea.../dp/B01D4U23O8

No inverter losses, no system stress and easily controllable. Also possible to use it with a voltage-sensitive relay.

You can set it up as a dump load for your solar / wind or a manual switch.

Ross

[Mantas]

thank you everyone for answering to me. To make this post more clear - yes, I was talking about heating water for the shower, not for coffee regarding the inverter I think it is 230V as its European boat.

12V DC heating element is what I am looking at after the "no" answer from electrician. But if I am thinking correctly with 12V element it would take longer to heat water than via inverter. And how about once in marina connected to shore power?

[Tillsbury]

The inverter can certainly do it. There are only two issues -- one is whether you have sufficient energy to do it on a regular basis (referred to in the above posts), and the other is whether it's wired up to make it possible at present.

The previous owner on my boat warned me not to have the electric hot water heater on by mistake as when he'd done it in the past it had sucked the batteries down so quickly he was in trouble (much smaller battery bank than yours, though). I have rewired my A/C and hot water heater so it comes off before the inverter gets involved, so now I cannot power the hot water heater from the inverter (it only does it with generator or mains power). I've chosen to do this so that I can't inadvertently run my batteries down by mistake, but it means I can't get hot water from the batteries now. But it doesn't sound to me as if this is the problem from what your electrician said.

[01kiwijohn]

Originally Posted by Mantas

Hello,

So I asked electrician in the boat yard (where I am refiting my first boat) can I run my Sigmar SM40 (220V - 800W) water heater from the Victron Phoenix 12/3000w inverter and he said no and that I need to add one more Victron inverter and connect them both. Can someone explain me why 800W heater cannot be run on 3000W inverter? thanks

Voltage is 220, AC. I think your electrician is telling you that you're not going to get enough amperage

[MikeTC]

After my 620ah agm bank is full (typically around mid day) I frequently use my 2000w cont inverter to heat shower water heater with 1200w element. Can't do this in NZ winter with 800w solar.

[yachtgemini]

a 12-volt hot water heater is s l o w and in a marina it will rely on the battery charger. It really is a good option if you spend a lot of time on the hook with surplus wind and solar... this is all about compromise.

However, there is also another option depending on where you cruise which is to use a hydronic (water heating) diesel heater from Espar etal and have a separate coil in the water tank. This is a great option if you are cruising higher latitudes and doing a major system upgrade.

Personally I would avoid loading up the inverter and batteries with a big resistive load like a water heater. Sure the inverter will do it and you may get lucky but it is increasing your risk of failure.

Depending on the age of your hotwater tank you may also want to consider getting a tank with fittings for 2 immersion heaters and swap one out for a 12 volt unit.

You could end up spending a lot of money in pursuit of that shower while 50 cent ear plugs may solve your noise problem.

[a64pilot]

Originally Posted by 01kiwijohn

Voltage is 220, AC. I think your electrician is telling you that you're not going to get enough amperage

Doesn’t matter, Watts, is Watts. Forget amperage.
He either didn’t understand, there is something we aren’t being told, or something.

800 W is a small water heater though, mine is 11.7 amps at 120 V so that makes it 1404 Watts.
I bet though it’s rated at 1500W though, 1400 is an odd number.

Only point is 800W for a water heater isn’t a large load.
It is however with inverter inefficiencies etc probably about 75 amps to the battery bank.
I assume at 800W it’s not a very big water heater?

Changing to a 12V heating element isn’t going to matter much, Watts are Watts, power is the same if you change voltage you just change amperage is all. Need much bigger cabling etc.
You would however not lose any inverter inefficiencies, which I’d guess are about 10%. So you would use 10% less of the battery bank, but as has been pointed out, what about when your on generator or plugged in? Then your pulling that 800W out of your charger, and unless you have a big one, it’s not enough, so then your cycling your bank cause the power comes from it and is replaced by the charger, but it’s still a cycle, and batteries only have so many.

[yachtgemini]

European dock power was traditionally very limited, often to 4 amps at 230 volts. Our heater has an 800 watt 230 volt element in a 60 litre tank (15 gallons).

He said his boat is European and I suspect the 800 watts is correct.

Ross

[Simi 60]

We run a 1.8kw Rheem 150 litre hot water system off of solar panels and inverter
Would love a smaller 800w 50 or even 30 litre model but have yet to find one that compares in price to a household model

[yachtgemini]

https://www.svb24.com/en/sigmar-mari....html#fullSize

zoom in 800 watts at 230 volts.

[Tin Tin]

The 3000 w inverter will run a 800 w water heater at say 70amp draw on batteries. Unless you wish to run other big loads at the same time eg micro wave (say 1500w) , electric kettle (1800 w) in which case you will need more inverter power for the brief time these things are running.

[Simi 60]

Originally Posted by yachtgemini

https://www.svb24.com/en/sigmar-mari....html#fullSize

zoom in 800 watts at 230 volts.

Yep, at least 4x more by the time I get it here than a household unit like this.


https://www.samedayhotwaterservice.c...-water-heater/

[Mike Banks]

I used on demand LP gas. When one turned on the hot water tap, the hot water system ignited and a couple of seconds later one had unlimited hot water as long as the water tanks were full and the gas bottles held some gas. The system is remarkably efficient.

I have also used direct solar--which costs nothing once set up and is for the most part silent, just a little pump to circulate the water through the collector and storage cylinder. If I had bulk solar electricity available as well as wind and impeller power I might well consider a switch operated from the house batteries charge controller to divert extra charging capacity into the hot water service once the batteries are fully charged. I have such a "Catch Power" switch on my own domestic solar service in my shore dwelling.

Once could also have some ability to retrieve heat from the engine and exhaust manifold cooling systems, especially if one uses keel cooling.

[SieveSailor]

Originally Posted by s/v Jedi

You should ask the electrician to explain why an 800W load can’t be powered from an 3,000W source.
Spoiler: of-course you can do that

What Jedi said. I can't imagine what a second inverter would solve in this case unless you have undersized wiring from battery to inverter, in which case rewiring would be for more cost effective. Maybe talk to another electrician.

[Simi 60]

Originally Posted by Mike Banks

Once could also have some ability to retrieve heat from the engine and exhaust manifold cooling systems, especially if one uses keel cooling.

Works well on day one getting to destination.
The next week sitting there taking in the scenery is the problem