Hot water heater through an inverter?

[bcboomer]

[QUOTE=Boatwright;3450852]"What do you guys think?"


For example: A 1,500 watt resistance element (the smallest size available) will draw about 140 amps @ 12v when run through your inverter @ 90% efficiency. If you don't know volts from amps, that is a large! current.

Nah, Isotemp Spa heaters use 750 watt/115v elements.
That's less than 60 amps when my batteries are topped up. My 15 litre tank takes 1/2 hr to heat up, so say 30 amp/hr a day.
Who needs continuous hot water?

[Cheechako]

Originally Posted by Sailing_Pasha

I have a 2014 Oceanis 41 and it has a (factory installed) hot water heater which gets the power from the engine at the moment.

The person who will install our new inverter says it's not a smart idea to put the hot water heater through the inverter and keep it as it is which means we'll have hot water only when we run the engine or through shore power.

What do you guys think?

That's how my boat was set up (Engine and shore power) and I was fine with it. I would never try to run a hot water heater off the batteries through an invertor.

[Pete7]

There is another solution and that's diesel water heating like the Webasto Thermo Top range. This will also give you hot water for radiators if you were to sail somewhere cold for part of the year.

Pete

[LoudMusic]

We need a lot more information about your boat.

I run my water heater via my inverter. My water heater is a measly 900w water heater. My inverter is 3000w. My battery bank is 1200Ah 12v lithium (~14,000wh). I have 2100w of solar. Running the water heater from my inverter is no problem, but we had that in mind when we built the system. I'd like to replace it with a 1500w heating element.

The water heater also has a coolant loop from one of my engines (catamaran, two main engines). This is obviously the preferred way to heat the water if we intend to be motoring anyway.

[mitiempo]

[QUOTE=bcboomer;3450902]

Originally Posted by Boatwright

"What do you guys think?"


For example: A 1,500 watt resistance element (the smallest size available) will draw about 140 amps @ 12v when run through your inverter @ 90% efficiency. If you don't know volts from amps, that is a large! current.

Nah, Isotemp Spa heaters use 750 watt/115v elements.
That's less than 60 amps when my batteries are topped up. My 15 litre tank takes 1/2 hr to heat up, so say 30 amp/hr a day.
Who needs continuous hot water?

And Johnson Pump's AquaH water heaters are available with 500 watt elements. This link shows 230 volt versions but 120 volt is sold in North America.

https://www.spxflow.com/johnson-pump...water-heaters/

[Capt. Ray]

Why would people want a hot water heater? Personally I find a cold water heater more useful.

[Pete7]

Originally Posted by Capt. Ray

Why would people want a hot water heater? Personally I find a cold water heater more useful.

Well, some of us live 50' North and a shower or even washing up in winter is kinda tough. It's a bit like asking why does everyone ask about AC in Mx or Florida, surely they live there because they like the warmth

[Franziska]

Originally Posted by Pete7

Well, some of us live 50' North and a shower or even washing up in winter is kinda tough. It's a bit like asking why does everyone ask about AC in Mx or Florida, surely they live their because they like the warmth

I think he is referring to the fact that the heater warms up cold water to become hot water. :-)

[Capt. Ray]

Originally Posted by Pete7

Well, some of us live 50' North and a shower or even washing up in winter is kinda tough. It's a bit like asking why does everyone ask about AC in Mx or Florida, surely they live there because they like the warmth

WHOOSH!

[Pete7]

Originally Posted by Capt. Ray

WHOOSH!

In my defence it's Sunday morning and I haven't had a second cup of tea yet

[Toys_with_time]

Originally Posted by Sailing_Pasha

I have a 2014 Oceanis 41 and it has a (factory installed) hot water heater which gets the power from the engine at the moment.

The person who will install our new inverter says it's not a smart idea to put the hot water heater through the inverter and keep it as it is which means we'll have hot water only when we run the engine or through shore power.

What do you guys think?

Like others I can use surplus solar energy to pump into my water heater via the inverter but I also have a solar water heater and on a warm to hot day that can produce more hot water than I need. Not expensive to build, very simple and zero running costs. For some water heaters it is also possible to get a dual 12v / 240v (or 110v) element
TwT

[Cadence]

[QUOTE=mitiempo;3451071]

Originally Posted by bcboomer

And Johnson Pump's AquaH water heaters are available with 500 watt elements. This link shows 230 volt versions but 120 volt is sold in North America.

https://www.spxflow.com/johnson-pump...water-heaters/

But it still take the same amount of energy/watts/BTUs to heat or maintain the temp.. It may be more with a lower wattage element Recovery would be slow.
I had, years ago, an on demand 120V unit with not more than a pint reservoir and it worked great. I can't find them today?

[CatNewBee]

Totally feasible, we run our water heater (220V / 1200W) off the inverter. it is resistive load, a 2kVA inverter (1600W) can handle it easily. It is about 100A draw on a 12V battery, with LFP batteries an easy task. 30minutes gives you 60°C hot water for 50Ah, you can get it to 95°C in an hour if you want to, spending 100Ah. Not sure if we have a 40 or 60l boiler from Quick.

With a big 2kW solar array, you can almost run it straight from solar.

[Sierra]

When I upgraded my solar I had a timer installed that closed a contacter to heat the water when not on shore power. I set the timer to 1 hour so I did not need to remember to turn it off. As some have suggested above I wait until the batteries are close to full (gone over to absorption) then turn it on the solar starts working hard again. I have a 3000w inverter and it handles the load, about 70 amps easily.

[mitiempo]

There is a 12 volt water heater from Whale that uses 25 amps DC. 3 gallon size.
https://www.whalepumps.com/marine/pr...-Electric-Only