Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 18-02-2015, 00:16   #1
Registered User

Join Date: Oct 2012
Location: Currently Tasmania after Pacific crossing
Boat: Catalina 42
Posts: 217
Run water heater from inverter?

I have a Prosine 2000 inverter putting out 120v. The water heater is 120v but is only set up to run from shore power. The common bus bar is shortened so as not to include the water heater and battery charger.

Surely, it's within the capacity of the Prosine to run the water heater?

I have an 850 ah battery bank and 600w solar.



Sent from my iPad using Cruisers Sailing Forum
__________________

__________________
Amnesia II is offline   Reply With Quote
Old 18-02-2015, 00:41   #2
Registered User
 
Rustic Charm's Avatar

Join Date: Jun 2011
Location: Tasmania, Australia
Boat: Bieroc 36 foot Ketch
Posts: 4,898
Re: Run water heater from inverter?

Quote:
Originally Posted by Amnesia II View Post
I have a Prosine 2000 inverter putting out 120v. The water heater is 120v but is only set up to run from shore power. The common bus bar is shortened so as not to include the water heater and battery charger.

Surely, it's within the capacity of the Prosine to run the water heater?

I have an 850 ah battery bank and 600w solar.

Sent from my iPad using Cruisers Sailing Forum
Gee, I would think you will drain your bank quick smart doing that.
__________________

__________________
Rustic Charm is offline   Reply With Quote
Old 18-02-2015, 01:01   #3
Marine Service Provider

Join Date: Oct 2011
Posts: 1,205
Re: Run water heater from inverter?

Shirley,

it's with-in the inverter capacity.

butt,

is it with in the battery capacity?

YEP.

but is it with-in the charge capacity?

DOUBT it!

Lloyd

Quote:
Originally Posted by Amnesia II View Post
I have a Prosine 2000 inverter putting out 120v. The water heater is 120v but is only set up to run from shore power. The common bus bar is shortened so as not to include the water heater and battery charger.

Surely, it's within the capacity of the Prosine to run the water heater?

I have an 850 ah battery bank and 600w solar.



Sent from my iPad using Cruisers Sailing Forum
__________________
FlyingCloud1937 is offline   Reply With Quote
Old 18-02-2015, 01:04   #4
Registered User

Join Date: Jan 2009
Location: Home port is San Diego, California but currently cruising the East Coast of the USA.
Boat: Contest 48
Posts: 638
Images: 1
Re: Run water heater from inverter?

We have a 20-liter water heater with an 850-watt, 120-volt element and we run it off our inverter all the time. We don't leave the inverter on any longer than it takes to heat a tankful of water - about 20 minutes - and we curse ourselves if we forget and leave it on longer. That might draw about 25 amps out of a 12-volt battery bank but that doesn't seem too unreasonable to us.

Fair winds and calm seas.
__________________
nhschneider is offline   Reply With Quote
Old 18-02-2015, 01:21   #5
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,751
Re: Run water heater from inverter?

We have a 1500 watt immersion heater and (nominally) 3000 watt inverter. My school bus type alternator puts out about 2000 watts at cruising speed (while motoring, obviously).

I have used my inverter to power the immersion heater when the engine coolant loop was not working (air lock). Immersion heaters are pure resistant loads and no problem as long as they are within the capacity of the inverter and the alternator powering it.

I don't think it's a very good idea, however, to do this on a regular basis, especially if you have a car-type alternator, which is not made to power big loads on a continuous basis. It's much more efficient to heat the calorifier using waste heat from the engine.

I wouldn't run the immersion heater from batteries. Our fairly large battery bank contains about 3 to 4 kW/h of usable power. Heating up a tank of hot water requires at least 1 kW/h of power and would need more than the 1/3 to 1/4 of the bank's capacity implied by this, because of Peukert's factor. Why would you spend so much (if not all) of your battery power doing this? You would just need to charge again anyway. Maybe only if you want a shower just before you start motoring somewhere, but even in this situation, you are putting wear and tear on the batteries by cycling them hard like that. I just wouldn't do that. Maybe if you have just really abundant solar power.
__________________
Dockhead is offline   Reply With Quote
Old 18-02-2015, 06:52   #6
Registered User

Join Date: Oct 2012
Location: Currently Tasmania after Pacific crossing
Boat: Catalina 42
Posts: 217
Re: Run water heater from inverter?

Thankyou all. I should mention I also have a 180amp alt, so it may well be reasonable to run the motor for 1/2 hr with the alt supporting the batteries and inverter.


Sent from my iPad using Cruisers Sailing Forum
__________________
Amnesia II is offline   Reply With Quote
Old 18-02-2015, 06:58   #7
cruiser

Join Date: Feb 2008
Location: North Charleston, SC
Boat: Camano Troll
Posts: 4,669
Re: Run water heater from inverter?

Quote:
Originally Posted by Amnesia II View Post
I have a Prosine 2000 inverter putting out 120v. The water heater is 120v but is only set up to run from shore power. The common bus bar is shortened so as not to include the water heater and battery charger.

Surely, it's within the capacity of the Prosine to run the water heater?

I have an 850 ah battery bank and 600w solar.



Sent from my iPad using Cruisers Sailing Forum
Yep the battery bank and inverter could run the water heater for a few minutes. Possibly not long enough to get the water hot though.

If you are thinking of running the engine to produce electricity to charge the batteries to power the inverter to make 120 volts AC to run the water heater, why not just connect the water heater to the engine to use waste heat to heat the water? If the water heater doesn't have a built in heat exchanger (most marine water heaters do), consider replacing the water heater with one that can does.
__________________
rwidman is offline   Reply With Quote
Old 18-02-2015, 07:12   #8
Registered User

Join Date: Oct 2010
Location: Abaco, Bahamas/ Western NC
Boat: Nothing large at the moment
Posts: 820
Re: Run water heater from inverter?

Does not sound like a good idea to me. Why not buy one of the solar adapters that screw into the drain location and plumb that into your engine cooling line?
__________________
Tingum is offline   Reply With Quote
Old 18-02-2015, 10:52   #9
Registered User

Join Date: Jan 2010
Location: St Michaels, MD
Boat: Cal 46-3, 46' ketch
Posts: 190
Re: Run water heater from inverter?

In big round numbers... any load drawing around 1000w at 120v will draw 100 AMPS from your 12v battery bank on inverter power. Any 1500w load at 120v will draw about 125 AMPS from 12v while being powered from inverter, regardless of brand. That's just how ohms law works.

So if your water heat takes half an hour to come up to temp... your have pulled half those figures in 'watt-hours' from your battery. So if you had a fully charged single 100 A-hr battery you would be down to its recommended 'not to exceed' 50% capacity limit. If you had engine running and alternator putting in 30a or solar putting in 30A... just subtract the 30a from the load of 100a (or 125a) and redo the watt-hour math to figure watt- hour load on the battery.

You have to do what you have to do, but batteries only have so many discharge/ charge cycles. Using them up to heat water is the ultimate tough duty on them and their life expectancy. But again... you got to do what you got to do! If you ever change out the water heater, strongly suggest you replace with one that also supports heating via engine's wasted heat cooling system. Then while you are charging batteries/ moving to next anchorage you are automatically generating two days worth of normal hot water use. That's how most of us do it.


Sent from my iPhone using Cruisers Sailing Forum
__________________
W3GAC is offline   Reply With Quote
Old 18-02-2015, 11:21   #10
Registered User
 
cwyckham's Avatar

Join Date: Apr 2011
Location: Vancouver, BC
Boat: Niagara 35
Posts: 1,870
Re: Run water heater from inverter?

Quote:
Originally Posted by W3GAC View Post
... strongly suggest you replace with one that also supports heating via engine's wasted heat cooling system. Then while you are charging batteries/ moving to next anchorage you are automatically generating two days worth of normal hot water use. That's how most of us do it.


Sent from my iPhone using Cruisers Sailing Forum
Wow. You can keep your hot water hot (or warm) for more than a few hours? I think I need to find a way to insulate my tank better!

Oddly, that never occurred to me.
__________________
cwyckham is offline   Reply With Quote
Old 18-02-2015, 12:53   #11
Registered User

Join Date: Jan 2010
Location: St Michaels, MD
Boat: Cal 46-3, 46' ketch
Posts: 190
Re: Run water heater from inverter?

Yes. I just have a standard 5 gal Ratian w/o any extra insulation. We practice the Navy shower technique of low water sink & shower use. The engine has a 180 degree thermostat so the hot water is frightfully hot compared to home settings and only takes a crack of the hot valve to get normal temp shower/ KP water. And actually wrapping the hot water tank would likely extend the shelflife of the hot water perhaps to 3 and maybe even still usable to a 4th day if not diluted much by usage. Good idea I'll try it myself.

For washing dishes I put a little Dawn in about half cup of very hot water and use one of those brushes designed for dish washing (9" handle. Dawn seems to do a much better job cutting grease than the other dishwashing products we tried, even with cold water. Once all the stuff has been brushed off and temporarily stacked (still soapy) I use just a trickle of water to rinse the items one by one. You can clean up after a meal for four with 1/2 to 3/4 gal of water and practically no hot water. In the Caribbean we did that final cold water rinse over a pot to capture that soapy water to use again on mask/ snorkel... what ever else only needed cooler soapy water to work.


Sent from my iPhone using Cruisers Sailing Forum
__________________
W3GAC is offline   Reply With Quote
Old 18-02-2015, 13:10   #12
cruiser

Join Date: Feb 2008
Location: North Charleston, SC
Boat: Camano Troll
Posts: 4,669
Re: Run water heater from inverter?

Quote:
Originally Posted by cwyckham View Post
Wow. You can keep your hot water hot (or warm) for more than a few hours? I think I need to find a way to insulate my tank better!

Oddly, that never occurred to me.
My water is still hot the next morning after sitting 15 hours or more. I don't remember the brand of heater but it's whatever came on the boat, nothing special.

Like W3GAC's heater my water comes out the same temperature as the engine coolant so that can be 175 degrees or so. There should be a tempering valve but there isn't. We just know hot it is and use it accordingly.
__________________
rwidman is offline   Reply With Quote
Old 18-02-2015, 13:57   #13
Senior Cruiser

Cruisers Forum Supporter

Join Date: May 2013
Location: Oregon to Alaska
Boat: Wheeler Shipyard 83' ex USCG
Posts: 1,708
Re: Run water heater from inverter?

I have a power boat with room. It has a 50 gallon hot water heater and incinolet toilets. The inverter easily runs the heater (3500 watts) and toilets. I optionally can heat water with a diesel stove coil or the generators. The heater has additional added insulation so the hot water will last several days if not used. I have a galley switch so I can turn the heater on in anticipation of need. The inverter setup provides 2 legs of 120v or 240v ac from a 48v dc bank. Prior inverter was 12v based. Having 24v or 48v also means smaller cables, etc. Everything runs thru the inverter. On shore power the ac passes thru the inverter and charges the dc banks.
My batteries allow the use of ac for refrigerator, freezer, tv, lights and computer, for several days if not heating water. Also, when steaming I use the inverter for ac needs while a alternator keeps the batteries up. So I save running a generator.
I have been on the ocean a long time and know plumbing, electricity and so on. My boat is 73 years old, professionally converted from a USCG cutter to a Monk design. This is not a super yacht and I am not rich or even well off and rarely meet a boater with less money to spend. An inverter like mine is about $2500 and some changes to battery bank cables.
Also, at dockside, shutting off a house sized hot water when not being used saves about $30/month on 0.068/kwh power.
__________________
Lepke is offline   Reply With Quote
Old 18-02-2015, 14:09   #14
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 7,458
Images: 69
Re: Run water heater from inverter?

Quote:
Originally Posted by Amnesia II View Post
I have a Prosine 2000 inverter putting out 120v. The water heater is 120v but is only set up to run from shore power. The common bus bar is shortened so as not to include the water heater and battery charger.

Surely, it's within the capacity of the Prosine to run the water heater?

I have an 850 ah battery bank and 600w solar.



Sent from my iPad using Cruisers Sailing Forum
Depends on the Wattage of the water heating element. Ours is 850 Watts and can be run off the 1500 Watt inverter.

It does take a lot out of the batteries though, I've only ever done it a few times, usually when motoring on a sunny day, and we have more power than we know what to do with.
__________________
44'cruisingcat is offline   Reply With Quote
Old 19-02-2015, 07:37   #15
Marine Service Provider
 
AnchorageGuy's Avatar

Join Date: Mar 2003
Location: Wherever the boat is!
Boat: Marine Trader 34DC
Posts: 4,618
Re: Run water heater from inverter?

We've been cruising for 25 years and we have to have hot showers every day. Our 2500 watt inverter easily runs our hot water heater. It only takes about 15 minutes to get the water hot enough for a comfortable shower for both of us and enough for dishes. The key is to run no longer than necessary. So we don't forget, we use a kitchen timer when we turn on the water heater. Consider changing out the water heater to one that will heat off the engine coolant. We have always had this type and it saves time running off the inverter. Your battery bank is plenty sufficient. I'm sure you probably have a battery monitor to watch your power usage. Taking showers during the day when you have assist from the solar panels will also help. I see no problem at all with your set up. Chuck
__________________

__________________
Chesapeake Bay, ICW Hampton Roads To Key West, The Gulf Coast, The Bahamas

The Trawler Beach House
Voyages Of Sea Trek
AnchorageGuy is offline   Reply With Quote
Reply

Tags
inverter, water

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Isotherm Freezer - Run, Stop, Run, Stop... Cruisin Cat Electrical: Batteries, Generators & Solar 8 24-04-2014 19:06
Hot Water Heater / Block Heater? - 3GM30 BareProductions Engines and Propulsion Systems 9 23-02-2013 19:12
Run water heater via inverter? Bash Electrical: Batteries, Generators & Solar 27 10-01-2013 08:41
Will Yamaha EF2000iS inverter/generator run a Nespresso coffee machine? timj Electrical: Batteries, Generators & Solar 3 07-05-2012 17:27
Gas Water Heater or Combined Calorifier / Immersion Heater ? simonmd Plumbing Systems and Fixtures 5 30-12-2010 08:50



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 20:20.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.