My 79 H33 has a raw water cooled Yanmar 2gm. Several years ago I took out the old 5 gallon 110v hot water heater and installed the Tiny Titan water heater shown. It works great. Only one problem.....no hot water underway. I have a 1000 watt inverter but the hot water heater element is about 1300 watts so the inverter kicks off with overload if I try to use it.... even with the engine and 55 amp alternator My question is: Can somebody suggest an easy way to reduce the resistance load of the hot water heater say by half bringing it within the capability of the installed inverter?
Reducing electric hot water power demand
- Thread starter Terry Arnold
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Can you replace the heating element
in the hot water heater with a lower wattage element? Is there another place to install a second element? If there is, running 2 1300 watt elements in series will cut your current draw in half. Likewise, replacing the existing 1300 watt 120 volt element with a 1300 watt 240 volt element will also cut the current in half. You can also wire your hot water heater to run on 12 volts DC, but the BTU output will be reduced bu a factor of 10.
in the hot water heater with a lower wattage element? Is there another place to install a second element? If there is, running 2 1300 watt elements in series will cut your current draw in half. Likewise, replacing the existing 1300 watt 120 volt element with a 1300 watt 240 volt element will also cut the current in half. You can also wire your hot water heater to run on 12 volts DC, but the BTU output will be reduced bu a factor of 10.
If you have a propane or CNG system...
...and you have the space, I'd go with a Paloma "On-Demand" water heater. I have one on my boat and NEVER run out of hot water and have hot water anytime I want; at the dock, on the mooring, underway. Not expensive, either. Cheers, Bob
...and you have the space, I'd go with a Paloma "On-Demand" water heater. I have one on my boat and NEVER run out of hot water and have hot water anytime I want; at the dock, on the mooring, underway. Not expensive, either. Cheers, Bob
replacement element
If the tank uses a standard appliance part element (likely but not for sure) they are readily available in 120v, 1000w, and are only $20 or so. 750 watt in some configurations. Or, as suggested, use a 240v element on 120 volt. Half the voltage, half the current, 1/4 the power. 3000w, 240v rated element would give 750w at 120v. (Takes almost twice as long to heat up the water as 1300w though.) It's likely to be longer so be sure it fits. Don't try 12 volts as that's 1/10 the voltage which would be 1/100 the power. You'll have a really long wait for hot water!
If the tank uses a standard appliance part element (likely but not for sure) they are readily available in 120v, 1000w, and are only $20 or so. 750 watt in some configurations. Or, as suggested, use a 240v element on 120 volt. Half the voltage, half the current, 1/4 the power. 3000w, 240v rated element would give 750w at 120v. (Takes almost twice as long to heat up the water as 1300w though.) It's likely to be longer so be sure it fits. Don't try 12 volts as that's 1/10 the voltage which would be 1/100 the power. You'll have a really long wait for hot water!
Actually
I don't think the heating element cares whether it is 12v or 120v..If it is a 1000 watt element, it is going to pull 83Amp from the battery(if wired in with heavy gauge wire) I think all this has to do with a "resistance load?" Brian
I don't think the heating element cares whether it is 12v or 120v..If it is a 1000 watt element, it is going to pull 83Amp from the battery(if wired in with heavy gauge wire) I think all this has to do with a "resistance load?" Brian
Electric water heating a bad ideal
Electric water heating is a bad idea for boats too small to carry a large generator. Your 1300 Watt heater will use roughly 108 Amps at 12 Volts, more like 115 Amps considering inverter losses. Even if you reduced the current demand to 50 Amps it would be a tremendous drain on your battery bank. With a 200 Amp hr battery bank you could only run it for 4 hours before the batteries were completely drained. A much better solution is the heat exchanger hot water heater. In these, hot engine-cooling water is run through a heat exchanger in the water heater tank. This produces hot water whenever the engine is running with virtually no extra load on the engine. They usually come with a 110 Volt electrical element as well so that you can have hot water when the engine is running and unlimited hot water at the dock when connected to the 110 Volt and water supplies. I am sceptical of the safety of the propane powered instant hot water heaters. There was one on my boat when I bought it and I have removed it. If you really must keep your current heater, why not just get a larger inverter? Changing from a 1300 watt 120 Volt element to a 1300 Watt, 240 Volt element run at 120 Volts will cut the heating power of the element by a factor of four, not 2. A 2000 Watt 240 Volt element will put out 500 watts of heating power at 120 volts but still will draw around 45 amps from your 12 Volt batteries.
Electric water heating is a bad idea for boats too small to carry a large generator. Your 1300 Watt heater will use roughly 108 Amps at 12 Volts, more like 115 Amps considering inverter losses. Even if you reduced the current demand to 50 Amps it would be a tremendous drain on your battery bank. With a 200 Amp hr battery bank you could only run it for 4 hours before the batteries were completely drained. A much better solution is the heat exchanger hot water heater. In these, hot engine-cooling water is run through a heat exchanger in the water heater tank. This produces hot water whenever the engine is running with virtually no extra load on the engine. They usually come with a 110 Volt electrical element as well so that you can have hot water when the engine is running and unlimited hot water at the dock when connected to the 110 Volt and water supplies. I am sceptical of the safety of the propane powered instant hot water heaters. There was one on my boat when I bought it and I have removed it. If you really must keep your current heater, why not just get a larger inverter? Changing from a 1300 watt 120 Volt element to a 1300 Watt, 240 Volt element run at 120 Volts will cut the heating power of the element by a factor of four, not 2. A 2000 Watt 240 Volt element will put out 500 watts of heating power at 120 volts but still will draw around 45 amps from your 12 Volt batteries.
Garry...
I don't understand your skepticism with regard to propane/CNG fired demand water heaters. These have been enjoyed by boaters around the world for many years. They're safe, easily maintained, and pose no more of a danger than your stove/oven. I own a Nonsuch 30 and it still has the original 24 year old Paloma water heater in it. It is happily working away providing me an endless supply of hot water. As a matter of fact, Hinterhoeller Yachts used these water heaters or similar ones exclusively throughout production. Like any other piece of equipment, if you don't maintain it, it is susceptible to fail. However, the components are fail-safe. If the pilot or flame goes out the gas shuts off. Annual maintenance takes all of about twenty minutes. By following the NFPA and ABYC rules and reg for propane/CNG systems installation, you should not have any problems at all. I would urge all boaters to look at these units and learn more about this alternative source of hot water. No electricity, no electrical circuit to run, no breaker to install, no plugging in to shore power, no running the engine for a paltry five-gallons of warm water (heat exchangers do not work effectively unless the engine is under a load). By the way, Garry...if you still have your propane water heater, I would be interested in taking it off your hands if you're not going to use it. Cheers, Bob
I don't understand your skepticism with regard to propane/CNG fired demand water heaters. These have been enjoyed by boaters around the world for many years. They're safe, easily maintained, and pose no more of a danger than your stove/oven. I own a Nonsuch 30 and it still has the original 24 year old Paloma water heater in it. It is happily working away providing me an endless supply of hot water. As a matter of fact, Hinterhoeller Yachts used these water heaters or similar ones exclusively throughout production. Like any other piece of equipment, if you don't maintain it, it is susceptible to fail. However, the components are fail-safe. If the pilot or flame goes out the gas shuts off. Annual maintenance takes all of about twenty minutes. By following the NFPA and ABYC rules and reg for propane/CNG systems installation, you should not have any problems at all. I would urge all boaters to look at these units and learn more about this alternative source of hot water. No electricity, no electrical circuit to run, no breaker to install, no plugging in to shore power, no running the engine for a paltry five-gallons of warm water (heat exchangers do not work effectively unless the engine is under a load). By the way, Garry...if you still have your propane water heater, I would be interested in taking it off your hands if you're not going to use it. Cheers, Bob
Coleman water heater - 2300-700
Terry - do you need hot water like at home or will camping style work for you? Coleman has an OUTDOOR on demand hot water heater that runs off LP cylinders and is quite inexpensive as far as hot water heaters go. Depending on how you use your hot water maybe something like this would work? Anyway, it's something to think about. http://www.coleman.com/coleman/colemancom/detail.asp?product_id=2300-700&categoryid=2200 http://www.heatershop.com/coleman_hot_water_heater_2300_700.html
Terry - do you need hot water like at home or will camping style work for you? Coleman has an OUTDOOR on demand hot water heater that runs off LP cylinders and is quite inexpensive as far as hot water heaters go. Depending on how you use your hot water maybe something like this would work? Anyway, it's something to think about. http://www.coleman.com/coleman/colemancom/detail.asp?product_id=2300-700&categoryid=2200 http://www.heatershop.com/coleman_hot_water_heater_2300_700.html
12 volt water heating
Thanks for the thoughtful replies. A 240 volt element as Reudi first suggested would seem to be the easiest....but the Tiny Titan doesn't take standard water heater elements...though there may very well be a 240 volt element for it somewhere since the mfg is Italian. Any suggestions for locating one? So far I just can't find it. I agree with Gary that electric water heating is not normally a good idea, but a raw water cooled engine like mine can't use the heat exchanger hot water system. Propane heater sounds good but I don't have propane on the boat already and am resisting any further systems. same with John's camp hot water heater. I am thinking about wiring one of the plugs in the duplex receptacle that the Tiny Titan plugs into as 12 volts and just basically leaving it on all the time under way, hoping that at least the 12-15w of power will temper an otherwise cold shower since the Tiny Titan is well insulated. I don't mind heating water on the stove for dishwashing and drinking. Thanks again.
Thanks for the thoughtful replies. A 240 volt element as Reudi first suggested would seem to be the easiest....but the Tiny Titan doesn't take standard water heater elements...though there may very well be a 240 volt element for it somewhere since the mfg is Italian. Any suggestions for locating one? So far I just can't find it. I agree with Gary that electric water heating is not normally a good idea, but a raw water cooled engine like mine can't use the heat exchanger hot water system. Propane heater sounds good but I don't have propane on the boat already and am resisting any further systems. same with John's camp hot water heater. I am thinking about wiring one of the plugs in the duplex receptacle that the Tiny Titan plugs into as 12 volts and just basically leaving it on all the time under way, hoping that at least the 12-15w of power will temper an otherwise cold shower since the Tiny Titan is well insulated. I don't mind heating water on the stove for dishwashing and drinking. Thanks again.
12V Elect H.W. Heaters
Operating a 120V Electric Heater on 12V will produce about 1% the nameplate wattage, and won’t provide any appreciable water heating in any practical length of time. Electric Water Heaters are a fixed* resistance device. This means that the wattage achieved is a direct result of voltage applied (W = V 2 ÷ R). If the voltage varies, the heater wattage will vary by a squared relationship of the voltage (ie: 12/120 x 12/120 = 0.1 x 0.1 = 0.01). Hence, a 1000 Watt 120 Volt heater, (R = E2 ÷ W = 120 x 120 ÷ 1000 = 14.4 Ohms) operated on 12V, would produce the equivalent of about a 10 Watt Heater (W = 12 x 12 ÷ 14.4 = 10 Watts). *Resistance heaters (and incandescent lamps) actually change resistance (increasing) as they heat up. The hot/cold resistance ratio varies with element construction, but can be as much as 20:1. This is why your Ohmmeter won’t measure 14.4 Ohms on the above example. There are 12V Water Heaters, but they require very large Amperages to operate. I’d recommend sonething like Hotwire's 12V/120V combo’ element - One loop is 12V at 300W; the other loop is 120V at 500W. This unit allows you to have Electrically Heated Hot Water at dockside (120VAC Shorepower) or “out there” on 12VDC Power. It requires about 25Amps at 12V, so you’ll probably only use it with the engine/alternator running. http://www.svhotwire.com/divert_loads.html These water heater elements fit a standard 1" NPT fitting. The 12/24V model has a pair of 25A/12V elements. Can be wired for 25 or 50 amps at 12V (300 - 600 Watts), or in series for 25 amps at 24V ($90) http://www.gaiam.com/retail/product.asp?product_id=25078 1600W (67 Amp) Water Heating Element 12/24V ($157) http://www.4lots.com/index.asp?PageAction=VIEWPROD&ProdID=823 BTW: The “Tiny Titan” doesn’t appear to be particularly suitable for marine installations. Neither do I find any heating elements other than the standard 1300W 120V supplied. http://www.americanwaterheater.com/support/manuals/tiny-titan.pdf HTH & Regards, Gord
Operating a 120V Electric Heater on 12V will produce about 1% the nameplate wattage, and won’t provide any appreciable water heating in any practical length of time. Electric Water Heaters are a fixed* resistance device. This means that the wattage achieved is a direct result of voltage applied (W = V 2 ÷ R). If the voltage varies, the heater wattage will vary by a squared relationship of the voltage (ie: 12/120 x 12/120 = 0.1 x 0.1 = 0.01). Hence, a 1000 Watt 120 Volt heater, (R = E2 ÷ W = 120 x 120 ÷ 1000 = 14.4 Ohms) operated on 12V, would produce the equivalent of about a 10 Watt Heater (W = 12 x 12 ÷ 14.4 = 10 Watts). *Resistance heaters (and incandescent lamps) actually change resistance (increasing) as they heat up. The hot/cold resistance ratio varies with element construction, but can be as much as 20:1. This is why your Ohmmeter won’t measure 14.4 Ohms on the above example. There are 12V Water Heaters, but they require very large Amperages to operate. I’d recommend sonething like Hotwire's 12V/120V combo’ element - One loop is 12V at 300W; the other loop is 120V at 500W. This unit allows you to have Electrically Heated Hot Water at dockside (120VAC Shorepower) or “out there” on 12VDC Power. It requires about 25Amps at 12V, so you’ll probably only use it with the engine/alternator running. http://www.svhotwire.com/divert_loads.html These water heater elements fit a standard 1" NPT fitting. The 12/24V model has a pair of 25A/12V elements. Can be wired for 25 or 50 amps at 12V (300 - 600 Watts), or in series for 25 amps at 24V ($90) http://www.gaiam.com/retail/product.asp?product_id=25078 1600W (67 Amp) Water Heating Element 12/24V ($157) http://www.4lots.com/index.asp?PageAction=VIEWPROD&ProdID=823 BTW: The “Tiny Titan” doesn’t appear to be particularly suitable for marine installations. Neither do I find any heating elements other than the standard 1300W 120V supplied. http://www.americanwaterheater.com/support/manuals/tiny-titan.pdf HTH & Regards, Gord
Gord,
You DO plan to live a LONG time DON'T you!!!? And you DO plan to spend it all HERE, don't you!?
You DO plan to live a LONG time DON'T you!!!? And you DO plan to spend it all HERE, don't you!?
Why not...
...run your engine and click on the inverter? I'm sure someone could do the math for me, but with 30 amps going out of even a stock alternator, and more from a newer, regulated alternator, running the engine for the 15 minutes the electric part of the heater needs to warm up the water shouldn't knock too much off the house bank. And, I personally believe that for normal use (unless you're plugged in all the time - say each night) a house bank should be 400 amp hours anyway, so you're not taking too much out, and can continue to run the engine to put more back in. It's nice to have hot water in the morning, since we like morning showers, but we've learned to adapt to showering when HW is available. Some people like to shower at night. Heck, some probably not at all, but then this wouldn't be a thread of interest to them, would it? "Good Old Boat" magazine, a few issues ago, had some other good shower ideas: the usual pump spray and H20 Sunshowers, where you add some hot water from the stove. Also works, too. Help me with the math, Gord and Fred.
Stu
...run your engine and click on the inverter? I'm sure someone could do the math for me, but with 30 amps going out of even a stock alternator, and more from a newer, regulated alternator, running the engine for the 15 minutes the electric part of the heater needs to warm up the water shouldn't knock too much off the house bank. And, I personally believe that for normal use (unless you're plugged in all the time - say each night) a house bank should be 400 amp hours anyway, so you're not taking too much out, and can continue to run the engine to put more back in. It's nice to have hot water in the morning, since we like morning showers, but we've learned to adapt to showering when HW is available. Some people like to shower at night. Heck, some probably not at all, but then this wouldn't be a thread of interest to them, would it? "Good Old Boat" magazine, a few issues ago, had some other good shower ideas: the usual pump spray and H20 Sunshowers, where you add some hot water from the stove. Also works, too. Help me with the math, Gord and Fred.
StuFor Bob Todd
I just don't trust them and its gone to the dump already. Enjoy yours but I recommend you install a sniffer in the head.
I just don't trust them and its gone to the dump already. Enjoy yours but I recommend you install a sniffer in the head.
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