Use caution – only a qualified technician should accomplish the following procedures. Electrical and LP gas safety issues are involved.
- Your 120 volt heating element will use 10 to 12 amps of power.
- Our recommended heating element will use 3 to 4 amps.
- Yes, your water heater will not heat up as fast, but you can use the LP gas heat at the same time as the electric.
- Remove the 120-volt, 1440-watt heating element and replace it with a 236-volt, 1440-watt element. This replacement will look just like your 120-volt element. Ace Hardware, True-Value Hardware, Lowe’s and Home Depot should be able to supply the element you wan for about $10.
- Check the condition of your anode, if you have one, flush the water heater tank while you are there. Magnesium anodes work better than zinc or aluminum. If 50% of your anode is gone, replace it. Atwood brand water heaters do not require an anode. Their tanks are porcelain lined.
If you are qualified:
- Disconnect the 120-volt power from the water heater; better yet unplug your rig from the pedestal. Your convertor will provide 12 volt DC power if not disabled.
- Turn of the LP gas at the tank.
- Disconnect the volt DC power – best done by disconnecting the wire(s) from the
negative post of the coach batteries. - Run water through the hot water faucet until the heater tank is cold.
Turn off the water to the rig at the pedestal. - Open the hot water faucets to release the pressure from the hot water tank. Do not
open the pressure relief valve to relieve the pressure. The seals in these valves have a
tendency to seep after they are tripped. Small particles in the water stays in the seal
and causes this seeping. - Carefully remove any gas lines or burner tubes found in the way of the heating
element. - Remove the cover, wiring and heating element. A lug wrench could be used to
remove the element if it is the right size. - Take this element with you to the store. Purchase the same size element but, but a
236/240 volt element, in the 1200 to 1500 watt range. You will be wiring up a 236-
volt element with the same wires you used to connect to the 120-volt element.
Do not over tighten the element, and only give the LP gas lines ¼ turn with a wrench
after hand tightening. - Close all faucets and turn on the water at the pedestal. Fill the tank with the faucets
closed, this will allow an air cushion to develop in your tank. Water expands as it
heats up and you need this space. - Check for water leaks, turn on the hot water faucets to make sure the tank is full.
Turn on the 120-volt power, connect the 12-volt power and open the LP gas valve at
the tank. Check for gas leaks with a non-ammonia soapy solution. - These water heaters reach a temperature of 140 degrees F, Be aware of this scald
hazard.
Every morning you will have a full tank of hot water, use your hot water only as needed.
Enjoy that extra power, you have given yourself 6 to 8 amps to use for other appliances.
Happy Camping
Fred Brandeberry
RV101BYFRED.COM
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GMAs
Now if you really want to save the propane and elect… and you have a motorhome… one needs to check into the vehicle engine… heating the water for you…
I have one on the PU that you can start the engine.. and it heats the water exchanger up… pump water in one side and hot water out the other… for a outdoor shower.. etc…
Not hard to make up using copper tubing fittings… but we also made one up that went in line with the MH hot water heater.. here we used a closed loop on the existing HW heater.. inlet/outlet with a restrictor… so that the hot water in the exchanger then side drafts the water in the hot water tank… (no pump needed) while going down the road then the engine water heats the hot water tank.. nice and warm.. about 160 deg… little less than the 195 thermostat on the enigne.. so we found…
No valving… and was easy to install.. as well as it helped keep the engine cool going down the roadway… we used to refer to it as the co-gen system of MH water heating…
One could do the same with a onboard generator.. by using the exhaust as a heat exchanger.. or if you hve one of the new water cooled gen sets… use the hot water from it too…
One could use some design work and probably make up something that would work with the ext gen’s also… thinking outside the box… but along the lines of co-gen systems… to increase effecency… when out back…
Just a idea to throw out while on the subject… I know some have tried the solar water heaters too… which seem to be a little light in the ability to heat water.. when you needed it in the cold climates…
GMAs
GMAs
Hey how come someone doesn’t have on the market a flash water heater like they do for houses now… tankless… would seem to me to be a better idea… effecency?
GMAs
No the dumbest was the guy who dipped rags in gas… stuffed ’em in the water heater flame tube and lit ’em to get hot water… Now that is dumb…
Actually at first glance it appears to be logical… use a doubble voltage element and save half the current… but when you do the math… it comes out to be not as expected… so to say dumb…. not necessar’ly so… I am sure a lot of people who are not physics minded might think that this is a good idea.
Tossing it out to the public is a great way to find out if the thing is going to fly or not… as their are some who are smart and some who are not so smart in the area of consern. Others just sit on the fence like old crows and repeat things like parrots… point to both sides as dumb and dumber.. when in fact they are the ones that never discuss why they think its dumb… to which then … smile…
Ideas are the foundation of developments …. good or bad…
GMAs
RJ Cole
This is one of the dumbest ideas I’ve seen posted anywhere.
Steve Seekins
Great idea IF your goal is to reduce your maximum amperage draw because of pedestal limitations, etc., but it will not save any electricity – still takes the same amount to heat the water and recovery time will be twice as long – hence to supplement with the propane as needed.
However, in your instructions, you neglected to note that you MUST test the propane connections after re-assembly – either with a suitable bubble solution or with an approved electronic combustable gas leak detector (Bacharach Leakator, Testo 316-1 or similar). Failure to do this can result in explosion or fire. Better yet, have it checked by a certified/licensed propane technician.
Steve
BPI Building Analyst/Envelope Specialist
GMAs
Ahhhh… I agree.. can you show me the figures where heating the same amount of water slower is going to be more effecent. Actually heating it with the higher amperage/power/ element is more effecent.. as it doesn’t have to run as long.. and you get the heater up to stable temp quicker.
About the only thing I can see is saving your energy is the IR loss of the wire using the higher amperage element. Heating the water slower… allows more loss over time throught the exposure of the tank as it has a loss rate too. If the loss rate is a dirivitive of the overall gain in heated water… then it will take more energy to heat the water over a longer periode of time. (why your water heater comes on by itself every so often… to maintain the temp is due to the exposure losses) If your using 2 or 3 amps… then they are going to be consumed contenious.. (actually going from the 12 amp 120volt element.. your going to consume 6 amps at 240 volt.. thus its not 2-3 amps but rather 6 amps+ at 120 volts too… E=I*R 120volts /12 amps = 10 ohms…. P= I*E thus P = 12*120= 1440… 1440/240 = 6 amps/2=3 amps contenious.. thus we get P=I*E 120*3 = 360 watts of heating power.. or 1229 btu input per hour.. instead of the regular element 4917 btu per hour…. The loss accroding to Attwood of the normal propane/electic water heater is aprox 350 btu per hour.. thus your net gain per hour using a lower current on the element is only 1229-350 or 879 btu per hour.. not much for hot water recovery…. (I will leave the math of rasing a gallon of water from 50 to 114 degrees to others… but graphing it out on the computer… is quite interesting… )
one gallon of water, which weighs approximately 8.34 pounds. So, you’d need 8.34 BTU to increase one gallon of water one degree F.
Note how the amount of time was not important. Whether you heat the water slowly or quickly doesn’t matter. You will still require 8.34 BTU to raise the temperature of a gallon of water one degree F.
As to using the propane at the same time… we have done that.. but the advantage of using the elect in the campground is to keep the propane useage down as well as the noise… These things are not made for effecency anyway… but rumble along when the blow torch is glowing…
I also doubt that you will find a attwood or surb water heater element at home depot or Ace hardware… last time I checked… special order from Camping world or one of the other suppliers..
Actually running your RV on 240 volt power is much better… if you have it wired for it.. and can easy convert over from the normal 120… We had ours wired for both with a flip of the switch… (no before you go saying.. what!!!) Indeed the 240 is broken down into 120 volt circuits within the trailer just like your house has…
But, ours is a special application… when we’re out.. and the number of times we have used the 240 side of things.. I can count on one hand… thus, its not cost effective to have your RV converted to work on both… Some AS had this as a option at one time… as EU runs on 240 volt only… In the US we standard on 120…
Don MacConnel
Running a 220 volt element on 110 volts reduces the power to 25% of the 220 volt wattage rating. Sure enough the current draw is reduced so extra amps are available for other purposes.
I really like the idea but it doesn’t save electricity, it just draws less current over a longer time. In this case four times longer and recovery time is four times longer. Total watt hours are the same.
Ernie Hadfield
Attwood heaters don’t require an anode rod because the tanks are aluminum. Suburban tanks are steel lined with “glass”, just like your water heater at home.
Darrel
Hi, I’m having dificulty understanding how using a smaller heating element will save you anything. It seems to me that it will just take twice as long to heat but will use the same amount of electricity. Please explain.