Changing to a 230 volt water heater

[Hikerdogs]

According to the Atwood spec sheet the rate of recovery when using electric only is 6.2 gallons per hour. When using gas its 13.5 gallons per hour. When using both gas and electric it's 17.8 gallons per hour.

http://www.atwoodmobile.com/images/waterheater.pdf

Even if you double the recovery rate when using 240 volts it's still far less than when using the gas and electric option. The most economical and easiest option would be to use the gas/electric option currently available.

[stik]

Originally Posted by Hikerdogs

According to the Atwood spec sheet the rate of recovery when using electric only is 6.2 gallons per hour. When using gas its 13.5 gallons per hour. When using both gas and electric it's 17.8 gallons per hour.

http://www.atwoodmobile.com/images/waterheater.pdf

Even if you double the recovery rate when using 240 volts it's still far less than when using the gas and electric option. The most economical and easiest option would be to use the gas/electric option currently available.

Thanks be to Hikerdogs for the common sense solution

[ShapeShifter]

Originally Posted by Old Scout

Careful--alot of campgrounds dont have true 240v [phased] hook-ups--not sure what that does to neutral lines, load lines, etc.

I would hope that in reality it's "only a few" campgrounds and not "most" that have illegal cheater wiring as you mention. The idea of having a proper 120/240 volt split phase service is that the neutral line balances the loads between the two hot lines, and only sees the difference in the current between the two hot lines. With 50 amp protection, that means that the most current the neutral can ever see is 50 amps (when one line is drawing 50 amps and the other is drawing nothing.) If both lines are drawing the full 50 amps, the neutral will actually have no current flowing in it.

With the cheater service you mention, where the two hot legs are from the same feed, then the neutral wire will carry the sum of the current in the two hot legs, not the difference. That means with a fully loaded line drawing 50 amps on both hot leads, the neutral will be carrying 100 amps, which would be a serious overload. That's why the cheater service you mention is illegal.

Theoretically, there is no danger hooking up a 240 volt heater element: if one were to be plugged into a cheater service as you describe, the heater would be seeing zero volts, and simply won't work. But things often don't follow theory: "In theory, there is no difference between theory and practice. In practice, there is."

The danger comes in with the non-standard wiring: can it be done in a way that is safe? Remember, just because something works, does not mean that it's safe, and will work safely in all conditions. I'm not sure what the codes have to say about the proposed arrangement, but whatever is done should be done legally and according to code. For example, the current to the heater is controlled by a relay, one which I assume is single pole. Generally, codes call that both hot lines to a 240 volt load should be switched, which means replacing the relay with a double pole relay. I'm sure there are many more potential issues that should be considered, most of which are likely not obvious.

Then there is the issue if the heater itself and the controls can handle the extra power dissipation of the larger element. It would probably be prudent to run these changes by the water heater manufacturer, and I would be surprised if they officially condone it. I would also run all changes past a licensed electrician and/or local building inspector -- both for your own safety, the safety of a future technician working on the heater, and the safety of future owners.

If you haven't guessed, I don't think it's a good idea.

[CampDaven]

Never seen a 240V outlet on a camp pedestal. Only 110
When running electricity and gas, we don't run out of hot water.

[ShapeShifter]

Originally Posted by CampDaven

Never seen a 240V outlet on a camp pedestal. Only 110

You've never been to a park that has 50 amp sockets? You must go to a very limited range of parks if they've only ever had 30 or 20 amp sockets.

A properly wired 50 amp socket has two hot lines: between either hot line and neutral it is 120 volts, between the two hot lines it is indeed 240 volts.

[CampDaven]

Originally Posted by ShapeShifter

You've never been to a park that has 50 amp sockets? You must go to a very limited range of parks if they've only ever had 30 or 20 amp sockets.



A properly wired 50 amp socket has two hot lines: between either hot line and neutral it is 120 volts, between the two hot lines it is indeed 240 volts.

My RV cord door says 110 V only. Yes, I use 50 A all the time! Yes I knew there were 2 120V hots. No I didn't stay at a HEI. No I don't see how I could use the 50A outlet for my RV and also one 240v heater (about 17A draw). Would need to plug into another pedestal. Camp would love that!! No I don't see why electric/gas ain't good nuff.
Why not 2 120v elements at 3000W?
No video? It never happened.

[mel s]

Originally Posted by CampDaven

Never seen a 240V outlet on a camp pedestal. Only 110
When running electricity and gas, we don't run out of hot water.

CampDaven
The 50AMP receptacles you've seen in campground pedestals you ARE 240V.
So called 50AMP RVs see, (and use), each/both of the 2 120V legs of that 240V as 2 separate 120V legs/lines.

BTW 50A receptacles actually provide 100 AMPs of electricity to a 50A coach.... (50A via EACH of the 120V lines/wires in what are commonly known as 50A shore power cords).

For more information please see and read: http://www.bobhatch.com/electricStuff/whats_it_mean.htm
Or Google "how does a 50A shore power receptacle work?"

Mel
'96 Safari

[LadyFitz...]

Originally Posted by ShapeShifter

I would hope that in reality it's "only a few" campgrounds and not "most" that have illegal cheater wiring as you mention...

The wiring he was referring to is not "illegal cheater wiring". Some campgrounds use 120/208v three phase wiring to the pedestals. This is quite legal and safe (in fact, many RVs now display both 120/240v and 120/208v compatibility right on the RV). RVs usually need only one or two 120v connections, the latter sharing a common neutral, which you can get from 120/240v split phase and from 120/208v three phase. Three phase wiring is cheaper to install and often to get delivered to the park from the utility. For a resistive load, you would be able to get away with the 208v but heating capacity would be reduced.

That said, I doubt what you are considering would be practical plus it appears you may not know enough about electrical systems to be tackling an off the wall project like this.

[Winepress]

Originally Posted by ShapeShifter

I would hope that in reality it's "only a few" campgrounds and not "most" that have illegal cheater wiring as you mention. The idea of having a proper 120/240 volt split phase service is that the neutral line balances the loads between the two hot lines, and only sees the difference in the current between the two hot lines. With 50 amp protection, that means that the most current the neutral can ever see is 50 amps (when one line is drawing 50 amps and the other is drawing nothing.) If both lines are drawing the full 50 amps, the neutral will actually have no current flowing in it.



With the cheater service you mention, where the two hot legs are from the same feed, then the neutral wire will carry the sum of the current in the two hot legs, not the difference. That means with a fully loaded line drawing 50 amps on both hot leads, the neutral will be carrying 100 amps, which would be a serious overload. That's why the cheater service you mention is illegal.



Theoretically, there is no danger hooking up a 240 volt heater element: if one were to be plugged into a cheater service as you describe, the heater would be seeing zero volts, and simply won't work. But things often don't follow theory: "In theory, there is no difference between theory and practice. In practice, there is."



The danger comes in with the non-standard wiring: can it be done in a way that is safe? Remember, just because something works, does not mean that it's safe, and will work safely in all conditions. I'm not sure what the codes have to say about the proposed arrangement, but whatever is done should be done legally and according to code. For example, the current to the heater is controlled by a relay, one which I assume is single pole. Generally, codes call that both hot lines to a 240 volt load should be switched, which means replacing the relay with a double pole relay. I'm sure there are many more potential issues that should be considered, most of which are likely not obvious.



Then there is the issue if the heater itself and the controls can handle the extra power dissipation of the larger element. It would probably be prudent to run these changes by the water heater manufacturer, and I would be surprised if they officially condone it. I would also run all changes past a licensed electrician and/or local building inspector -- both for your own safety, the safety of a future technician working on the heater, and the safety of future owners.



If you haven't guessed, I don't think it's a good idea.

If both legs are drawing 50 amps, the neutral will also be at 50 amps in phase with each leg. Should not see current draw between L1 and L2 in a RV situation.

[ShapeShifter]

Originally Posted by CampDaven

My RV cord door says 110 V only.

Are you sure about that? Take another look. There is a decal by my shore cord that says "THIS CONNECTION FOR 120/240 VOLT, 3-POLE, 4-WIRE, 60 HERTZ, 50 AMPERE SUPPLY" and I'll bet yours has the same label. The 2009 Camelot Owner Manual also says that on page 166, even including an image of the rating label that matches mine.

Originally Posted by LadyFitz...

The wiring he was referring to is not "illegal cheater wiring". Some campgrounds use 120/208v three phase wiring to the pedestals. This is quite legal and safe (in fact, many RVs now display both 120/240v and 120/208v compatibility right on the RV).

There is some ambiguity about what he was referring to. Having two hots that are in phase with each other such that there is zero volts between them is most definitely illegal. Splitting off a three phase supply so that there are 208 volts between hots is legal, although my coach does not say it is compatible with such an arrangement (see the exact wording on my coach immediately above, my owner manual verbiage is similar and makes no mention of 208V compatibility.) That being said, I agree that I have no 240 volt loads in my coach, so I don't see where plugging into a 120/208 socket would cause me any problems. (The only question is my Intellitec EMS that looks for high voltage between the two hots to determine if it is a 50 amp service: will it recognize 208V as being a 50 amp supply?)

That being said, there are some high-end all-electic coaches out there that do have 240 volt loads in them (like an electric cooktop.) How will do those work on a 120/208 service? Are the compatible? Wouldn't their 240 volt loads be running at about 80% power output? (I do understand the basic idea behind three phase power, but I know I don't know a lot of details, like the implications of the difference between Wye and Delta configurations.)

That said, I doubt what you are considering would be practical plus it appears you may not know enough about electrical systems to be tackling an off the wall project like this.

It's not my project, I'm not the one considering doing the conversion. I think I know a bit more about electrical service than a lot of people (especially the theory, not so much the practice) but I am sure there are a lot of people who know a lot more than I. And I know that I don't know enough to do such a conversion properly: If I were so inclined (and I'm not!) I think I could make it work, but I'm not convinced it would be safe in all circumstances nor do I think it would meet codes. That's the basis for my previous comments: it's easy to make it work, but it's much harder to make it work safely. I also completely agree with you in that if you have to ask how to do something like this on an Internet forum, you probably don't have enough knowledge to do it safely. It's the parts that you don't know that you don't know that will come back and bite you!

Originally Posted by Winepress

If both legs are drawing 50 amps, the neutral will also be at 50 amps in phase with each leg. Should not see current draw between L1 and L2 in a RV situation.

Agreed that a typical RV does not have 240 volt loads, but the rest of your statement is outright wrong. If the two hot lines are 180 degrees out of phase relative to each other, as they must be in a proper 120/240 split single phase system, then the single neutral conductor that is shared between the two hots will most definitely have the difference between the two hot currents. If both hots are drawing exactly the same current (be it 50 amps, 10 amps, or even 1 amp) the neutral will have no current on it.

Read up on the "Connections" topic of this article, which explains it better than I can: Wikipedia: Split-phase electric power

Note that this applies specifically to standard 120/240 split phase power. 120/208 derived from three phase power might have some subtle (or not so subtle?) differences.

[BFlinn181]

An RV 50 amp outlet has two legs of 120 v 50 amp capacity. The two legs are 180º out of phase from one another, thus the neutral wire never 'sees' any more than 50 amps at any instant. I'd suggest that a 50 amp Progressive Ind. EMS be installed in your RV to monitor what power is available to you.

Rather than install the beefier heating element, like others have suggested, why not turn on the LP gas function of the water heater? In addition, do you have an Oxygenics shower head to restrict water flow but mix in air to make it feel like more water?

[336muffin]

Originally Posted by thunderjet

As I am very cheap I am not changing the water heater just adding new element, breaker and 3 way switch about 40 dollars. My math tells me my 10 gal 1500 watt heater from start up takes 1 hour and a 4000 watt takes about 24 minutes. On a reheat from t stat make that 20 minutes down to 8 minutes. And I think t stat cycling would not be overshooting temp any more than normal element.

Thanks for all input

I have had this rv for all of its 10 years and do all of the service.
I was more worried about future owners or service techs.

I also wanted more hot water on the cheap, so I went another direction. I insulated my existing water heater with fiberglass and the hot line with cheap and simple water line insulation from building supply, $20.oo done. Lots of hot water and fast recovery time. We fulltime and this worked for us very well.

[Winepress]

Originally Posted by ShapeShifter

Are you sure about that? Take another look. There is a decal by my shore cord that says "THIS CONNECTION FOR 120/240 VOLT, 3-POLE, 4-WIRE, 60 HERTZ, 50 AMPERE SUPPLY" and I'll bet yours has the same label. The 2009 Camelot Owner Manual also says that on page 166, even including an image of the rating label that matches mine.





There is some ambiguity about what he was referring to. Having two hots that are in phase with each other such that there is zero volts between them is most definitely illegal. Splitting off a three phase supply so that there are 208 volts between hots is legal, although my coach does not say it is compatible with such an arrangement (see the exact wording on my coach immediately above, my owner manual verbiage is similar and makes no mention of 208V compatibility.) That being said, I agree that I have no 240 volt loads in my coach, so I don't see where plugging into a 120/208 socket would cause me any problems. (The only question is my Intellitec EMS that looks for high voltage between the two hots to determine if it is a 50 amp service: will it recognize 208V as being a 50 amp supply?)



That being said, there are some high-end all-electic coaches out there that do have 240 volt loads in them (like an electric cooktop.) How will do those work on a 120/208 service? Are the compatible? Wouldn't their 240 volt loads be running at about 80% power output? (I do understand the basic idea behind three phase power, but I know I don't know a lot of details, like the implications of the difference between Wye and Delta configurations.)







It's not my project, I'm not the one considering doing the conversion. I think I know a bit more about electrical service than a lot of people (especially the theory, not so much the practice) but I am sure there are a lot of people who know a lot more than I. And I know that I don't know enough to do such a conversion properly: If I were so inclined (and I'm not!) I think I could make it work, but I'm not convinced it would be safe in all circumstances nor do I think it would meet codes. That's the basis for my previous comments: it's easy to make it work, but it's much harder to make it work safely. I also completely agree with you in that if you have to ask how to do something like this on an Internet forum, you probably don't have enough knowledge to do it safely. It's the parts that you don't know that you don't know that will come back and bite you!





Agreed that a typical RV does not have 240 volt loads, but the rest of your statement is outright wrong. If the two hot lines are 180 degrees out of phase relative to each other, as they must be in a proper 120/240 split single phase system, then the single neutral conductor that is shared between the two hots will most definitely have the difference between the two hot currents. If both hots are drawing exactly the same current (be it 50 amps, 10 amps, or even 1 amp) the neutral will have no current on it.



Read up on the "Connections" topic of this article, which explains it better than I can: Wikipedia: Split-phase electric power



Note that this applies specifically to standard 120/240 split phase power. 120/208 derived from three phase power might have some subtle (or not so subtle?) differences.

Interesting concept. So if I have L1 drawing 20 amps and L2 drawing 20 amps, I do not need a neutral as you state the neutral current is zero. What is the return path for L1 and L2?

[BFlinn181]

Originally Posted by Winepress

Interesting concept. So if I have L1 drawing 20 amps and L2 drawing 20 amps, I do not need a neutral as you state the neutral current is zero. What is the return path for L1 and L2?

The 2 legs are independent of one another, they share the common neutral wire but 180º out of phase. If each leg is drawing 20 amps, the neutral would be showing 20 amps of current, not zero.