Water Heaters

I recently had an electric water heater rupture and called a handyman to replace it for me as I was out of town. This is in a 3 bed, 2 bath singlewide with 4 people living in it.

The handyman and I miscommunicated as I NEVER buy the mobile home water heaters and this case proved my reason for this.

The old tank was 40 gallons so he replaced it with a 40 gallon mobile home tank. The problem is twofold.

The 40 gallon mobile home water heater has only one element (3500 watts). It cost $297 at Lowe’s. It is inferior and yet costs $100 more than the standard 40 gallon water heater that has two 4500 watt elements.

Things to keep in mind is that if you upgrade to 4500 watt elements, my research indicates that you are past the max of 80% rating on the 12 gauge wire and 20 amp breaker (which this house has).

Within 2 days the tenant called me to complain that their hot water lasted only about 7 mins into their shower. Glad I paid $100 extra for this junk mobile home tank.

I went and bought a standard 40 gallon water heater with the two 4500 watt elements. I bought 2 replacement 3500 watt elements and swapped them out. I have several homes with 50 gallon water heaters (with 10 gauge wire and 25 or 30 amp breakers where I can use these if needed) so no money lost there.

We replaced the mobile home water heater with this heater and returned the old heater to Lowe’s. They gave me my money back so I now have a better units and $100 saved.

For years I have known people who replace mobile home water heaters with stick built but they never mention wire size or breakers and this conerns me. In the past I have made upgrades to the wire and breaker if necessary (had to have an electrician do this for a set up inspection one time).

I hope to never spend extra money to buy a “mobile home” water heater again. I probably have a few that were purchased years ago or were installed prior to my buying the homes. I have only installed one such heater by intention and that was strictly due to time constraints and I kick myself for it to this day. I should have gone another route and the idea of researching swapping the elements was born. My $100 mistake is your gift.

For those in the know on such things as this please feel free to punch holes in this theory. I don’t want to give anyone poor advice.

One last comment. This idea was confirmed for me when I later inspected the original water heater in the home described above and found that it was indeed a 40 gallon heater with two 3500 watt elements in it and as best the tenant could tell me it had been in the home as long as they had (over 13 years).

Tony

Tony, just be glad you don’t have to deal with gas water heaters.

The “mobile home” units feature a “direct vent” and sealed combustion. They take air in from the underneath of the home, and vent it out the roof. The reason being, not to consume the oxygen in the room the unit is located (typically a bedroom closet).

The bad part: they’re almost twice as expensive as a standard residential gas water heater. To find one for $650 is a pretty good deal.

Some people do replace them with standard residential units, but if the utility company ever sees it (for example, when turning on new service) they will disconnect the unit, tag it, and cap the gas line.

Good to know about the difference in electric units, as I do have two or three units that I’ve sold that had those.

Jeff

Tony,

Very good information. I was aware that the standard heaters will replace the mobile home heaters but not about the issue of the wrong size elements.

I am printing out your post so that i will remember to replace the 4500 watt elements with 3500 watt ones when I see 20 amp breakers.

Thanks!

TT

[QUOTE=Tarheel T;883045]Tony,

Very good information. I was aware that the standard heaters will replace the mobile home heaters but not about the issue of the wrong size elements.

I am printing out your post so that i will remember to replace the 4500 watt elements with 3500 watt ones when I see 20 amp breakers.

Thanks!

TT[/QUOTE]

With most upgrades from “mobile home” water heater to standard water heater you will likely have to extend the water lines to the top of the unit but this is no big deal. A couple of fittings and you are all set.

I echo what TT said. Thanks for sharing!

Tony,

Thanks for pointing this out. I live in a MH and have had one replaced by a plumber. I have no idea what he put in, though I suspect it was a standard home heater, since it does have 2 elements.

When this heater was put in, I had had the plumber out because virtually all of our plumbing was stopped up due to very hard water. He cleared out the lines and informed me the water heater was full of sediment and had to be replaced (even though it worked!). I went along and it cost me $650.

Recently this water heater stopped working and I had my nephew take a look. Turned out one of the elements was cracked and both were extremely corroded. The tank was also full of sediment. He took it out and dumped out the sediment and replaced both elements for a cost of only $12 for the elements. I was amazed that it only took $12 to fix. I’m pretty sure a plumber would have insisted on replacing it. I did pay my nephew $200 in labor, since he worked on it for a good while. But pretty good compared to $650.

Tony,

Thanks for pointing this out. I live in a MH and have had one replaced by a plumber. I have no idea what he put in, though I suspect it was a standard home heater, since it does have 2 elements.

When this heater was put in, I had had the plumber out because virtually all of our plumbing was stopped up due to very hard water. He cleared out the lines and informed me the water heater was full of sediment and had to be replaced (even though it worked!). I went along and it cost me $650.

Recently this water heater stopped working and I had my nephew take a look. Turned out one of the elements was cracked and both were extremely corroded. The tank was also full of sediment. He took it out and dumped out the sediment and replaced both elements for a cost of only $12 for the elements. I was amazed that it only took $12 to fix. I’m pretty sure a plumber would have insisted on replacing it. I did pay my nephew $200 in labor, since he worked on it for a good while. But pretty good compared to $650.

Thanks Tony,
Now something else to worry about! Not. I have probably replaced 40 water heaters over the years and never paid attention to the wiring issue. I did find a few wired up to other loaded breakers. The first time, I noticed the MoHo water heaters were about $15 more, so being the notorious cheap skate, I bought the house heater and never went back. I did notice a price-difference creep, most likely due to a national decrease in demand for mobile home water heaters, causing the price to go up.

Now that you’ve pointed this out I’d like Glen(OH), the electrician, to weigh in.
Glen?

Hey Leslie, I have seen them completely blocked up with calcium up to the bottom element. I’m impressed your nephew had the patience to clean out all that calcium. You should be able to find a new 30 gal electric for about $225 plus your nephew’s time to replace it next time.

Steve

[QUOTE=Dr B(OH);883062]Thanks Tony,
Now something else to worry about! Not. I have probably replaced 40 water heaters over the years and never paid attention to the wiring issue. I did find a few wired up to other loaded breakers. The first time, I noticed the MoHo water heaters were about $15 more, so being the notorious cheap skate, I bought the house heater and never went back. I did notice a price-difference creep, most likely due to a national decrease in demand for mobile home water heaters, causing the price to go up.

Now that you’ve pointed this out I’d like Glen(OH), the electrician, to weigh in.
Glen?

Hey Leslie, I have seen them completely blocked up with calcium up to the bottom element. I’m impressed your nephew had the patience to clean out all that calcium. You should be able to find a new 30 gal electric for about $225 plus your nephew’s time to replace it next time.

Steve[/QUOTE]

Steve,

I hope Glen or any other electrician will jump in here and let me know if my research is correct or not. If you talk with him, please ask him to post.

Thanks,

Tony

Leslie,

For about $100 in parts you can install a simple canister filter in your main line and protect your water heater and all the appliances in your house from this sediment.

Since doing my first plumbing repair many years ago, and seeing what the inside of a pipe looks like, I’ve done this ever since on every house I’ve lived in. The “gunk” that accumulates is amazing and is enough in itself to convince you that you never want to drink tap water again!

Plus, installing a canister filter is a heckuva lot cheaper than replacing a water heater or appliance.

I also recommend flushing your water heater once a year by opening up the drain valve. Of course, you will want to attach a hose to it first and run it outside. On most mobile homes I purchase, I attach an old washing machine supply hose (with one end cut off) and run it under the home through a hole drilled in the floor. This makes an annual flush a 2 minute job!

Michael(KCMO)

[QUOTE=Tony Colella;883063]Steve,

I hope Glen or any other electrician will jump in here and let me know if my research is correct or not. If you talk with him, please ask him to post.

Thanks,

Tony[/QUOTE]

[QUOTE=Tony Colella;883063]Steve,

I hope Glen or any other electrician will jump in here and let me know if my research is correct or not. If you talk with him, please ask him to post.

Thanks,

Tony[/QUOTE]

Hi Tony,

You’re right about the derating of the wire size when installing a water heater.

The National Electric Code considers water heaters to be “continuous loads”, since there is a good chance that they will operate continuously for over 3 hours. Doing multiple loads of laundry with hot water is an example. When sizing the wire for a continuous load, you must take 125% of the full load current and size your wire accordingly.

As an example, take a 40 gallon hot water heater with 4500 watt elements (remember, only one element is used at a time). To get the full load current you divide the 4500 watts by the 230 volts supplied from your electrical panel. This gives you a current draw of 19.5 amps. Multiply the 19.5 by 125% and you get your continuous load current of around 24 amps. 12 gauge wire would be sufficient in loads that are not continuous because 12 gauge can handle 20 amps and the initial current calculated was 19.5 amps. But since the water heater is a continuous load the wire must handle 24 amps and 10 gauge wire with a capacity to handle 30 amps must be used.

If you do the math with a 3500 watt element you’ll find that the continuous load current is 19 amps. 12 gauge wire with its 20 amp capacity would work fine.

Just remember, never to use a 30 amp breaker with 12 gauge wire or a 20 amp breaker with 14 gauge wire. If you are replacing a water heater with a new model having 4500 watt elements, and it was originally fed with a 20 amp circuit using 12 gauge wire, you have two choices. One is to run a new 30 amp circuit with 10 gauge wire and a 30 amp circuit breaker or downgrade your elements to 3500 watts.

Hope this helps!

Glen (OH)

[QUOTE=Glen (OH);883095]Hi Tony,

You’re right about the derating of the wire size when installing a water heater.

The National Electric Code considers water heaters to be “continuous loads”, since there is a good chance that they will operate continuously for over 3 hours. Doing multiple loads of laundry with hot water is an example. When sizing the wire for a continuous load, you must take 125% of the full load current and size your wire accordingly.

As an example, take a 40 gallon hot water heater with 4500 watt elements (remember, only one element is used at a time). To get the full load current you divide the 4500 watts by the 230 volts supplied from your electrical panel. This gives you a current draw of 19.5 amps. Multiply the 19.5 by 125% and you get your continuous load current of around 24 amps. 12 gauge wire would be sufficient in loads that are not continuous because 12 gauge can handle 20 amps and the initial current calculated was 19.5 amps. But since the water heater is a continuous load the wire must handle 24 amps and 10 gauge wire with a capacity to handle 30 amps must be used.

If you do the math with a 3500 watt element you’ll find that the continuous load current is 19 amps. 12 gauge wire with its 20 amp capacity would work fine.

Just remember, never to use a 30 amp breaker with 12 gauge wire or a 20 amp breaker with 14 gauge wire. If you are replacing a water heater with a new model having 4500 watt elements, and it was originally fed with a 20 amp circuit using 12 gauge wire, you have two choices. One is to run a new 30 amp circuit with 10 gauge wire and a 30 amp circuit breaker or downgrade your elements to 3500 watts.

Hope this helps!

Glen (OH)[/QUOTE]

Thanks Glen.

When I recently ran into this issue I had upgraded the wire to 10 gauge wire for a larger tank with 4500 watt elements. Asking around at Lowe’s and online I was told to use a 25 amp breaker. That is what I used but in the future I will go with 30 am breakers. Reflecting back on using the 25 amp breaker I feel that the issue I will encounter will be the breaker tripping (which it hasn’t) but at least in this case the breaker is the weak point and not the wiring. So far there have not been any calls about this breaker but like I said, in the future I will either go with 10 gauge wire and 30 amp breaker or downsize the elements to 3500 watt if the wire is 12 gauge wire on a 20 amp breaker.

[QUOTE=Tony Colella;883101]Thanks Glen.

When I recently ran into this issue I had upgraded the wire to 10 gauge wire for a larger tank with 4500 watt elements. Asking around at Lowe’s and online I was told to use a 25 amp breaker. That is what I used but in the future I will go with 30 am breakers. Reflecting back on using the 25 amp breaker I feel that the issue I will encounter will be the breaker tripping (which it hasn’t) but at least in this case the breaker is the weak point and not the wiring. So far there have not been any calls about this breaker but like I said, in the future I will either go with 10 gauge wire and 30 amp breaker or downsize the elements to 3500 watt if the wire is 12 gauge wire on a 20 amp breaker.[/QUOTE]

Tony,

I wouldn’t be concerned with using the 25 amp breaker. Remember the actual full load current for a 4500 watt element is 19.5 amps which is about 20% below your breaker rating. Unless you have a short circuit or a ground fault, that breaker should carry that current continuously without tripping.

One other thing to remember is that the local code requirements have precedence over the national code. It could be possible that in your area that 4500 watt water heaters have to be protected with 25 amp breakers. The guys in the electrical dept. at Lowes and HD usually have a good handle on the local codes.

Glen (OH)

[QUOTE=Glen (OH);883108]Tony,

I wouldn’t be concerned with using the 25 amp breaker. Remember the actual full load current for a 4500 watt element is 19.5 amps which is about 20% below your breaker rating. Unless you have a short circuit or a ground fault, that breaker should carry that current continuously without tripping.

One other thing to remember is that the local code requirements have precedence over the national code. It could be possible that in your area that 4500 watt water heaters have to be protected with 25 amp breakers. The guys in the electrical dept. at Lowes and HD usually have a good handle on the local codes.

Glen (OH)[/QUOTE]

Actually the kid at Lowe’s that they had me wait for had no clue. He did what I did and used his smart phone. I went to google but he went to Lowe’s website and came up with the 25 amp breaker which like you said is sufficient, just not as common.

I tell you what I have always been the guy that intentionally waits for technology until everyone else is bored with what I then think is awesome! My recent upgrade to a droid has proven to be extremely helpful. Not only can I handle texts, email and phone calls but just being able to stand in lowes and google what parts I need (like this) has saved me a great deal of time and helped me to learn things (like the breaker and wire sizing).

Tony

i too recently emerged from the electronic dark ages and bought an i-phone.
Steve

I’ve replaced my mh-hwts w/ standard hwts and never even thought about elements wire Gage or breakers - never had a problem yet. But it gives me something to check if (when) I do have a problem.

The math makes sense, and I guess I should replace the elements, or at least look @ the circuits . . .