Water heater - electric vs. gas + more

[scottydl]

The water heater in my current RV is the first one I've had with both electric and gas options.  The electric switch is only accessible from outside (behind the service panel) and the gas switch is only accessible from inside (near the rest of the monitor panel functions). 

I just figured all this out within the last few days, while I was flushing out the tank and sanitizing my water system in preparation for a couple late-season weekend camps this Fall (we just bought the trailer a few weeks ago).  The previous owner didn't even know there WAS an electric heating coil, she told me it was gas only.  :  But I verified the electric option works, as it got a tank full of water piping hot when left overnight.

- When camping on unmetered shore power (and with these dual-option heaters), is it recommend to leave the electric coil on all the time and use gas to supplement heat when needed?  I know the gas will heat the water quicker.  Just wondering what everyone else usually does.

- This heater has the anode rod plug which is also new to me.  I put a brand new one in yesterday.  How long should those last, and can I remove and store a partially-spent rod during the off season?  I don't really want to throw it out after only a couple trips this Fall.

- Lastly but related, the threads on the drain opening (for that tank plug to screw in) are rusty and VERY worn.  I was only able to get the plug screwed in about 3 revolutions out of 10-12 total possible.  It was tough to turn the ratchet after that and I didn't want to force the plug too much more.  I have teflon tape on the plug threads and the hot water did not seem to leak overnight, but I'm sure the plug would go in further if the tank-side threads were in better shape.  I have a tap & die set, but nothing nearly big enough to fit the drain threads.  Thoughts?

Lots of various water heater questions there, but I figured it made sense to put them all in one place. 

 

[Rene T]

The water heater in my current RV is the first one I've had with both electric and gas options.  The electric switch is only accessible from outside (behind the service panel) and the gas switch is only accessible from inside (near the rest of the monitor panel functions). 

When camping on unmetered shore power (and with these dual-option heaters), is it recommend to leave the electric coil on all the time and use gas to supplement heat when needed?  I know the gas will heat the water quicker.  Just wondering what everyone else usually does.

- This heater has the anode rod plug which is also new to me.  I put a brand new one in yesterday.  How long should those last, and can I remove and store a partially-spent rod during the off season?  I don't really want to throw it out after only a couple trips this Fall.

- Lastly but related, the threads on the drain opening (for that tank plug to screw in) are rusty and VERY worn.  I was only able to get the plug screwed in about 3 revolutions out of 10-12 total possible.  It was tough to turn the ratchet after that and I didn't want to force the plug too much more.  I have teflon tape on the plug threads and the hot water did not seem to leak overnight, but I'm sure the plug would go in further if the tank-side threads were in better shape.  I have a tap & die set, but nothing nearly big enough to fit the drain threads.

I never use the propane while on campground shore power. Save it for when you need it.  Take a closer look inside for a switch for the electric. I think that the majority of the RV's have a switch inside and the one you found on the outside. I think the one on the outside is primarily there for a technician to secure  the power while working on the unit. I use to shut that one off in the fall when winterizing to prevent someone accidently turning on the power before I had a chance to fill the tank with water.

The lifespan of the sacrificial anode will depend on the minerals in the water you're using. The minerals attack the rod instead of your tank. You can take the plug out for the winter. I always take my plug out and just let the air dry things out. While it's still wet, it would be a good time to flush it out though.  When the anode gets down to about 90 percent gone, then change it. It will require you to remove it and inspect it once a month or so probably to inspect.  Then you'll be able to tell what the lifespan will be.

The threads of the pipe plug and tank are 1/2" pipe threads. In other words, they are tapered. Do not try to run a straight tap in there unless it is a pipe tap.  If after screwing in the plug 3 turns and you're using Teflon tape and you don't have any leaks, you're doing fine.

 

[Larry N.]

I can't answer the other parts, but:

- When camping on unmetered shore power (and with these dual-option heaters), is it recommend to leave the electric coil on all the time and use gas to supplement heat when needed?  I know the gas will heat the water quicker.  Just wondering what everyone else usually does.

When I had that arrangement in a TT I usually left the electric on when we were (home), though I'd sometimes turn it off at night (not always - not very convenient)). We'd find that water was still hot enough, after it being off overnight, to allow for the "first-thing-in-the-morning" use (except shower), but then we needed to turn it on again. But often we'd just leave it on, too.

Depending on use, an anode rod may last for a year or a bit more. I'd check it at least every season, then you'll get a feel for how long it lasts for you.

 

[Gary RV_Wizard]

Just use the electric when you have shore power available at the right price. You can also turn the gas on if you want to speed up the recovery time (two heaters are faster than one!), but for a factory electric heating element there probably only a small difference between the reheat time of gas alone vs electric alone.  Probably a 3-5 minutes on a 6 gallon tank?  Either one will give you reasonable hot water in 20 minutes. Still, the gas burner has more btus than the standard 1400 watt  electric heater (about twice as much), so it does heat somewhat faster. 

The life of an anode rod depends on the water it is exposed to, basically the amount and type of minerals in the water.  There is no need to remove when the tank is drained - nothing happens to it when there is no water in the tank. And if there is water in the tank, it is always best to have it in place. In some regions an anode may last for a couple years or more, while in others just a few months of continuous use. It is all but impossible to predict until you get some experience with the water quality in the areas you visit. I would suggest carrying a spare and checking it periodically.

A Suburban heater has a factory-installed electric switch outside. The RV builder may or may not install another inside, so yours likely does not have one. You can add it if you like - just a switch in series with the 120v circuit to the heater. Then leave the outside switch on all the time and use the inside one as needed.

The heater has a thermostat, so you can just leave it on all  the time. That's what thermostats are for, right?

 

[HappyWanderer]

We only use gas if electricity isn't available, or won't support everything we want to run. If we're on limited power and A/C isn't needed at night we'll turn on the water heater overnight, then turn it off before using the A/C in the morning. The water in the tank stays warm enough to use throughout the day for handwashing and incidental use.

 

[Alfa38User]

It sound like you have a Suburban brand water heater. I use a 1 1/16" six point socket on that plug.

I learned here on this forum that you should NOT use Teflon tape on that drain plug. The reason is that the anodes purpose will be defeated by isolating it from the casing. Couple of turns probably wont hurt though as there will be a least some threaded portion in contact with the case. I am not using it any longer and never have a leak.

My current anode has lasted 6+ years but will probably be changed out this coming winter, need it or not. The anode I had replaced had nothing left of it, just the 'nail'  that the anode material is fastened to. It was (and still is) on city water here in SW Florida, but at that point it was about 8 years old, probably never looked at nor flushed out by the PO, judging by what came out at that time. I drain and flush each spring after 6 months of use. We use it on electric all the time (24/7) and fire up the gas if a quicker recovery is required (as in multiple showers).

You could try wire brushing those threads and work the plug in and out a bit to get a better connection if necessary.

 

[John From Detroit]

- When camping on unmetered shore power (and with these dual-option heaters), is it recommend to leave the electric coil on all the time and use gas to supplement heat when needed?  I know the gas will heat the water quicker.  Just wondering what everyone else usually does.

Well. that is what I do (I can not speak for everyone)

How long should an anode last:  Depends on the water, Some last years, some only one season.

You could only get it in a few turns: IF it is not leaking that is the definition of "Far enough"  If it is leaking you have a problem.


Since the electric switch is hard to access... If it is a 120 volt switch (Often is) can you just use the circuit breaker (indoors) or add a switch indoors (Any decent electrican can do it)

I like mine, two switches both on the master house control panel.. but I have a different heater.


I'm sure you will have more questions.. We love questions.. I've learned more solving other people's problems then I have my own .. and gotten help with a few of my own in the process.

 

[scottydl]

A Suburban heater has a factory-installed electric switch outside. The RV builder may or may not install another inside, so yours likely does not have one.

This seems to be the case (exterior switch only), and would explain in part why the previous owner didn't even know about the electric option.  I may add an interior switch eventually, but I also don't mind just flipping the exterior switch and leaving it on each time we set up for camping.

It sound like you have a Suburban brand water heater. I use a 1 1/16" six point socket on that plug.

That's exactly what I did too, bought an individual socket just for that purpose the other day.  It was worth the $4 to avoid busting my knuckles always trying to handle the plug with a adjustable pliers or vice grips like I did in my previous RV. 

Interesting justification on the non-use of Teflon tape.  I wanted to help out with the leaking potential, since it was obvious that the plug was not going to screw in all the way due to the worn-down threads.  But the tape might not make a difference either way.  I'll try to work a wire brush in there and clean up the threads some more.

 

[Ned]

The threads will cut through the tape and furnish the necessary metal to metal contact.  But instead of the tape, try a bit of plumbers pipe dope.  Should keep the threads from freezing, prevent leaking, and still allow the contact.

 

[Gary RV_Wizard]

I wouldn't worry about the teflon tape insulating and stopping the cathodic action.  The threads cut right through it and touch the skin of the tank, and that's all that is needed. I probably wouldn't use it myself, though, unless there was a leakage problem. If you do need a thread sealer on a hot metal tank fitting, I would use a paste-type thread sealant. Maybe something like Rector Seal T+2.
http://www.homedepot.com/p/RectorSeal-T-Plus-2-1-75-oz-Non-Stick-Thread-Sealant-23710/100116773

 

[kdbgoat]

Neither of mine have had an inside switch for the 120v element. The dealer I bought from tells everyone to just turn off the breaker to the water heater. Personally, I don't like to use a breaker for an on/off switch. If working on the heater, I will turn off the outside switch first, then turn off the breaker if needed.

 

[8Muddypaws]

I added an interior switch to mine when I had a Suburban.  It was easy enough because the back of the water heater was accessible.  Other RVs may not have that easy access.

 

[John From Detroit]

You can also add the switch at the power panel side.. Either end of the 12ga wire works just fine.

One piece of advice. Make sure the switch is rated at least 20 real amps not 20 radio shack amps.. Use a standard house wall switch type switch but rated for at least 20 amps.. Yes I know that's more than the heater draws.

But I do not trust modern ratings.

IN the old days that 20 amp switch might well have been labeled 10 amps. (But 15 would have been OK) today ..  IT's labeled 20,, but 15 may still be OK.  More than that not.

 

[Lou Schneider]

The anode rod uses tapered pipe threads, not flat threads like a screw.  It's normal for pipe threads to bottom out against the sides of the tapered socket before all of the exposed threads are engaged.

On my Suburban heater, the electric element produced about 1/3 as much heat as the gas flame.  It's thermostat also cut out at a lower temperature than the gas thermostat (both are non-adjustable).  If I just used electric heat, it took three times as long to heat the water and the temperature wasn't as hot as using the gas.

If I was in a full hookup site that included electricity, I'd leave the electric element on all the time, then turn on the gas about 5-10 minutes before I stepped into the shower to get the extra heat.  Then I'd turn the gas off when I was finished showering and let the electric element carry through until the next shower.

If I had to pay for electricity, I usually just ran the gas flame because in most locations, propane produces heat more economically than electricity.

 

[Deez]

I'm new to the forum and was reading this post with great interest. I recently purchased a 2010 Heartland 5th wheel with the electric/gas water heater. I was surprised to find that after several hours on electric only the water was only luke warm. I used propane to bring it up to temp and to shower then switched back to electric only. Hot water lasted about a day and then back to luke warm. I'm assuming this is not normal? How do you test the electric element?

 

[Alfa38User]

There are a few things to check first before blaming the element. My Suburban provides sufficient hot water for most purposes using the electric although for a faster recovery between multiple showers and a bit hotter, we do use the gas to help out. We leave the electric on 24/7 while snow birding in the unit.

Warm can be interpreted in many ways by different folks but it might be wise to check that the outside shower, if equipped, is shut off at the faucets and not just at the shower head itself. The same goes for the inside shower if the shower head has a shutoff. Either one still on only a bit will cause a cold-hot mixing effect and give a 'warm' result.

For Deez, Welcome!! I think your condition, if accurately reported,  is not normal but the tank thermostat/high temp cutoff unit also enters into the picture as well as a less than adequate element. You can run both at the same time and then turn off the gas and see if that does anything different.

For a condition of "lasts a day' it seems that the tank is being switched off and not cycling as it should under either gas or electric if left on.... and also assuming it is adequately insulated.

In a Fifth wheel, most people turn off this tank when traveling. Certain motor homes are equipped with a 'motor aid' system or an 'aqua-hot' system which are different and use the engine cooling system to maintain the hot water all the time while traveling without additional  gas or electric needed.

The thermostat and cutoff unit can be replaced as one piece but be sure it is touching the bare tank properly before jumping to that conclusion. The only way to check the element itself (that I know of) is to measure it's resistance but that usually works only if it is really defective (goes open) which means replacement anyway!!

 

[Deez]

Thanks for the info. The water stays hot when using propane, but decreases if switched to electric only. This is my 3rd 5th wheel but the first with electric as an option on the water heater.