Atwood 10 Gallon Propane/Electric version questions.

Please see attached image for details.

I'm going to attempt a flush & clean of my water heater with only a you tube video (https://www.youtube.com/watch?v=IKg0R9oiMP0) for experience.  I'm waiting on a Tank Rinser to arrive at Home Depot right now.

1) The pressure relief valve (circled in yellow) is old, rusty, and pointing at an angle towards the "electrical box" on the upper right.  Being a perfectionist I'd like to replace it but not sure if doing so will potentially break the pipe thread coming from the tank itself.  Any recommendations?

2) The drain valve (circled in light blue) is pointed straight at some wiring.  Can I & should I: Unplug those wires before draining? I'm not sure if water hitting the wires or the open connections upon unplugging the wires is the better move.  I'm also just assuming that they pop off easily.

3) I actually haven't tested the water heater yet.  Should I see if it works before flushing and cleaning? After? Or does it not matter?  I'm told it's been close to a year since it was last used by the previous owner.


Thanks as always for your time.

The PT relief is a standard temp and pressure type available at any plumbing supply), but may be a smaller thread than typical for a household heater. Probably 1/2" rather than 3/4". As far as removing it, proceed cautiously. The tank is aluminum, so the threads, and even the side wall, can be messed up easily. If it doesn't want to move, keep applying a penetrating oil to loosen it.

If the heater is turned off, removing (or not) those wires is academic. Just make sure it is off (no power).

I flush mine with a plain old hose pressure nozzle, but one of those wands you can insert in the hole is handy. It's more a matter of repeatedly squirting in water and draining than the type of tool used. Repeat until it runs clear.

I would fire it up once before flushing. No sense having to wonder if you did something to mess it up if you try it later and it doesn't work. It's easier on the mind to have a before & after comparison.

Thanks, Gary!

Updated questions:
1) Using just the hose nozzle wouldn't there be a chance of getting clear water coming out despite build up on the reverse side of the tank that's facing you when you insert the water stream?

2) Do you personally use just hose water and no Vinegar, which would save me the time of finding my RV water pump if I even have one?

I would make shure it works before I did anything gas and electric. With water pressure on the system I would open the relief valve to make shure it will open and leave it alone. You don't need vinegar to flush it. You can probably get the majority of sediment out with a hose pressure nozzle like Gary suggested. The key is to do it at least annually as part of your routine maintenance.
I would by a couple of the drain plugs (they come in a two pack) The cheap plastic plugs have a bad habit of cracking. The hole/threads are Pipe standard.
Bill

I see no reason to use vinegar, though it doesn't hurt. Vinegar is a mild acid and is probably intended to scour the tank walls a bit, but IMO that's wishful thinking. The tank walls in an Atwood are designed to be self-protecting and if you could remove any scale, all you would get is a thinner tank wall and maybe a leak. What's the point of that?

All you want to do is flush out any accumulated sediment from the bottom of the tank. The sediment is mineral salts that have settled out of the hot water over time. There may be none, or a lot, depending on the water quality where it was used. I've seen as much as an inch or tow of the stuff, but it rinses out easily enough. Squirt water in, then let it rush back out, carrying the sediment. If the water has a milky appearance, repeat until it is largely clear.  I've squirted water in via the drain hole and via the PT relief and have no preference for one vs the other.

You can also let the RV water system run water into the tank and then remove the plug to flush. Then put the plug in and let it partially fill again, and drain once more. A slower procedure than flushing with a hose, but some folks seem uncomfortable with squirting in water under hose pressure. Even though the RV's internal plumbing does pretty much the same thing tofill the tank.

Thanks, Gary!

I was visualizing a film of sediment on all 6 walls of the tank as opposed to a collection on the bottom so your post is educational for a newbie such as myself.

Hope we saved you some work!

So when trying to test out the heater I've got the following:

1) Two switches inside the RV which I *think* I've now distinguished between the Propane and Elec switches but my only reasoning is the small amount of hot water which I note in #4 below.

2) I assumed the red light being on was a good thing but now saw a video stating it should just turn on for a moment or so and then turn off if all is good.  Is this for both Electric and Propane switches/lights? The video was referring to the Propane part of the heater when it mentioned the light should go off.  The one that I believe is the Propane switch immediately lights red and stays that way, which makes sense since I've removed the Propane Tank from the RV upon purchase and use it as a spare grilling tank.  The one that I believe is the Elec switch - and is my focus of this post - immediately lights red, then goes out for a few moments, then comes back on solid red.  It also doesn't heat much over the course of hours (see #4 below).

3) When testing the hot water I got some air coming out of the sink in spurts along with water. 

4) I only got what I'd guess to be a liter or so of legit hot water at one point then it's back to warm, which might just be the normal temp of Florida water coming into the system.  I know the water heater is full, at least up to the Atwood air pocket, since I can open the pressure relief fully and have water coming out equal to the amount I'm putting in via the garden hose.  How can I get such a small amount of truly hot water from a 10 gallon tank? Wouldn't the electrode heat all 10 gallons to warm then warmer before a small portion gets to hot?

Any help would be great.  Both switches are at the other end of the RV and I see no way to follow the wiring without tearing apart a lot of the RV that I don't want to do.

Sorry for the confusing post.  I'm confused myself at the moment and am doing my best to convey what information I've got. :/

Sounds like you still have too much air in the tank.

Opening the outer overpressure/overtemp valve only verifies the water has reached it's level.  It's thermostatic element is normally submerged, so the actual tank outlet is higher than the valve.  Turn on the hot water at the faucet and let it run until the air bubbles stop - that's when the tank is properly full.

The electric heating element is only about 1/3 as powerful as the gas flame because of the limited electrical power available.  It's meant to supplement the gas flame, not replace it.  Since hot water rises, using a limited heat source like the electric element by itself it's possible to produce a hot pocket of water at the top of the tank with lukewarm water underneath.

Another problem with a relatively small tank like this is the incoming water swirls the tank contents, cooling the output faster than the electric element by itself can reheat it.

Get your flame working and see if you still have the limited hot water volume.

Thanks for the info, Lou.

Uggh. I was hoping to perpetually avoid Propane.  I'm sure I'll be back to this thread but I'm definitely going to read up on the Propane system and clean out the parts before testing.  I fear this thing going up in flames while I'm not close by.

I've actually been opening the pressure relief valve every so often so that explains the air bubbles.  I had read somewhere that problems could arise if the air pocket inside the water heater got filled and was trying to avoid that.  Was that incorrect information? Is there no way for it to get filled or should I be relieving the water on occasion?

And about the lights: When I have both Propane and Electric going correctly should both lights go on for a moment and then turn off if all is running correctly? I still don't have an answer to the Electrical side of that question and just want to hopefully verify that it's general information.  If I turn on either heating element and a solid red light remains does that immediately indicate a problem somewhere even if I can ultimately visually see the gas flame?

You don't need propane. At worst the electric element just takes a bit longer to heat the whole tank full. I have a 10 gallon Atwood and rarely ever use propane mode. And I have plenty of hot water within 30 minutes of turning the electric on, and a usable amount in about 15 minutes.

The electric mode switch is provided by the RV maker, not Atwood, so how the red light works (or even if it has a red light), depends on the specific RV.  My original switch had no indicator light, so I replaced it with one that does light up to show it is on. Yours could be either way.

Way back in the day it was usual for the propane mode switch to keep the red light on when the switch was on, but then Atwood changed it so that the red light goes off as soon as the presence of a gas flame was verified. That change was probably about 20 years ago, if I recall correctly. 

There should be no need to open the PTR on a regular basis. Or ever, if the tank & water system is working normally. Just get the air pocket set initially and then leave it alone unless you have reason to suspect a problem.

Any idea on what my current situation would indicate then:  A tiny bit of legit hot water over the course of about 4 hours?  I would think the electrode works since it got to hot at all but after so much time how could the rest not also be hot or at least very warm from being in the same 10 gallon tank. :/  I've got all air pockets out and am now testing again without propane involved.  Of course I'm juggling this testing with other life stuff that needs to be done today so I might not be able to get back to these forums until tonight/tomorrow though I'll try to pop back in soon.  Thanks as always!

I've got an "opening" sealed shut (for whatever reason) that I'm hoping allows me to reach the back of the WHeater to test the electrical portion as soon as I get a multimeter.  I just got back from Home Depot and my mind is re-boggled at all the options on those things so I'm gonna research what options I need... or just go back and buy one of the higher end ones hoping to be prepared in most/all situations.

You don't need a fancy multi-meter (VOM) for RV work. One of the $5 from Harbor Freight is sufficient.

It's easy enough to see if the water in the tank has heated up.  You can (cautiously) open the PTR and check the water directly. Ot just feel the PTR itself - it will be real hot if the tank cntents have heated up.

If you have a single valve heater bypass system, there will be a check valve on the hot water outlet. If that gets sticky (from hard water mineral salts), you will often get little or no hot water flow from the tank. The nearby water gets hot, but as soon as you use that you don't much more from the tank. Just a little hot, or maybe none at all. You can also get that symptoms if another faucet has both hot & cold valves open at the same time, e.g. a shower faucet that is turned off at the head rather than the faucet itself. Check your inside and outside shower valves. Likewise, slightly open or defective heater bypass valves will let cool water override the hot from the tank.

Irony: I've now taken yet another "shower" while yet to take an actual shower in this RV.   I wasn't sure if the plastic shut-off valves were "screw until tight/screw until loose" or simply "aim in the right direction" and found out the wet way as one flew apart when I turned it clockwise too many times.  I'm hoping that it only flew out due to my turning and will still work going forward.  I'm going to turn the water pressure on again when things dry off and the sun is out tomorrow.

If I understand the basic concepts of what you've described then it looks like you may have been right and there was a bypass open, though not the one labeled #13 on page 7 here: http://www.askforatwood.com/manuals/waterheaters/MPD%2093050%20PS%204.9.09.pdf but instead one on the PEX tubing system of the RVs water lines.  I'll find out tomorrow.

I got access to the back of the WHeater, which is exciting for me!   Pic attached.  I'm not currently seeing anything in the atwood documentation on what I'm guessing is a red light* towards the top of that electrical cover box in the pic.  The switch on the side is "on".  That whole box doesn't match the atwood documentation in the PDF posted in the prior paragraph.  Anybody have info?

*If it's a light then it doesn't illuminate steady when I turn either water heater switch on. However if it lights for a moment when I hit the switch I wouldn't know since I'm alone atm and the switch is about 15 feet away.

The bypass system, if any, is supplied by the RV maker and is not part of the Atwood heater. The valves and plumbing can vary quite a bit, even though they all are doing much the same thing.

That manual you cited is for another model of heater, one that is only remotely similar to yours. Not surprising it doesn't match up. This one is probably pretty close: http://bryantrv.com/docs2/docs/operating/atwood1.pdf

I've not seen that sort of box on an Atwood before, so am guessing it too was installed by the RV maker.

Did you ever identify the model number of this heater, so that the proper manual and service-related info/parts can be used?

Model: GC10-1E

For good or bad it seems I'm working with the original.

The bypass was leaking this morning but seems to be ok on a quick pull-apart-and-put-together-again.  Testing the WHeater once before leaving for some of today's non-RV stuff.  The light on the back still isn't illuminated but that could very well be a problem indicator or an all-is-good indicator for all I know right now.

I had a 1997 King of the Road 5vr and it had a Atwood with that box on the back. I use to shut the power off using that switch and also the inside switch was turned off when winterizing.  That was a good safety switch which would not get turned except by me when I knew the heater tank was full of water.

Thanks for the input, Rene.

I've now got working hot water using only electric! And in case anyone comes across this thread or asks the same questions as I did:  The red "light" (if it's in fact a light) remains non-illuminated on the back of the box residing on the back of the WHeater.

Thanks again for all the information given on this matter!!!