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Topic: Converting to an on-demand water heater (Read 3578 times) previous topic - next topic

Re: Converting to an on-demand water heater

Reply #40 –
Thanks John,
Reading up on the Atwood anode thing... Found out that the anode for aluminum tanks should be magnesium vs zinc. I will try soaking with a vinegar solution (as suggeted to me by another forum member) for awhile and see if it loosens up. The WH is out right now and it will be awhile before I will be ready to reinstall the old one or put a new one in, so not in a rush ATM.
Don

Re: Converting to an on-demand water heater

Reply #41 –
On saving shower hot water when boondocking:  Dick Ward posted a mod about a year ago (I think) that added a timer and valves and plumbing to circulate water from the hot water taps on the shower and the lav back to the fresh water tank, so when you were going to take a shower, you would trigger the timer and all the hot water in the lines would be sent back to the tank for some set-able period until ready for a shower.  Very clever solution for boondocking!

Adding a circulating pump for quicker hot water

It's somewhere down on my to do list...

Re: Converting to an on-demand water heater

Reply #42 –
Quote from: acousticart –
Thanks for the suggestions Steve, I believe that Dave K. Posted a how to on the balancing mixing valve... I will have to look into that option. I am not sure I even understand what it does VS. an ordinary mixing valve, but it sounds cool! Or hot:). Speaking of water heaters, I pulled the drain plug on mine (or what I thought was the drain plug!), and there is something still in there that seems like it will never come out. I wonders if maybe it is some sort of check valve, or? Got nothing! Here is pic of it, anybody know what it is? Since our 3-way water heater was working when I took it out, if I could be sure the tank was good, I would think about getting new Styrofoam insulating kit for it, clean it out really well and put it back in. On the other hand, it is a lot of work and maybe the peace of mind of having a new unit before beginning full timing might be worth the expense (about $600 for a new 10gal 3-way with heat exchanger). Any comments?

Don,

I would replace it if I were you.  We had our original heater (same as yours) develop a leak about 2 years ago, and I replaced it with a new one.  Couldn't get the model with a heat exchanger delivered in time to meet our travel schedule, and I went with a 2-way (120V + propane), which has been fine.  The styrofoam insulation on the new ones  keeps water plenty hot all day while we're travelling. 
BTW- Atwood says not to use an anode on their tanks. - Not needed since they are aluminum.
And BTW2 - reconnecting it with  reinforced flex hose, (instead of PEX,) makes the installation a whole lot easier!

Re: Converting to an on-demand water heater

Reply #43 –
Quote from: Peter & Beth –
The Atwood three way WH in the 97 U270 is OEM and works like a top.  It is 10 gals. and I've never run out of hot water taking very long showers whether using the electric or propane feature.  I'm very satisfied with its performance.
I agree wholeheartedly, Peter.  The Atwood 10 Gal. Aluminum units, treated and cared for properly, are another reason that the U270's shine in their simplicity and longevity.  We've never had a complaint or problem with ours in 12 years.  A mud dauber screen (and simple cleaning annually) and it's good to go, never short of hot water on or off the road.
One issue that many ignore is NEVER consider a sacrificial anode of any flavor, Magnesium OR Zinc.  I know the unit won't last forever, but exactly the same unit will be my first choice when I need to replace it.
Quote from: acousticart –
................Speaking of water heaters, I pulled the drain plug on mine (or what I thought was the drain plug!), and there is something still in there that seems like it will never come out. I wonders if maybe it is some sort of check valve, or? Got nothing! Here is pic of it, anybody know what it is? .................................................
Don,
Your previous owner did you an unintentional disservice, removed the NYLON (or maybe it is TEFLON)  drain plug and installed a sacrificial zinc (mostly aluminum) anode in the the drain fitting.  That is in direct conflict with the ATWOOD owner's manual for our three way heaters.  The aluminum/zinc fitting story is as follows:
The aluminum/zinc sacrificial anode provides very little driving current to protect an aluminum tank, especially when softer water happens to be  in the tank, so it isn't providing any protection to speak of...........it is just creating issues as follows:
    • The AL/ZN anode produces about 1000 times it's volume in corrosion byproducts
       
    • That's just junk that sits in the tank or gets deposited downstream in all the pinch points/ wrong places
       
    • The original AL/ZN anode starts to expand the day anyone installs it and it becomes hard, if not impossible to remove it (what you've experienced)
       
    • The AL/ZN anode crumbles off the center core mounting rod, junking up the bottom of the heater and the mounting rod itself becomes weak and sacrificial (again, what you've experienced)
       
    • Free aluminum molecules/radicals get carried along in the hot water stream and they do all kinds of ugly things to liver, brain, kidney, spleen and neural systems
       
    • All because someone wanted to be a good guy and protect the aluminum shell of the heater (in contradiction with the OEM's directions).
I don't believe vinegar will dissolve it. 
If it were me , my choices would be:
    • If I could grasp the broken anode core rod with needle nosed vise grips, I'd keep gently working on it (it may be soft enough to yield the expanded material enough to work it back out of the drain opening).  Then I'd thoroughly flush the sacrificial junk out of the tank each month, for several months. 
       
    • If that doesn't work, replace with a new Atwood of same model
You also have the option of pushing the broken anode through and then just try to minimize the ingestion of any of the hot water (use only cold water for cooking after flushing any residual hot water from the common plumbing (before each cold water cooking use).
Good Luck and Merry Christmas to all!

Neal :)

Re: Converting to an on-demand water heater

Reply #44 –
Thanks Neal! Excellent and informative post as usual. I think we are just going to replace it with another 3 Way Atwood of the same model. Too bad the PO decided to add an anode... I will salvage the electronics etc. from the old one for spares. It is just too much hassel to put the old one back in and have to deal with all the gunk in it and the possibility of it starting to leak etc. I like the styrofoam insulation on the new ones. Looks much more "tidy" than the cardboard box around the old one.
Don

Re: Converting to an on-demand water heater

Reply #45 –
Dave,

We have decided to replace the WH. Looking forward to the improved performence via the styrofoam insulation. What kind of flex hose did you use? The fittings on the both the old heater and on the manibloc appear to be pipe thread, while those braidied stainless steel hoses typically used for home washer hook up use garden hose type thread. Were these one you made yourself to length? If not how long were the ones you used?

Thanks, Don

Quote from: Dave Katsuki –
Don,

I would replace it if I were you.  We had our original heater (same as yours) develop a leak about 2 years ago, and I replaced it with a new one.  Couldn't get the model with a heat exchanger delivered in time to meet our travel schedule, and I went with a 2-way (120V + propane), which has been fine.  The styrofoam insulation on the new ones  keeps water plenty hot all day while we're travelling. 
BTW- Atwood says not to use an anode on their tanks. - Not needed since they are aluminum.
And BTW2 - reconnecting it with  reinforced flex hose, (instead of PEX,) makes the installation a whole lot easier!

Re: Converting to an on-demand water heater

Reply #46 –
Don,
I used braided hose on mine as well when I replaced the WH.  Home Depot (or Lowes) should have ones that have NPT on both ends.  I don't remember the length I used but they are long enough such that you can set the WH on a stool (face down) and make all the connections.  Then it's just a matter of inserting it in without pinching wires or hose.  I think I had to re-tighten the fittings again after the first use of the new unit - the rubber seals relaxed a bit and I had some minor drips - it's been good ever since.  Another thing that might be different on the new unit is how the AC element is turned on.  The old one was independent of the gas control ( lighted AC switch at the foot of the bed).  The new one uses the gas control circuit board with a second 12 volt switch (first switch being for gas).

I replaced mine in 2006 with a 3 way.  I don't think the "motor assists" is very good on the new ones.  It's just a short aluminum tube welded for a couple of inches to the tank.  If I remember correctly the old WH had a tube that went inside one end and out the other.  In practice the new unit doesn't seem to heat the water nearly as much as the old unit.  I wouldn't think twice about just using a 2 way unit next time.  Maybe others have had better experience with the  new motor assist.

Re: Converting to an on-demand water heater

Reply #47 –
Thanks John, that is helpful. I will look for the NPT threaded braided hose at Home Depot. I definitely see how much easier that will make the install!
Don

Re: Converting to an on-demand water heater

Reply #48 –
Various length NPT braided hose from Home Depot - just like you would use on a sink, etc... I had a tough time getting one fitting to stop leaking on the house side piping, and we ended up replacing it with a shark bite fitting.

The 'winterize bypass system' on the back of my old heater was worn out and the valves hadn't worked for years (I honestly didn't even know they were there). Since we are in FL and would never need to winterize anyway I elected to not duplicate the system.

Re: Converting to an on-demand water heater

Reply #49 –
The motoraid works as well on the new one as the old. It heats up quickly and the Styrofoam casing holds the heat in very well - far better than the original spun fiberglass roll. I can have hot water 6-8 hours.

Re: Converting to an on-demand water heater

Reply #50 –
That is indeed good to hear! Wish I could find a cut away view of the Atwood tank with the heat exchanger... We will definitely replace our unit with a three way.
Don
Quote from: Dave Head –
The motoraid works as well on the new one as the old. It heats up quickly and the Styrofoam casing holds the heat in very well - far better than the original spun fiberglass roll. I can have hot water 6-8 hours.

Re: Converting to an on-demand water heater

Reply #51 –
Quote from: acousticart –
Dave,

We have decided to replace the WH. Looking forward to the improved performence via the styrofoam insulation. What kind of flex hose did you use? The fittings on the both the old heater and on the manibloc appear to be pipe thread, while those braidied stainless steel hoses typically used for home washer hook up use garden hose type thread. Were these one you made yourself to length? If not how long were the ones you used?

Thanks, Don


Don,

I did just what JohnFitz did for the braided hose.  Readily available from Lowes or Home Depot.  Our coach has the 120V switch at the foot of the bed, and I just wired the 12V control line for 120V heating to be on all the time.  That way, we aren't confused about how to turn 120V heater on and off, and I didn't have to wire in a new 12v control switch!

Re: Converting to an on-demand water heater

Reply #52 –
I would be surprised if it changed much. I compared my old tank to the new one and they were virtually identical event though they were 17 years apart. Controls were handled differently, especially for the 120V heater, is all.

Re: Converting to an on-demand water heater

Reply #53 –
Make sure you check the inside diameter of the braided hose, there is a big difference between it and pex. ^.^d

Re: Converting to an on-demand water heater

Reply #54 –
I put in an RV 500 tankless and couldn't be happier. Got tired of problems with AquaHot and when it developed a leak that required complete replacement I did the change. Our '96 U-295 didn't have a regular water heater so I put it on a shelf just above the water pump in front of the right rear wheels. Cut through the bus door for the vent cover and put the heater as close to the door as I could before screwing it down. All the hot water we want and need to adjust to some cold for showers or it's too hot!

Re: Converting to an on-demand water heater

Reply #55 –
Hi Larry!
Welcome to the Forum. That is a nice coach you have! It was great seeing it and talking to you today. I was impressed with your water heater installation... very clean job. We may go that route when it is time put her back together after the bulkhead repair.
Regards, Don & Tys

Re: Converting to an on-demand water heater

Reply #56 –
So what are you using to heat the coach?

Re: Converting to an on-demand water heater

Reply #57 –
Electric when it's available and included, otherwise, we try to stay where it's warm. Our coach is one of those with wheels so it rolls down south pretty easily.