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Installation Of 2 Atwood Water Heaters
Just finished the installation of 2 new water heaters. I wish I had seen the information that John Wade shared about Atwood water heaters before we ordered ours. Link Here
We ran into the exact same problems that John did. The most significant problem was the threads pulled out of bolt holes that hold in the heating element and the thermostat controller retainer for the top water heater.
The original water heaters had the engine coolant inlets and outlets on the back side and all the other connections on the front side. The new water heaters had all of the water inlets, water outlets, engine coolant inlets, engine coolant outlets, and electrical connections on the front side. It sure was crowded making all the new connections in the front side.
Conclusions:
1 – I cannot recommend Atwood water heaters for the reasons the John Wade stated in his posting that I also ran into.
2 -I f you have to replace your Marathon installed water heaters, tt will be a lot easier if the new water heaters are configured like the originals with the engine coolant loop inlets and outlets in the back of the water heater.
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9 Replies
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I replaced mine last weekend with 2 Kuuma units. It was no cake walk.
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Nice job guys….
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Tim and TG, could you please put more info here on what you ordered (brand, model, etc) so I can research further? Looks like I’ll be in this water heater club soon. I measured the existing which are 16 x 16 x 16. The 11 gallon Kuumas are something like 22 or 23 inches deep and I don’t see how they would fit. Can’t find the Atwoods, they seem to be out of stock everywhere.
Kirby
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Kirby,
Be aware that the different brands of water heaters list their dimensions differently. Some list just the “box” dimensions, some include the mounting feet in the front to back dimensions, and some include the mounting feet, and any and all connections in the front to back dimensions. For example, Look Here.
Just my opinion.
I cannot recommend Atwood water heaters. I had to repair the threads that hold in the heating element, the thermostat controller retainer, and the mounting bracket feet, (the same 4 bolt holes) as described by John Wade in his posting. On one of the water heaters, the insulation was folded in half on the top portion of the tank. That left half of the tank with no insulation. I repaired the insulation easily but if I hadn’t removed the casing I would never have known that most of the top of the tank had no insulation as delivered. I used them, but only with numerous repairs and modifications.
Having said (written?) that, I used the Atwood 94550.
Good luck
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Tim, thanks. Where did you find/buy the Atwoods?
Kirby
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We got them from “Marine Engine Parts”.
They look to be “out of stock” currently.
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I ordered mine from Defender Marine. For the record, and I believe this was discussed on another post, I replaced the original pair of Atwood 11 gallon units with a pair of 6 gallon Kuuma units, product #501145, so I’ve gone from 22 gallons of hot water to 12 gallons. So far, this has not been a problem for my wife and me.
I made this decision after talking to Marathon and learning that their replacement units would not only require modifications to my water bay configuration, but were back-ordered at the time. My OEM units were leaking internally and I had valved them off to avoid deterioration of the floor in the water bay. Total price for the Kuuma’s was $515 and they would fit in the same footprint as the OEM units so I figured that worst case this could be temporary solution.
That said, the installation was not easy. Marathon provides a single 15 amp circuit to the water bay. Each of the new units pulls 15 amps, so I had to modify the new upper unit to accept the 2-stage thermostat that was installed on the original Atwood unit. I was not happy having to grind the mounting bolts off the tank of the brand new Kuuma unit but was committed to a point in the project that I did not have a choice. I can post a picture of that modification if anyone is interested.
Next problem was that the original units not only had connections for the heat exchanger loop on each but cross-connections between the two as well. This allowed both units to run off the Webasto loop when sitting still OR off the engine loop while going down the road. My new units only have one “in” and one “out” so I currently have one loop hooked to the upper unit and the other on the lower. Marathon suggested abandoning the engine loop and just using the Webasto loop for both and plumbing them in series. My question is can I use a “y” connector and cross-pollinate these two loops. The jury is still out on this so I will let you know what I learn.
In short, I’ve got hot water and a dry water bay for now. Hope this helps.
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Well done TG… Marathon does change things, my 02 water heaters only had 1 shut off valve on each heater, so I assume they tied the webasto and engine coolant lines together prior to the water heater bay. My 04 is like yours, 4 cut-offs an in and out each for both engine and webasto. I turn them off, scalding water is not fun from engine temp coolant.
1999 XLV X-6872, liberty #440 -
It appears that some of your coaches have 10 gal. heaters stacked on top of each other. Our Country Coach and the heaters in a cabinet side-by-side. I replaced the 2 Atwood 10 gal. units with 1 20 gal. unit which easily fit in the same space with room to spare. All the connections were easily accomplished and the only “draw back” is that there is 1 heating element for the 20 gal. vs. 2 (1 for each 10 gal.). I have not seen any negative to this over the last 5-6 years and I don’t have to worry about both heaters kicking in and blowing circuits. I have never had to wait more than 10 minutes to have enough hot water for both of us to get showers.
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