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Surfairstrea · 11-28-2015, 08:43 AM

I have been thinking about setting up with a tankless water heater. Thought I would experience all the wisdom this site has to offer.
What do you guys/gals have to share?
LPG or Electric?
Specific models that have a proven record?

Thanks,
Steve

switz · 11-28-2015, 09:05 AM

There is not enough battery power to run an electric instant on water heater. Most units here in the states are looking for 240Vac if they are to be powered in a home. I have this design in two structures and the 120Vac energizes the control circuit and burns natural gas to heat the water.

We have installed the Truma 'AquaGo custom' model in both the Classic and the 23D. It uses minor 12Vdc power for the control circuitry and uses the propane for fuel.

Truma AquaGo® provides instant hot water while on the road

One of the advantages of the Truma is that it is a smaller box size than the stock 6 gallon water storage tank models. That makes installation much easier for the Vintage trailer crowd. Another major advantage is that they are made in Germany instead of China like all the other RV water heaters. You can see the quality in the fit and finish and there are distributors in the US.

I chose the 'AguaGo custom' (which is the middle unit of the three models) which has a circuit to keep itself from freezing if the battery power and propane are left on. Otherwise, a simple flip of a valve can drain the system.

Propane is not being used to keep the 6 gallons hot all the time, just when the hot water is needed.

rmkrum · 11-28-2015, 02:29 PM

I installed a PrecisionTemp 500 in place of the 6 gallon Atwood. Wife loves the long, hot showers without worrying about running out of hot water. Slightly taller than the Atwood but fits in the same width. Makes NO noise when turned on and sitting, and very little when heating water. The Atwood would wake me up an night with the sound of water heating. See other posts on the forums about perceived issues, and other opinions--I've had no issues and, although it's pricey, I feel it was well worth it. It does need good water flow and propane pressure to work correctly, so be sure your propane regulator is working right and you do not use a cheap external pressure regulator. We've used ours with no issues in 26 degree weather (on internal water pump), You may need to add an accumulator tank to reduce pump surging--the Atwood has an air bubble that helps with this, the PrecisionTemp, by design, does NOT have or need an air bubble in it. This PrecisionTemp has freeze protection as well. Atwood makes a licensed copy but I don't know that much about it.

switz · 11-29-2015, 08:09 AM

Also, the Truma 'AquaGo comfort' weighs 34 pounds less than the six gallon standard Atwood water heater. That swap out is removing about 84 pounds of fixed weight or increasing payload for your stuff by 84 pounds.

BoldAdventure · 11-29-2015, 09:23 AM

switz do you have a picture of the outside door for the water heater? I noticed it looks really different from the standard atwood. Curious if you reused yours or modified it?

The Truma looks really appealing though. I think this is on our wishlist.

Surfairstrea · 11-29-2015, 12:50 PM

Swath,
I spent some time this weekend going over the Truma website. Looks like a great product. After reading all of the other posts, from early 2000, it looks like flow rates were a problem for the that time. Are you happy with the flow rates that the unit is able to obtain under the demands of a given water temperature?
Steve

Mixter · 11-29-2015, 01:25 PM

I just bought the Atwood OD-50 on demand water heater. PPL had it for 681 with door, shipped. I'm not ready to use it yet, as I currently need it to be in place as I'm installing all new belt line trim after shell off resto. I wanted to have the water heater in place so that my trim will match up to the water heater door, so had to make a choice.

I'm not a fan of super heating a traditional tank up real high, so that I can "mix" in cold water to reach ideal temp. When bench testing my old Atwood 10 gallon, I found that I could have plenty of hot water doing it this way because when mixing in super hot water, I could get alot of mileage out of the 10 gallons. But #1- I dont like the idea of heating up 80 lbs of hot, hot water to do that, and #2, I want to setup an external hookup to my Hot line so I can have a Hot shower outside. I dont want to "mix" Hot and Cold to do this. Rather, I like my Hot side to be about 120, so I can just turn either Hot OR Cold on fully, with no mix. An On Demand style fit this bill for me. Not to mention, I can have endless hot showers for me and my family of 5.

The Precision Temp RV550 and the older RV500 have stellar reviews. But the RV550 is $1100. The Atwood OD500 is supposedly the old Precision Temp RV500, so I took a chance, since its saving $400 bucks.

Since I'm not anywhere close to using this thing, I thought I better bench test the unit because if I go to use this thing in a year and it doesnt work, I'd be up a creek.

Bench test was simple, and I was vey impressed. It has the PT technology of the modulating valve, which increases the burner to keep up with high flow rate, and reduces the burner for lower flow rate so that it doesnt create scorching hot water on low flow. It kept up with my home hose water pressure at wide open no problem, which I'm sure is more than 2- 2.5+? gpm flow. AND it produced consistent hot water all the way down to just a trickle of flow. I had read reviews about these being sensitive to gas pressure and water flow. I did not find this to be the case with my bench test.

Hope that helps. I didnt find a whole lot on these units when I was researching.

rmkrum · 11-29-2015, 02:09 PM

Ours is a 550. I like it because it handles freezing temperatures automagically as long as propane and power is on. Easy camping in 20 degree weather. Heard it light off once--it's really quiet. I don't know if the Atwood has freeze protection.

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Mixter · 11-29-2015, 02:19 PM

Yes- Atwood OD50 comes with same freeze protection.

rmkrum · 11-29-2015, 05:02 PM

Ok. Makes sense since it's a licensed copy.

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Mixter · 11-29-2015, 05:52 PM

Yeah- wouldve done the original because of the reviews, but gambled on 400 savings to go with what for all I could tell was a rebrand. Although thats assumption.

switz · 11-29-2015, 08:30 PM

The Truma door we used comes only in white (see first photo of installed door on the 23D that extends down below the belt line). We covered the main door panel with Airstream external skin aluminum and painted the edges a silver color. (see the silver photos from the Classic where the mounting is above the trim line). The cover is made of Corlon so getting the proper primer and paint is necessary.The wasp cover is a standard part we found.

Note that the Truma has smaller overall dimensions the the Atwood. So we had to install 'aluminum studs' to frame a smaller opening in the side of the trailer and then skin that like in a repair. That work gets hidden by the larger frame of the cover.

We have an adequate flow when showering having to adjust the shower valve to cool the water down. Minimum water flow of 0.4 gallon per minute is required to cause the burner to come on to heat the water. There is a sensor to continuously adjust heater output based on volume of water flow and the inlet water temperature so the water temperature leaving the heater is around 120 degrees (same as in my home instant on unit).

Mixter · 11-30-2015, 06:50 AM

That looks great!

switz · 11-30-2015, 07:07 AM

Forgot to mention that the white cover shown above was converted to the aluminum appearance after all the fitment exercises were complete.

BoldAdventure · 11-30-2015, 09:34 AM

Did you have a place do that work? If so I want to get their information. That's well outside of my DIY scope but it looks fantastic. Nice work!

pmclemore · 11-30-2015, 09:44 AM

I have a tankless heater at home, and it works well there - you can run your shower continuously. However I would not buy one for my trailer as we often camp where there is no sewer hookup. When you take "navy" showers, every time you turn off the water, the water heater turns off. These systems do not work as well when you turn them on and off.

If you always have a sewer hookup, you can just leave the water running and you will not have an issue. For those who like to dry camp, you should consider carefully.
Pat

Mixter · 11-30-2015, 02:37 PM

For what its worth, I dont know that mine would be an issue for navy shower. Granted, thats not what I bought it for, but the bench testing was quite impressive. It fired up instantly, and I saw no more than a "slight" fluctuation in temp when cycling on/off. I guess because the lines still have hot water in them, and the water in the heat exchanger was still hot, so not really sure why there would be an issue.

I too, read some comments discussing this prior to my purchase, but I can confirm no issue with the Atwood OD50 here. Perhaps maybe with the Girard, which doesnt have many good reviews?

switz · 11-30-2015, 07:36 PM

Both of the Truma 'AquaGo custom' units were installed by A&P Vintage Trailer Works in Paradise, TX as part of a long list of modifications. The Classic's unit was Paul's first install of the Truma product and the 23D was about his fourth. He is very pleased that the size is much smaller than the Atwood tank heaters for restoration work on the vintage trailers where space is at a premium.

This installation off loaded about 84 pounds of weight consisting of the 6 gallons of water and the net weight difference between the Atwood and the Truma.

A&P Vintage Trailer Works | Repair Restore Update Vintage Trailers by A&P Vintage Trailer Works

rmkrum · 11-30-2015, 08:19 PM

In really cold weather, with our rear wet bath, and the water heater in the bottom of the wardrobe forward there is a noticeable delay of 1-2 seconds before you get hot water at the shower. I have more of an issue adjusting the temp in the shower because of the long shower hose. Takes a bit of patience. Once the temp is dialed in, it's flat out stable. Besides, if wife is happy, everyone's happy.

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switz · 12-01-2015, 08:04 AM

Unless the water heater is just below the faucet and regardless of the hot water generator, the volume of water in the hot water line from the heater location to the faucet has to be purged before one feels any warmth.

The Quick shower on/off technique has the same water cooling between squirts regardless of the source.