Frustrated with water tank safety overflow and tankless water heater

Joseph_67097999e8f07

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Just purchased brand new 2024 Imagine AIM. My first camper was an R-pod and I wanted to get a slightly larger unit but still light enough to tow with my SUV. Took it out the last few days just to test it and learn how everything works and I’m very frustrated. Seems like I made a bad purchase. I love the build quality and the floor plan but this unit is obviously meant to only be in a campground with electrical and water hook-ups. For 6 years with the R-pod, I NEVER had connections (in Wyoming and love to camp up in the mountains and get away from civilization.) I never had a problem running out of water, propane or battery for 3 night/4 day trips, but in just one and a half days this unit ran out of water and TWO batteries were very low despite the rooftop solar charging. My main complaint is the water. This freshwater tank has safety overflow only because it is possible to fill it from the city water connection. However, I always fill my tank from the gravity connection, which does not require overflow protection. We stopped halfway along the road and could still see water coming out of the overflow tubes from the tank if the RV was slightly unlevel. (NOT from the main tank drain valve) When we got to the campground, the command center showed freshwater tank only 2/3 full. Then, we discovered the horrors and inefficiency of a tankless water heater requiring too much water flow before the water gets warm, thus wasting even more water. My 2 questions for the experts out there: #1: since I ONLY fill my freshwater tank by gravity fill, is it safe for me to seal off the two overflow tubes from the freshwater tank? #2: any tips or tricks in settings to get the tankless water heater to heat faster? The manual said if it was cold outside to turn the flow knob in the water heater compartment towards minimum for faster water heating but I tried that, and it did not make any difference at all.

I can always get around the electricity hog of this camper by investing in a generator. But without a water supply that can last me 3 nights/4 days, I may as well sell this 1 week old camper because Boondocking is all I do.

Thanks in advance,

Joe
 
Welcome to the forum.

There are a lot of threads here that talk about how the overflow on the fresh water tanks seem to keep syphoning off water. Lots of folks put on a shutoff valve on the overflow and stop the flow once the tank is full. And everyone of those threads comes with a warning to remember to open that valve when filling so you don't overfill your fresh water tank lest it rupture.

As for the tankless heater. I have no experience with them so cannot comment on that. I do know that when we need to conserve water we first run the hot water into a container until it gets hot. Then we use that water to flush the toilet. But I'll guess having dry camped a lot you already know that trick.

yep - new campers, lots of electronics, lots of loads always drawing from the batteries. So now manufacturers put on a minimal solar system. It seems like that what newer campers like - electronic "stuff". We've always relied on amply battery(s) supply and a small 2000 watt generator (or 2 the wanting air condition).
 
I am not sure how Grand Design deals with venting the fresh water tank since you have gravity fill. I would say, as long as that tank is vented and you don’t created a closed system, you can probably get by closing off the overfill tube(s).

As far as the tankless water heater, the number one complaint seems to be the amount of water that gets wasted waiting for it to get warm. Since the flow control knob will slow the process for getting the hot water from the heater to the faucet, any decrease in the time it takes to heat the water will be nullified by the lower flow rate.

I am actually in the process of writing an article on tankless water heaters and can share some of the data that I have gathered regarding this very subject. While my example below is somewhat generic, I think it helps explain the reason for the extra wasted water.

In an RV, typical water supply lines are ½”, internal diameter. Since the volume of ½” pipe is .0102 gallons per foot (gal/ft), you would have to expel just over .2 gallons of water before you would feel hot water from a 20’ run of pipe if you had a tank type water heater – a fair estimation of total hot water line between a water heater and kitchen sink in many RVs. Since a tankless water heater must first ignite, then heat the water, a process that takes 19.5 seconds on my demonstrator tankless water heater system set at 124 degrees Fahrenheit, it takes considerably longer for hot water to reach the faucet. With a flow rate of 1.2 gallons per minute (gal/min) or .02 gallons per second (gal/sec) – the standard for low flow water faucets, it would take an additional 10 seconds or a total of 29.5 seconds for full temperature water to reach a faucet connected by 20’ of ½” water pipe. That means that you would have to expel .59 gallons of water before you get full temp water at that faucet with a tankless water heater vs. just over .2 gallons of water with a tank type water heater.”
 
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I use 7 gallon Reliance (Aqua-tainer) blue jugs (the kind with the large cap/spigot). I removed the spigot and force threaded a brass garden hose bibb (I wish the manufacturer had molded female npt for their spigot).

The Nautilus panel sanitize setting will suck water out of the container using the pump. I rotate the modified cap between containers (I have four of them).

I don't like the warm up time either for using the fresh tank, but love the on demand heater when we have full hookups.
 

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We recently got our Reflection with an on demand water heater. Our previous TT was a Transcend with a 6 gal tank. Most of the threads that were helpful said to 1) set the temp for 102-106 degrees for showers and 2) only turn on the hot water spigot. The tankless water heater output temperature is vey dependent on flow, so only running one spigot makes the flow constant and from my observations very dependable. If you need to do dishes, turn it up to 120 degrees. In other words, don’t turn on the cold water at all, you will be adjusting the temperature and the tankless water heater will be changing in the opposite direction. We recently camped for 3 nights with electric only (dry camping) and had enough for both of us to take showers each day (3 x 2 showers). The only negative is that the 6 gal water heater would tell you when your shower is done, the tankless water heater lets you linger probably longer than needed. It is still nice finishing the shower with hot water!
 
I am usually on full hook-ups so we are big fans of the on-demand water heater, but when were are using the fresh water tank we have a 2 gallon bucket in the shower to catch the water when it is heating up. We then use that water to add to the toilet after each flush instead of filling from the peddle, so we end up with no water really wasted.
 
Just put a shark bite valve on the overflow and close it. I used this one because I wanted it to be obvious at a glance if it was open or closed. But there are also cheaper smaller ones.




You ran out of water because it all siphoned out .. stop that and it should do much better.

Also check that your solar charger is actually charging, they aren’t always perfect first trip.
 
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I am not sure how Grand Design deals with venting the fresh water tank since you have gravity fill. I would say, as long as that tank is vented and you don’t created a closed system, you can probably get by closing off the overfill tube(s).

As far as the tankless water heater, the number one complaint seems to be the amount of water that gets wasted waiting for it to get warm. Since the flow control knob will slow the process for getting the hot water from the heater to the faucet, any decrease in the time it takes to heat the water will be nullified by the lower flow rate.

I am actually in the process of writing an article on tankless water heaters and can share some of the data that I have gathered regarding this very subject. While my example below is somewhat generic, I think it helps explain the reason for the extra wasted water.

In an RV, typical water supply lines are ½”, internal diameter. Since the volume of ½” pipe is .0102 gallons per foot (gal/ft), you would have to expel just over .2 gallons of water before you would feel hot water from a 20’ run of pipe if you had a tank type water heater – a fair estimation of total hot water line between a water heater and kitchen sink in many RVs. Since a tankless water heater must first ignite, then heat the water, a process that takes 19.5 seconds on my demonstrator tankless water heater system set at 124 degrees Fahrenheit, it takes considerably longer for hot water to reach the faucet. With a flow rate of 1.2 gallons per minute (gal/min) or .02 gallons per second (gal/sec) – the standard for low flow water faucets, it would take an additional 10 seconds or a total of 29.5 seconds for full temperature water to reach a faucet connected by 20’ of ½” water pipe. That means that you would have to expel .59 gallons of water before you get full temp water at that faucet with a tankless water heater vs. just over .2 gallons of water with a tank type water heater.”
Excellent idea, i camp off grid a lot and water consumption has been a bit frustrating. thanks
 
In an RV, typical water supply lines are ½”, internal diameter. Since the volume of ½” pipe is .0102 gallons per foot (gal/ft), you would have to expel just over .2 gallons of water before you would feel hot water from a 20’ run of pipe if you had a tank type water heater – a fair estimation of total hot water line between a water heater and kitchen sink in many RVs. Since a tankless water heater must first ignite, then heat the water, a process that takes 19.5 seconds on my demonstrator tankless water heater system set at 124 degrees Fahrenheit, it takes considerably longer for hot water to reach the faucet. With a flow rate of 1.2 gallons per minute (gal/min) or .02 gallons per second (gal/sec) – the standard for low flow water faucets, it would take an additional 10 seconds or a total of 29.5 seconds for full temperature water to reach a faucet connected by 20’ of ½” water pipe. That means that you would have to expel .59 gallons of water before you get full temp water at that faucet with a tankless water heater vs. just over .2 gallons of water with a tank type water heater.”
This doesn't match my experience. My TWH reaches full temperature (as shown by the wall meter) in 3 to 4 seconds. When showering, we use a small bucket to catch the water as it heats up. There's rarely very much water there.
 
This doesn't match my experience. My TWH reaches full temperature (as shown by the wall meter) in 3 to 4 seconds. When showering, we use a small bucket to catch the water as it heats up. There's rarely very much water there.
On your RV, the close proximity of the water heater to the shower will certainly make a difference. Three to four seconds seems fast, mine takes that long just to sense water flow and light. There are a lot of variables that come into play, one of the biggest being incoming water temperature. I did most of my testing on a 65,000 btu TWH (not Furrion), high flow water pump, incoming water at 68 degrees, and water heater set to 124 degrees.

Since the copper tubes on the heat exchanger first run around the outside and act as a preheater before entering into the flue where the real heating is done, the water heater will heat the water much faster each time the hot water is turned on (until the temperature stabilizes). Where the problem comes in, is when the hot water is turned off briefly, then back on. The flue fan continues to run for a brief period to cool the heat exchanger down to a safe temperature, then when you turn the water back on, cold water is introduced until the burner reignites. On a hot day with the water hose sitting in the sun, that incoming temperature may very well be close to 100 degrees. For those that camp in colder climates, that water may be in the 30’s or 40’s.

I attached the entire article I wrote. Keep in mind, this is very generic and not specific to any RV manufacturer or water heater manufacturer. Of the three units I tested, two had water mixing chambers, and the burner sizes ranged from 40,000 btu to 65,000 btu. It was intended to help people better understand why their tankless water heater operates differently than their old tank type water heater, and to help them modify their usage to make it work better for them.
 

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