Water heaters, tankless vs. tanked in RVs.

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

kwplot34

Member
Joined
Jan 18, 2022
Posts
13
Location
Missouri
We boon dock mainly and our new motor home has the tankless. The biggest issue we had with it was the water wasted waiting for the hot water to come out. Solved that by having a 5 gallon water container and run the water in the container till hot, when container gets full I just pump the water back into the holding tank. Over a 7 day stay it wound up saving us about 10 gallons of water.
We have had this unit for a little over a year now and are getting use to the tankless, if asked which water heater would I rather have I would say doesn't matter to me, everything has it's advantages and disadvantages.
 

DonTom

Well-known member
Joined
Apr 21, 2005
Posts
6,796
Location
Auburn, CA or Reno, NV
Solved that by having a 5 gallon water container and run the water in the container till hot, when container gets full I just pump the water back into the holding tank.
I assume you mean pump back to the freshwater tank. How do you pump it back? What do you use for a pump?

I may start doing that too. Sounds like a good idea for when boondocked, as the tankless wastes a lot of water warming up.

IMO, the MANY disadvantages outweigh the single advantage of a tankless, especially when only one person, such as in my case. But that is a great way to solve one of the major issues with the tankless when boondocked.

-Don- DeRidder, LA
 

kwplot34

Member
Joined
Jan 18, 2022
Posts
13
Location
Missouri
I assume you mean pump back to the freshwater tank. How do you pump it back? What do you use for a pump?

I may start doing that too. Sounds like a good idea for when boondocked, as the tankless wastes a lot of water warming up.

IMO, the MANY disadvantages outweigh the single advantage of a tankless, especially when only one person, such as in my case. But that is a great way to solve one of the major issues with the tankless when boondocked.

-Don- DeRidder, LA

Yes I pump the water back into the fresh water tank.
I purchased a small 110v water pump from Menards, I have one hose that goes in the 5gl container and the other hose hooks up to the fresh water fill, takes about 2 min's to put the container empty. I will try to remember when I am out by the RV today to get a pic of the pump.
The water waste either at the kitchen sink or the shower waiting for the the water to get hot is the only downside we have had with the system.
Don't try and control the water temp by mixing water with the hot/cold, on/off , set the water temp with the controller and use full hot water at the shower.
 

DonTom

Well-known member
Joined
Apr 21, 2005
Posts
6,796
Location
Auburn, CA or Reno, NV
Don't try and control the water temp by mixing water with the hot/cold, on/off , set the water temp with the controller and use full hot water at the shower.
Yes, that is what I do. I set mine to 105F and only use the hot. But is the shower is stopped it comes back on way too cold and the way too hot, so it has to settle down each time. Way too many bugs for an RV, IMO.
The water waste either at the kitchen sink or the shower waiting for the the water to get hot is the only downside we have had with the system.
That's just one of the issues, but perhaps the main one.

-Don- in the DeRidder Waffle House, LA
 

Alontheway

Well-known member
Joined
Sep 12, 2021
Posts
246
Location
Alageorgia
Lou, no, not a blend tank, but just a tank inline with the pipe, the hot pipe, only the hot pipe, not a blended version. The pressure would not change at all whatsoever. The reason for a little tank is that instead of water running through a tiny pipe and being hot or cold or really hot at times, that when it hits the bulbous in-line tank portion that the incoming water has to mix with all that 1 gallon of water already in there and the output will be a more consistent temp of various temps of hot water from the wide range of hot water temps that come out of an on-demand heater due to turning water on and off...

I only turn on the boiler when I need it. In the summer 8 minutes is all that is needed to heat water for a shower. No sense to have that tank cycle on and off heating the water all day/ all night when it will not be used. The tans are not insulated all that great, and you will burn more than 8 minutes worth of propane per day just maintaining the heat than to just heat it up when needed - that is if you only need hot water for showers. If you use hot water 24/7 then keep it on. If just for a shower then heat when needed -save propane.
 

DonTom

Well-known member
Joined
Apr 21, 2005
Posts
6,796
Location
Auburn, CA or Reno, NV
So if it's say 20 degrees out. and the unit is not fully insulated to the outside.. it can freeze..
Mine uses a DC heater that comes on somewhere below 40F. I wonder how much current that thing draws when boondocked. Anybody know? I am plugged in here anyway, so it doesn't matter for now.

The worse of the deep freeze is over here. It's a fairly nice day here today, but some rain coming tomorrow.

-Don- DeRidder, LA
 

Alontheway

Well-known member
Joined
Sep 12, 2021
Posts
246
Location
Alageorgia
Your DC heater uses a LOT of power is the answer. If boondocking then turn that option off, unless you have plenty of solar or other charging going on.
The tank is insulated and at only 20 deg outside temps a previously-heated tank will stay above freezing inside with no problem (assuming you mean freezing at night and above freezing in the day). You can cut yourself a little foam piece to put inside the outer door of the boiler to help insulate the entire thing from the outside, but be sure to remove it before lighting up.d
It will take a lot of cold weather to freeze a 6 gallon tank overnight.
 

DonTom

Well-known member
Joined
Apr 21, 2005
Posts
6,796
Location
Auburn, CA or Reno, NV
It will take a lot of cold weather to freeze a 6 gallon tank overnight.
But there is no six-gallon tank in a tankless. And there is no way to turn it off, it's automatic when the temp gets too low, 40F, I think is where it comes on, IIRC.

Another disadvantage of the tankless in an RV.

Perhaps we should make a list of them, as there are quite a few of them.

-Don- DeRidder, LA
 

Skookum

Well-known member
Joined
Dec 19, 2018
Posts
744
I think we'll have a tankless in the new one. Not looking forward to some of its limitations. Then again... A buddy has an RV (tanked hot water) and a fitting leaked. The whole tank drained through the fitting and soaked the bedroom floor, all 10 gallons of it.
 

WILDEBILL308

Well-known member
Joined
May 6, 2012
Posts
3,126
Location
FORT WORTH TEXAS
Yes, Oasis or Aqua Hot is great -- love it -- especially with water hookup- unlimited indeed. But they don't have a hydronic system for gassers, as far as I know.
Call and ask. It should be doable the only problem is the burner runs on diesel. I don't know if they make one that can use gas or propane. I will just suffer along with my old diesel for now.
Bill
 

A Traveler

Well-known member
Joined
Aug 25, 2014
Posts
444
That is me with my Y2K RV. I turned it on perhaps an hour or so before I thought I needed to use it.

-Don- Deridder, LA
Say what? Would you do that in your sticks and bricks home? Honestly, what some of you do to save a couple of pennies borders on the ridiculous.

I turn on my hot water heater when we begin a trip. During the trip I will switch between propane or electric as needed. It is turned off when we get home. Done.
 

DonTom

Well-known member
Joined
Apr 21, 2005
Posts
6,796
Location
Auburn, CA or Reno, NV
Say what? Would you do that in your sticks and bricks home? Honestly, what some of you do to save a couple of pennies borders on the ridiculous.
Why do some people think everything is about money? It's about saving propane when boondocked for several weeks three hundred miles away from the nearest available propane.

I would be very happy to pay ten times the going price for propane in some areas.

-Don- Boondocked in Giddings, TX
 

Larry N.

Well-known member
Joined
May 26, 2010
Posts
8,999
Location
Westminster, Colorado
Call and ask. It should be doable the only problem is the burner runs on diesel. I don't know if they make one that can use gas or propane. I will just suffer along with my old diesel for now.
Bill
The hydronic systems need to be built in, Bill. The complexity in that type of system would be prohibitively expensive to add in later, and it would probably mean almost disassembling the coach. These things have distributed heat exchangers in different spots in the coach for furnace heat, AND they have the entire hot water system of faucets, etc, fed through them, they get heat from the engine block, and some versions provide engine block heaters in addition to the more normal type. It's like adding hot water floor heaters in a S&B house in that addon isn't practical.

As a result, it would only be if the coach manufacturers decided to install them in gassers that we would see that-- unlikely in my opinion.
 

WILDEBILL308

Well-known member
Joined
May 6, 2012
Posts
3,126
Location
FORT WORTH TEXAS
I think we'll have a tankless in the new one. Not looking forward to some of its limitations. Then again... A buddy has an RV (tanked hot water) and a fitting leaked. The whole tank drained through the fitting and soaked the bedroom floor, all 10 gallons of it.
Nothing to stop a tankless from leaking so I don't see that as any benefit. That is some serious stretching to find a problem/reason.
A Traveler, I agree. If the few cents it cost to keep hot water on tap is going to be a problem, well. I don't/ didn't care what it cost in my last coach. My wife liked to have hot water to wash her hands after using the restroom. That was reason enough to keep it on. Now the motor keeps it hot when driving and the electric heaters do when plugged in and if it is realey cold I turn on the diesel burner. Unlimited hot water and no problems like the tankless or the propane electric tanked ones.
Bill
 

WILDEBILL308

Well-known member
Joined
May 6, 2012
Posts
3,126
Location
FORT WORTH TEXAS
Why do some people think everything is about money? It's about saving propane when boondocked for several weeks three hundred miles away from the nearest available propane.

I would be very happy to pay ten times the going price for propane in some areas.

-Don- Boondocked in Giddings, TX
Please tell us where you are camping 300 miles from a propane supply? If concerned with propane usage you need to get a extend a stay kit. Robot or human? (funny what the link turned into, I am leaving it as it still works)Then you run off the external tank and just refill as needed. Heating water doesn't take nearly as much propane as the furnace does.
Bill
 

DonTom

Well-known member
Joined
Apr 21, 2005
Posts
6,796
Location
Auburn, CA or Reno, NV
Please tell us where you are camping 300 miles from a propane supply?
I could probably tell you low propane stories all day long.

Try to buy propane in NM the afternoon before Xmas or on Xmas day. I went through that three years ago. I finally got my propane in AZ where they sell it at gas stations, unlike in NM, where they don't sell it at gas stations. At least not in the southern part of NM where I was three years ago. That was when my refrigerator quite working, ran out of propane. Coming back from a long boondocked stay at the Big Bend of Texas.

Motorhomes usually (always?) have non-removable propane tanks. That means the RV has to go to get the propane, which is often a hassle. I had to do that last month when in the Everglades. I had to devote a day to drive to Homestead to get propane. That time wasn't a big deal, just a small hassle and a wasted day of my 14 days of being boondocked there.

But if there is a way to double my propane capacity, I sure would love to hear about it.

-Don- Giddings, TX
 

DonTom

Well-known member
Joined
Apr 21, 2005
Posts
6,796
Location
Auburn, CA or Reno, NV
if asked which water heater would I rather have I would say doesn't matter to me, everything has it's advantages and disadvantages.
Sure, in some cases the endless hot water of a tankless is a great advantage, such as if a family wants to shower one after the other when having city water at an RV Park.

But for just one person, the tankless is ALL disadvantages and NO advantage at all. Not even one advantage-Zero-zip, boondocked or at an RV Park, still none.

Again, I can live with my tankless, but I prefer the 22-year-old tanked in my old RV MUCH over the tankless in this new 2022 RV. I had NO complaints at all with my Y2K RV water heater. But in this new RV, I am reminded every morning when I try to use warm water to wash my face and have to waste many gallons of water to do it when boondocked. Not that big of a deal except when boondocked for a long stay.

-Don- Giddings, TX
 

WILDEBILL308

Well-known member
Joined
May 6, 2012
Posts
3,126
Location
FORT WORTH TEXAS
But if there is a way to double my propane capacity, I sure would love to hear about it.
Not paying attention to your propane supply and not re filling before you run out is not the same as being 300 miles from any propane supply.
Well apparently you didn't read what I posted. Get an extend a stay and you can triple your propane capacity.
Bill
 
Top Bottom