Tankless water heater

[Raspy]

As far as propane use goes, I run my fridge from a day before we leave until a day after we return. On propane while we are gone, and shore power at home the day before and after. We are almost never hooked up to shore power while traveling. We cook great dinners and breakfasts on the propane stove. In winter I set the heat at about 55 at night, and warm it up in the morning to 60-65 when we first get up, and then off. I turn on the water heater until it is warm, then turn it off and shower. The water heater is only used for showering, or to prevent freezing the lines if it is really cold. I have a recirculating pump that keeps the lines warm and gives instant hot water at the faucets and shower, to preserve water and prevent freezing. I'd rather preserve water than propane. And when it gets really cold on the highway, I'll start the water heater and turn on the recirc pump. This got us over a couple of mountain passes at about 8 degrees, late at night, with no problems. And working our way along, late at night in a snow storm, trying to make Winnemucca.

[steve dunham]

Originally Posted by Raspy

As far as propane use goes, I run my fridge from a day before we leave until a day after we return. On propane while we are gone, and shore power at home the day before and after. We are almost never hooked up to shore power while traveling. We cook great dinners and breakfasts on the propane stove. In winter I set the heat at about 55 at night, and warm it up in the morning to 60-65 when we first get up, and then off. I turn on the water heater until it is warm, then turn it off and shower. The water heater is only used for showering, or to prevent freezing the lines if it is really cold. I have a recirculating pump that keeps the lines warm and gives instant hot water at the faucets and shower, to preserve water and prevent freezing. I'd rather preserve water than propane. And when it gets really cold on the highway, I'll start the water heater and turn on the recirc pump. This got us over a couple of mountain passes at about 8 degrees, late at night, with no problems. And working our way along, late at night in a snow storm, trying to make Winnemucca.

Hi Raspy , your recirculating hot water system sounds like a good way to save water . We seldom cook in our trailer beyond making coffee and in the Spring / Fall when camping we heat water on the propane cooktop
I am amazed at the ingenious methods people devise to use as much electricity and propane as possible thus justifying 2-30 lb propane tanks - 6 lithium batteries- 800 watts of solar - a 3000 watt inverter , a 4000 watt Honda generator and taking 15 minute showers
I will admit I am lazy and cheap so I have no intentions of spending that kind of money nor installing and maintaining that much stuff !

[redbarron55]

PS ; Tankless water heaters have their place , camping without hook ups is not one of them !!
Noisy & wasteful !!
The tankless is far quieter than the tank type water heater as (at least mine) makes almost no noise whatever. About the same noise as your grill.
As to wasteful the fault would be in the tap that is turned and not the heater.
We spent a month in a state campground in Decora Iowa with no hookups and somehow survived. A lot of the further north campgrounds have no water or sewer due to freezing weather.
Don't blame the appliance for lack of discipline in water usage, just because it does it's job well.
It sounds more like lack of experience with the small tankless water heaters rather than some inherent flaws in them.
The fact that somehow you think that the small ones are noisy would reinforce that.
They are difficult to find a good place to mount, but then they take up a lot less space than the tank and space is very valuable in a little trailer.
Again the biggest problem with mine is the corrosion in the contacts on the battery compartment not making good connection. I replaced the contact with a better part from a battery holder, but soldering a wire between the two batteries will work as well. Since the batteries last a very long time it is not a big hassle. (a spare set of D cells with the connecting wore would be a good idea, perhaps.)
I made the mounting cabinet from stainless steel and Lexan to keep it out of the weather and road spray, but other accommodations would work as well.
So the advantages might be
1. Light weight
2. Low cost
3. More room for storage in the trailer
4. Quieter
5. No trapped 6 gallons of water in the heater.
6. Low LP gas usage.
7. Unlimited hot water.
8. Easily adjustable water temperature and flow
Cons
1. Harder to find a mounting spot
2. Requires some discipline on water usage since #7 above
3. People compare them with Tankless for a house.
4. Different
5. Requires thinking outside of the "Box"
6. Is not "made" to go into a camper space.

Either way
1. It takes less water running if the hot water line is short and small diameter.
2. Water discipline counts.
3. The water you use goes into the gray tank and needs to be controlled just like the potable water.
4. If you haven't had experience your opinions are just that - opinion not based on experience.

On a completely different note I have considered using the heater in a closed loop to feed a small radiator with a fan for space heating using a small pump. The plan is to use the water line going to the sink for the feed and Teeing off to the pump and radiator and then back to a small accumulator tank to recirculate. This way there would be no delay in getting the hot water to the furthest fixture and space heat as well.
A nice winter project for FrankenScamp... Since the heater has a thermostat to control the water temp it should not overheat the water, but a pressure temp relief valve would still be necessary. Now to find a spot for the radiator and fan. (a nice quiet computer fan should do nicely)

[CarlD]

JD - I whole heartedly agree with your assessment. I considered permanently mounting the water heater somewhere and using it for space heating also. I think it is very doable. You could use a heater out of a vehicle. If you have space for a small baseboard radiator, you wouldn't even need a fan. A thermostat, circulator pump, pressure accumulator and relief valve would probably do the trick. The one major concern I had with this design is freezing in cold weather. Since you are using fresh water for both heating and hot water you can't treat it with antifreeze, and if your unit is outside it would freeze up if it is not running. maybe a heat exchanger could overcome this problem but it starts to get complicated.

[Raspy]

The recirc pump for instant hot water is very nice. Hot water is already at the faucet and waiting. It is arranged such that one loop serves the kitchen sink, the bath sink, the shower, and freeze protects the cold supply to the outdoor kitchen. I ran a line from a tee in the hot shower line, close to the shower, to a circulator placed next to my water pump, to the cold supply line that feeds the outdoor kitchen, which completes the loop back to the water heater. By having the circ pump in the same compartment as the pressure pump, that area gets freeze protection too. An accumulator is an important part of the system, to keep the pressure stable. These should be in any system that uses a tank type water heater anyway.

Using the water heater for space heating would be a fun project. Either a fan/coil system, baseboard, or radiant heating in the floor. Radiant would be the best, but would cost about 1 1/4" of headroom and require new flooring.

JD, I'm wondering if your Mini Split system can be installed on its side, laying down? Are they OK in that configuration?

[redbarron55]

I don't think you can lay the outside unit on it's side as the compressor probably cares where the oil tends to collect. Other than that I would not know. The electronics would not care.
Since the water tank and pressure pump is under the bed in the rear running the hot water all the way back there might not be a good idea. The accumulator in my system is in the front after the sink tap off so it would be in the circulation path If I were to tap off the hot side of the sink to go to the pump/radiator and then return the water to the sink cold side.
The problem with returning it other than in the line to the heater by itself is the cold water would be hot too.
The other issue might well be that the accumulator is a plastic Attwood unit and it may not like the heat.
Another issue would be to make sure that the pieces you use do not have lead or other contaminants since the potable water is shared with the heater circuit.
If you use an automotive heater coil then it might be a good idea to choose one with aluminum tubing to be sure that copper ones are not soldered with lead.

[steve dunham]

An hydronic fin tube heating system is designed for water in the 180 to 190 Deg F temperature range . A water heater is not designed to heat water to that high of a temperature . I am not saying it won’t work in a trailer but it won’t provide the advertised BTUs .

[Raspy]

Originally Posted by steve dunham

An hydronic fin tube heating system is designed for water in the 180 to 190 Deg F temperature range . A water heater is not designed to heat water to that high of a temperature . I am not saying it won’t work in a trailer but it won’t provide the advertised BTUs .

Steve,

Baseboard or fin tube systems run fine on lower temperature water. It just means a slightly larger unit is required to output the same number of BTUs as one running at the higher temp. But the actual required size has a lot of variables anyway. Probably, the best choice would be a fan coil system in a cabinet, as it would be less in the way. As I recall, my water heater high limits at 140 degrees, which is where I ran all my baseboard or radiator systems in houses anyway. Over the years, I can't remember ever designing a system to run at 180 degrees, even though that is what they are designed to do. Another option might be to install a flat, sheet metal radiator type system vertically on the closet wall. It would look sort of like an old fashioned wall heater that used to be put in homes. No floor space or cabinet space given up. And no fan noise. It could even be mounted on the closet door and swing with it, if no other spot was available. At 140 degrees it would be less dangerous to the touch than at 180 degrees. Just some thoughts.

[steve dunham]

Originally Posted by Raspy

Steve,

Baseboard or fin tube systems run fine on lower temperature water. It just means a slightly larger unit is required to output the same number of BTUs as one running at the higher temp. But the actual required size has a lot of variables anyway. Probably, the best choice would be a fan coil system in a cabinet, as it would be less in the way. As I recall, my water heater high limits at 140 degrees, which is where I ran all my baseboard or radiator systems in houses anyway. Over the years, I can't remember ever designing a system to run at 180 degrees, even though that is what they are designed to do. Another option might be to install a flat, sheet metal radiator type system vertically on the closet wall. It would look sort of like an old fashioned wall heater that used to be put in homes. No floor space or cabinet space given up. And no fan noise. It could even be mounted on the closet door and swing with it, if no other spot was available. At 140 degrees it would be less dangerous to the touch than at 180 degrees. Just some thoughts.

A lot depends on degree days , insulation , wall space , orientation, window type & size , and outside design temp
I have done homes where on the North and West walls we ran dual fin tube in order to pump enough heat into the living space to maintain a reasonable temperature
I have done homes with dual boilers , one was a hot deck boiler with outside anticipator control and the second boiler was thermostatically controlled
When converting homes with gravity heat with cast iron radiators to a modern boiler , we had to add a second high limit set at 140 deg F so the cast radiators did not get too hot and burn people
Normal residential water heaters are not designed to heat a house
A propane furnace in a trailer makes a lot more sense than trying to reinvent the wheel IMHO.
I would have to run the calculations and see if the heating system could pump enough btu’s into the trailer to overcome the heat loss and raise the interior temperature.
Our home heating system was sized based on a design temp of 25 below zero F and when temps drop to 30 below zero F the interior temp of our home drops to around 62 degrees
That’s why God gave us wool sweaters and wool socks

[Raspy]

Steve,

I agree about not reinventing the wheel on the heating system, just because we can. But in a perfect world, radiant heat in the floor would be delicious. Quiet and comfortable, with no wall space given up or fans running. It's just extremely impractical to retrofit.

The tank type water heater seems perfectly capable of carrying the heating load, but they are loud and not very efficient. At night while camping, especially out in the desert, the quiet is one of the main attractions.

So, we'll soldier on with the the forced air heater as designed. Now that I've got a proper thermostat, in a good location, all is well. At some point, the goal has to be something other than working on the trailer.

[Ron Divin]

Originally Posted by rogerfb

1986 17ft BF My water heater is finnished, considering a Camplux tankless, it should fit nicely to right of sink above the fridge, It will have to be vented,
Any comments or advice appreciated

No comment re. brand. But we have installed two high end tankless in prior motor home and 5th wheel. Plus we have had in our restraunts. They are great when they work but getting repaired/parts when down + major issues. Parts and repair services for the tank version's = not problem.

Another issue: if not on constant pressure shore water ie. internal tank/pump the supply varies as the water pressure and pump sedge mess up the tankless controls generating reset issue at times.

My vote is no Tankless unless you are pretty close to full time in one site near a larger metro area where parts and service more available. Have fun!

[redbarron55]

Big difference in home and high end tankless and the cheap one used in most of the world.
Before you decide that it doesn't work you should try one.
They are cheap at less than $100 and work well.
They have some drawbacks, but the biggest is finding the space to mount one and vent it.
Lots of negativity on these small water heaters. Not much of it from the people who actually use these small units.
I fail to see the problems with them, but my experience is limited to 5-6 years of using one on fairly long tours. Including on and off city water.

[Ron Divin]

Originally Posted by redbarron55

Big difference in home and high end tankless and the cheap one used in most of the world.
Before you decide that it doesn't work you should try one.
They are cheap at less than $100 and work well.
They have some drawbacks, but the biggest is finding the space to mount one and vent it.
Lots of negativity on these small water heaters. Not much of it from the people who actually use these small units.
I fail to see the problems with them, but my experience is limited to 5-6 years of using one on fairly long tours. Including on and off city water.

Understood - not being argumentative - just commenting from our experience. I use a portable propane at hunting camp ~ $150 with a batt operated full force pump (no push/push) out of a 250 gal. plastic holding tank and it works fine. Need to make sure to open disconnect water and open pit cock drain valve in freezing weather or the coils burst.

[Stephen_Albers]

My target is 4 season operation. When everything is up and running and with great improvements in insulation, 4 season operation seems nearly a no-brainer. But a specific strategy is needed for powering down in cold weather. My present plan is to empty all liquid tanks and lines for freeze protection. A tankless hot water heater that is freeze protected seems preferable to a conventional 6-gallon hot water tank that is hard to completely drain. Powering up brings the internal temperature above freezing and then melting snow provides water. Are there any problems with this plan? Tnx, Stephen

[Glenn Baglo]

Originally Posted by Stephen_Albers

A tankless hot water heater that is freeze protected seems preferable to a conventional 6-gallon hot water tank that is hard to completely drain.

You don't need to drain every ounce. There is plenty of room for ice to expand. Damage is caused by expanding ice in a confined location.

[jeffminnesota]

Nubi here, it is fascinating to read of the infinite innovation of RV owners. Thanks for sharing your experiences

[MBrad]

I work for a water heater manufacturer. DESCALE! If you do not descale once every year, you will end up with a boat anchor. Maintenace will be your friend. There are kits available and it is easy to do. Everyone else has good info for you. Lots of good comments already. Look for minimum flow requirements. IMO, I would replace your old tank with a new tank style unless you want long showers. Less maintenance, fewer parts to fail.

[rogerfb]

I started this thread never thinking it would go so far, lots of interesting points,
But I found a much later atwood water heater same style as original, it came from a person stripping a damaged trailer to use frame for mini home, & at $40 I cannot complain, all installed