Atwood water heater to be transformed in heating system

[Ruediger]

Sitting in my rv. 20 degrees c in the south of spain. But winter coming also here. Thought today, the airstream heating to energy-hungry. To loud, too. And the constant on and off nerve-wracking. Sitting and thinking and came up with using the atwood water heater to be connected with 2-3 floor radiators. Small separate water pump. And good to go for non-freezing temperatures. I always boondock. So electricity during winter time important to monitor. Anybody had a similar idea in the past and made it happen? Gut feeling: 1 day working with all tubing. Your feedback appreciated, fellow campers.

Best, ruediger

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[MrMark52]

It’s not the heater that’s energy hungry - it’s your coach (or trailer).

And that typically the LP furnaces are over-sized for the heat demand - especially at 20 degrees C.

Your idea is a good - your basically building a hydronic heating system - keeping in mind a few things - 1) most MoHo/RV water heaters have a 9000 BtuH capacity, 2) there are efficiency losses of heating the water, and additional efficiency losses doing the same again through the floor radiators, 3) expansion tanks will be needed for a closed loop system, 4) insuring your water pump can handle 140 degree water - to name a few.

Better to just get some electric heaters - electric heat is virtually 100% efficient, and the only way to improve that efficiency is to go to a heat pump, but heat pumps are noisey just as the furnaces are.

You can go thru the math of the cost of 1kWh of electricity (which is 3413 BtuH), and LP (which is 91,452 btu/gal) - versus the efficiencies of how the energy is used to determine what heating source to use.

In the end, you’ll probably find it more beneficial to improve the coach’s insulation and add the electric radiant or somewhat forced air electric heat.

[Ruediger]

Originally Posted by MrMark52

It’s not the heater that’s energy hungry - it’s your coach (or trailer).

And that typically the LP furnaces are over-sized for the heat demand - especially at 20 degrees C.

Your idea is a good - your basically building a hydronic heating system - keeping in mind a few things - 1) most MoHo/RV water heaters have a 9000 BtuH capacity, 2) there are efficiency losses of heating the water, and additional efficiency losses doing the same again through the floor radiators, 3) expansion tanks will be needed for a closed loop system, 4) insuring your water pump can handle 140 degree water - to name a few.

Better to just get some electric heaters - electric heat is virtually 100% efficient, and the only way to improve that efficiency is to go to a heat pump, but heat pumps are noisey just as the furnaces are.

You can go thru the math of the cost of 1kWh of electricity (which is 3413 BtuH), and LP (which is 91,452 btu/gal) - versus the efficiencies of how the energy is used to determine what heating source to use.

In the end, you’ll probably find it more beneficial to improve the coach’s insulation and add the electric radiant or somewhat forced air electric heat.

Excellent return, mr.marks. My shortage is electricity while boondocking. Spain in general excellent for it. Next to the beach if you like. And the smaller villages in the countryside often with free of charge parking next to the city center. Wanting to attract more tourists. But, no electricity. Just water to be added.
But as you said, its also a btu question. Which i have to look into. Not very much the parts. I do expect less electricity to be used because the heater fan in comparison with a pump the one consuming more.

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[MrMark52]

Aghh - I missed the boon-docking part -

See if you can find a 1 kw or so generator that will run on LP., or some deep cycle coach batteries, inverter, and solar panels.
Or the fallback to gasoline powered (assuming you don’t already have a generator on your coach).

Do the math to figure out what capacity of each (deep cycle batteries, inverter, solar panels, or generator you’ll need against guesstimates of what you think it will keep the coach at a reasonable temperature.

As it gets colder, your noisey furnace will be better muffled by the covers over your head.

Until then, the colder it gets, the more layers of clothing you add, combined with # of blankets.
We’ve got friends who don’t use their coach furnace(s) until it reaches 45 degrees F (~7 C). And no electric heat, even though they typically DON’T boon-dock.

[Old-Biscuit]

Atwood uses a 8800btu rated burner assembly in 6 gallon models
Atwood uses a 10,000btu rated burner assembly in the 10 gallon models

2001 tear model RV would probably have 6 gal/8800btu Atwood (GC6A-8E most likely)

Propane has a recovery rating of 10 gal/hr from initial fill temperature

[153stars]

Since you thinking outside the box. Take a look at China diesel heater in on u tube. One is Webasto clone that are installed in big rig trucks and heavy equipment. The other is freestanding external type. But you need to add vent/s from outside to inside. I would be a little less willing to cut vent in Airstream than conventional trailer.
Link to first and highest btu freestanding one I ran across. 27,300 but
SILVEL 12V 8KW Diesel Heater, All-in-One Diesel Air Heater, Portable Diesel Heater with LCD Monitor & Remote Control, Fast Heating for Tent, Car, RV, Truck, Camper, Trailer, Motorhome https://a.co/d/1vFDcNE

[Ruediger]

Originally Posted by 153stars

Since you thinking outside the box. Take a look at China diesel heater in on u tube. One is Webasto clone that are installed in big rig trucks and heavy equipment. The other is freestanding external type. But you need to add vent/s from outside to inside. I would be a little less willing to cut vent in Airstream than conventional trailer.
Link to first and highest btu freestanding one I ran across. 27,300 but
SILVEL 12V 8KW Diesel Heater, All-in-One Diesel Air Heater, Portable Diesel Heater with LCD Monitor & Remote Control, Fast Heating for Tent, Car, RV, Truck, Camper, Trailer, Motorhome https://a.co/d/1vFDcNE

Was looking today in the specs. Indeed, the smallest model has 8000 btu. More then 2,5 kw to be used. With additional isolation more then enough. The good thing with the atwood: almost inaudible after start.i simply need heating down to 0 degrees c. ( 32 fahrenheit). No snow falls in southern spain. I still believe, my solution is by far the easiest. Pex lines, floor heater (twice), and some valves. My atwood - as usual - next to fridge, living room and sleeping area. I need a solution while working interior. For a good night sleep at 40 degrees fahrenheit, i fully agree with more blankets 'winter-approved'. But working and freezing over the day is performance-killer. Anybody out there with an easier solution? Boondocking with only solar panels as said. Onan on board, too. But the onan nerve-wracking like my furnace.

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[Ruediger]

And yes, im looking for an easy solution. Well-known that germans tend to appreciate over-engineering. I learned with my american rv, that simple solution are frequently more sympathetic. (Like jim, the seller said two years ago: ruediger, i like it simple, simple, simple). [emoji2]

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[153stars]

The initial listings in last few years of diesel heaters is listed in only kw of heat ,not electric used. Maybe they use that as heat unit in China instead of btus IDK. The listing shared convert to btus of heat . Is it perfectly accurate ,I can't tell you. But you can find many tent and off grid vids of people installing and using them as well as class B van life types. Pretty sure a few members here installed the clone units for boondocking. They are not supplying with several thousands of watts of electricity to run burner blower, fuel pump and fan. One of reasons for installing was to save battery use. My guess pulls far less watts than main fan in rv furnace.

Originally Posted by Ruediger

Was looking today in the specs. Indeed, the smallest model has 8000 btu. More then 2,5 kw to be used. With additional isolation more then enough. The good thing with the atwood: almost inaudible after start.i simply need heating down to 0 degrees c. ( 32 fahrenheit). No snow falls in southern spain. I still believe, my solution is by far the easiest. Pex lines, floor heater (twice), and some valves. My atwood - as usual - next to fridge, living room and sleeping area. I need a solution while working interior. For a good night sleep at 40 degrees fahrenheit, i fully agree with more blankets 'winter-approved'. But working and freezing over the day is performance-killer. Anybody out there with an easier solution? Boondocking with only solar panels as said. Onan on board, too. But the onan nerve-wracking like my furnace.

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[shootist]

You'll want antifreeze in it, or boiler coolant. Jetta water pumps are about the right replacement for the expensive aqua hot pumps as far as flow rate and pressure. The only question I would look into is how much of a duty cycle can the Atwood handle. Maybe you'll want to cut the temperature output back a bit if it's not enough.

[Ruediger]

Originally Posted by shootist

You'll want antifreeze in it, or boiler coolant. Jetta water pumps are about the right replacement for the expensive aqua hot pumps as far as flow rate and pressure. The only question I would look into is how much of a duty cycle can the Atwood handle. Maybe you'll want to cut the temperature output back a bit if it's not enough.

Excellent question. Thought the same. Can the atwood handle many cycles per day. Anybody knowing more about it? I would do regular maintenance cycles on a weekly base seeing if there is to much usage within the burner area. Thanks for all you your input. Helpful as always. I will report right here after installation if this a good way to go for low/ medium interior heating.

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[shootist]

Originally Posted by Ruediger

Excellent question. Thought the same. Can the atwood handle many cycles per day. Anybody knowing more about it? I would do regular maintenance cycles on a weekly base seeing if there is to much usage within the burner area. Thanks for all you your input. Helpful as always. I will report right here after installation if this a good way to go for low/ medium interior heating.

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Duty cycle refers to how many minutes out of an hour it can stay running. ei 30 minutes per hour is 50%

[danhannah]

Maybe make a small test installation under the bathroom sink, in that cabinet. You will already have hot water lines, and can tap in with Pex.

If you can find 12 volts nearby, a small computer fan to blow through the heater coils.

Send pictures! I think it is a great idea.

[MrMark52]

I can not see where any water heater can’t run 100% of the time (or a 100% duty cycle) - except that when it’s running it’s using energy so there has to be an adequate source of energy available.

Duty cycle is more relevant to motors and things providing torque. For instance, your water pump.

The suggestion of Post 13 took a direction that I think the OP needs to clarify - are you thinking to utilize your Atwood heater for both hot water and heating, or is the plan to use a separate Atwood water heating system?
Your approach to design varies depending on which way you want to go - and each has pro’s/con’s.