Atwood water heater to be transformed in heating system

[yeloduster]

Originally Posted by 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

Sent from my BBB100-5 using iRV2 - RV Forum mobile app

Sounds like an ingenious plan. I have hydronic hot water heat in my home and I circulate boiler water through a heat exchanger in my water heater for domestic hot water.

My experience says there are some considerations. I presume you intend to use the same Atwood water heater for your domestic hot water as you do for your heat:

• Because your heat loop will be connected to the water supply you need some type of backflow preventer to assure that hot water is not pushed back into your water supply. Something like this: BACK FLOW PREVENTER
• You mentioned a circulator pump. Here is an example that is relatively inexpensive and will handle the heat: Circulation Pump.
• You will need a valve that controls the water flow: Zone Valve.
• I'm not sure what you have in mind for a radiator. The Pex pipe is too good an insulator and will not radiate enough heat. You might consider something like THIS. Finding a way to mount it might be difficult.
• Here is an inexpensive but effective thermostat: Thermostat.
• Your thermostat should run a relay that turns on the pump and opens the valve. Any 12V relay should do.

Additional thoughts. My boiler temp is set at ≈170° F (77° C). Your water heater will not heat the water that hot. New more efficient home heating systems circulate ≈130° F water but they have MUCH more radiator than than I do. Cooler water in your radiator reduces the radiant heat from your radiators. You may not be able to transfer enough BTU from the water heater to your interior space. Add as much radiator as you can. Extract as much heat from the circulating water as you can. More heat extracted means more heat in your interior space.

Any time you draw hot water from the water heater for washing dishes, bathing, etc. you will lower the temperature of the water from the water heater into your heating system. It might work OK and maybe not!

The demands of your heating system will greatly increase the operation time of the water heater. I don't know if the water heater can handle that much usage!?

I estimate the parts listed above will cost ≈$325 USD and then you will have shipping costs. I don't know what such supplies might cost in Spain!?

Regardless of how you decide to do it I think you will spend much more money than you think by the time you get it to function well!

It sounds like a fun project. Let us know what you decide to do and how it worked out.

[MarvinG]

I also cannot stand the on off noise of the furnaces even during daytime! And I also can sleep under cover and lower temps but HATE to work or exist in a cold daytime environment.

I have successfully used the Big Buddy propane heater with window cracked for ventilation and good working carbon monoxide dectectors, for sure one where I sleep. I set my heater up in the front on the motor cover doghouse. Wonderfully warm and quiet. In your case, at least, you do not have to worry about keeping the pipes in the basement warm, given your projected minimum temps.
Others will chime in with concerns regarding CO and certainly those concerns are valid if not addressed. The only real down turn I experienced was condensation was somewhat increased. For weekend use I just wiped the windows down. This really wasn’t a real problem, again I say for weekend only use. Full time, perhaps it could lead mold/mildew problems if not addressed.

[MrMark52]

Originally Posted by MarvinG

I also cannot stand the on off noise of the furnaces even during daytime! And I also can sleep under cover and lower temps but HATE to work or exist in a cold daytime environment.

I have successfully used the Big Buddy propane heater with window cracked for ventilation and good working carbon monoxide dectectors, for sure one where I sleep. I set my heater up in the front on the motor cover doghouse. Wonderfully warm and quiet. In your case, at least, you do not have to worry about keeping the pipes in the basement warm, given your projected minimum temps.
Others will chime in with concerns regarding CO and certainly those concerns are valid if not addressed. The only real down turn I experienced was condensation was somewhat increased. For weekend use I just wiped the windows down. This really wasn’t a real problem, again I say for weekend only use. Full time, perhaps it could lead mold/mildew problems if not addressed.

A byproduct of most any liquid fuel combustion is moisture - odd but true.

Unvented (or in this case, minimally vented) combustion and resulting CO is all good, until it isn’t - even when depending on a CO detector. But you won’t be around to tell the story of “remember that time that the CO detector battery died . . . . .?”

[Old-Biscuit]

Atwood standard model uses a 140*F T-stat
Heating only occurs when temp drops below 110*F
Duty cycle can be 100% ---no harm/no foul just propane/AC consumed

One could change out standard t-stat to a higher temp one as used in the XT Models (160*F) which uses a Mixing Valve to control output to 130*F -----more available hot water with same size tank

Where are you going to reroute the heat exchanger return to?
Cold inlet size of WH Tank----need backflow/check valve so it doesn't go into cold inlet supply

[Alpine36]

King makes some really cool “residential” style hydronic heater units. I think the toe kick models are nice. We used to install those under the bench seat in our utility service bucket trucks, in electric version. Our trucks were equipped with QD5000 gen sets. Crews loved them, since we could no longer idle our Cummins all night long.
Not cheap, but also not Chinese. (Made in Seattle)
Something to consider once you figure out the return loop situation…

https://king-electric.com/products/hydronic-heaters/

[shootist]

Originally Posted by MrMark52

A byproduct of most any liquid fuel combustion is moisture - odd but true.

Unvented (or in this case, minimally vented) combustion and resulting CO is all good, until it isn’t - even when depending on a CO detector. But you won’t be around to tell the story of “remember that time that the CO detector battery died . . . . .?”

I know propane makes water when it burns but I didn't know any other fuel did?

[MrMark52]

Originally Posted by shootist

I know propane makes water when it burns but I didn't know any other fuel did?

Yep - take a chilled pan, set it on a natural gas cooktop burner, turn the burner on full blast. You’ll see moisture condense on the sides of the pan for a few moments until the pan heat below the dew point of the exhaust.
You can chill the pan by putting 50/50 mixture of ice/water in the pan for a few minutes.
Works best with an aluminum pan, but time of condensing is shorter.

[shootist]

Originally Posted by MrMark52

Yep - take a chilled pan, set it on a natural gas cooktop burner, turn the burner on full blast. You’ll see moisture condense on the sides of the pan for a few moments until the pan heat below the dew point of the exhaust.
You can chill the pan by putting 50/50 mixture of ice/water in the pan for a few minutes.
Works best with an aluminum pan, but time of condensing is shorter.

Propane actually makes water when it burns, not condensation.

[MrMark52]

Semantics -

Yes, makes water when it burns as do many fuels - condensing of the produced water (superheated water vapor) on a cold surface is proof.

[MarvinG]

Exactly.

[shootist]

Originally Posted by MrMark52

Semantics -

Yes, makes water when it burns as do many fuels - condensing of the produced water (superheated water vapor) on a cold surface is proof.

You really don't understand. Condensed water is everywhere. We call it rain. Propane chemically makes water when it burns. Just like a hydrogen fuel cell produces water as exhaust. Look it up.

[shootist]

[QUOTE=shootist;6384292]You really don't understand. Condensed water is everywhere. We call it rain. Propane chemically makes water when it burns. Just like a hydrogen fuel cell produces water as exhaust. Look it up. Natural gas also produces water when burned. So I was asking what other gases produce water when they burn. Not cold surface condensation of water already in the air.
So I looked up a few more , acetylene, butane, they both also produce water. Don't know why you didn't just answer me straight or say go look it up.

[Ruediger]

Originally Posted by yeloduster

Sounds like an ingenious plan. I have hydronic hot water heat in my home and I circulate boiler water through a heat exchanger in my water heater for domestic hot water.

My experience says there are some considerations. I presume you intend to use the same Atwood water heater for your domestic hot water as you do for your heat:

• Because your heat loop will be connected to the water supply you need some type of backflow preventer to assure that hot water is not pushed back into your water supply. Something like this: BACK FLOW PREVENTER
• You mentioned a circulator pump. Here is an example that is relatively inexpensive and will handle the heat: Circulation Pump.
• You will need a valve that controls the water flow: Zone Valve.
• I'm not sure what you have in mind for a radiator. The Pex pipe is too good an insulator and will not radiate enough heat. You might consider something like THIS. Finding a way to mount it might be difficult.
• Here is an inexpensive but effective thermostat: Thermostat.
• Your thermostat should run a relay that turns on the pump and opens the valve. Any 12V relay should do.

Additional thoughts. My boiler temp is set at ≈170° F (77° C). Your water heater will not heat the water that hot. New more efficient home heating systems circulate ≈130° F water but they have MUCH more radiator than than I do. Cooler water in your radiator reduces the radiant heat from your radiators. You may not be able to transfer enough BTU from the water heater to your interior space. Add as much radiator as you can. Extract as much heat from the circulating water as you can. More heat extracted means more heat in your interior space.

Any time you draw hot water from the water heater for washing dishes, bathing, etc. you will lower the temperature of the water from the water heater into your heating system. It might work OK and maybe not!

The demands of your heating system will greatly increase the operation time of the water heater. I don't know if the water heater can handle that much usage!?

I estimate the parts listed above will cost ≈$325 USD and then you will have shipping costs. I don't know what such supplies might cost in Spain!?

Regardless of how you decide to do it I think you will spend much more money than you think by the time you get it to function well!

It sounds like a fun project. Let us know what you decide to do and how it worked out.

This the one I thought about. Industry style. Fitting into my Vintage RV. It def makes sense to do some outside testings. If I remind gas heating in Germany, the water temp is around 60 degrees C. Or even less. Therefore as you said: Space and volume matters.

[Ruediger]

Christmas around the corner. It´s a great honour for me being part of this community. At the beginning reading learning. Nowadays still learning and more willing to share and discuss. As already said: Nothing comparable in Europe. Great people, this community always willing to share and interfere. I wish all you Merry Christmas and peaceful days ahead. Got some updates about the harsh winter conditions approaching mid and east of the country. Stay safe, safe travels if needed. And more then willing to continue this discussions after enjoying for a few days Christmas and family. Warm regards, Rüdiger