Heating using the hot water tank.

PEX is what my plan uses. It's readily available, approved for potable water and can take the heat. It's only downside is that it is fairly stiff , but can be formed to a 5" radius in 1/2" sizes.
 
My radiant heat home system uses 1/2" Pex. I have plenty left over from that job. Guess I better make sure that particular brand is potable water rated.
 
The water tank pump and external inlet for CR are in what looks like the head board at the rear.
image.php

The water heater is on the right side behind the bulkhead. The plan is to have the heater core stored above the water pump and on hoses that I can pull out and place some place (undecided where).
 
With all the interest, knowledge and experience shown/mentioned by posters, it is surprising no one has made the first working system. I would try right now, but I have not actually decided which water heater to buy. MtnDon, I am cheering for you and your project.
 
Bob we have had no real problems with out Atwood DSI and the only problem was it acquired a spider one year, once it was blown out no problem. I did encounter one being TIG welded after the owner let it freeze when full. Aluminum tanks can be repaired.
 
For me the deciding point was the physical dimensions. The Suburban and the Atwood are laid out differently. The Suburban tank has the long dimension perpendicular to the wall of the trailer. The Atwood has the long dimension of the tank parallel to the wall of the trailer. The Suburban fits between the usual 16" wall rib spacing of a CT. Note I said "usual"; that can vary from CT to CT manufacturer. The Atwood won't fit between 16" OC (on center) wall ribs. If you can cut and weld steel ribs that is not an issue. Otherwise.....

Of course with a CarMate trailer and the wood wall studs you don't need to weld.That does make configuring the cutout for an Atwood slightly less of a problem than if the trailer had steel wall ribs/studs.
 
Atwood makes a Water Heater that has a Heat exchanger built in to it. Nobody uses it anymore but they still make it.

Model GCH6A-10E

http://www.americanrvcompany.com/Atwood ... Trailer-RV

It was originally designed to heat water in a water heaters tank from a Motor homes Engine coolant system. As I said, nobody uses this system anymore (That I know of)

In the mid to late 80's a few Manufactures used this product in a different way. Allegro was one.

They would take the "In and Out" on the water heaters exchanger, create a sealed system , filled it with Anti Freeze and connect it to the "IN and out" in a heater core. Some of these Heater cores had Fans, and some were Gravity systems. (simple explanation)

As long as the Water heater was on, you got heat to the Heater Core and it was simply shut off in warmer months.

Now, This was definitely a "Lowering the River instead of raising the Bridge" approach.

But!

They worked! Despite there Logistical Problems

How ever over time were no longer used.

Happy Trails

Len
 
Hi Len,
I originally thought about them and even mentioned that in one of my much earlier posts. I believe Bruce also mentioned it.

And I really believe it would work very well. But my wish list of stuff for my project has gotten to be very high $$$$$ wise.
The regular Attwood/pilot/6 gal/gas only can bought now for $303 and the one with the heat exchanger costs about $543. I could use that $143 elsewhere. Yes, I am starting to get frugal now ( not cheap). MtnDon, just for the heck of it, I am going to look at the Suburban's demensions. I could afford to give up vertical space to gain more horizontal space in the cabinets.

At least for me, i am several weeks away from the point of working on this phase of the project, so I still have time to digest all the comments here and make my final decision.
 
Stage One Test:

This is a very basic hookup for the first performance test.... The general layout...



I'm running the tests off my 12 VDC power supply with a watt meter. The two white PEX pipes in the upper right come from connections near the water heater hot and cold connections. Blue tape = cold(er) pipe.

A closer up view of the heater and pump...



The hot pipe connects to the inlet side of the pump. The pump is rated at a flow rate of approximately 3 gal/minute. The finned radiator is a transmission cooler, approximately 6 x 12 inches. The fans are secured with wire ties; quick and easy for testing. They are oriented to blow air through the fins. At present the pump and fans are wired up to run continuously. At present I do not have a temperature controller or thermostat. That will come if this first stage is deemed a success.

Close up shot of the watt meter reading. This was taken moments after turning the power on. Taking a photo of the display is a tad difficult and needed some manipulation...



With pump and fans running the amp draw is at 0.67 with the watts at 8.7 (at 13.3 volts).

The plan is to run all night and see how many watt-hours are used and what the temperature inside the trailer is in the morning. The water heater thermostat is set at medium. The test started late this afternoon (4:30 PM MST) with the exterior temperature at 58 F and dropping. The trailer interior was at 70 F. The overnight low is forecast to be 37 F.
 
The pump is very quiet. The fans are nearly inaudible. 19.1 dB for one fan. The pump is rated at <45 dB. Maybe tomorrow I'll get the dB meter out and see what it indicates.
 
MtnDon, as Bruce said....way to go.
My gut tells me it will work.
I say this because I just went out to turn the 72W work light bulb off in my trailer. It has been 32 degrees for an hour or so outside. It is 27 now. The inside of the CT was 42 degrees and I have no ceiling insulation, just 1 1/2" of foam in the walls and floor. I think I will go back and turn it on to see what the temps are in the AM after being on all night.
 
One of my ideas is to box in the core and fans; locate that in front of the shower stall lip/ledge. That can be seen behind the fans in photo #2. Use an expanded metal grill on the front to prevent toe kicks from damaging the fins. The height will work and the backside could have air inlets from both ends.
 
MtnDon,
Do you see using a thermostat which would engage a relay at selected settings? Without doing much research, that was my thinking.
 
You may want to measure the inlet and outlet temps to see if there is room to slow down the pump.
Tom
 
lrrowe":11rayb0r said:
MtnDon,
Do you see using a thermostat which would engage a relay at selected settings? Without doing much research, that was my thinking.
Click to expand...

I plan on using a 12 volt temperature controller, similar to the 120 VAC version I used on the slow cooker hack. My plan is to simply turn the pump and fans on and off together, at the same time. It contains a relay switch good for 10 amps. More than enough. I don't see a lot of benefit to having the fan turn on and off via its own snap switch or whatever. The system is so small I feel that is unnecessary and just another complication.
 
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