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Old 10-05-2016, 04:34 PM   #21
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Name: Steve
Trailer: Scamp 13
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Originally Posted by gordon2 View Post
I am also wondering if, with the Atwood side vent option, would it be worth the effort to add ducting that goes through the bottom front of the cabinet to the floor level. I think this may make it quieter and also improve heat distribution somewhat.
The side vent model uses a different fan that draws more power.
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Old 10-05-2016, 05:12 PM   #22
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Trailer: 1998 Casita 17 SD
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Originally Posted by tractors1 View Post
Note that if the motor runs too slowly, there won't be enough air pressure to close the sail switch, which controls the gas valve. This would become even more of a problem as the battery voltage falls while boondocking.
Hi Charlie
the new blades are from the NE16seq and when installed on the old motor move a lot more air. Changing out the motor to the 16SEQ motor would be best but also expensive. I used a variable voltage regulator to dial down just the voltage to the motor and have tested it down to below 9v dc and it will still activate the sail switch. Others have tested it over at the casita forum including Gene and have got similar results. Basically this just converts the 12SE and 16SE to a 16seq. The blades and motor are the only difference in them
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Old 10-05-2016, 09:12 PM   #23
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Originally Posted by John Linck View Post
Still hoping some company will introduce a gravity furnace with no electrical demand, no noise and no fan. Had one 40 years ago and loved it in my first camper. Nice even heat, no noise and convection exhaust to the outside.

Many direct vent household heaters have the similar features and use the same principles. Why not in RV's?

Can't quite face the fumes and moisture of the catalytic heaters.

John
The Duo-Therm gravity furnace in my 4500 is awesome! Silent and warm. The only thing it lacks is an external thermostat and a lower setting (low=high, med=very high) I just crack a window. I'm tempted to try and source another for spare parts. Why reinvent the wheel. O'yeah, "safety".
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Old 10-06-2016, 06:08 AM   #24
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Name: Gordon
Trailer: 2015 Scamp (16 Std Layout 4) with '15 Toyota Sienna LE Tug
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Originally Posted by stevebaz View Post
The side vent model uses a different fan that draws more power.
I see that on the specs chart on lower right of page one HERE, all the models are spec-ed at 3.4 amps except for the previously stated discontinued model. I would buy the lower amp model in a minute if it was still being sold.
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Old 10-06-2016, 06:52 AM   #25
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Originally Posted by Patricia D. View Post
...
I am just curious about the difficulty of the Propex installation. This was my first choice, if I decided that I really do need a furnace. Is it possible to briefly describe the problems as you see them?
Thanks.
The complications with the ProPex are related to installation on my Scamp 16 (layout 4). These issues might be different on different trailers and in any case could be overcome. In fact, it is such a nice heater it might be worth the extra effort, it is just adding more complications than I want to tackle. I’m sure that some will think I am getting bogged down in details of little concern but this is how I see it…

The ProPex unit is designed so that a primary installation option is under-floor however there is no room under my trailer for it underneath except at the back, and I do not want to add any more weight at the back since I already have to make an effort to not go under 10% tongue weight. Plus I would have to remove a sewer hose holder that I mounted under the rear floor.

Installation in the lower side cabinet (perpendicular to the camper’s body and under the stove in my case) would probably not leave enough room for ducting. It also makes it very difficult to access the gas connection. I could use it without any duct but that creates more noise and less efficiency since the cold air intake is right next to the hot air output.

The exhaust flue must be between .75 and 2 meters and should terminate at the outside of the trailer and not within specified distances from windows, etc. This is so that exhaust gas does not enter the camper. The exhaust flue can get near 300 degrees heater and should not be run in contact with the wood floor or close to any area that would be damaged by high heat. All this is do-able, just more difficult and ProPex does not even publish safe clearances for the flue and duct so it’s a bit of a gamble. The output duct should not be in direct contact with anything that could be damaged by heat, especially near the heater. The heater also requires about one inch clearance whereas the Atwood is a zero-clearance appliance, making the install simpler.

ProPex install instructions are at: http://www.propexheatsource.co.uk/hs...r-installation
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Old 10-11-2016, 12:08 PM   #26
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Name: Gordon
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I decided on the Atwood 7912 over the ProPex heater and made a trip to one of the largest RV dealer/Service Centers in the Carolinas who is an authorized Atwood dealer. I took some photos of the Scamp and the cabinet where the furnace goes. I spent about 30 minutes discussing the installation of a furnace in my Scamp with the service department. The first thing I found out was that they were not really familiar with the smallest RV furnaces and upon investigation they said that the 7900 series (as well as the 8012 model) were discontinued. I had my doubts about that so I called Atwood and even they did not seem to know... the exact words were “my best is that yes, they are discontinued.” The Atwood person went on to say they could still be found in the retail chain, or you could use a Suburban furnace. So left on my own I did some more research and it seems that the current offerings from (Dometic)-Atwood is the AFS series. So I am looking at the AFSSAD12, 12,00 BTU input, 9,120 BTU out, 2.4 amps.

I figured I could buy the furnace myself and have the RV place install it. I discussed an option with the technician to use the side vent option on the Suburban or Atwood furnaces. My thought was that by running a short vent to the cabinet overhang so it discharged downward onto the floor, it would be much more comfortable than having the warm air discharged at knee level. This should not be much added work over an above the basic installation.

That is when I found out that the technician thought it would him take about a half day to do it on a Scamp (and to do it so its looks good). So figure 4-5 hours labor… That is at $126 an hour. Ouch.

So, my research continues. I am wondering if the Atwood can be installed with the service door on the outside. It is 12.5 wide by 7.5 high and it looks like the curve of the camper will make it hard to get a good seal on the outside service door. Or should I just use the small (3.5 inch circular) vent hole and plan on removing the furnace when it needs service? Anyone have experience with this?
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Old 10-13-2016, 12:53 PM   #27
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Name: Kelly
Trailer: Trails West
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Originally Posted by tractors1 View Post
Note that if the motor runs too slowly, there won't be enough air pressure to close the sail switch, which controls the gas valve. This would become even more of a problem as the battery voltage falls while boondocking.

Speed of movement needed by the motor and the power of the motor to generate sufficient CFMs to move the sail switch. That depends on the design of the fan blades and on the quality of the bearings they turn on. There are many blade designs that are superior to the barely good enough blades for "built to cost" products.

One example of poor fan blade design is the truly inefficient fan blades in most RV stove vent hoods that have truly marginal CFM capability given their size and the motor that powers them. An example of efficient blade design is the blades in the Fantastic Fan that are designed for good CFM.

Fan blade design is important and those old RV furnaces did not use very good fan blades in the manufacture of them. But I can't speak as to the blades in newer furnace units as I have not been hands on with one of them.
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Old 10-13-2016, 02:03 PM   #28
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I would suggest you stick to campgrounds with electrical hookups and buy a $20 electric heater when camping in the shoulder seasons. Sounds like it would be cheaper. Or you can do what we do. Flannel sheets, lots of blankets and a big dog.
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Old 10-13-2016, 04:37 PM   #29
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Name: Kelly
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Originally Posted by Daniel V. View Post
I have been on a similar quest for a while myself, and came across this one recently...
BISMAR

Not sure about availability and haven't read about any RV install yet, but perhaps worth inquiring about.

There are quite a few direct vent propane furnaces on the market. I have had one in a house before. The issue is how you will vent them as the vents they use are created for passing through the thick walls of a home versus the thin walls of a fiberglass trailer. Many of them vent through the roof rather than walls. However the exterior vents that fit them are not made for use in a vehicle in motion. So no matter the maker of them you have to figure out how you will adapt them as far as the venting.

The Marine propane heaters do have vent stacks that are made to go through the roof and they are going to have a smaller diameter chimney stack as well as a cap made for travel. They already have the right types of exterior vents including ones for sloped or curved roofs. They are made to be used in fiberglass boats so you know the flue temperature will not be an issue for safe installation in a fiberglass trailer. But you do have to follow carefully the instructions for clearances from adjacent surfaces not just beside and below but also above.
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