Atwood Furnace vs. Suburban Furnace

[Tenor]

Is there any consensus that one is better than the other?  For my intended use, webasto and proheat etc. are kinda out of my league.  Can anyone answer if Atwood furnaces have to have the door sized hole cut in the side of the bus, or can they just use the exhaust/intake piece that I see in their acess doors?  I really don't like putting holes in the walls, so I want to keep the necessary ones small as possible.  Thanks!

[TomC]

I have the Atwood 35,000btu and did have to cut out a rectangular hole in between the steel supports-but after painting the access door the same as the bus you barely notice it.  It has been a good furnace, virtually no maintenance in 8 years (except to keep it clean).  Mine is mounted next to my stove above floor-so it is a bit on the noisy side.  I believe they are making a variable speed fan version now that I would highly recommend.  Once the temp is sufficient, it then usually runs on a much quieter low speed fan unless big heating is required.  If I had to do it again, I will buy another Atwood, but as stated with the variable speed fan.  Good Luck, TomC

[TomC]

One more comment-if I remember correctly you have to cut a hole in the side of the bus since the furnace is installed from the outside.  Course you probably could modify it to obtain the smaller opening you're wanting.  Good Luck, TomC

[Tenor]

I would prefer to install an Atwood from the inside and just plumb the exhaust/intake through the wall.  When you open the access door on the Atwood's, does the exhaust port stay in place, or does it swing off with the door?  I have not had a chance to look at one in person to see how it might need to be modified, or if it can. 
Thanks!

[JohnEd]

I have the Hydraflame in a S&S.  It is a 73 vintage furnace and RV and I still use it for weekend work(beach).  I bought it in 90 and the furnace started emitting noxious fumes shortly thereafter.  The big heat exchanger box had rusted through and I was getting carbon monoxide blown into my living(dying) space.   Fortunately I figured it out after a few days of burning eyes cause I think the fourth day would have been the "charm".

Hydra flame came through with a new unit in a couple days for $30.  Support seems to be out there and they still make the old models.  Mine is a 40K BTU and it will drive you out of the place in a few short minutes and the air temp at the register will sting your fingers.  Make sure you use ALL the distribution ports or the furnace will cycle due to the over temp relay shutting it down while the thermostat is calling for more heat.

Your gas pressure in your coach might be a problem area.  Mine was and the furnace had been installed for many many years.  At your propane tank regulator you will find a plastic plug.  Remove that plug and you will see a large screw plug with a slot for using a screw driver.  The gas pressure in a coach is set using a water column device and the pressure IS CRITICAL.  Not complicated....CRITICAL!

I had three propane devices.  The furnace ROARED when on and sometimes, though infrequently, didn't light.  After I got the manual I read that the flame should be blue and an inch long.  It was orange and maybe 3 inches long.  Gas pressure was really way to high.  The stove seemed fine but the water heater sounded like a Delta jet aircraft prior to noise abatement.  I checked my pressure with the water gauge and found it to be way high so I turned it down to spec and the furnace was still getting a little too much gas.  The furnace was the hardest to get into to change the jet so I adjusted the pressure for an optimum flame profile and that pressure was just slightly out of tolerance on the low side.  Then my stove would NOT work and the water heater was barely functional.  The RV store had a tournament assortment of jets for the water heater but nothing for the stove.  Got the correct jet in the water heater and drilled out the stove orifice with some carburetor jet drills and all was well.  The furnace output is drastically reduced but is still more than I will ever need anywhere.  That Hydraflame must have been putting out 100,000 BTU's originally.  No wonder it burned up the exchanger.  Lost the control board in 93 and not a peep out of her since.  Propane works!  In the middle of the night you can hear every single relay and spark and ignition and blower...silent during the day but not at night.  Then again, I can't hear Wifey breathing during the day so's I can notice

DO NOT plumb with those gas tubing connectors that use ferrules.  Guaranteed failure and that means RV gas fire.  Very "ungood".  Each appliance MUST have it own dedicated run from the gas manifold/distribution pipe and those connections must be double crimp compression fittings.  Copper is easy to double crimp.  My distribution is a black iron 1/2 inch gas pipe that runs down the center of my coach underneath and outside.  A tee is installed where a copper line will break out to a device and the coper is run up through the floor right near the device input connection.  This keeps as much of the gas line as possible outside the coach.

I have carbon monoxide AND propane sensors inside the coach and wouldn't leave home without them.

HTH,

John

[travelingfools]

John, is there a reason to not run the 1/2 inch black iron right up to the fixture ? Im guessing movement ? I was thinking about running black iron up to the fixture, then a short flexable gas line between the pipe and fixture..

[JohnEd]

The black iron is a safety code, I have no doubt.  When I think about what you said....you will have a piece of flexable copper between your iron pipe and appliance.  It doesn't matter if it is 1 inch long or a few feet you have two connections.  In the S&S I am sure it was for manhour considerations at the time of mfr. that they chose copper runs from the manifold/dist pipe.  Mine have a 14 inch loop of excess copper at the appliance so you can disconnect and move the line aside to R&R the appliance and reconnect the tube without difficulty.  Copper gets really hard with age...work hardened even if there is no "work".

I liked my Hydraflame/Atwood interior mount furnace because it didn't remove a lot of insulation from the wall.  The hole was little more than a 2x4 footprint.  There is something to be said about outside access being convenient but I don't think efficiency or insulation is one of them.  These furnaces are selling for $600 and used to cost $150.  I would install the best deal that came my way but I would definitely lean to the Atwood/Hydraflame and modify the interior of a cabnet or sink base to fit it in.  You are going to bugger up those areas anyway to install ducts or vent the furnace to the interior.

Regardless of which propane you get consider this:  Glue, bolt screw or rivet metal or wood to all of the sheet metal surfaces of the furnace except the heat exchanger box.  They move a LOT of air and do get to rumbling.  Mount the furnace on a thin/thick sheet of rubber.  Glue wood to the interior panels of cabnets near the furnace cause they start in with harmonics, also.

Good luck with this.  Propane is the most painless way to heat, in my humble opinion.  I "want" hydronic though.

John

[Hartley]

I installed the Suburban 35k in my MC9.. Only takes a 4 X 6 cut out hole.

I installed a couple of the Atwood units in a Flyer a few years ago, They take
such large holes that it was difficult to find a good place.

The other problem is everything is outside in the weather and is not tamper
resistant on the furnaces that have outside access service doors. Wasps, Mud dobbers and other bugs and critters love them.

The suburban is all one slide out unit inside its housing. Easier to maintain
as they don't get water saturated in bad weather because they are inside.

Good Luck figuring out what you want... Takes a while sometimes...

Dave....