truck camper heater upgrade

[wagoneer]

I like the propane heater in my camper but the fan sucks the life out of my batteries. I am thinking about replacing it with a 12 volt friendly heat resistant replacement has anyone done this upgrade?

 

[B and C]

I have never heard of this heat resistant upgrade. Got a link to what you are talking about?
I would like a furnace fan option that is battery friendly too.
My search terms came up with a lot of unrelated stuff.

 

[wagoneer]

The fan is located behind the burner unit, I am going to pull the unit out and see if I can replace the blades with a lighter option. or place a fan behind the cover/grate that draws and not pushes the heat?

 

[B and C]

My furnace (Suburban) has a vane in the airflow that is connected to a switch that allows the furnace to ignite. The fan comes on and closes the switch to then light the burner. This vane switch would still need to be incorporated. It is a safety feature. When the fan stops it turns off the burner. I don't remember for sure but I think the fan is a squirrel cage blower to force enough air to overcome the vane switch.

You got me thinking about a high CFM muffin fan though with maybe a bigger vane and/or a lighter spring on the vane. I would have to take a closer look at the exploded view of the furnace to see if a muffin fan could fit where the squirrel cage fan is. I like pushing air better than pulling it plus the fan motor stays cool. Ducting is easier too.

 

[wagoneer]

My concern exactly having worked in HVAC and thermocouplers and other safety features would not want a work around but something safe and reliable
also thinking muffin fan, thanks for the feedback.

 

[user 13531]

Does your heater have a multi-speed fan setting? If not, is it possible to add that feature to your system. Mine has a high/low setting on the stat for both heating and cooling systems. I haven't measured the load between the settings but there is a substantial difference in air flow.

 

[Willy]

Depending on space available, you might want to look into an 'old fashioned' convective vented furnace and hook up a 12v computer fan w. a thermocouple for 'forced air'. ..Willy.

 

[hugemoth]

Never heard of upgrading the fan to one that pulls fewer watts. Is this an Atwood heater? As I recall the old Atwood heaters draw around 7 or 8 amps when fan is turning which will drain an RV battery completely on a cold night. They are really designed for use when plugged into shore power. If you do come up with a more energy efficient replacement fan you could probably sell a lot of them.

 

[wagoneer]

Thanks Willy been too busy to take a closer look but will today, It's an older on or off no in-between settings. I have 2 x 6 volt 120's wet cell in a 1993 slide in.

 

[tx2sturgis]

Have you looked at the Wave Catalytic heaters?

You may not have enough room but it might be an option. They don't use any DC from the batteries.

 

[B and C]

Wave catalytic heaters give off carbon monoxide and water vapor as a byproduct of burning propane. Furnaces vent outside, no need to provide ventilation.
My furnace is connected to a thermostat and cycles on and off as the thermostat setting dictates and I CAN sleep while using it.

 

[tx2sturgis]

Wave catalytic heaters give off carbon monoxide and water vapor as a byproduct of burning propane.  Furnaces vent outside, no need to provide ventilation.
My furnace is connected to a thermostat and cycles on and off as the thermostat setting dictates and I CAN sleep while using it.

Yes, and every single piece of technology we use has risk...including driving a vehicle...(you can actually get killed in a vehicle!)....but we don't discourage people from driving. 35,000 to 40,000 people die in traffic accidents in the USA every year. The number of campers who die from carbon monoxide poisoning is an EXTREMELY low number. But it's not zero, of course. 

Everything has pros and cons....RV furnaces tend to kill batteries (if there is no solar or shore power) and are terribly inefficient.

Catalytic heaters, again, with proper air flow and ventilation, give off miniscule amounts of carbon monoxide (much less than an infra-red type like a Mr Buddy) and won't kill you or your batteries.

They DO give off some water vapor and need a supply of oxygen. But they are nearly 100% efficient. 

And tens of thousands of RVers around the country sleep comfortably with Wave Catalytic heaters running all night. I have used them, often running on low all night, for 18 winter seasons now...I ain't dead yet.

 

[user 13531]

I've got an Atwood 8520-IV 20K BTU furnace, if I'm reading this manual correctly it draws 4.6 amps...

http://www.atwoodmobile.com/manuals/furnaces/MPD 33179 SP 1.08.pdf

 

[user 13531]

Correction...

Leave it to Jayco, my manual is not for the furnace in my rig. I have an Atwood Hydro Flame AFMD20 20K BTU and it draws 4.2 amps... My rig is 23' with no slides but is ducted with a heated winterized under belly...

At 25K and 30K BTU systems amp draw is 7.5 and for the largest 34K BTU system draw is 11.1 amps...

 

[B and C]

Yes, and every single piece of technology we use has risk...including driving a vehicle...(you can actually get killed in a vehicle!)....but we don't discourage people from driving. 35,000 to 40,000 people die in traffic accidents in the USA every year. The number of campers who die from carbon monoxide poisoning is an EXTREMELY low number. But it's not zero, of course. 

No need to get snarky.  I was trying to keep this thread on track and not get derailed into alternative heat sources.

 

[tx2sturgis]

No need to get snarky.  I was trying to keep this thread on track and not get derailed into alternative heat sources.

Sorry if it came across as snarky, but it seems every time the subject comes up, someone makes them sound like they will kill you dead in your sleep the first night of use.

Cars, pogo sticks, bicycles, skateboards, airplanes, busses, trains, guns, golf clubs, chainsaws, pocket knives, parachutes...and propane heaters....the list goes on and on of things that can kill you if misused, but provide a benefit if used properly.

RV furnaces are normally very safe....but they are also noisy, in-efficient, and can kill RV batteries in short order if there is no power to charge them.

Just pointing out that an additional heat source, with the RV furnace as a backup, can be a good solution.

 

[B and C]

The best I can tell from looking at pictures as I can't find an exploded view of one is there is a squirrel cage fan on each end of the fan motor shaft. One is for blowing heated air into the cabin and the other one supplies fresh air for combustion.

The only thing that comes to mind then is to put a rheostat in the power line to the blower motor to control its' speed. Could this could be a safety hazard if the fan is slowed to much?

Thoughts or ideas appreciated.

I have 250Ah of battery so not a big concern to me but I like to trim power requirements wherever feasible but not looking for alternative heating options unless they work like the furnace with no combustion in the living area, works off a thermostat, fits in the furnaces space and does not cost an arm and a leg... I really don't want to replace mine either as it works so well with no bother on my part.

Think I will leave well enough alone as it suits me perfectly.

Thanks for bringing it up Wagoneer. It has given me food for thought.

 

[tx2sturgis]

Ok restart.

Yeah the blower speed has to be high enough to keep the 'sail switch' engaged...and reducing the blower speed too much might cause the burner to shut down, or, the heated air temperatures might rise too much due to low airflow. 

Since the ductwork tubing is usually plastic, this might be a concern.

 

[user 13531]

Sail switch would close and kill the burner, fau's normally have a high temperature limit switch that takes care of that issue as well. I'm guessing the newer rv heating units are considerably more efficient and most come with 2 stage motor and stat/panel board to control same. Since max amp draw on my unit 4.2 amp, low fan setting must be something less than that.

It's supposed to drop to 32F tonight at my location, I'm going to kill the shore power and see if my single battery will drive the heater tonight.

It was 37F last night, I set the stat to 62F before bed, the unit only cycled twice over night. Again I'm sure all our rigs have different energy loss issues with windows, construction materials, insulation, etc...

 

[user 13531]

So my heater cycled (4) times last night with a 62F stat setting and exterior ambient temp of 32F. I'm running a single 2017 Interstate SRM-24 140RC deep cycle battery. Since I'm not running solar, I just have the standard OEM idiot light monitor system. There was no change in the monitor reading (Full charge last night - full charge this morning). Keep in mind this is a 23' box and I keep the bathroom door closed, so I only heat the remaining 18' or so feet of the camper. I timed one of the four cycles and the heater fan ran approximately 6 minutes from start to stop. So maybe 24 minutes of total heater fan activity over night, couple amps of demand maybe....