Alternate (quiet / low power) fan for Hydroflame 8012 furnace?

Discussion in 'Heating / Cooling Systems' started by TroySmith80, Feb 3, 2015.

  1. TroySmith80

    TroySmith80 New Member

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    I have an '84 Palomino with the hydroflame 8012 furnace. Everything works well, but the fan is pretty noisy and I'm also always looking to reduce power usage anywhere i can. According to the manual, this furnace draws 1.6 amps. I'd love to have one of the old fanless style heaters, but they seem to be pretty rare. My dad said he had one in a camper long ago and he loved it.

    I actually tried running my furnace without the fan by bypassing some of the safety switches. The flame died out pretty quickly and i realized that there are actually 2 fans in the furnace, the larger one blows air past the heat exchanger and into the camper, but there is a smaller one that actually circulates the intake/exhaust combustion air from outside the trailer. So when that smaller fan wasn't running, the flame died down and went out.

    12v computer case fans run extremely quiet and low power. I think they run around .1-.25 amps. I know they don't push nearly as much air as the fan in the furnace, but that that might be ok if it can run more of the time without being obnoxious and draining my battery. I'm wondering if i could put one or two larger case fans for the cabin air circulation, and a smaller one for the combustion air circulation. Has anyone ever tried this?
     
  2. R00

    R00 Active Member

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    Don't try to run your furnace without the fan unless you want to burn your trailer down. Sail switches and thermocouplers are there for a reason.

    That said, I have the same model furnace, and it is a noisy booger. Mine has developed a troubling bearing whine on startup as well :-(
     
  3. TroySmith80

    TroySmith80 New Member

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    Thanks R00,
    I should have mentioned that my only intent in bypassing the safeties was to run the furnace while i sat right there and monitored how hot things got. I wanted to begin to get an idea of whether it would be safe with less airflow than the stock fan provides. I suspect it would not be safe relying on convection only (no fan).

    Does anyone know why they quit making fanless rv furnaces?

    I also have a buddy heater, maybe what i ought to do is just plumb a "T" into the gas line so i can hook up the buddy heater... that's a whole different kind of dangerous though. Much easier to accidentally set a blanket or piece of clothing on fire. Also, we have an infant daughter who will be toddling around this summer. One probably doesn't need to worry about CO buildup or low-oxygen in a tent camper. Ours seems pretty darn drafty.
     
  4. Customer

    Customer Well-Known Member

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    Safety, the old RV gravity furnaces would often overheat and the heat exchanger would crack. That crack would then allow CO into the RV.
     
  5. pej

    pej Member

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    Some install a voltage regulator on the furnace to keep the voltage lower. On shore power your furnace fan is running at 14.5 volts or higher. The furnace will happily run at 12 volts or even 11.5. The fan noise is significantly reduced at these lower voltages.

    2001 Palomino Pony21, '11 Ford Escape. www.headpond.ca/Palomino.html
     
  6. Nandy

    Nandy Active Member

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    If you want a quieter furnace then buy you one unless you really know what you are doing. Air flow will not only control your heat but will keep you alive too. Many risks, for CO poisoning to setting your camper on fire while you sleep. BTW, do no bypass your safety switches unless you know what your are doing. Those are there to protect you too.
    1.6 amps is very low already for a furnace so I am not sure you will find much lower than that.

    If you are on shore power use electric ceramic heaters, you can power one with the pup wiring and use a large gauge drop cord to power the other one. We have done that arrangement in 20 deg weather and we been toasty inside. That was in the big pup. I use the small pup for when I boondock and I have a low amp furnace too, (i might have your exact same model) and it noisy but it dont bother me. I could last a weekend on my group 29 battery if I use it just for sleeping.
    Some use Buddy heater or alike. I had use some of that while tent camping but not for sleeping. Many do, they are silent.

    Good luck.
     
  7. TroySmith80

    TroySmith80 New Member

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    Pej, that is a fantastic tip, thank you! The reduced noise would be great. I wonder if power usage would go down as well, or if current draw would go up as voltage goes down, so that the net effect is null?

    I never camp where there is power, so plug-in heaters are out. The buddy heater is an option, but like i said, it makes me nervous due to the fairly high fire danger.
     
  8. Nandy

    Nandy Active Member

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    then if you dont camp where there are power then Pej advise would not work. Your battery dont supply 14.5+ vdc. You see that on batteries on chargers or coming from a converter.
     
  9. TroySmith80

    TroySmith80 New Member

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    True, but a good charged battery should be putting out more than 11 volts, so turning it down a little might help, a little. Some googling shows that voltage regulators are under $10, so not too much to lose i don't think. I'd still rather use smaller/quieter fans. Not sure i will use the heater enough to justify too much monkeying around. I have more projects than time.
     
  10. lifespeed

    lifespeed Member

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    Replace the fan motor if the bearings are noisy. You already have the lowest power furnace. Concentrate your efforts on the power supply side with dual batteries.

    Messing with your furnace as described could win you a Darwin award.
     
  11. TroySmith80

    TroySmith80 New Member

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    How much have lights advanced since this furnace was first designed and came on the market in... what, the 70s?

    I don't think dc motors have had a breakthrough quite as significant as the leap from incandescent to LED lights, but there are brushless motors now, and i'm sure other innovations that would allow one to very safely reduce the noise and power consumption of a 12 volt furnace.

    I know a lot of people are reluctant to even consider innovation in applications like this due to safety concerns, but there are safe ways to experiment and innovate. I definitely wouldn't sleep in the thing unless it still had functional over-temp safety and sail switch safety. As long as those are there and functional, it should be fine. Also, i'd probably run it on max temp in my driveway for a week before putting my family in it, just to have extra confirmation.
     
  12. lifespeed

    lifespeed Member

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    Turning electric power into mechanical has been efficient for nearly a century. The only way you could significantly reduce power would be a corresponding reduction in motor power output and a corresponding reduction in air flow. This will break the operating parameters of the furnace as the air flow has to move the heat out of the heat exchanger. You can slow down the fan speed by reducing the voltage, but this doesn't reduce electric consumption unless you use a highly-efficient DC-DC converter for the task. And then you are back to overheating the heat exchanger by not moving the heat out. Efficiency gains from replacing the motor to a different design would be at best a few percent, and mechanically very difficult.

    As for noise, is it just air flow noise or is the motor squealing? The former is not really negotiable, the latter is fixed with a new motor. How do you propose fitting a "different", quieter double-ended squirrel cage type of fan with it's accompanying combustion fan into the existing mechanical design?

    If you want to use a forced air furnace you have to provide electric power. Less than 2A for the furnace you have is completely reasonable. You only have two alternatives: more battery power and solar if you want to go that route, both practical and reasonable to implement. Or an electric-less catalytic propane heater that exhausts inside the PUP.

    Feel free to re-design your furnace and prove me wrong by posting the details of your success. [;)]
     
  13. R00

    R00 Active Member

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    Why hasn't anyone designed a large catalyst heater for permanent installation in RV's? They're so much more efficient!
     
  14. R00

    R00 Active Member

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  15. crackerJack

    crackerJack Well-Known Member

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    IMO... The safety and performance of a forced air furnace that exhausts to the outside is unmatched. I installed the Atwood 8012 and am satisfied with it.
     
  16. lifespeed

    lifespeed Member

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    That Atwood 8012 is supposed to be the way to go for low electric consumption at less than 2 amps. I have the 7916-II, and even at 3.5 amps find it works just fine with dual batteries and solar.
     

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