I have a 2005 Fleetwood Excursion 39S DP with good front air conditioning and heat. Having said that, there's a cold spot under the dash where my feet are so I'm looking for a small 12VDC heater to mount under there for use while driving. I've looked at the heater hoses and they would be a pain to reroute. I have sufficient extra 12V power under the dash and there's lots of open fuses.I've been searching the internet for 12V heaters and not finding anything that looks good. In reading Amazon reviews, nothing has looked good there either, though a lot of the reviewers had unrealistic expectations such as heating large vehicles during the middle of winter.If you can recommend a small 12VDC, my feet would appreciate it.Bill

I strongly recommend doing a good search for air leaks in that area first.When in heater mode, the heat should be blowing down near the floor near your feet. If it is not, there may be a problem with the ducting dampers.To get a good amount of heat from 12 volts, the current is too high for "standard" wiring and sockets.

12V heaters would be too high amp to be practical.Check for outside entry or reposition floor duct.

You could try just wiring up a standard little 120v electric heater. Resistance heating elements don't care if they have AC or DC flowing thru them. A 1500 watt heater on 120v would be roughly a 150 watt heater on 12v. I would think that might be about right to warm up the foot area under the dash.The problem might be the fan in the heater. Ideally you'd find one with no fan but that would probably be kind of large. You might be able to swap out the fan motor for a 12v DC model.

KD4UPL wrote:You could try just wiring up a standard little 120v electric heater. Resistance heating elements don't care if they have AC or DC flowing thru them. A 1500 watt heater on 120v would be roughly a 150 watt heater on 12v. I would think that might be about right to warm up the foot area under the dash.The problem might be the fan in the heater. Ideally you'd find one with no fan but that would probably be kind of large. You might be able to swap out the fan motor for a 12v DC model.That's an interesting idea, I'll have to play with an extra heater I have when I get home. Thanks.Bill

Need a small 12VDC heater | Good Sam Community

GordonThree
Explorer
Mar 27, 2017
time2roll wrote:
Wear some socks ;)

Heated socks from REI or a motorcycle outfitter.
wa8yxm
Explorer III
Mar 27, 2017
Ok, if you visit the great WHITE north.. In the winter, you will find many 12 volt "Defroster" type heaters, designed to aid in defrosting the windshield they run about 100 watts.. Plug in to the accessory socket

I Do not really recommend them.. but that's about the best you can do.

IF you have an inverter there is "The World's Smallest Space Heater" 150 watts at 120 volt, and they ahve been advertissing "The Wall Hugger" I think it's 250 watts, pluggs into a standard wall outlet but no cord, plug is attached to the housing.
rockhillmanor
Explorer
Mar 27, 2017
Go to a Loves or Flying J and find the truckers section inside the store. It is usually way in the back and out of the way. Close to where the truckers check in etc.

THAT is where you will find a plethora of good 12v DC heaters, etc.

Once I found the truckers sections of stuff for sale I no longer buy the cheaper and usually poor quality items sold for RV's.
GordonThree
Explorer
Mar 27, 2017
Keep in mind the 12v accessory outlet is really designed poorly and intended for light loads like cell phone charging and GPS.

Trying to pull 100+ watts for a long period through one will likely work but might also melt the outlet, due to the poor design.
Trackrig
Explorer II
Mar 27, 2017
GordonThree wrote:
Keep in mind the 12v accessory outlet is really designed poorly and intended for light loads like cell phone charging and GPS.

Trying to pull 100+ watts for a long period through one will likely work but might also melt the outlet, due to the poor design.

Within reason, I don't have to worry about the power requirement. I have a huge power cable from the batteries to the fuse panel under the dash that has very lite power draw on it. I will not be using a 12V outlet to power the heater.

And referring to the above idea of using a 120AC heater wired into the 12V, I have some extra 12V ball bearing computer fans left from installing vent fans on my refrigerator cooling upgrade that I could install on the heater.

Bill
DrewE
Explorer II
Mar 27, 2017
KD4UPL wrote:
You could try just wiring up a standard little 120v electric heater. Resistance heating elements don't care if they have AC or DC flowing thru them. A 1500 watt heater on 120v would be roughly a 150 watt heater on 12v. I would think that might be about right to warm up the foot area under the dash.
The problem might be the fan in the heater. Ideally you'd find one with no fan but that would probably be kind of large. You might be able to swap out the fan motor for a 12v DC model.

A 1500W 120V heater uses 12.5A and so has a resistance of about 9.6 ohms. Assuming the heating element resistance is constant with temperature (which is not exactly true), this would mean 1.25A at 12V, or a power of 15W. That's not enough heat to really be noticeable.

In more general terms, for a purely resistive load, power varies with the square of applied voltage. For a factor of ten difference in voltage, the power consumption changes by a factor of one hundred.

More readily practical might be installing an inverter and using a low-powered 120V heater off of that. A heating element would be just fine with an MSW inverter, though the shaded pole fan motors used in many heaters might not run quite as well.
Jagtech
Explorer
Mar 27, 2017
Maybe a heated floor mat would be the solution ?
Winnipeg
Explorer
Mar 28, 2017
Maybe you can find the cause of the cold spot? Something moved out of place, or maybe an opening?
AllegroD
Nomad
Mar 28, 2017
Winnipeg wrote:
Maybe you can find the cause of the cold spot? Something moved out of place, or maybe an opening?

This is my recommendation. If you have an air incursion, a heater will only be a mild relief and run constantly, as the cold air will still be coming in and flowing over your feet.
crasster
Explorer II
Mar 29, 2017
These are "ok..."
Harbor Freight 12v heater.

They run off the lighter. Pretty warm. They don't replace the car heater but would be fine to put feet next to. :) Just be sure to turn it off when your feet are warm.

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