Best small electric heaters

RV furnaces typically have efficiencies in the 70-something percent range. So, your 35K probably puts out around 26K in heat. So, ~5 electric heaters.

What percentage of the furnace BTU actually gets into the RV?
Or how do you compare a 35,000 BTU (input) furnace to a 5100 BTU electric?

travelnutz wrote:
myredracer,

The total voltage drop in the 6' long 16 gauge power cord (13 amp load rating) stranded copper wire with 1500 watts (12.5 amps) at 120 volts of AC going to the electric heater is only 6/10 of 1 volt. Meaning the heater is getting 119.4 volts of the 120 volts at the outlet. Negligible loss and means the 1500 watts would only drop to 1492.5 watts delivered to the heater's element due to voltage drop! The 16 gauge heater wire is not the issue at all for not getting a 1500 watts reading as claimed of the watts being consumed.

Further, even assuming there's 120 volts actually measured at the RV's entry circuit breaker box from shore power and then having a run of 25' of 14 gauge copper wire to the outlet the heater is plugged into, there still would only be a 1.6 volt drop at the outlet the actual heater wire is plugged into and with the heater turned on high selection. The 120 volts at the breaker would still measure 118.4 volts being delivered to the heater 16 gauge power cord. Check the voltage drop charts for yourself.

These 2 things are not the reason for the electric heater actually only drawing a measured 1300 or 1400 watts rather than the 1500 watts claimed by the manufacturer. Therefore, such heater will not deliver 5120 BTU's nor will it measure to be drawing 12.5 amps either.

Conversely, I can assure you that every 100 watt incandescent light bulb I've ever checked actually draws 100 watts just like is printed on the bulb but never had a claimed 1500 watt electric heater actually draw even as much as 1400 watts or even close to 12 amps of 120 volt AC.

Got my Mythbusters hat out and did a test on two 1500 watt ceramic cube heaters we have at home.

In the US, portable space heaters like these must comply with UL standard 1278 which requires a heater's rated output (as shown on it's label) to be at the voltage shown on the heater's label which for both heaters is 120 volts. Power input cannot be higher than 105 percent of it's rating (1575 watts for a 1500 watt heater). This standard has over 100 pages of very stringent requirements they must meet to become certified. In Canada, these heaters must comply with CSA standard 22.2 no. 46. I couldn't find a free copy of the Canadian standard online, but I would expect it to have the same stringent requirements as UL 1278, and wouldn't be surprised if the requirements are even higher. I am not using a high accuracy voltmeter or ammeter but they do correspond closely with two other voltmeters & ammeters I have.

The 1st heater is branded Comfort Zone and is labelled UL 1278. At 117.0 volts the heater draws 12.26 amps which is 1434 watts. To find the heater's wattage rating at 120 volts, it would be (120/117) x (120/117) x 1434 = 1508 watts. By UL 1278, power input is measured at the cord's plug. I did measure the voltage drop in the cord anyway and it was 0.8 volts.

The 2nd heater is branded Lancaster and it's label says it complies with CSA 22.2 no. 46. At 120.6 volts it draws 12.6 amps which is 1520 watts. At 120 volts, the power (using above formula) would be 1505 watts. The second test was on a different day hence the different voltage. (Our nextdoor neighbor has a manufacturing shop with 3-phase power and I suspect he is dragging the voltage down.)

As far as I can see, heaters should draw close to their listed rating at the listed voltage. There is also no benefit to a manufacturer reducing a heater's output since UL 1278 requires testing voltage to be adjusted until it produces the rating on it's label. It would be interesting to see someone try this on other heater types like say an oil-filled type. BTW, if you have a heater, it must be UL or CSA listed (on it's label) and if not, don't use it.

As a FWIW side note, Nichrome heating wire resistance goes up as it's temp. increases as the 2nd photo shows. I found that the initial current draw of the Comfort Zone heater was around a peak of 20 +/- amps during the first 4-5 seconds after being turned on. It took around 15 seconds or so before it reached a steady state of 12.26 amps. The second photo shows it's current at 19.89 amps (it changed too quickly to get a pic at the peak). This won't trip a circuit breaker because the duration is so short.

i have one of these love it!! Keeps the trailer nice and toasty during those cold spring and fall camping trips.

I always prefer to use the CG's electricity before i use my propane.

myredracer,

The total voltage drop in the 6' long 16 gauge power cord (13 amp load rating) stranded copper wire with 1500 watts (12.5 amps) at 120 volts of AC going to the electric heater is only 6/10 of 1 volt. Meaning the heater is getting 119.4 volts of the 120 volts at the outlet. Negligible loss and means the 1500 watts would only drop to 1492.5 watts delivered to the heater's element due to voltage drop! The 16 gauge heater wire is not the issue at all for not getting a 1500 watts reading as claimed of the watts being consumed.

Further, even assuming there's 120 volts actually measured at the RV's entry circuit breaker box from shore power and then having a run of 25' of 14 gauge copper wire to the outlet the heater is plugged into, there still would only be a 1.6 volt drop at the outlet the actual heater wire is plugged into and with the heater turned on high selection. The 120 volts at the breaker would still measure 118.4 volts being delivered to the heater 16 gauge power cord. Check the voltage drop charts for yourself.

These 2 things are not the reason for the electric heater actually only drawing a measured 1300 or 1400 watts rather than the 1500 watts claimed by the manufacturer. Therefore, such heater will not deliver 5120 BTU's nor will it measure to be drawing 12.5 amps either.

Conversely, I can assure you that every 100 watt incandescent light bulb I've ever checked actually draws 100 watts just like is printed on the bulb but never had a claimed 1500 watt electric heater actually draw even as much as 1400 watts or even close to 12 amps of 120 volt AC.

smkettner wrote:

SoundGuy wrote:

MrWizard wrote:
Most are around 1500 watts which is 12.5 amps at 120vac ...

In theory yes but in reality hardly does any electric heater advertised or labelled as "1500 watts" actually consume that much power, in some cases much less. I have a gaggle of so-called "1500 watt" electric heaters and only one of them comes anywhere near close to drawing 1500 watts, rather ~ 1440 watts, with all the rest much less. My Kill-a-Watt meter is a handy device for measuring actual draw like this. :)

I believe the rating is at 125 volts. Wattage drops fast because with less voltage there is also less amperage.

Most portable heaters have 16 gauge cords and if you include the voltage drop in the supply wiring to the recept. it's plugged into I would guess that a heating element never sees the nominal rated voltage. If you look at the label on a heater it will say "120 volts" on it and it would have to comply with a UL standard and be ETL or CSA, etc. safety listed. The correct way to see if a heater draws it advertised wattage would be to open it up and measure the voltage at the element's terminals and if necessary compensate by calculation if the measured voltage isn't at it's rated/listed voltage.

Road Dog wrote:
I have been using a Vornado for6 years. The best I have found after owning all the others. It's quiet and yet it moves the air all over the coach. I think I paid $79. Great product!

I agree that the Vornado has one of the best portable heaters on the market. Be aware that they too have a large line of heaters. Some really basic.
The greatest selling point for me is that Vornado has a few models that the fan can be set to be on continues and the heat cycles as needed. This offers a continuous white noise. I really dislike a heater that wakes me up as it cycles on and off.

SoundGuy wrote:

MrWizard wrote:
Most are around 1500 watts which is 12.5 amps at 120vac ...

In theory yes but in reality hardly does any electric heater advertised or labelled as "1500 watts" actually consume that much power, in some cases much less. I have a gaggle of so-called "1500 watt" electric heaters and only one of them comes anywhere near close to drawing 1500 watts, rather ~ 1440 watts, with all the rest much less. My Kill-a-Watt meter is a handy device for measuring actual draw like this. :)

I believe the rating is at 125 volts. Wattage drops fast because with less voltage there is also less amperage.

While space heaters are cost effective, the one thing they don't do in cold weather is heat the basement. I have also heated the 5er with a couple small 1500 watt heaters set on low in both ends of the trailer. We only did that due to the partial failure of our propane regulator.

I really don't like using portable electric heaters, but our hand was forced. I have chosen to go a different route for electric heating.

The product name is not accurate as the units are not inexpensive, but provides electric heat directly into the duct system to heat basement and H2O pipes.

RV Comfort Systems

I fulltime and have used one of the oil filled heaters for 3 years now while over-wintering in the brutal arctic conditions of Florida. It's great. Totally silent and has high and low settings. It just seems to put out a lot of heat. Seems more 'gentle' then the other types.

I also have another oscillating fan driven electric heater, but I don't use it since I discovered the oil filled type.

The oil filled type takes a few minutes to get going and put out heat but they never seem to get too hot to the touch (especially on low). It also has a tip over switch. They are simple, cheap, and seem like a very safe alternative.

I have an overhead fan in my fiver and usually set it under the fan to disperse the heat. Failing that, one could get a small, quiet, box fan to set behind it.