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Old 01-27-2011, 07:39 AM   #1
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Resistance / convection heaters

What is the largest/best/most efficient wattage for a portable electric heater that one could safely use when on shore power? Is 1500W ok? I see folks using these in other RV's and have decided it's probably better/cheaper/safer than using the propane furnaces - although mine work just fine for chilly mornings/evenings (I did have to replace one motor/blower in one unit, however). Thanks, D&D.
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Old 01-27-2011, 07:49 AM   #2
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1500 Watts is about the biggest you'll find that run on 110 vac, because of the current draw and the capacity of the duplex outlet. Watts = current X voltage, so 1500 Watts at 110 volts will draw about 14 amps, and most duplex outlets are fused (breaker) at 15 amps.

I use two of them in our trailer here when a freeze is predicted, and they do the job. However, it rarely gets below the mid 20's here.
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Old 01-27-2011, 08:02 AM   #3
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The propane furnace will more evenly disperse the hot air, but an electric one will be okay. Sometimes I use a small fan to circulate the air when using electric. Do not get it near the shower, trust me!!. zz
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Old 01-27-2011, 08:07 AM   #4
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Yes, 1500w is the largest you can get off the shelf, for 120 volts. You can run two of them with a 30a shore power connection as long as you don't also run an electric water heater or a microwave or convection oven at the same time.

I have one permanently installed which is more convenient, and I believe safer. No cords, and it's out of the way where people won't trip over it, and away from towels, bed linens, and other things that might burn.

http://www.airforums.com/forums/f427...ble-64289.html

King Electric makes a good tabletop heater that is small, light, and quiet, called the HFC 1500. I have one of these I've been using in the bedroom. It's quiet enough for that.

People usually recommend oil filled heaters, which do work great, but they're big and heavy.
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Old 01-28-2011, 08:13 AM   #5
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The problem I see is that the furnace, on our Land Yacht, heats the tanks as well as the living area. I guess if it does not get too cold the electric heater would work. Is electric really cheaper than propane?
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Old 01-28-2011, 08:16 AM   #6
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Quote:
Originally Posted by BarnacleBill View Post
Is electric really cheaper than propane?
I think it is, and I don't have to take the tank down to the electric company every two weeks and get a new tank of electric.
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Old 01-28-2011, 11:28 AM   #7
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Quote:
Originally Posted by BarnacleBill View Post
The problem I see is that the furnace, on our Land Yacht, heats the tanks as well as the living area. I guess if it does not get too cold the electric heater would work.
Two 1500W electric heaters will keep the trailer reasonably warm down to around 30 degrees. ( fact based furnace thread).

I wouldn't be too concerned about the tanks and plumbing freezing, with two 1500w heaters going and the interior temp kept around 70, unless you have night temps below 20 and day temps below 30, at which point the electric heat won't really keep up anyway.

Quote:
Is electric really cheaper than propane?
It depends on what you pay for propane, whether your electricity is metered, and if so, how much you pay for electricity.

Typically propane for RV use is around $3 a gallon although prices vary widely both with swings in the underlying fuel price and how much extra the dealer is marking it up.

20 kwh of electricity has about the same usable heat content as 1 gallon of propane (assuming 99% efficiency for the electric heat and 80% for the propane furnace), so here's a little chart for the break even point.

Propane Electric
1.50 0.08
2.00 0.10
2.50 0.13
3.00 0.15
3.50 0.18
4.00 0.20

Typically campgrounds don't meter electricity and charge a flat fee instead. If you are parked at your house or someplace else where you're paying the going rate for electric service, you're probably paying around 12 cents a kwh although again rates vary widely.

But there are reasons to run electric heat besides pinching pennies. As SteveH notes it eliminates the hassle of refilling the tanks. In cold weather with 30 degree lows and 50 degree highs the electric heat will keep up just fine (if you have two 1500w heaters), but if you ran the furnace instead you'd go through two or three gallons of propane a day, so you'll go through more than two 30# bottles a week.

Sometimes this is a major hassle particularly if you are parked in one spot for an extended period of time and your tow vehicle is a Touareg or Suburban or something else that can't really carry propane tanks safely. Many propane dealers have daytime hours only so if you are working a day job and living in your trailer getting the tanks filled is a real problem.

Also, unless you're using a heat pump (which I wouldn't recommend), electric heat is generally quieter, even if you've taken steps to quiet down the furnace and deal with blower rumble..
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Old 01-28-2011, 11:45 AM   #8
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Incidentally, though it comes up less often, the same logic applies to water heaters.

My water heater runs on either gas or electric, and combined with the availability of both gas and electric heat, I don't end up using much propane except when boondocking or when temps drop below 30 degrees. I think used 15 gallons last year.
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Old 01-28-2011, 12:21 PM   #9
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EdenPure heaters have quartz infrared elements that they advertise do not dry out the air. I would say most trailers have excess humidity inside so resistance heaters my be a better choice to help get rid of some humidity. Resistance heaters have about the same watt-btu ratio.
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Old 01-28-2011, 12:48 PM   #10
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Technically, no heater dries out the air in the sense of removing water from it.

The heavily-marketed EdenPure heaters, while well made and quiet, are no more or less efficient and no more or less air-drying than any other electric heater.

Warmer air has a lower relative humidity because it has more capacity to hold water. This is true regardless of whether the air has been warmed by an EdenPure heater or something else.
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