BTU versus watts, Propane versus electrical heaters

mike-s wrote:
And what was the voltage at the wall plug, while they were turned on?

Unloaded, hovering around 121 vac ... with each heater voltage drop obviously varied according to draw ... sorry, didn't make a note of it.

And what was the voltage at the wall plug, while they were turned on?

SoundGuy wrote:
Yeah, you're guessing alright. :W Rarely does any so-called electric heater labeled as "1500 watts" ever come close to drawing that much power ... the only way to know is to measure it.

myredracer wrote:
Afraid I have to disagree with a blanket statement like that. I just tested a couple of heaters and one was 1505 watts and the other 1508. If it's not reading close to 1500 watts at exactly 120 volts at it's plug, it's either non-compliant with UL (or CSA) or it's output is not being measured in accordance with UL testing. I'd test a few more but don't any more around the house.

OK, let's play tit for tat then. :W

I just grabbed 3 different electric heaters I have here in the workshop, 2 of which I use regularly in the camper as our primary source of heat, relying on the gas furnace only to augment heat when outside temps really begin to fall. Measurements were taken with a P3 Kill-a-Watt that claims 0.2% accuracy, then I also remeasured with an inexpensive EM100 energy meter purchased at Canadian Tire, results with that meter are shown in brackets. In each case the heater was allowed to stabilize for several minutes and readings taken were whatever the meters said was the maximum on that particular heat setting.

Heater 1 is an ultra quiet Bionaire, is CSA certified, and is stamped 1500 watts - not even close, measured 537 watts (514) on High, 236 watts (224) on Low.

Heater 2 is a typically noisy Lancaster, is UL certified, and is stamped 1500 watts - measured 1170 watts (1130) on High, 758 watts (728) on Low.

Heater 3 is a very noisy SuperFurnace, is CSA certified, and is stamped 1500 watts - measured 940 watts (893) on High, 660 watts (630) on Low.

As you can see not one of these heaters is drawing anywhere near 1500 watts so I'll repeat - one cannot rely on any label that may be affixed to any given heater to accurately determine how much power it actually draws, you gotta measure it. :W

mike-s wrote:

brulaz wrote:
The catalytic Olympia heaters are apparently more efficient with less moisture released than the others,

Someone has been lying to you. Burning propane is burning propane. It may be efficient in terms of complete/safe combustion, but it's going to produce water (and carbon dioxide) according to the same chemistry as the others - C3H8 + 5O2 = 3CO2 + 4H2O.

No liars, just a mistaken assumption on my part. You are right.

With respect to vented propane heaters, I cannot find anything as small (3-6K BTU) as the unvented Olympia Catalytic heaters. The smallest I've seen (10K) is ~10" thick and would be more difficult to fit in our trailer's small living space. But doable. They are also quite a bit more expensive.

SoundGuy wrote:
Yeah, you're guessing alright. :W Rarely does any so-called electric heater labeled as "1500 watts" ever come close to drawing that much power ... the only way to know is to measure it.

Afraid I have to disagree with a blanket statement like that. I just tested a couple of heaters and one was 1505 watts and the other 1508. If it's not reading close to 1500 watts at exactly 120 volts at it's plug, it's either non-compliant with UL (or CSA) or it's output is not being measured in accordance with UL testing. I'd test a few more but don't any more around the house.

I imposed my own rule on whether to use unvented cat heat with regard to moisture:

Up to 30% relative humidity I'll use it

Higher than 30% humidity I want vented heat.

No "98%" heaters for RVs yet?

I have posted this before but we are still alive so I will post it again. For the last ten years and three different coaches one class C and two class A. In all of them we have used a Small Single block MR Heater propane heater plumbed to the coach on board propane tank. We have Two CO detectors that never make a sound unless I test them which I do regularly. There is no odor from the heater. We have no unusual moisture inside.

Many have screamed we we were going to die. Nope-doing just fine. We use non serviced sites in state parks most of the time and virtually never use our two furnaces.

Jim

Hi mike-s,

The equation I worry about is this:

2 C3H8 + 7 O2 = 6 CO + 8 H2O

Carbon monoxide is such a nasty substance.

mike-s wrote:
Someone has been lying to you. Burning propane is burning propane. It may be efficient in terms of complete/safe combustion, but it's going to produce water (and carbon dioxide) according to the same chemistry as the others - C3H8 + 5O2 = 3CO2 + 4H2O.

As long as you are using 1500 watts you would get more BTU from a heat pump as long as it was not too cold.

I've never had trouble with excessive moisture from our cat heater
But we do live in a dry mild climate, not the wet North East