Which heater is best: Forced air, ceramic or catalytic?

By Greg Illes
We were up on the North Rim of the Grand Canyon, boondocking out in the Kaibab Forest at around 8,500 feet elevation. It was October, and the nights were regularly dropping into the 30s (F).

Our stock cabin heater, a standard Suburban 30,000 BTU fan-driven beast, had long since been sidelined in favor of a small propane heater. Oh, we still used the “big heater” for warming up the coach in the morning or after long absences. But the “little heater” was very nice at maintaining the cabin temperature. At first we used a Mr. Heater, but later moved up to a 10,000 BTU free-standing unit. It was made with two ceramic panels that glowed red-hot at full tilt. Even later, we mounted that heater on a cabinet.

But that chilly October night, the little auxiliary heater simply would not stay lit. Not even its pilot would stay lit, sputtering and flickering and dying until we finally gave up. We spent that night listening to the noisy fan go on and off, and thinking about all the wasted propane being blown out the side exhaust (used to vent combustion gases).

After the trip, I did some research on these ubiquitous ceramic heaters. I discovered that the design of these units has an inherent limitation, and that they simply cannot be relied upon to operate anywhere above 4,500 feet elevation. It’s a little complicated and slightly technical, but stay with me here …

Essentially, the safety-oriented ceramic-heater design will not allow the heater to function when oxygen levels drop – as they do with rising elevation. Normally, the combustion process produces carbon dioxide (CO2). But at low oxygen levels, in a “burner” style design, reduced oxygen causes the creation of carbon monoxide (CO), a deadly gas. Not good.

The “blue flame,” or open-flame, heaters are a different variation on the ceramic style, but their combustion technique also limits them to 4,500 feet or less. The specs vary slightly among manufacturers – if you can find the specs at all, that is. Calls to manufacturers about altitude were often met by dumb silence.

More research revealed that only one type of heater would work at high altitudes – the catalytic type. Catalytic heaters don’t actually burn propane, they catalyze it. The consequence of this is that there is NO possibility of catalytic heaters generating CO. As a result, their design does not require oxygen sensors, and they will operate independently of oxygen density.

CERAMIC vs. CATALYTIC vs. OPEN-FLAME vs. FORCED-AIR

At that point, I thought I had it knocked. Just buy a different heater, one with a catalytic design.

Then I found out that true catalytic heaters – suitable for RV use – were:

• Made by only one manufacturer – Camco “Wave” series
• Cost almost 3X as much as higher-power ceramic/flame heaters

Ouch. No competition, captive market.

But, oh well. Out here in the mountainous West, less-than-4,500-feet excludes thousands of square miles of great space to explore. So I bit the bullet and bought a Wave-8.

Fabulous! It worked anywhere, at any altitude, giving off copious silent heat at nearly 100% efficiency. I mounted it on a swivel panel on that same cabinet, so we could direct the heat where we wished. Opening a window slightly to provide oxygen and vent water vapor, we were truly happy campers …

Until about two years later, after maybe 6-8 months of actual use. Then it started getting temperamental and going out. Within a few nights, it quit completely. Ugh. Back to Mr. Noisy again.

Back home, I called up Camco and talked to a Wave technician. Had I been scrupulous about keeping the catalytic screen covered when not in use? Yes. Had I spilled or sprayed anything against it? No. Was I giving it good propane? Yes. From west of the Mississippi?

HUH – WHAT?

Yeah, I heard him right – it turns out the propane in the Western states is contaminated (intentionally) with a lubricant that eventually ruins the catalyst in the Wave catalytic heaters. No mention of this whatsoever in the product literature (of course). And nothing that can be done about it either, according to the tech. They are “working on it.”

I’m now faced with a crummy choice – buy a cheap ceramic heater that will last indefinitely but won’t work at altitude, or buy an expensive catalytic heater that has to be replaced every few years. (Actually, only the catalytic element has to be replaced, but the cost is nearly the same as a new heater.)

Well, I really hate that noisy forced-air heater, and I’m not going to be camping exclusively at low elevation – so I’m stuck with the short-life catalytic for now. Maybe somebody at Wave will figure it out? I won’t hold my breath.

So here’s a quick summary of my multiple years of experimentation: FORCED-AIR

• Standard on virtually all RVs, thermostatically controlled
• Big, heavy, expensive (but built-in and well-hidden)
• Heats the cabin very quickly, much faster than portables
• Noisy
• Battery hog (8-10A) – can drain batteries overnight
• Propane hog – 70% efficiency at best, much heat is exhausted outside RV

CERAMIC or BLUE-FLAME

• Inexpensive substitute for forced-air heater
• Available with thermostat
• Uses NO battery current
• Nearly 100% efficient
• Generally long-lasting and trouble-free
• Available in portable and wall-mount
• Intermittent or non-op at >4,500-feet elevation
• Can produce carbon monoxide

CATALYTIC

• Much more expensive substitute for forced-air heater
• Thermostat not available
• Uses NO battery current
• Nearly 100% efficient
• Operational to 12,000 feet elevation
• Cannot produce carbon monoxide
• Must be covered when not in use, susceptible to dust/dirt/spills
• Configurable to free-standing or wall-mount
• Fuel contamination (western states) requires periodic replacement

As you can see, the choice is not always clear, or easy. But I hope this rundown helps you shortcut your learning curve, and/or maybe explain some mysteries you’ve yet unsolved. Good luck staying warm.

Greg Illes is a retired systems engineer who loves thinking up RV upgrades and modifications. When he’s not working on his motorhome, he’s traveling in it. 

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