The "a" models may violate RV building codes in some areas, making the "ET" version the only option available in those areas.

Note added 8 December 2001:  Olympian has revised its product line and changed the model numbers, but the characteristics of the new models are still quite similar to those reported above.

If used in an unventilated space, any propane heater will consume oxygen until there is inadequate oxygen for human breathing. The oxygen sensor in the ET models senses a low oxygen level and turns off the heater if the level gets too low for safety.

Although the oxygen sensor makes the heater safer, it has the disadvantage of requiring electricity, and also cannot be used at altitudes above about 4000 feet. For many RVers, this is a really major disadvantage, since many of the nicest camping locations are at higher altitudes, and the main use of the heater is for the cool nights found at high elevation.

Because these heaters use oxygen and emit water vapor, any space in which the heater is used must be ventilated (a window opened slightly), both to add new oxygen and to get rid of the excess moisture. Olympian recommends one square inch of free air opening per 1000 BTU/hr of heat output for "rooms of average airtightness". I have found that our travel trailer is leaky enough to provide sufficient oxygen for two people to breathe while the heater is in use without opening windows. A friend with a large high-end fifth wheel trailer has also found this to be true. We ventilate anyway, largely to keep the moisture level reasonable. But it's comforting to know that if we forgot to open a window before going to bed, it wouldn't kill us.

This comment should be understood in the context of our own tolerance for reduced oxygen levels. We have camped at altitudes of 10,000 feet and hiked as high as 14,000 feet without problem. Individuals with impaired heart/lung function, or those who suffer from altitude sickness at much lower elevations, will want to be much more careful about ventilation.

For our 35' travel trailer, we chose the 5800 BTU/hr manual model and fitted it with legs and a 10' flexible hose for portable use. We also purchased a fitted vinyl cover, to preserve the life of the platinum catalyst by keeping out dust and dirt while the heater is not in use. A typical price for this model is $300, plus $11 for the legs, about $18 for the cover, and about $35 to $80 for flexible hose and copper fittings to tap into the existing propane piping. RV Solar Electric offers these heaters at good prices, and also offers both a fixed and portable installation kit, each containing everything needed for a typical installation.

My installation was rather simple. My furnace is under the sofa in the living area, in the middle of our trailer. I unscrewed the propane line from the furnace, screwed a "T" fitting into the furnace, screwed the propane line back into one leg of the "T", and attached a shutoff valve and the flexible line to the other leg of the "T". When not in use, the catalytic heater, still attached to the hose, slides under the sofa, in a vacant space adjacent to the furnace. The 10' of hose is sufficient to allow placing the heater most of the way down the hallway, pointing into the rear bedroom, or in the kitchen pointing at the dinette seating, as well pointing at any of the seating positions in the living area. (This is an easy do-it-yourself project, but only if you understand basic plumbing procedures and materials and understand how to test for propane leaks).

Our 35' travel trailer (without slide-outs) is fairly average as to air infiltration and insulation quality - some are significantly worse, and some are significantly better. Under typical conditions, our 5800 BTU/hr heater's high setting will maintain the entire trailer at 25 to 30 degrees above the outside temperature. The specific region toward which the heater is pointing will be about five degrees warmer, and a person at which the heater is pointed will feel even warmer because they are absorbing the radiantly beamed heat. With this heater, we have boondocked comfortably in night-time temperatures down to about 27 degrees. We generally travel so as to stay in areas where the night-time temperature is rarely below 50, and under these conditions, the lowest setting can be too warm. For many people, the smaller 2800 BTU/hr heater would be a better choice. In very large or poorly insulated rigs, or for colder climates, the big 7600 BTU/hr model may be desirable.

Comparing Costs of Electrical and Propane Heat

One gallon of LPG (Liquified Petroleum Gas - the more accurate name, since what we usually call propane is actually a mixture of propane, butane, and smaller quantities of assorted other similar gases)  contains about 91,500 BTU of energy, depending on the exact mix of the various gases.  Since  propane heaters have an efficiency ranging from perhaps 50%  to 90% (I'll use 80% in this calculation), the useful energy content is approximately 73,200 BTU, which is 21.44 kilowatt-hours.  (1  KWH = 3414 BTU).

Thus, if electricity costs $.10 per KWH,  LPG would have to cost $2.14 per gallon in order for the cost per unit of energy to be the same for the two sources.  

Simply multiply the cost of a KWH of electricity by 21.4 to determine the cost of propane per equivalent amount of heat energy.  (This is a compromise number.   For a traditional propane furnace, use 17.42 (assumes 65% efficiency);  for a catalytic heater, use 24.12 (assumes 90% efficiency). 

Some campgrounds have electricity included in the cost of the campsite, but charge an extra $2.00/day for use of an electric heater.  To determine whether to use electricity or propane in this situation, you have to know in advance how much heat you will need each night.  For example, if you ran a 1500-watt electric heater continuously for 10 hours, you would use 15 KWH at a cost of the $2.00 surcharge, or $.133/KWH.  If propane costs less than $3.22/gallon, it will be more economical to use a catalytic propane heater (or $2.32 for a conventional furnace).