You might be familiar with propane as a common fuel for barbecues, but it's also a very effective fuel for heating your garage, greenhouse, or workshop.
Before you go too far, though, keep in mind that liquid propane garage unit heaters are less likely to be in stock than natural gas garage unit heaters. This means they often have longer lead times and higher prices than their natural gas counterparts.
If you need your LP garage heater quickly, we strongly recommend purchasing instead a natural gas garage heater and an NG-to-LP conversion kit. The conversion kits are relatively simple to install, allowing you to get the equivalent of a standard LP garage heater in much less time, and often for less money too.
For those of you looking to stick with the standard liquid propane garage unit heater, here's what you need to know to find the right one.
Choosing a Heat Exchanger Material
In many cases, you will have an option of choosing between two heat exchanger materials, aluminized steelor stainless steel.
Aluminized steel is the standard material used for heat exchangers and is known for its ability to reliably transfer heat over may years of use. In standard applications, you can't go wrong with aluminized steel.
Stainless steel is a stronger, more expensive option that comes with two benefits. The first is that it will typically last longer than an aluminized steel heat exchanger, as it is able to withstand more stress over time. The second is that it can better handle corrosive elements found in workshops and similar environments. If your unit heater will be exposed to corrosive chemical fumes or excessive moisture, stainless steel is the way to go.
Choosing a Venting Style
Liquid propane garage heaters will need to be vented to the outdoors to prevent carbon monoxide and other combustion gasses from building up inside your work space. These unit heaters offer two primary styles of venting to choose from depending on your building’s architecture and your personal preference.
Rather than relying on the hot combustion gasses to naturally rise up and out of your space, power vented unit heaters use a fan to help push exhaust to the outside. This fan-assisted method allows you to vent either vertically through the roof or horizontally through the wall.
While power venting is a great option for many applications, it does rely on the air inside your space for the combustion process. This means you will not only be venting air you’ve already heated to the outside, but negative pressures can be created by drawing indoor air through the unit heater without replenishing it. This, in turn, can cause unwanted air leaks in your walls, doors, and/or windows.
Direct Vented (a.k.a Sealed Combustion)
In small, tightly sealed spaces, a unit heater will quickly exhaust the air available for combustion. In such situations, a direct vented unit heater is optimal. This type of venting will draw outside air in for combustion, which also increases overall efficiency, since you’re not exhausting air you've previously heated.
You will also want to use direct venting in environments containing a high concentration of airborne particles, or even small amounts of combustible airborne particles. Since the intake air in direct vent systems is drawn from outdoors, you don't have to worry about these dangerous particles getting pulled into the heater and potentially causing a large explosion.
High Efficiency Options
With the invention of direct venting has come dramatic improvements in unit heater efficiency. While not all direct vented unit heaters have efficiencies over 90%, there are high efficiency options with both aluminized and stainless steel heat exchangers. If you're looking for a way to save money in the long run, this is a great option for you.