Choosing a Natural Gas Garage Heater

Choosing a Natural Gas Garage Heater

Fan forced natural gas garage heaters burn fuel in a heat exchanger to produce heat. Natural gas garage heaters are very common in populated areas that have natural gas piped throughout neighborhoods.

Get more details and pricing on these: Natural Gas Garage Heaters

Operating Principle
When there is a need for heating, the fuel from your natural gas line flows through a gas valve inside the garage heater. A spark or pilot flame ignites the fuel and a flame is produced inside a heat exchanger. When the heat exchanger reaches a pre-set temperature, a fan turns on which blows space air through the warm heat exchanger. The air entering the heat exchanger absorbs the heat from the heat exchanger, resulting in a warmer discharge air temperature. As the fuel is burned, by-products of combustion leave the garage heater through a vent pipe also called a chimney.

Common Gas Garage Heaters

Natural Gas Garage Heater - Images

Benefits of fan forced gas garage heaters:
•Powerful, fast self contained heat producers. They don't rely on a centralized boiler to supply heat.
•Low clearance requirements on low profile heaters.
•Most heaters have adjustable louvers to help direct warm air where you need it most.
•Durable. All unit casings are treated for corrosion resistance and finished with a baked-on, high solids paint.
•Huge range of sizes and styles to match the heater to your heating load. If selected properly, you don’t have to worry about under or over sizing.
•The fan can run in the summer without heat to help circulate air.
•Natural gas garage heaters are always ready to run. You don’t need to worry about replenishing your fuel supply.

Drawbacks of natural gas garage heaters:
•Gas fired heaters require more maintenance and service then other types of heaters.
•By-products of combustion require special attention. If the heater is not vented properly, dangerous fumes can enter your garage.
•Clearance requirements must be met. A flame is present. You must be sure combustible materials (fixed or airborne) stay away from the unit heater.
•Dirty, dusty or corrosive atmospheres require special attention.
•Fan forced heaters move large volumes of air which can kick up dust in your garage.

Natural Gas Garage Heater Configurations:
Gas garage heaters blow air horizontally into the space. Adjustable louvers allow for vertical adjustment of airflow. Most major manufacturers also offer horizontal louvers that allow for side-to-side adjustment of airflow. Gas garage heaters for can be broken down into several categories based on the venting type and heat exchanger design:

Venting Types:

Good: Gravity Vented Garage Heater
Due to low cost and compact design, gravity vented propeller unit heaters are a good choice for some garages. The term gravity vented refers to a garage heater that vents naturally, without the assistance of a fan. A gravity vented garage heater uses the air in the garage for combustion. The warm by-products of combustion rise out of the garage heater through a flue pipe to the outdoors. A gravity vented heater is the least expensive style; however, you must be sure the following conditions exist:

1) Your garage can not be under a negative pressure. If your space is negative, the by-products of combustion will not vent properly and you will experience nuisance tripping from a safety switch that senses a blocked flue vent. Negative pressures occur when air is being exhausted from a space without any source of make-up air. Gravity vented heaters can be very sensitive to pressure changes. Sometimes a bathroom exhaust fan turning on can be enough to trip off a heater. If you have a gravity vented heater that is experiencing nuisance trip outs, you may want to install an aftermarket power venter that gets installed in the flue vent pipe to help push the by-products of combustion in the right direction.

2) Specific vent pipe routing is required. Gravity vented heaters operate on the principle that hot air rises. Vertical venting through the roof of your garage is preferred. Sidewall venting is more difficult. Venting through a roof can become more expensive since you need to completely weatherproof the hole in the roof. The manufacturer’s detailed installation instructions must be followed closely.

3) Since the air inside the heated space is being used for combustion, it is important that the atmosphere is clean. If you are comfortable lighting a match in your garage, then you should feel comfortable about running a gravity vented heater. If there are any combustible dusts (woodworking) or fumes in your garage, choose a separated combustion design which is explained below.

Gravity Vented Heater – Vent pipe attaches to the top

Natural Gas Garage Heaters - Gravity Vented Garage Heater Units

Better: Power Vented Garage Heater
A power vented heater is very similar to a gravity vented heater with the addition of an integral flue vent booster fan. On a call for heat, the booster fan turns on to ensure the by-products of combustion will be vented properly. Power vented heaters are the most popular type of gas garage heater. The booster fan allows for greater flexibility with flue pipe routing. Horizontal venting is very easy. In a garage, most venting is done through a sidewall to avoid costly roof modifications. Many of the major manufacturers are phasing out gravity vented heaters and are replacing them with power vented heaters as their entry level product.

Power Vented Heater – Vent pipe attaches to flue vent booster fan

Natural Gas Garage Heaters - Power Vented Garage Heater Units

Best: Separated Combustion Garage Heater
Separated combustion heaters are rapidly gaining in popularity. While traditional gravity and power vented heaters utilize space air for combustion, separated combustion heaters are sealed from the space. Separated combustion harage heaters have 2 flue vent pipes. 1 flue vent pipe draws in air from the outdoors and 1 flue vent pipe exhausts the by-products of combustion back outside. This sealed combustion design eliminates concerns about burning the air in the garage. Separated combustion heaters are a must in woodworking areas where fine dusts can ignite with an open flame. Separated combustion heaters are usually slightly more efficient since they do not use the heated air in your space for combustion.

The only drawback to a separated combustion heater in your garage is the 2nd vent pipe. A 2nd vent pipe requires a 2nd hole in your wall or roof. Most manufacturers offer concentric vent kits that allow the 2 vent pipes to join at a galvanized metal box on the interior of your garage. The box combines the 2 vent pipes on 1 end and diverts them into a pipe within a pipe on the discharge end. This allows you to only penetrate your wall or roof once. This also can make your unit more efficient as the warm flue exhaust warms the cold outside intake air.

Separated Combustion Garage Heater – 2 pipes attach to unit

Natural Gas Garage Heaters - Separated Combustion Garage Heater Units

Heat Exchanger Designs:
Traditional natural gas garage heaters are tall and narrow. Most manufacturers are transitioning towards the newer tubular heat exchanger design. Tubular heat exchanges are more flexible and resist cracking over time. This design also allows the heater to be wider and shorter which is helpful in garages that do not have ample overhead clearance.

Natural Gas Garage Heaters - Tall vs Narrow Garage Heaters
Standard natural gas garage heaters come with aluminized steel heat exchangers. Aluminized steel is more then adequate for typical garage and workshop installations. The life expectancy for a natural gas garage heater in a clean environment is 20+ years. If your application involves high humidity levels or mildly corrosive atmospheres, your natural gas garage heater will last a lot longer if you upgrade to a stainless steel heat exchanger.

Options and Accessories:
Natural gas garage heaters have several options and accessories to help meet your specific requirements. High CFM blowers, 2 stage units, wall mounted thermostats, air deflectors and vent caps are very common accessories used in garages. If you’re not sure what to order, call us and we will recommend a heater to meet your specific needs.

For pictures of the most common natural gas garage heaters, visit:

Natural Gas Garage Heater Installation Overview:
1) Suspend the garage heater using threaded rods or angle iron. Some of the low profile heaters include angle iron for mounting directly to the ceiling.
2) Install natural gas piping.
3) Install vent pipe.
4) Wire a low voltage wall thermostat to the heaters terminal strip.
5) Wire the high voltage power required to operate the heater. This is usually 120 volt power in garages.

Commonly Asked Questions:

1) How do I calculate the heating load for my garage?
ANSWER: Contact Ultimate Garage Heater or use our simple garage heater calculator tool. Do NOT fall for equipment that is advertised as “will heat up to 400 square feet”. Heating a 400 square foot insulated garage in Florida is a lot different then heating a 400 square foot un-insulated metal garage in Maine. 1 heater can not magically service both 400 square foot spaces. Call us; we are happy to run a detailed engineering calculation that will help you pick the perfect heater for your space. You do not want to undersize, and you do not want to oversize.

2) How do I control my natural gas garage heater?
ANSWER: A wall mounted 24 volt thermostat is required. When there is a call for heat, the thermostat sends a signal to the natural gas garage heater to turn on. Upgraded thermostats include a “fan” switch which allows you to operate the fan with no heat in the summer.

3) How do I determine how much heat a natural gas garage heater will generate?
ANSWER: Natural gas garage heaters are listed by their fuel inputs. For example, a 100,000 BTUH heater will consume 100,000 BTU’s of fuel per hour. The actual heating output depends on the heater’s efficiency rating. If the heater is 80% efficient, the actual heat output will be 80,000 BTU’s per hour. Do not pick a heater based on the nominal size. Many people think this is the actual heat generated. They end up with a unit that is undersized.

4) What is the best location in my garage to install my natural gas garage heater?
ANSWER: The heater should be located in the coldest area, and it should be angled slightly so it blankets warm air across the coldest wall.

5) What is the best location to install a wall mounted thermostat in my garage?
ANSWER: The thermostat should be mounted in a location that represents a good average temperature in your garage. If it is located in a cold spot, it will falsely run the unit heater more then it should. If it is located in an area that receives direct sunlight, it will falsely run the garage heater less then it should. A well insulated interior wall is the best spot for the thermostat.

6) I have a natural gas garage heater that is 30 years old and in perfect condition. How do I convert this to propane?
ANSWER: Most manufacturers will only produce parts for equipment that is 20 years old. After 20 years, it is assumed the heater will be replaced with newer, more efficient technology. In some situations, you may be able to contact the manufacturer of the gas valve directly for an aftermarket conversion kit.

7) How can I compare the cost to operate natural gas, propane, oil and electric garage heaters?
ANSWER: Contact Ultimate Garage Heater. We can calculate your heating load, and then convert that information into operating costs ($/hour) for various fuel types.

8) What is included in a natural gas to propane conversion kit?
ANSWER: Different fuel types operate at different flow rates and pressures. The springs and orifices inside the gas valve needs to modified to match the fuel type. On some equipment, the igniter also requires an upgrade.

9) How do I decide if a separated combustion natural gas garage heater is required?
ANSWER: If you’re not comfortable lighting a match in your space, then you need a separated combustion heater so that there is no open flame being exposed to the heated space.

10) How do I vent my natural gas garage heater?
ANSWER: You must carefully read the installation instructions for your specific heater. Manufacturers do a good job outlining common practices. Local codes may dictate venting requirements and override the manufacturer’s recommendations. It is not a good idea to buy your vent pipe in a “kit”. There are several types of vent pipe, and the inexpensive kits that are designed to fit all installations don’t always form a perfect seal. A kit that offers “flexibility” means there are a lot of expandable pieces and joints that need sealing. The fewer joints you have, the safer your system will be. Hang your heater in the best possible spot for comfortable heating. Draw a sketch of the venting required and bring it to you local plumbing or home goods store. They will know your local codes, and they will select the pieces in the longest lengths available. This saves a lot of extra joints that can be very dangerous if they are not sealed properly.