Car Pre-Heater

What could be nicer on a cold winter morning than getting into a warm car!

But how?

Remote start is an option, but for most its an option that must be installed aftermarket and with your car idling you end up burning a lot of gasoline while sitting in your driveway. Not to mention needlessly polluting the environment.

An alternative solution is to put a small electric heater in your car, have it on a timer and turn it on to heat your car before you get in it. It can really get the car nice and warm, and its great at melting snow and ice off your vehicle.

Now I know that this is not warming up the engine, but with a warm interior, you can drive your car until the engine is warm with very little discomfort. Also, having the electric heater in the car helps melt ice on the windshield and other locations that may have accumulated on the vehicle before you go to use it.

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Step 1: Supplies

To pre-heat your car you need:

Small Electric Heater

(The type that blows air. Do not use radiant or other types. The heater should be of very stable design and not easily knocked over. The heater should have mechanical switches, not electronic since it will be powered up without you there to set it.)

Outdoor Extension Cord (Suitably Rated*)

Outlet Timer (Suitably Rated*)

Extension Cord Connection Box (example)- Optional, needed if heater cord exits vehicle.

*A Suitable Electrical Rating is essential to make sure you are not overloading the device. Electric heaters draw lots of electric power and the cord and timer need to be rated for at least the electrical load of the heater or more.

Also to prevent energy loss and excess heating, long extension cords need to be the correct gauge (or size of wire). The larger the load and the longer your extension cord needs to be, the larger gauge it should be (For wire gauge the smaller the number the larger the wire size; i.e, a 12AWG (American Wire Gauge) is larger than a 14AWG cord). Here is some excellent information on selecting the correct extension cord.

Step 2: Put the Heater in the Car

Now this step can BURN YOUR CAR TO THE GROUND if done improperly! Please be careful.

CAUTION - This is an electrical project utilizing hazardous household (mains) voltage and current. You are also using an electric heater that can easily start fires. Making a mistake can result in property damage, personal harm or even death. You need to be familiar with electricity, heaters and their hazards. If you are not knowledgeable and comfortable with this project do not attempt it. You take full responsibility for the project you build/assemble. I may be taking risks that are acceptable to me, but may not be acceptable for you or your circumstances. Build/assemble at your own risk. If you do not understand or have questions consult a professional. Sorry for the disclaimer, but if you burn something down or kill yourself it's your own fault, not mine. :-)

Electric Space (Air) Heater instructions tell the user to keep all flammable materials at least 3 feet from the front, top and sides of the heater. This is important because if you don't keep flammable materials away they can catch fire! Virtually everything in your vehicle interior is flammable so technically you need at least three feet from the heater to any portion of the interior of your vehicle.

Placement of the heater in the vehicle is critical and must be verified as correct or you can DESTROY YOUR VEHICLE!

I NEVER use the heater on its highest setting. Always use the LOWEST SETTING if it will do the job. If you can place the heater in a back open area (like the flat cargo area in the back of a minivan) where you have 3 feet of clear area on the front and sides this is ideal. However, most of us will need to put the heater in a more confined location.

In order to set up your heater in your car without the necessary three feet of space around it you should do the following: (You have to decide if this is something you want to do since it is not following the heater manufacturers instructions and introducing risk - so be smart. Your situation is unique and may not be suitable for using a heater).

Run your heater in the house and get a feel for how the air exits the heater. Note how the hot air flows. Often because of fan rotation and grill design more air will exit one side of the heater than another, or the air will exit at an angle you would not expect. Back out in the vehicle, based on your finding the path of the exiting air, place the heater so the airflow will be directed away from nearby surfaces. Make sure the heater stable on a level even surface so it won't be likely to tip over should the vehicle be jostled. With the heater on the lowest setting run the heater for a couple of minutes and then open the car and feel the adjacent surfaces, including any overhanging projections (dash, etc.). Make sure they are only reasonably warm and not hot to the touch.

Repeat the above 'test' of running the heater and checking for overly hot surfaces for 5, 10, 30, minutes etc to make sure that the heater is not overheating any surfaces and causing a fire hazard. If a surface gets too hot you can try repositioning or relocating the heater. If a surface still gets too hot you will not be able to use this Instructable. When it doubt, don't do it -- better to be cold and have a car than burn it to the ground. :-)

Make a mental note of the heater's location (or even mark on the floor mats the location) since you will most likely be leaving the heater in the car and will need to reposition it each time you use it.

Step 3: Run Extension Cord From Vehicle to Outlet

Run the extension cord from the vehicle to the electrical outlet. Finding a suitable electrical outlet may be the most difficult part of this instructable. The electrical outlet needs to be a GFCI (Ground Fault Circuit Interrupter) type that is protected from the elements so that when it is in use the contacts are not subject to rain or other moisture. The timer also needs to be protected from the elements unless it is suitable for outdoor use and exposure to rain, etc.

The extension cord is going to exit the vehicle through the door. It is important to make sure the vehicle door does not pinch or damage the extension cord. Clearance between the vehicle and body vary from model to model and vehicle door gaskets vary and yours may not be thick or resilient enough to prevent damage to the cord. If the extension cord is too thick to pass through the door then you can try the heater cord as it is usually the flat style and thinner. If both cords still get pinched, damaged or look like they might be, then I'm sorry but this Instructable will probably not work for you.

Of course, if the heater cord is exiting through the door and you are making the connection between the heater and extension cord outside of the vehicle you need to use some type of weatherproof cover to keep things dry and safe.

Step 4: Set Your Timer and Plug It In!

Set your timer per the manufacturers instructions with the correct time of day and when you want the heater to turn on. Make sure the heater is turned on to the lowest heat setting and plugged into the un-powered extension cord. You can experiment to see the amount of time you want the heater to run to get the car nice and toasty warm.

It is also wise to set an off time to turn the heater off just prior to using the car so that the extension cord is de-energized and not a risk of shock when you unplug the heater - particularly if it has been raining or snowing.

When you enter your vehicle you can unplug your heater, make sure its cord is inside the vehicle, and make sure the extension cord is outside of the vehicle. The unplugged extension cord should be protected from the elements and out of the way of the vehicle (don't drive over the cord) and not in the way should other vehicles pull into the same location.

You're now ready to drive off in a warm vehicle!

Enjoy!