With the windchill, it's 30 degrees below zero on the jobsite. Murphy's Law — anything that can go wrong, will go wrong — dictates that if the heater will ever break, this is the day.

But as ruthless as Murphy's Law might be, it can be countered with proper care and preventative maintenance before the first snowflakes fall. Regular checks throughout the season should help keep the heat circulating. If worse comes to worse, being familiar with troubleshooting tips for indirect-fired heaters will make faster work of repairs.

Preseason preparation

Don't wait until winter storms into the worksite before pulling out your portable, indirect-fired heater for initial checks. Look everything over while there's still time for replacing a part. Also, use this time to train anyone unfamiliar with indirect-fired heaters on the proper and safe use of the unit. Locate the operator's manual, preview the information and place it in a readily available location.

Next, walk around the heater, ensuring all decals and safety information are intact, undamaged and readable. If not, call the manufacturer to get some replacements on the way. Even experienced workers need reminders sometimes on fuel type and cautionary measures. Additionally, it can help protect you against negligence allegations.

Check out the ductwork, as well. You'll want to make sure it is adequate for the locations in which it will be used during the winter season. It is also important to check that none of the ductwork was torn or damaged during the off-season.

Next, start the heaters for a trial run and check their burning efficiency. Keep in mind that heaters will need to be tuned relative to the altitude in which they will be operating. Air thins as elevation increases, which will affect the air-fuel ratio necessary for complete combustion. With elevation changes, it may be necessary to change the fuel nozzle size or adjust the air band and shutters. Operating at higher elevations will require less fuel, more air or a combination of both.

A Bacharach Oil Burner Smoke Tester should be used to check and tune heaters to determine the amount of soot being carried by the exhaust gases. The tester consists of an air pump and probe. To use, insert the probe into the exhaust/chimney and pump 10 cycles of air. Afterward, remove the filter from the tester and hold it to the gray chart that accompanies the tool to determine if soot levels are appropriate. If not, adjust the air band and shutters to allow more or less air into the mixture. While the tester will cost a couple of hundred dollars, it'll be well worth the investment by preventing problems and maximizing efficiency.

Check it off once a day

Once the temperature drops and the heater season begins, start each day with a list of checks to ensure proper and safe operation. While the checklist may seem lengthy, each step will only take a matter of seconds. Once it becomes routine, it should take no more than a few minutes to look everything over before getting started for the day.

This list covers portable, self-contained heaters that also include a diesel-driven generator providing electrical power for the fans and motors. When using other models, you will still need to perform checks and preventative maintenance according to manufacturer's recommendations.

• Visually inspect the heater by walking around the outside. Ensure that all decals and safety warnings are still in place and legible and that no dirt accumulation could be disguising a problem. Look at the tires. Are they properly inflated and in good condition? Check for fuel or oil leaks, as well.
• Check the hitch assembly and safety tow chains (on self-towing models) to make sure that not only are the components securely in place but that they are not in need of repair. Inspect the jack, as well, to make sure it works properly.
• Make sure all of the lug nuts are torqued to about 80 or 90 foot-pounds. On new self-towing models, the lug nuts should be checked again after traveling the first 100 miles.
• Conduct a fluid check, ensuring that coolant, engine oil and fuel levels are sufficient.
• Look over the battery, making sure it is fully charged, that the terminals are tight and clean, and the electrolyte level is adequate.
• Ensure the ground rod and cable are undamaged so there's no question of the components functioning properly during operation.
• Confirm that the air cleaner is firmly attached and the air joints are sealed.