Generally, an oil furnace is considered safer than a gas furnace for several reasons. While both types of furnaces can produce carbon monoxide, a leak in an oil furnace is easier to detect due to the smell. Oil furnaces also don't connect to a gas pipeline, which reduces the chance of a fuel leak. Most importantly, heating oil is not combustible, whereas natural gas is highly flammable. This means there is a much lower risk of combustion or explosion with an oil furnace. However, an oil furnace can still pose a fire hazard if it tips over.

No, it is not safe to leave a propane heater on overnight. Even if you’re using the heater in a well-ventilated space, the heaters can emit carbon monoxide that can lead to fires. Be sure to fully turn off and secure the propane heater before clearing the area. 

According to the National Fire Protection Association’s Code NFPA 25 (titled “Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems”), private fire hydrants must undergo inspection once per year, with an accompanying flow test and any necessary maintenance performed on the same schedule. Keep in mind that your town, city, or county may adopt more or less strict testing requirements. 

No, a chirping smoke alarm is usually a sign of an issue with the power supply of the unit. This is easily solved by replacing the battery to stop the smoke alarm from beeping. If the chirp continues, review the owner’s manual to determine the cause. These chirps are short and not as loud as the beeping of the alarm itself. If you can’t tell the difference, it’s best to treat it like an activated alarm until you find the cause.