What to do when you have No Heat !
The best way to trouble-shoot your heating system is to go through the following items one by one, even if you feel sure you know what the outcome will be.
1. Thermostat checks
i) Is the system selector switch in the "heat" position?
ii) Is the temperature set at least 3 degrees above current room temperature?
iii) If your thermostat is electronic, are the batteries charged?
2. Filter Checks
i) Is your furnace filter Dirty ? A dirty fitler will cause your furnace to run for a very short time then turn off giving you little to no heat and in some cases may cause a complete shut down of the furnace.
Replace your filter if its dirty and reset your furnace.
Dirty Air Filter Vs Clean Air Filter
3. Electrical checks
(A) Items to check at the furnace
i) Your heating system may be equipped with an emergency shut-off switch for the furnace. If so, make sure it is turned ON. In most homes, the emergency shut-off switch looks just like a regular light switch and will be located close to the furnace. (Trace the wire from the switch to the furnace to make sure you have the right switch.) It is quite common for this switch to be turned off accidentally. If the switch is ON, but the fan still doesn't operate, proceed to the Items to check at the electrical panel.
ii) Some heating systems also have emergency cut-out switches that are activated when a door or service panel is removed. Often the furnace door is not replaced properly after a filter cleaning and the cut-out switch will prevent the furnace from coming on. Check to make sure all access doors are properly secured and fitted.
(B) Items to check at the electrical panel
The breaker for the furnace should be in the "ON" position. If the breaker has been tripped, it will be in a position between ON and OFF. To reset, turn the breaker all the way off and then back on. If you have fuses instead, make sure the fuse hasn't blown. If it has, replace it with the same-sized fuse.
WARNING: If a breaker keeps tripping or a fuse keeps blowing, you should contact a qualified service technician to inspect your system to determine why you are having problems.