Wall heater furnaces are a great way to heat smaller homes with natural gas or propane service. This style of heater typically works well and has very few problems. However, from time to time it will be necessary for you to troubleshoot problems. Thankfully, most wall heater furnace problems are simple to resolve and unless the heater has a major part that has failed, you can get them working in short order.
To troubleshoot your home's natural gas wall heater furnace, follow these steps.
Step 1: Verify Your Home has Active Gas Service
If you turn up the thermostat and the wall heater doesn't come on, then it's entirely possible it doesn't have any gas present to burn. Rather than testing the heater itself, turn on another gas appliance in your home, such as your kitchen stove or dryer, and verify your home's gas service is on and the gas is flowing.
Step 2: Verify the Wall Heater has Active Gas Service
Once you have verified the home has active gas service, then you need to verify the heater's gas line is open. To do so, take off the service panel and check to ensure the gas shut off valve is open and the heater is set to "on".
Step 3: Check the Pilot Light
If the gas line is on, then check to make sure the pilot light is still burning. If the flame has gone out, then you need to relight it. If you don't feel comfortable doing so, then call your natural gas utility for assistance. If you are comfortable lighting the pilot, then do so.
Step 4: Check the Wall Thermostat
Once the pilot light is lit, you can be assured the gas service isn't causing the problem. At this point, the issue is either the thermostat or a part inside of the heater.
Check the wall thermostat and ensure it isn't blinking asking for a new battery. If so, then replace it. A low battery is enough to cause your heater to refuse to turn on.
Step 5: Consider the Wall Heater Has a Failed Internal Part
If you reach this step and the wall heater still hasn't come on, then it's very likely the thermocouple or another internal part has failed and it's a good time to call for help.
Step 6: Call a Professional HVAC Technician
Since gas lines are obviously a risk for explosion if they aren't properly handled and connected, you should always hire a professional furnace repair technician to perform any repairs you are unsure of or uncomfortable making yourself. Additionally, if a part has failed inside the heater, then a professional repair is warranted.