The thermocouple is a copper rod that the pilot flame heats-up. When it gets hot enough, the thermocouple signals that there is enough heat to burn the gas fuel being released into the appliance—and so it allows the gas to be released to the burners. In some cases where the pilot light won’t stay lit, the thermocouple needs to be adjusted or replaced. This is generally a job for a professional.
If you live in a warmer climate, your air conditioner is likely one of the most essential pieces of equipment for your home. The best course is to perform regular routine air conditioner maintenance to ensure its smooth operation during the warmest months of the year. Annual tune-ups by a professional HVAC technician will increase the lifespan of your unit. When repairs are needed, be sure to hire a technician trained and certified in HVAC repair for best results. Following these guidelines will ensure that you are comfortable and cool through the summer season.

The use of furnaces, space heaters, and boilers as a method of indoor heating could result in incomplete combustion and the emission of carbon monoxide, nitrogen oxides, formaldehyde, volatile organic compounds, and other combustion byproducts. Incomplete combustion occurs when there is insufficient oxygen; the inputs are fuels containing various contaminants and the outputs are harmful byproducts, most dangerously carbon monoxide, which is a tasteless and odorless gas with serious adverse health effects.[14]

^{Without proper ventilation, carbon monoxide can be lethal at concentrations of 1000 ppm (0.1%). However, at several hundred ppm, carbon monoxide exposure induces headaches, fatigue, nausea, and vomiting. Carbon monoxide binds with hemoglobin in the blood, forming carboxyhemoglobin, reducing the blood's ability to transport oxygen. The primary health concerns associated with carbon monoxide exposure are its cardiovascular and neurobehavioral effects. Carbon monoxide can cause atherosclerosis (the hardening of arteries) and can also trigger heart attacks. Neurologically, carbon monoxide exposure reduces hand to eye coordination, vigilance, and continuous performance. It can also affect time discrimination.[15]}
The cost to replace your gas furnace will vary based on the type and size of furnace you select, labor and installation costs, and any repairs your HVAC system may need. Nationally, average HVAC prices for a heating specialist range between $1,800 and $2,500. It’s important to select the right size gas furnace for your heating needs. A furnace that’s too small won’t heat your house properly, while a furnace that’s too large will run inefficiently, cycling on and off and likely breaking down sooner. HVAC specialists calculate your exact heat needs by measuring your home and incorporating variables such as the regional climate and your home’s level of insulation. Retail pricing for gas furnaces can range from $650 up to $3,000 and more. The higher the AFUE (annual fuel utilization efficiency) rating of the furnace, the more efficient it is at turning fuel into heat and the lower your carbon footprint and utility bill will be. HVAC installation costs are often based on an hourly rate and can range from under $50 to over $100 per hour, depending on the company and the furnace being installed. Higher-end furnaces cost more to install because they require added labor and expertise. For a typical installation, it might take two HVAC installation pros one day or less to remove your old furnace and replace it with a new one.