The Heat Handbook Team 
Last updated: July 2026 · Reviewed against manufacturer installation guidelines A thermal expansion tank protects your water heater and plumbing from the pressure that builds when water heats and expands. On a closed plumbing system (one with a check valve or pressure reducing valve), an expansion tank is often required by code — and it … Read more
Last updated: July 2026 · Reviewed against oil furnace service documentation Oil furnaces heat millions of homes, especially across the Northeast, and they work differently from gas furnaces — burning heating oil from a storage tank through a burner and nozzle. That means different maintenance, different problems, and a different repair approach. Whether yours won’t … Read more
Last updated: July 2026 · Based on Mitsubishi Electric heat pump documentation Mitsubishi is one of the most popular heat pump brands in the U.S., especially for ductless mini-split systems. They are known for quiet operation, strong cold-climate performance, and reliability — but like any system, they have common issues, blink error codes, and need … Read more
Last updated: July 2026 · Reviewed against Carrier, Goodman and Mitsubishi service documentation A heat pump blowing cold air in heating mode is one of the most common complaints — and often not a real problem at all. Because heat pump air is naturally cooler than furnace air, and because heat pumps run periodic defrost … Read more
Last updated: July 2026 · Reviewed against HVAC identification guidelines The easiest way to tell if you have a heat pump: turn on the heat, then go check the outdoor unit. If the outdoor unit runs in winter when you are heating the home, you have a heat pump. If it only runs in summer … Read more
Last updated: July 2026 · Based on 2026 US contractor pricing Furnace repair costs $150 to $650 for most common fixes, with the national average around $300. But the range runs from a $15 flame sensor you can clean yourself to a $2,000 heat exchanger that often means replacing the whole furnace. Knowing what each … Read more
Last updated: July 2026 · Based on Goodman service documentation and diagnostic codes Goodman furnaces are known for being affordable and widely serviceable — parts are common and most repairs are straightforward for any HVAC technician. Whether your Goodman is not igniting, short cycling, or flashing an error code, this guide covers the most common … Read more
Last updated: July 2026 · Reviewed against Carrier, Goodman and Trane service documentation The furnace limit switch is a safety device that shuts off the burners if the furnace overheats — and when it fails or trips repeatedly, it is a common reason a furnace short cycles, blows cold air, or stops heating. The good … Read more
Last updated: July 2026 · Reviewed against Carrier, Goodman and Trane operating instructions Most furnaces built in the last 25 years do not have a standing pilot light — they use an electronic igniter instead. If you have an older furnace with an actual pilot, or a gas wall/floor furnace, here is how to find … Read more
Last updated: July 2026 · Reviewed against Carrier, Goodman and Trane service documentation The flame sensor is behind more furnace no-heat calls than almost any other part — and cleaning it is often a free, five-minute fix. This thin metal rod confirms the burner has actually lit; when it gets coated in carbon, it can … Read more