How Does a Home Inspector Inspect a Gas Forced-air Furnace?


Industry standards of practice state that an inspector should open accessible panels to inspect installed heating equipment. The inspector is supposed to describe the energy source used to create the heat, as well as inspect the heating equipment, venting and distribution systems.

So, how does the inspector meet these standards when he/she is using visual noninvasive inspection techniques? After all, when you order a home inspection, you want to be sure the furnace is operating correctly.

NPI/GPI has high standards for its inspectors, and we recommend the following methods for furnace inspection:

  • Locate the thermostat(s) to operate the system. The thermostat should be centrally located in the house and away from other sources of heat.
  • Examine the exterior of the furnace for rust, corrosion, soot etc.
  • Use a gas sniffer on all visible gas lines joints and connections.
  • Identify the furnace, and note the serial number, age and input BTUs. This information is often found inside the burner panel.
  • Remove the draft shield and examine the burner heads, combustion chamber, and verify that the correct piping is used for gas supply. Replace the shield and panels when complete.
  • Note the color and condition of the flame for a proper burn.
  • Inspect the flue for gas leaks, rust, corrosion and proper clearances from combustibles.
  • Note any unusual noise or vibration from the blower fan.
  • Note any unusual odors.
  • Check the blower fan and filter for cleanliness.
  • Use the gas detector at the nearest supply register to check for any leaks.
  • Make sure the furnace is located in an area that provides ample air supply and has adequate room for service access.
  • While the unit is running, check for air delivery in the rooms.
  • Complete an overall inspection of the ductwork.

As with all elements of a home inspection, the inspection of the furnace inspection is visual and noninvasive; however, normal service panels are removed to inspect the furnace. A thorough inspection of the heat exchanger is not in the scope of work for a home inspection, so don’t be fooled by inspectors who tell you they’ve checked the heat exchanger.

The furnace’s data tag information can be included in the report, as well as the unit’s BTUs, manufacturer and age of the unit. Photo documentation of the furnace also should be included in the report.

If issues are discovered, then the home inspector should recommend further evaluation and repairs as needed by a qualified heating contractor.

By Kenn Garder, National Accounts Manager and Technical Support, NPI/GPI Corporate

Top Five Problems Revealed During a Home Inspection

Purchasing a house is a major decision, and a home inspection report can be used to assist in the decision-making process. Here are some of the more common issues found during a home inspection.


Poor Grading and Drainage

Water should run away from any structure to help prevent moisture intrusion. If the soil around a house slopes toward the house, or if water pools around the perimeter of the foundation, that moisture can create hydronic pressure in the soil that can move the foundation, causing cracks and leaks that can lead to extensive damage and expensive repairs. If water wicks into the wood framing members, the wood will rot over time. This moisture also provides a haven for wood-destroying organisms (WDO) because it provides a water and food source.

Erosion around the perimeter of a house may be caused by water spilling over gutters due to clogged downspouts or downspouts that terminate near the foundation. Downspout extensions or spill ways can be installed to keep water away from the foundation.

Roof Coverings

The roof of a house is designed to withstand most of what Mother Nature can dish out, whether it be rain, wind or sun. If installed properly, the roof should keep water out of the home.

The life expectancy for roof coverings varies depending on the material. Asphalt composite shingles, for instance, typically have a life expectancy of 15 to 25 years. As the roof covering ages, it can become more susceptible to water infiltration and leaking.

Plumbing Problems

Notice a theme here? Controlling water is one of the most important issues in home maintenance.

Leaking supply water and drain lines can cause damage to walls and floors, or they can become the water source for mold and mildew. Outdated (galvanized) or problematic systems (polybutylene) can develop leaks more frequently. Wax rings under toilets can develop leaks and damage the floor around the toilet or the ceiling below.

Electrical Issues

House fires caused by faulty wiring and overloading circuits are common. It is not unusual for a home inspector find evidence of DIY additions to a home’s electrical system. Many times these additions work but were not done properly, causing safety issues.

Exposed wire connections and double taps in the panel are also common problems. If your home inspector finds these or other electrical issues, he/she will recommend that you have the system evaluated and repaired by a qualified licensed electrician

HVAC Havoc

Inadequate maintenance of the HVAC equipment is common. Dirty condenser coils on the air conditioner condenser unit and dirty furnace filters can lead to major repairs. The equipment may be at or near its life expectancy and need to be replaced. Gas-fired furnaces may not burn properly.

With proper maintenance, an HVAC system can continue to heat and cool the house, but many times heating and cooling systems are “out of sight out of mind.”

This is a sampling of typical issues found during a home inspection. These items may vary depending on the geographical location of the property and the overall maintenance of the property.

By Kenn Garder, National Accounts Manager and Technical Support, NPI/GPI

Content originally published in February of 2016.

Benefits of a Pre-Listing Home Inspection

Benefits of a Pre-Listing Home Inspection

When you’re trying to sell your home, should you hire your own home inspector? It’s a good question, and it’s one many homeowners ask their real estate agents before putting their houses on the market. As it turns out, there are a lot of great reasons to get a pre-listing home inspection before a buyer makes an offer. We’ll tell you everything you need to know below for a smooth, hassle-free sale process.

1. You won’t be surprised.

There are certain flaws about your home you’re already well aware of, but what about the things you know nothing about? When you order a pre-listing inspection, you get a top-to-bottom report of hundreds of features and systems in your home. If any problems are revealed, you’ll have a chance to repair them or build repairs into your asking price. This is especially good for DIYers, who can save a lot of money by completing simple repairs themselves.

2. You can price your home more accurately.

Pricing is one of the toughest parts of selling your home, but a pre-listing inspection makes it easier. Once you have a full picture of your home’s strengths and weaknesses, you can be a lot more confident that you’ve arrived at the right price point. If a buyer sees that you’ve priced your home transparently based on an independent inspection, they may also be less likely to submit a lower offer.

3. You’ll save money in the long run.

Having to deal with a surprise repair that only comes to light during the buyer’s inspection can be more expensive than taking care of the problem yourself. Whether the buyer insists on an expensive contractor rather than a DIY repair or wants more money taken off your asking price than you think is fair, relying solely on a buyer’s inspection can be costly.

4. You’ll save time and stress on negotiations.

When all parties are fully informed about the home being sold, the process of selling goes much faster and cuts down on stress. Without a pre-listing inspection, the one question that’s bound to be on your mind is “what if there’s a sale-killing problem I don’t know about?” And if you do know about a problem that’s likely to affect a buyer’s decision, it’s better to get everything out in the open from the get-go.

5. You’ll make your real estate agent’s job much easier.

There’s a lot that goes on behind the scenes when you’re a real estate agent. When working to sell a home, an agent can spend days researching not only the house itself, but the neighborhood, schools and values of other homes in the area, too. When you add a pre-listing inspection to the data your agent is collecting, they can form a better idea of what your home will reasonably go for in the current market, which makes the process go smoothly for everyone involved.

Call National Property Inspections for a Full Assessment of Your Home

Your local NPI inspector has the professional training and experience to help assess the condition of your home’s structure and major systems. Give us a call today to schedule your pre-listing inspection.

How to Resolve a New Construction Defect

If your home inspector finds a defect in your new home, it is important that you immediately resolve the issue with your builder. There are specific actions you should take in the process of resolving builder problems in order to effectively correct the situation.

How to Resolve a Home Construction Defect

Home Inspection Checklist

A comparison sheet for consumers looking to find the right home. This checklist is intended to help homebuyers remember the positives and negatives of several properties.

Home Inspection Checklist

NPI Builder’s Warranty Checklist

No one knows your new home better than you do. Filling out this form can help your inspector provide the most complete information possible.

NPI Builder’s Warranty Checklist

Infrared information

Infrared technology helps trained professionals scan the inside of walls and ceilings to find evidence of water intrusion, missing insulation and electrical hot spots. As a result, consumers have more information to make safety and energy efficiency improvements.

Infrared Imaging Information

NPI Sample Report

A PDF excerpt from an NPI residential property inspection.

NPI Sample Report