Inspecting Heating Equipment

When inspecting a home’s central heating system, the Standard of Practice of ASHI (American Society of Home Inspectors) requires the home inspector to open “readily openable access panels” to perform the visual inspection. One may ask, so what is a “readily openable access panel”? ASHI defines this as: “A panel provided for homeowner inspection and maintenance that is readily accessible, within normal reach, can be removed by one person, and is not sealed in place”.

This does not mean that the inspector takes the heating system components apart to perform an invasive inspection or a clean and service, but rather removes the front panel that the manufacturer has supplied to perform a visual inspection of the visible components while the system operates. The inspector will operate the central heating system (such as a furnace, boiler, or heat pump) using its normal operating controls (meaning one [or more] thermostats) and observe the system’s basic function. In some older heating systems, more of the combustion process may be visible compared to newer heating equipment. Should abnormal sounds or anything out of the ordinary be observed with the system’s operation, these should be reported by the inspector.

ASHI requires that the inspector report the type of heating system (furnace, boiler, heat pump, electric baseboard, floor or ceiling radiant, etc.) and fuel source (natural gas, fuel oil, propane, electric, etc.). Keep in mind that a furnace, baseboard heater, and heat pump all heat air, whereas a boiler heats water which then heats the home. Many people often use the terms “furnace” and “boiler” interchangeably however they are actually very different systems and should not be confused. The exterior of the readily visible exposed ductwork or plumbing should also be checked by the inspector. Keep in mind, however, that most of the home’s ductwork or boiler piping is hidden out of view within wall coverings, behind insulation, etc.

The ASHI SOP doesn’t require the inspector to report the brand and approximate age of the heating system although some inspectors will include this info in their report (to further assist the client) assuming the information can be readily determined. In some cases, the unit’s serial number is no longer readable or the manufacturer’s tag is missing. Most modern (90%+) gas/LP furnaces have an approx. 15~20 year life expectancy. Electric heat pumps approx. 15 years. A steel boiler approx. 15~20 years whereas a cast iron boiler may last 35+ years. These life expectancies are often dependent upon whether or not the homeowner had their heating system professionally serviced annually. The lack of regular professionally servicing may sometimes cut a heating system’s useful service life in half.

A newly installed gas-fired forced warm air furnace.

An oil-fired hot water boiler.

A heat pump’s air handler.

The inspector should verify that all living spaces are being supplied with a permanent source heat; a space heater, for example, is not considered permanent. To be considered finished living space the area should have a permanent source of heat such as a heating register, a radiator or convector, or built-in baseboard heating unit. Finished areas of the home that are not heated should be noted in the home inspection report. The supply temperatures (at a heating register) from a furnace and heat pump (in either backup or regular heat mode) will normally be in the 90° F to 110° F range. The radiator or convector temperatures of a boiler are often in the 160~190° F range.

The ASHI Standards also require the inspector to inspect the heating system’s exhaust method, such as an exhaust pipe’s chimney connection or PVC venting. Heat pumps and electric baseboard units have no exhaust as neither uses a fossil fuel source.

Common issues that are found during the home inspection include improperly pitched exhaust pipes, metal exhaust pipes that have holes or evidence of water staining/condensation, and inadequate chimney connections. The exhaust venting should be properly pitched upwards (at least 1/4″ per foot of lateral run) to ensure proper draft and be adequately sealed into the chimney, such as with furnace cement. Water staining on metal exhaust pipes often indicates moisture condensation within the flue or the lack of a proper flue cap allowing rainfall down the chimney. Both issues should be addressed by a qualified HVAC technician to ensure the proper drafting of exhaust gases out of the home. When high-efficient heating systems are direct (2 pipes) or indirect vented (1 pipe), special care is needed to make sure that nothing blocks the exterior vents, such as vegetation, stored items, etc. and that the exterior vent pipe(s) won’t be prone to get blocked by snow, dirt, mulch, etc.

When a water heater and furnace or boiler both share a chimney flue or metal vent, for example, building standards require that the lower BTU-rated appliance (the water heater in most cases) connect to the chimney or metal vent connection above the higher BTU-rated appliance’s connection. Doing so helps the drafting of all connected appliances. A BTU is a British Thermal Unit defined as the amount of heat required to raise the temperature of 1 lb. pound of water by 1° F. An improper flue connection can prevent proper drafting of appliance’s exhaust gases out of the home and may allow carbon monoxide, for example, to fill the home. Keep in mind that a home inspection is NOT a code compliance inspection, but a prudent home inspector should be familiar with the various codes.

While ASHI does require the inspector to inspect the chimney (if applicable), as part of the inspection, the exposed portions of the chimney’s exterior should be viewed either from the ground, gutter level, or from the roof. Most of the chimney (where the home and chimney meet as well as the chimney’s interior) are not visually accessible and are, of course, excluded from a home inspection.

I routinely recommend to my clients that a qualified chimney professional (such as one who is CSIA certified) be consulted to perform a Level 2 clean/service, because there are areas of the chimney that I simply can’t see plus most homeowners don’t regularly have their chimneys inspected or serviced. A Level 2 Clean/Service entails a qualified chimney professional cleaning the chimney’s interior and then using either still or video photography to thoroughly inspect the chimney’s interior and exterior for defects. A blocked or otherwise compromised chimney can present an immediate safety hazard to the home’s occupants. A complex chimney repair can be quite expensive, so heeding the inspector’s recommendation for a thorough chimney inspection now can save the home buyer countless dollars and headaches later. Ignoring the inspector’s recommendation may leave the home buyer stuck with a huge repair bill should hidden issues exist but not be found until well in the future.

The ASHI Standards specifically exclude heat exchangers from the home inspection since they are most often out of view even when the front access panel is removed from a furnace or boiler. Also, the inspector does not perform efficiency measurements nor determine whether the heating system is adequately sized for the home nor determines if the HVAC ductwork is balanced or properly sized. Home inspectors also do not determine make-up (aka ‘combustion air’) requirements. Determining each of these requires complex measurements and calculations that a qualified HVAC professional is trained to do.

Also, excluded in the ASHI Standards of Practice are inspecting humidifiers, dehumidifiers, electronic air filters, solar heating systems, or the large storage tank systems (such as the Hydrokinetix units). A qualified HVAC professional should inspect/service these specialty units.

In some situations, however, the home inspector may not be able to fully inspect the heating system. One example is when stored items physically block access to the heating system. Home inspectors do not move the seller’s belongings, furniture, shelving, etc. to perform the inspection. All systems should be readily and safely accessible and fully operational (meaning circuit breakers, gas valves, service switches, pilot lights (if equipped), etc. must be on) prior to the inspector’s arrival to the home. When the HVAC system can’t physically be accessed, the inspector may only be able to verify the system’s basic operation by observing heat at the home’s registers or radiators.

This heat pump unit looks (and works) very much like a stand-alone air conditioner system, however heat pumps cool AND heat the home.

If the home has a heat pump system and the exterior temperature is higher than 60° F, running the heat pump in heat mode could actually damage the system. This temperature can vary by system manufacturer, but most inspectors use some temperature between 60° F and 65° F as their cutoff for running heat pumps and air conditioners. So, generally, a heat pump will only be run in either cool (A/C) or regular heat mode during the home inspection. Most heat pump systems have a backup heating source (electric strip heat in most cases), however, which can most often be tested at any exterior temperature. If the home inspector can’t fully inspect a heating system (for any reason), the inspector should note this fact and the reason in the report as well as recommend ensuring proper operation prior to the home’s closing, should conditions permit. Also, all central heating systems should be cleaned/serviced by a qualified HVAC professional (annually is recommended) to help ensure efficient and safe operation. The inspector should report whether recent (within the past 12 months) service records for the heating system are available as well. A seller being able to provide documentation that the home’s heating and cooling systems have been regularly (annually) professionally serviced goes a long way in buyer confidence of their next big investment, their new home.

One last item pertains to older heat pumps that use R-22 (Freon) as their refrigerant. As of 1 Jan. 2020, the import and manufacture of Freon is now prohibited in the USA. All new residential heat pumps and split A/C systems in the USA manufactured after about 2013 use R-410A (Puron). Should an older R-22 based system need a refrigerant recharge (more refrigerant), it is often more cost effective to put that money into a new system versus servicing an old system due to the price of R-22. Adding several pounds of R-22 to an old system can potentially cost enough to warrant saving that money and investing it, instead, into a new high efficient system. Puron itself is also now on its way out. Newer refrigerants (such as R-454B [also known as Opteon XL41″ or “Puron Advance”] and R-32) are now entering the residential HVAC market and will replace Puron in coming years.

Some other articles that you may be interested in include:
Energy Saving A/C Tips
Energy Saving Heating Tips
Heating Energy Cost Comparisons
Heat Pumps

Matthew Steger is a Certified Level 1 Infrared Thermographer, an ASHI Certified Inspector (ACI), and an electrical engineer. He can be reached at matthew@thehomeinspectorsnotebook.com. No article, or portion thereof, may be reproduced or copied without prior written consent of Matthew Steger.