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"Hi, this is John Customer and you inspected my house about 2 months ago. You stated in your report that the package unit was about a year old. Well we tried to use the heat yesterday, and the technician said the unit was about 15 years old and is shot!" It will cost me several thousands of dollars to replace the unit......"

To protect or customers, it is the practice of this company to take pictures of the serial plates of all high end appliances such as furnaces, compressor units, water heaters and other "built-in" appliances.  When we do get calls such as this we print out the pictures of the appliance(s) in question ALONG with the serial numbers and take them to our client stating that, "This is the unit our company had inspected!"

More often than not, the home owner finds out that the unit that the former owner paid thousands of dollars to replace looked better a their new home rather than the unit that was there.

Almost everybody has digital cameras today. Take a few minutes and take a picture of the "attached" items such as appliances, compressor units, furnaces and water heaters during your initial and final walk-through. It may be your only resource should something be changed or not present when you move in.

This posting and the continents written here are the intellectual property of Michael Thornton of Complete Home Inspections, Inc. providing Nashville home inspections for Brentwood and the Davidson and Williamson Counties of Middle Tennessee. The views and opinions expressed are just that - views and opinions of Michael Thornton and those who comment.  Information and is provided with the intent of educating and assisting home owners, home sellers, home buyers, real estate investors, and real estate professionals with information the can be used to make better real estate decisions. 

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This table is to be used as a guideline only. The actual age of units can vary depending upon maintenance practices and the manufacturer of the unit.

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In general, there are two kinds of home heating – central heating and area heating. The home inspection concerns itself with permanently installed heating systems, both central and area. The basic components of central heating systems include the following:

• A safe container in which to convert fuel or energy to heat. This includes a burner and combustion chamber for converting fossil fuels such as gas or oil to heat or a chamber containing a resistance coil for converting electrical energy to heat. When gas or oil is used, air must be supplied to the container for combustion purposes.
• A heat exchanger for transferring this heat to the air or to water. The heat exchanger that transfers heat to air is called a furnace; one that transfers heat to water is called a boiler.
• For fossil fuel furnaces and boilers, a disposal system of flues, vents, and chimneys to remove combustion products from the home.
• A distribution system of ducts or pipes that carry warm air, hot water, or steam throughout the house. Warm air may be conveyed through the distribution system naturally by gravity or pushed by a circulating fan. Hot water can be conveyed by gravity or set in motion by a circulating pump.
• Heat outlets such as registers or radiators for transferring heat into each room.
• Temperature and safety controls. Each central heating system requires a thermostat that turns the furnace or boiler on and off in order to supply heat as needed. And each is designed with automatic (and manual) safety controls that will turn off heating equipment when the equipment malfunctions.
• A home may be entirely with electric baseboards or wall-mounted area heaters or radiant panels. In this case, heat is generated within each room to be heated, not centrally through a distribution system.

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As per industry standards, the home inspector is required to inspect solid fuel heating systems, referring to fireplaces and wood stoves. As stated in the ASHI standards, the home inspector is not required to ignite or extinguish solid fuel fires or to observe fireplace insert flue connections.

For oil and gas-fueled furnaces and boilers, the home inspector inspects chimneys, flues and vents for proper installation and safety. Evidence of combustion products leaking into the home is reported as a safety hazard. Draft diverters are examined, and the smoke pipe is checked for the operation of dampers, corrosion, pitch, proper supports, and a seal at the chimney. If so equipped, the chimney cleanout is investigated to determine whether the chimney is blocked. The home inspector does not have the proper equipment and is not required to inspect the interior of flues.

 

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As per industry standards, the home inspector checks all visible ducts and piping for proper support, dampers, leaking (in hot water and steam systems), and insulation. The home inspector checks the condition and operation of all heat outlets such as registers, radiators, fan-coil units, and convectors.
 

• Heating distribution system: The inspection of the duct or piping system includes observing the operation and condition of fans and circulation pumps. Air filters are inspected for warm air systems. Although ASHI standards state the home inspector is not required to inspect electronic air filters. The home inspector checks humidifiers as far as their general condition and effect on other heating equipment, but is not required to inspect the operation of the humidifier.
• Heat source per room: A seemingly minor point, but important to customers, is the presence of a heat source in each living area. The home inspector checks for a heat source in each room and records its presence or absence in the inspection report. However, the home inspector is not required to determine or report on the adequacy of the heat supply to each room. The home inspector also pays attention to the location of cold air returns with warm air systems.

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The main operating control for a heating system is the thermostat, a temperature-sensitive device that opens and closes a circuit in response to changes in temperature. A thermostat normally operates at low voltage (24 volts), although some operate at line voltage (generally used with electric resistance heating). The older thermostats simply start the heating system on a call for heat and turn it down when the thermostat is satisfied. When the temperature near the thermostat falls below a preset temperature, the contacts within the thermostat close and activate the heating system. When the nearby temperature rises to the preset temperature, the contacts open again and shut it down.

In some thermostats, the contacts are exposed to the air. A layer of dust can accumulate on the contacts and interfere with normal operation. They can also burn or corrode. In modern thermostats, the contacts are enclosed in glass or have a sealed mercury switch in which a drop of mercury makes and breaks the circuit as it swings back and forth.

There are a variety of thermostats available today. Many newer models have setback features. Clock thermostats can be set to lower the temperature setting automatically at night and raise it again each morning. Generally, the temperature differential with this setback features is from 5 degrees to 10 degrees. Some can be programmed for double setback, where the homeowner can also have the heat raised and lowered automatically during the daytime as well as nighttime hours.

It should be noted that this thermostat has batteries in it. If the safety switch to the heating system is turned off and the batteries are low in the thermostat, it’s possible to blow its program.

Some thermostats have a blower control for forced-air systems. This control can be set so the blower operates automatically when the furnace is on or operates continuously for constant air circulation.

Most thermostats have an anticipator, which anticipates the preset point on the thermostat and turns the heating system on before the preset temperature is reached. This compensates for the lag time between closing the circuit and delivering the needed heat. The anticipator will also turn off the heating system just before the desired temperature is reached, letting the remaining heat in the combustion chamber bring the temperature up those last few degrees. The anticipator prevents overshooting, which occurs when remaining heat in the combustion chamber heats the house higher than the preset temperature after the burner is turned off.

The anticipator should be calibrated to the particular heating system in the house. If the anticipator is not set correctly, a condition called short cycling can occur. That’s when the anticipator shuts down the system too soon, so the desired temperature is never reached. Then the heating unit will immediately kick on again, only to shut down too soon. (There can be other causes of short cycling).

During the inspection of the heating system, the home inspector manipulates each thermostat to be sure it turns the heating system on and off. I always tell new inspectors that I am training to note the temperature setting before they test the thermostat. A simple rule that I follow is to increase the temperature by 10 degrees. That is enough to satisfy the testing of most  heating systems. 

When inspecting thermostats, I watch for the following conditions:

• Improper location: Thermostats should be located on inside walls of the home.  They should be in locations where factors other than normal home conditions won’t unduly affect the temperature in the area.  For example, thermostats in cold drafts or too near the front door can turn the heating system on too often.  Those located in the path of direct sunshine or fireplace flames won’t turn the heating system on often enough.
• Loose, unlevel: If the thermostat is loose on the wall or unlevel, the mercury can open and close the circuit inaccurately, and the calibrations won’t correspond to the actual temperature. Some home inspectors carry a thermometer and test the actual temperature against the thermostat calibrations. If differences are found, they should be reported. Customers should be advised that loose or unlevel thermostats should be fixed.
• Not working: If the heating system doesn’t kick in when the thermostat is manipulated, it can be for several reasons. The system may be turned off. Obviously, if the system doesn’t come on, the situation should be further investigated to determine if the problem is with the system or the thermostat. It can happen that dirt on the open contacts in the thermostat prohibits the circuit from closing. Open contacts should be cleaned regularly. Thermostats can suffer mechanical damage or simply fail. These should be replaced.
   

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Some homes have zoned heating, where each section or zone of the home is controlled by a thermostat. The term zone control means different areas of the house are under the control of different thermostats. Sometimes, zone control is achieved by installing totally independent furnaces or boilers for upstairs and downstairs heating, each with its individual thermostat. Electric baseboard heating and wall mounted strips may be installed as separate units in each room, controlled by wall thermostats or by elements mounted on the baseboard case itself.

A single heating system can be designed for zoned heating. With hot water systems, the boiler can have different circulators or zone control valves to provide heat to different parts of the home. With forced warm air systems, heat distribution can be controlled by motorized dampers in the heat ducts for various areas of the home.
 

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Another normal operating control for central heating systems is a master shut-off or safety switch with which to turn off the heating system by hand in the case of an emergency. Safety switches turn off electricity to the furnace or boiler and its controls. When the switch is off, raising the thermostat is no longer able to cause the equipment to fire.

With oil-fired heating equipment, a remote safety switch is required, usually at the top of the basement stairs or outside the furnace or boiler room, so the burner can be turned off without having to approach it. Remote switches often have a red cover plate to distinguish them from others. Gas-fired systems have safety switches either near the equipment or at a remote location, as is required in some areas of the country. With electric furnaces or boilers, its circuit breaker in a nearby electrical panel may serve as the safety switch.

Industry standards requires the home inspector to test the safety switch during the inspection of the furnace or boiler. When this master safety switch is turned off, the heating burner should stop. Any defective switches should be noted in his report. Some local areas require the boiler’s circulating pump or the furnace’s fan to remain in operation. It is up to the home inspector to find out what the local requirements are.

There is also a serviceman’s switch within easy reach of the heating unit which serves the same purpose as the safety switch. With gas and electric equipment, the safety and serviceman switch may be one and the same, although not with oil-fired furnaces and boilers.
 

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When inspecting the heating system, the home inspector needs to pay attention to the clearances around the heating unit itself and around exhaust pipes for oil and gas equipment.

Various models of furnaces and boilers may have different clearance from combustibles requirements, but typical requirements are at least a 6” clearance above the unit and 6” on all sides except the front of the unit. For oil-fired furnaces and boilers, a clearance of 24” is required between front of the unit and nearby combustibles, while gas and electric units require only 18”. The exhaust pipe requirements vary too, depending on type of fuel and material used. A single-wall metal pipe requires clearance of 19” for either oil or gas furnaces or boilers without a draft hood. With a draft hood a 9” clearance is required for oil, and a 6” clearance for gas. Double-wall pipes need clearances of only 2”, while a 1” clearance is enough for Type B gas vents.

Exhaust or smoke pipes should slope upwards towards the chimney at a slope of 1/4” per foot of length and be well supported. Smoke pipes should be as short as possible. Local codes give requirements about length and the number of elbows (bends) allowed in the run.

Chimney clearance typically follows the 3-2-10 rule. That is, the chimney should extend 3’ above the roof’s surface, and it should be 2’ higher than anything within 10’ of it, including the ridge, dormers, parapets, and so on. If a new addition is built that is higher than the existing chimney, the chimney must be extended to meet these requirements. Chimneys not constructed to these standards can experience back draft problems and spillage.

Fossil fuel heating units (oil or gas-fired, for example) must rely on a supply of combustion and drat air for safety. When units are located in closets or enclosed rooms, codes require 1 square inch of ventilation per 1000BTU’s of output. (A BTU is a British Thermal Unit, and 1 BTU represents the amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit). Closet doors should be louvered, top and bottom.

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The HVAC contractor who installed the furnaces and air handling units for this new construction property must have been having a bad day. The first error in the attached picture is quite obvious. The HVAC contractor forgot to finish sealing the ductwork to the side of the air handling unit. This is typically an easy straight forward repair.

The other thing that is wrong in this picture is not so obvious. The air handler is setting on bricks that were picked up from the construction site. Acceptable trade practices calls for units to be setting on neoprene stands designed to absorb the vibration from the air handlers. The vibration can damage the pan that is designed to absorb water in the event of a blockage in the main condensate drain. Stands cost about $10.00 each, bricks . . . EH . . .

He also forgot to attach the drain line to the drip pan under the unit. Well let's hope that today will be a better day.

So much has bee said about getting new construction properties inspected. Had these items not been found during the inspection, the home owners would have had the financial burden of repairing these items. The disconnected drain line could have caused damage to the ceiling if the main drain line and been clogged and water flowed out of the drain pan.

I advise my clients to occasionally check the condition of the attic air handlers.

• Check to see if there are any unusual noises or vibrations coming from the unit.
• Check to see if there may be trash or debris blocking the float switch.
• Check to see if water is collecting in the condensate pan. If there is, contact a HVAC contractor to service the unit.
• If the unit is more than 5 years old, semi-annual maintenance is recommended.

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Drain Not Connected to Drain Pan

Bricks improperly placed under Attic air handler and the ductwork has not be sealed to unit