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Heating system inspection procedure

A full heating system inspection consists of an evaluation of the operation of the boiler or furnace, the burner, the condition of the distribution system (wherever visible), and heat outlets-radiators or registers. During your interior inspection, each room should be checked to determine whether there is a heat outlet and if there is, whether it is properly located for maximum effectiveness. The area below the radiators should be checked for signs of leakage, and the dampers in registers should be checked for ease of operation. Distribution piping or ducts, which are often visible in the basement, crawl space, attic, and garage, should be checked for leaky joints and the need for insulation. Also, the thermostats should be checked for location (should not be in a draft), condition, and type. An automatic clock-type thermostat is more convenient and if used properly, will result in fuel savings. A broken thermostat must be replaced, and one that is loosely mounted must be resecured.

The boiler or furnace and the associated burner are inspected after completing the interior inspection. By the time you are ready to perform this inspection, you should know whether the house is heated by warm air, hot water, or steam. You can tell by the type of heat outlets-registers for warm air or radiators for hot water and steam. A radiator with one pipe attached is a steam radiator. When there are two pipes, it might be difficult to tell whether the radiator is used for hot water or steam. In this case, you should look at the boiler.

At first glance, two or more thermostats can lead to a false conclusion-that the house has a multizoned heating system. A house with a multizoned heating system will have more than one thermostat. However, a house with more than one thermostat need not have a multizoned heating system. The number of heating zones should be verified when you inspect the boiler or furnace. In a hot-water system, the zones are controlled by electrically operated valves, circulating pumps, or a combination of the two. For a warm-air system, the zones are controlled by electrically operated damper motors. Usually the number of thermostats indicates the number of independent heating zones. However, you might find more thermostats than zone controllers. I have inspected homes that had a one-zone heating system that was activated by two separate thermostats. When either thermostat called for heat, the entire house would be heated. Also, in older homes you might find an old non-functioning thermostat on a wall.

When you are ready to inspect the boiler or furnace, stand where you can see the burner, about 3 feet away. Have someone turn up the thermostat and activate the burner. It is important to be near the unit when the burner ignites to determine if there is a problem condition. A puffback with an oil burner, or flames licking back under the cover plate with a gas burner, is an abnormal condition and a potential hazard that must be corrected. Record it on your worksheet. If the unit does not fire, check the master switch. If the switch is on and there is an oil burner, push the reset button once. If the burner does not fire, there is a problem condition that must be corrected. If the gas burner does not fire and the pilot is lit, there is also a problem.

Once the unit is firing, check the overall condition. Is the boiler or furnace an aging unit? Do the burner and boiler or furnace appear to have been neglected? Are there signs of excessive corrosion (rust), dust, and flakes? Are there mineral deposits, indicating a past or current water leakage? If there is more than one heating zone, check each zone independently. This can be done by waiting until the burner or circulating pump (if a forced-hot-water system) shuts down and then activating the thermostat that controls the zone being checked. The thermostat should activate the burner or circulating pump, depending on the system (as described in chapter 14). Sometimes there is a time delay of about one minute or so between engaging the thermostat and activating the burner or circulating pump. This occurs because of the time that it takes to open the zone valve or damper physically. Also, some gas valves have a built-in time delay. However, if after five minutes nothing happens, there is a problem with the controls.

Check the condition of the smoke pipe. This is the horizontal section of sheet-metal pipe that connects the boiler or furnace to the chimney. In some cases, the boiler or furnace is connected directly to a prefabricated metal chimney, and there is no horizontal run. When there is, however, the pipe must have a slight upward pitch from the boiler or furnace to the chimney. If the pipe is long, it should be supported to prevent sagging sections. The pipe should not have corrosion holes, and the joints between sections should be tight. This pipe gets very hot and should not be within several inches of combustible material.

In recent years, direct-vent appliances (appliances that vent exhaust gas through a sidewall) have become more common. During your exterior inspection, if you see a direct-vent terminal below a window, check the distance between the top of the vent and the bottom of the window. If the terminal is too close and the window is open, flue gases could enter the house. The recommended distance for an appliance with an input of 50,000 Btu per hour is a minimum of 9 inches, and for an appliance with an input of over 50,000 Btu per hour, the vent terminal clearance is at least 12 inches. Also the bottom of the vent terminal should be at least 12 inches above the ground.

The various types of heating systems have specific items that should be checked during an inspection. Each is discussed below. At the conclusion of the heating system inspection, remember to turn the thermostat back to its original setting.

Of particular concern is whether there is an adequate supply of air for ventilation and combustion for the heating equipment. When the heating system is located in an unconfined space such as an unfinished basement, there is generally sufficient infiltration so that the air supply is usually not a problem. However, if the system is located in a confined space such as a small furnace room, provisions must be made for an adequate air supply.

To provide the needed air supply, openings must be made within 12 inches of the top and 12 inches of the bottom in one of the walls of the enclosure. Each opening should have a net free area of at least 1 square inch per 1,000 Btu of total input rating of the equipment in the enclosed space. The size of the opening can be reduced if the air supplied to the furnace room comes from the outdoors rather than from inside the building. If the adequacy of the air supply is a concern, you should have it checked by a professional.

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