Furnace Inspections

Inspect, Identify and Describe a Furnace

According to the InterNACHI Residential Standards of Practice, a home evaluation is a non-invasive, visual examination of a domestic dwelling that is created to identify observed material flaws within certain components of that house. Part of the house inspection includes the inspection, recognition and description of the heating system.

The inspector is required to inspect the heating unit utilizing typical operating controls, and describe the energy source and heating approach. The inspector's report will describe and recognize, in written format, the examined heating unit and will determine material problems observed.

In order to carry out an examination according to the Standards of Practice, an inspector needs to apply the understanding of what s/he understands about the different types of residential heating unit. To fully inspect and recognize a certain heating system, explain its heating method, and recognize any product defects observed, an inspector needs to have the ability to explain and go over with his/her clientel:

• the heating system;
•  its heating technique;
• its type or recognition;
•  how the heating unit runs;
•  how to preserve it; and
• the typical issues that might be found.

The inspector should be able to extensively examine a heating system, understand how a specific heating unit operates, and evaluate and reason as to its obvious condition. An inspector must also be able to justify his/her observations, opinions and recommendations that were written in the evaluation report.

Heating system Fundamentals

Let's concentrate on the fundamentals of a certain heating system called a heater. There are numerous methods to check, recognize and explain the various types of furnaces that may be discovered at an apartment utilizing non-invasive, visual-only examination methods. It depends on the inspector's judgment as to how detailed the examination and report will certainly be. For example, the inspector is not needed to identify the capability or BTU of the examined heating system, but lots of inspectors record that comprehensive details in their reports.

The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) specifies a heater as a "full heating system for moving heat from fuel being burned to the air provided to a heating system." Another definition of a furnace is "a self-enclosed, fuel-burning system for heating air by transfer of combustion through metal directly to the air." Taking these 2 meanings into consideration, there are two basic qualities of a heating system:

1. There is a fuel used to produce combustion; and
2. Heat is transferred to the interior air. Keep in mind that air-- not water or steam-- is made use of as the medium to convey the heat. This unique distinguishes warm-air heating unit from other kinds of heating systems.

Let's take a look at determining and explaining some warm-air heating unit called heating systems.

Many modern heaters are commonly referred to as central heating systems. The heater is typically centralized within the structure. The heater is utilized as the major, central warm-air heating unit. The heat of the furnace is forced (or increases) through a system of ducts or pipes to other places or spaces in the structure. The heating system does not always require to be centrally situated within the structure if the furnace is a forced warm-air system.

Heaters that have no distribution ducts or pipes are made use of in some heating applications. They are restricted in the size of the area that they can heat. They are set up within the room or location to be warmed and have no chance to disperse the heat to other places.

Recognition and Description of Furnaces

There are several methods to determine and explain a furnace making use of non-invasive, visual-only assessment methods, as required by the InterNACHI Standards of Practice. Furnaces can be identified and explained by:

•  fuel type;
• distribution;
• airflow;
• gravity or forced;
• effectiveness; and
•  ignition.

Fuel Type

One method to identify and describe a heating system is based upon the kind of fuel made use of to produce heat. Based on fuel type, one can classify a furnace as:

1.gas-fired;
2.oil-fired;
3. coal;
4. wood;
5.multi-fuel; or
6. electric.

Fossil fuels are used to produce combustion in the very first five types. The last one makes use of electrical energy. Whether or not electricity can be thought about a fuel is not crucial here, since an electric heating system functions in the same manner as the other fossil-burning heaters. The electric heater heats up air and disperses it. According to the Standards, an inspector is required to
explain the energy source in their report.

Distribution

The inspector is also needed to explain the heating approach. One way to do that is to identify the technique of how the air is dispersed throughout your house. Heaters can be recognized and described (or categorized) by the way the air is distributed. There are two broad classifications:

1. gravity warm-air heaters; and
2. forced warm-air heating systems.

The gravity warm-air heating systems rely mostly on gravity for circulating the heated air. Warm air is lighter than cool air and will increase and move through ducts or pipes. After releasing its heat, the air becomes cooler and heavier. The air drops down the structure through return registers to the heater where it is heated up once more, and the cycle continues. The extremely earliest types of furnaces were gravity-type furnaces. Sometimes they had a blower fan installed to move the heated air. They have actually primarily been replaced by modern, forced warm-air heaters.

Airflow

Forced warm-air furnaces can be identified and described by how the air flows through the heating system in relation to the warm-air outlet and the return-air inlet areas on the heater. There are three types of forced warm-air furnaces related to airflow:

1. upflow (highboy or lowboy);.
2. downflow; and.
3. horizontal.

Heater makers typically use the terms "upflow," "downflow" and "horizontal" in their literature that explains their items, including their marketing materials, and in their installation and operation manuals.

Upflow Highboy.

On a typical upflow highboy heating system, the warm-air outlet is situated at the top of the heating system, so warm air discharges from the top. The return-air inlet is located at the bottom or sides of the furnace. A cooling system is often contributed to the top of an upflow heater. A typical upflow highboy heater stands no higher than 6 feet and can occupy a floor space of 6 square feet (2 feet x 3 feet).

Upflow Lowboy.

An upflow lowboy heating system is developed for low clearances. Both the warm-air outlet and return-air inlet are situated at the top of the furnace. The lowboy is commonly set up in a basement where most of the ductwork is above the heating device. This compact heating system usually stands no higher than 4 feet. It is usually longer from front to back than either the upflow highboy or downflow furnaces.

Downflow.

A downflow furnace is likewise described as a counterflow heating system or a downdraft heating system. Warm air discharges out of all-time low of a downflow heater, and the return-air inlet lies at the top. The downflow heater is set up normally when many of the duct or pipeline distribution system is below the heating system. The ducts may be embedded in a concrete floor slab or suspended in a crawlspace listed below the heating system. The downflow heater is comparable in measurement to the upflow, however the warm-air outlet is located at the bottom instead of the top.

Horizontal.

A horizontal heater is developed mainly for setups with low, restricted space, such as a crawlspace or attic. A typical horizontal heater is about 2 feet wide by 2 feet tall, and 5 feet long.

Gravity Warm-Air Furnace.

A gravity warm-air heating system makes use of the fact that warm air is lighter than cool air, and warm air rises. In a gravity warm-air heater, warm air might rise through ducts or pipes. After releasing its heat, the air ends up being cooler and heavier. The air drops down the structure through return registers to the heating system, where it is heated up once again. The air is circulated through the house in this way.

The extremely earliest kinds of heating systems were gravity warm-air heaters. They were popular from very first half of the 19th century to the early 1970s. In some cases they had a blower fan installed to move the heated air. However the primary way the air moved through your house relied on how gravity affected the various weights of warm and cool air. Gravity warm-air heaters were in some cases referred to as "octopus" heaters because of its look with all of the pipes coming out of the centrally situated heating system. Many of these gravity heating systems are obsolete and at the end of their life span.

A gravity warm-air heating system can be described in among the following 3 ways:.

1. a gravity warm-air heating system without a fan;.
2. a gravity warm-air heater with an essential fan; or.
3. a gravity warm-air heating system with a booster fan.

A gravity warm-air heating system without a fan relies completely on gravity and the various weights of air to circulate the air through your house. The airflow rate is slow. The air flow and distribution of heated air is not reliable. It is all but difficult to successfully control the heat provided to individual spaces of your home. Occasionally an integral fan is installed in the distribution ducts or pipelines to decrease the internal resistance to airflow and boost air movement.

A booster fan is set up to do the same, but does not conflict with air blood circulation when it is not in use. A booster fan may be a belt-driven fan unit, resting on the floor and attached to the exterior of the heating device.

Floor and area heating systems run using the exact same concepts of gravity and air weights, as do the gravity warm-air furnaces. They differ by the way a floor or area heating system is designed to supply heated air to a certain space or space, and do not distribute air throughout your house.
Warm Air Rises

When a specific amount of air is warmed up, it broadens and uses up more area. Simply puts, hot air is less thick than cold air. Any compound that is less dense than the fluid (gas or liquid) of its environments will certainly float. Hot air floats on cold air since it is less thick, just as a piece of wood drifts because it is less dense than water. Warm air is often referred to as weighing less than cool air.

Gas Furnaces

There are a range of ways to describe various types residential gas heaters. Gas heaters can be categorized by:

1. the direction of the air flowing through the heating device;
2. the heating effectiveness of the device; and
3. the kind of ignition system installed on the device.

Airflow in Gas Furnaces

One way to recognize and explain a gas furnace is by the direction of the air flowing through the heating device, or the place of the warm-air outlet and the return-air inlet on the furnace. Gas furnaces can be described as upflow, downflow (counterflow), highboy, lowboy, and horizontal flow. Air can flow up through the heating system (upflow), down through the heater (downflow), or throughout the heating system (horizontal). The arrangement of the furnace should not considerably influence its operation, or your examination.

BTU

Gas heating systems can be categorized by their various abilities. A heater capability can be explained by BTU output. The BTU is identified by exactly what is required by the heating system for the structure, which is the duration of heat the system has to produce to change heat loss and supply the occupants a great convenience level.

AFUE

Heating systems can be identified and explained by heating efficiency. The energy effectiveness of a gas furnace is determined by its annual fuel utilization effectiveness (AFUE). The greater the score, the more effective the heater. The united state government has actually developed a minimum rating for heaters of 78 %. Mid-efficiency furnaces have AFUE ratings from 78 to 82 %. High-efficiency heating systems have AFUE scores from 88 to 97 %. Old, standing-pilot gas heaters have AFUE ratings from 60 to 65 %. Gravity warm-air heating systems may have effectiveness lower than 60 %.

BTU and Efficiency

BTU stands for British Thermal Unit. The BTU is a system of energy. It is around the amount of energy had to heat one pound of water 1 degree Fahrenheit. When cubic foot of natural gas contains about 1,000 BTUs. A gas furnace that fires at a rate of 100,000 BTUs per hour will certainly burn about 100 cubic feet of gas every hour.

On a gas furnace, there must be an information plate. On that plate there might be composed the input and output capabilities. For example, the information plate may say, "Input 100,000 BTU per hour." And it might also state, "Output 80,000 BTU per hour." While this heating system is running, about 20 % of the heat created is lost out through the exhaust gases. The ratio of the output to the input BTU is 80,000 ÷ 100,000 = 80 % effectiveness. This is the "stable state performance" of the heater.

Stable state performance measures how efficiently a furnace converts fuel to heat, as soon as the heating system has actually warmed up and is running gradually. Furnaces cycle on and off as they preserve their desired temperature level. Furnaces normally do not run as effectively as they launch and cool down. As a result, stable state efficiency is not as reliable a sign of the overall efficiency of your heater.

AFUE and Efficiency

The AFUE is the most extensively used measure of a heating system's heating effectiveness. It determines the quantity of heat delivered to your home compared with the duration of fuel that need to be provided to the furnace. Thus, a heater that has an 80 % AFUE rating converts 80 % of the fuel that is supplied to heat. The other 20 % is lost and lost.

Keep in mind that the AFUE refers only to the system's fuel efficiency, not its electrical energy usage. The U.S. Department of Energy (DOE) identified that heaters sold in the U.S. needs to have a minimum AFUE of 78 %, beginning January 1, 1992. Mobile home furnaces are required to have a minimum AFUE of 75 %.

The DOE's meaning of AFUE is the measure of seasonal or yearly performance of a furnace or boiler. It takes into account the cyclic on/off operation and associated energy losses of the heating device as it responds to changes in the load, which, in turn, is impacted by modifications in weather condition and resident controls.

Ignition Type

Gas heating systems can be identified and explained by the kind of ignition system on the heater. The different types of ignition systems are:
1.standing-pilot;
2.intermittent-pilot or direct-spark; and
3.hot-surface ignition.
The older gas heating systems have a standing-pilot light that is constantly burning. Modern heaters with greater efficiency ratings are gradually replacing these older, traditional gas furnaces.

Standing-Pilot

Standing-pilot gas heaters provide a substantial variety of domestic gas furnaces that are still in use today. A standing-pilot gas heating system is geared up with a naturally aspirating gas burner, a draft hood, a solenoid-operated main gas valve, a constantly running pilot burner (standing- pilot), a thermocouple security device, a 24-volt A/C transformer, a heat exchanger, a blower and motor assembly, and one or more air filters. The standing-pilot is the main distinguishing attribute of the low-efficiency traditional gas furnace.

Mid-Efficiency

A mid-efficiency gas furnace is equipped with naturally aspirating burner and a pilot burner. The pilot burner is unlike a standing-pilot. It does not run continually. The pilot light is shut down when the heater is not in operation (when the thermostat is not requiring heat). The heat exchanger is more effective than one inside a traditional heater. There is no draft hood. There may be a little fan installed in the flue pipe to create an induced draft, so these furnaces are often referred to as induced-draft furnaces. A mid-efficiency gas furnace is likewise equipped with automatic controls, blower and motor assembly, venting, and air filtering. Some mid-efficiency heaters will certainly have a motorized damper set up in the exhaust flue pipe. A mid-efficiency heater is about 20 % more energy-efficient than a standard gas heating system. A mid-efficiency heater has an AFUE score of 78 to 82 %. The intermittent-pilot is the major distinguishing attribute.

High-Efficiency

High-efficiency gas heaters have AFUE scores of 90 % and higher. A solid-state control panel regulates the ignition. There is no continuous pilot light. There are two or occasionally 3 heat exchangers installed inside a high-efficiency gas furnace. Condensate is produced when heat is removed from the flue gases. The temperature level of the flue gases is low enough to utilize a PVC pipeline as the vent exhaust pipe. There is no requirement to vent the exhaust gases up a chimney stack. There are 2 various kinds of high-efficiency heating systems:
1. one with an intermittent-pilot or direct-spark; and
2. one with a hot-surface ignition system.
The production of excessive condensate is the main distinguishing quality.

The very best Techniques

There are lots of ways to determine and explain a heater. According to the InterNACHI Standards of Practice, the inspector is required to inspect the heating systems making use of typical operating controls, and explain the energy source and heating method. The inspector's report shall describe and identify, in composed format, the inspected heating system, and will recognize material flaws observed.

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