In the second heat exchanger, the vapor condenses and turns into a liquid. For this reason, secondary heat exchangers are usually made from materials like stainless steel, coated steel, or fiberglass. Since these materials can withstand moisture, heat, and even acid.
What is a heat exchanger and what does it do?
In most common automotive heat exchangers, the two mediums contain fluids, which flow close to each other but separated by a metal having good heat transfer properties. Out of the two fluid in the two different mediums, one is hot and the other a cold fluid.
Is a heat exchanger the same as having a furnace?
Simply put, the heat exchanger does precisely what its name implies: it exchanges heat between the furnace itself and the air that will ultimately circulate through your home. Often taking the form of curving pipes or fins, the heat exchanger is an integral part of the furnace.
Which type of heat exchanger is more efficient?
Biomass is plant-based material used as fuel to produce heat or electricity. Examples are wood and wood residues, energy crops, agricultural residues, and waste from industry, farms and households. Since biomass can be used as a fuel directly (e.g. wood logs), some people use the words biomass and biofuel interchangeably.
Does the heat exchanger need an electrical supply?
An electric furnace does not have an heat exchanger because it burns no fuel such as gas or oil. Furnaces that burn fuels have heat exchangers that contain the products of combustion and send them up or out a flue pipe. Electric furnaces operate the same way as the smaller electric portable heaters you plug into a wall socket.
How do I know if my secondary heat exchanger is clogged?
It is important to spot the signs that may indicate that your secondary heat exchanger is plugged:The condensate in your condensate drain pan is brown or black. ... Your carbon monoxide alarm goes off. ... A Pungent Odor. ... Water Leaking from the Furnace.
What is the main purpose of a secondary heat exchanger?
There are many varied kinds of HVAC furnace secondary heat exchanger. Their chief aim is to exchange heat securely and other crucial functions, comprising space heating, cooling and refrigerating, power stations, and other procedures.
What is the difference between a primary and secondary heat exchanger?
The primary heat exchanger removes heat, but not to the point that water condenses. The secondary heat exchanger is made of stainless steel, removes more heat and condenses water from the gas.
Can a secondary heat exchanger be cleaned?
The secondary heat exchanger or “reheat coil” is almost always located directly above the blower making them prone to collecting more dust and debris than air conditioning coils. This is why it is imperative to access, inspect and clean these coils in order to properly clean the system.
How do you clean a secondary heat exchanger on a carrier furnace?
1:336:50How to Clean a Clogged Secondary Heat Exchanger with WaterYouTubeStart of suggested clipEnd of suggested clipTake off all the screws on the header plate. Pull the header plate and then just go after it withMoreTake off all the screws on the header plate. Pull the header plate and then just go after it with some soap and water so I'll show that next. So the swirl is are cleaned just using soap and water.
What causes high CO in furnace exhaust?
Holes or cracks in the exchanger can cause serious problems. Holes can allow the exhaust to enter the duct system and be distributed throughout the house. Holes and cracks can also allow air from the blower to enter the burner chamber and disrupt burner operation, increasing the amount of CO produced.
What are secondary heat exchangers made of?
Secondary heat exchangers are generally constructed from stainless steel or a coated steel material capable of withstanding heat, moisture and acid.
How does a heat exchanger work?
Put simply, a heat exchanger is a device which transfers heat from one medium to another, a Hydraulic Oil Cooler or example will remove heat from hot oil by using cold water or air. Alternatively a Swimming Pool Heat Exchanger uses hot water from a boiler or solar heated water circuit to heat the pool water.
Can a heat exchanger leak water?
A crack can cause the heat exchanger to leak water. This water will likely drip out from the bottom of the casing. If you've noticed a leak and can't seem to find where it's coming from, call a heating engineer to take a look in more depth for you.
How much does it cost to replace a secondary heat exchanger?
$1,000 to $2,000Replacing a secondary heat exchanger costs $1,000 to $2,000, depending on the brand, material, and furnace capacity. The secondary heat exchanger part alone costs $300 to $800. Some high-efficiency models use a secondary heat exchanger to reclaim the heat from the combustion gasses that normally vent to the outside.
Do all furnaces have a secondary heat exchanger?
Primary and Secondary Heat Exchangers All gas furnaces have a primary heat exchanger. High-efficiency furnaces have a secondary heat exchanger as well. This allows them to extract more heat from the flue gas than just a primary heat exchanger can.
What causes a heat exchanger to overheat?
The most common cause of an overheated heat exchanger is as simple as a dirty air filter. A clogged air filter restricts airflow through the furnace, overheating the heat exchanger, and eventually resulting in stress cracks. An over-sized furnace can also cause overheating and heat exchanger cracks.
What are the three 3 types of heat exchanger?
Types of Heat ExchangersShell and tube heat exchangers.Double pipe heat exchangers.Plate heat exchangers.Condensers, evaporators, and boilers.
Which heat exchanger is more efficient?
Plate exchangerPlate exchanger is the most efficient due to turbulent flow on both sides. High heat-transfer coefficient and high turbulence due to even flow distribution are important. However, a plate heat exchanger regenerator is restricted to low viscosities. With high viscosities, a special tubular may be required.
Which reactor is primary and secondary heat exchanger used?
In the nuclear power plants called pressurized water reactors, special large heat exchangers pass heat from the primary (reactor plant) system to the secondary (steam plant) system, producing steam from water in the process. These are called steam generators.
Where are heat exchangers used?
Heat exchangers are used in many engineering applications, such as refrigeration, heating and airconditioning systems, power plants, chemical processing systems, food processing systems, automobile radiators, and waste heat recovery units.
Heat Exchanger Design
There are several types of heat exchangers. Each has the same basic design principles, including:
Heat Exchanger Fluids
Shell and Tube: A set of metal tubes carries one fluid. The second fluid passes through and within a shell encasing the assembly. This design is suited for viscous fluids and those with a higher density of particulates.
What is a secondary heat exchanger?
Secondary heat exchangers are generally constructed from stainless steel or a coated steel material capable of withstanding heat, moisture and acid.
How does a heat exchanger work?
Heat exchangers, metal shells and tubes, work by transferring heat from one place to another. When a furnace burns natural gas or propane fuel, its exhaust/combustion by-products (also known as flue gas) enter and travel through the heat exchanger.
What is a high efficiency furnace?
If you have a furnace that is considered high-efficiency (90%+ efficient), it contains both a primary and secondary heat exchanger. As the combustion exhaust leaves the primary heat exchanger, it travels into a secondary heat exchanger where more heat is released from the flue gas and water vapor begins to form. This change of state from water as a vapor to a liquid releases latent heat in the secondary heat exchanger, bringing the furnace to an even higher level of efficiency. This is why high-efficiency furnaces are sometimes referred to as condensing furnaces. Secondary heat exchangers are generally constructed from stainless steel or a coated steel material capable of withstanding heat, moisture and acid.
Why is it important to have a flue gas exchanger?
Because the heat exchanger contains the flue gas inside of itself, it is important there are no holes, cracks or other deterioration. This type of deterioration that permits leakage and mixing of flue gas with the air being heated can result in incomplete combustion and the formation of carbon monoxide and other harmful by-products. Although your furnace may not immediately leak carbon monoxide into the living space, high CO levels make it unsafe to operate. Something as simple as the chimney getting plugged or damaged exhaust pipe can result in a very dangerous situation.
How does a furnace flue work?
The hot flue gas heats the metal as the gas makes its way to the exhaust outlet of the furnace. As this is happening, the hot metal heats the air circulating over the exterior of the heat exchanger.
What is the purpose of heat exchangers?
There are many different types of heat exchangers. Their purpose is to safely transfer heat, and they have many applications, including space heating, refrigeration and cooling, power stations, chemical plants, and other processes.
Can heat exchangers be inspected?
Some heat exchangers can be inspected visually. Others require specialty tools to examine the unit more closely. Our technicians are equipped with a camera with a flexible shaft that can see into inaccessible areas of your furnace to ensure a thorough inspection. We sometimes find internal issues in heat exchangers that would otherwise be hidden and appear in good condition from the outside.
What is a heat exchanger?
A heat exchanger is a device that transfers thermal energy from one medium to another. [2] . Heat exchangers not only assist in the cooling and heating of homes and buildings, but also help machines and engines work more efficiently. [3]
What is the purpose of heat exchangers in a gas furnace?
These units employ heat exchangers to raise the temperature of air before dispersing it throughout a building via ducts and registers. In a gas furnace, the heat exchanger is an airtight vessel with a hole at the bottom and one at the top, which is called the flue.
How does refrigerant work in an air conditioner?
Here are the different steps: In the air conditioner, the refrigerant channels through the various components, moving heat as it goes. The refrigerant starts out as a low-pressure liquid in the evaporator coils. A fan blows the warm air in an indoor space across the coils , and the refrigerant changes into a vapor as it absorbs the heat from ...
How does refrigerant work?
Refrigerant carries, absorbs and releases heat as it changes from a gas to a liquid and back again during the refrigeration process. [5] Here are the different steps: 1 In the air conditioner, the refrigerant channels through the various components, moving heat as it goes. 2 The refrigerant starts out as a low-pressure liquid in the evaporator coils. 3 A fan blows the warm air in an indoor space across the coils, and the refrigerant changes into a vapor as it absorbs the heat from the air and, in turn, cools the room. 4 A low-pressure warm gas now, the refrigerant travels into the compressor—usually located outdoors—where it converts into a high-pressure, hot gas. 5 The refrigerant moves into the condenser, also typically outside. 6 As air flows over the condenser, it carries away heat from the refrigerant with it, causing the refrigerant to change again into a high-pressure, cool liquid. 7 The refrigerant will cool off even more in the expansion valve before returning to the evaporator to absorb more heat to carry out of the building.
How does a gas furnace work?
[9] The heat exchanger in a gas furnace plays two roles: exchanging heat from the combustion process to the air blown over it and keeping toxic combustion gases separate from the heated air. [10]
How does a fan work?
A fan blows the warm air in an indoor space across the coils, and the refrigerant changes into a vapor as it absorbs the heat from the air and, in turn , cools the room. A low-pressure warm gas now, the refrigerant travels into the compressor—usually located outdoors—where it converts into a high-pressure, hot gas.
What is the second law of thermodynamics?
Heat flows from areas of high temperature to areas of low temperature, according to the Second Law of Thermodynamics. The HVAC system is responsible for reversing this natural flow, removing hot air from buildings in the hot summers and placing it in buildings in the cold winters. [1]
How does a heat exchanger work?
Put simply, a heat exchanger is a device which transfers heat from one medium to another , a Hydraulic Oil Cooler or example will remove heat from hot oil by using cold water or air. Alternatively a Swimming Pool Heat Exchanger uses hot water from a boiler or solar heated water circuit to heat the pool water. Heat is transferred by conduction through the exchanger materials which separate the mediums being used. A shell and tube heat exchanger passes fluids through and over tubes, where as an air cooled heat exchanger passes cool air through a core of fins to cool a liquid.
What is a shell and tube heat exchanger?
A shell and tube heat exchanger passes fluids through and over tubes, where as an air cooled heat exchanger passes cool air through a core of fins to cool a liquid. 2. What types of Heat Exchanger are available? There are many different types of heat exchanger available, the three main types that Thermex supplies are;
What are the factors that determine heat exchanger efficiency?
Heat exchanger efficiency can be defined in many ways, in terms of thermal performance there are several key factors to consider; Temperature differential - As discussed in point 3 (temperature cross-over) the difference between the hot fluid and coolant is very important when designing a heat exchanger.
What fluids can be used in a Thermex heat exchanger?
Standard Thermex Heat Exchangers are suitable for most fluids including Oil, Water, Water Glycol and Sea Water. For more corrosive fluids such as chlorinated salt water, refrigerants and acids other materials such as Stainless Steel and Titanium will need to be used instead. 4.
How long should I run a heat exchanger in clean water?
For heat exchangers on applications which use polluted, shallow or brackish sea water as the coolant and have copper alloy tubes, it is recommended to run the heat exchanger in clean sea water for several weeks first, this creates a protective layer over the tube material which helps to protect against corrosion.
What are the different types of heat exchangers?
Heat Exchanger Abbreviations and Terminology 1 ETD Extreme Temperature Differential 2 EGC Exhaust Gas Cooler 3 MGO Marine Gas Oil Cooler 4 HTHE Header Tank Heat Exchanger 5 CAC Charge Air Cooler 6 ACOC Air Cooled Oil Cooler 7 PHE / PHEX Plate Heat Exchanger 8 Shell Side Flow/Connections - Shell Side refers to the flow of a fluid, such as oil, over the external surface of the tube stack 9 Tube Side Flow/Connection - Tube Side refers to the flow of fluid through the tubes of the tube stack, usually the coolant Pressure Loss / Drop The level of back pressure generated by pumping the fluids through the heat exchanger circuits
What are the factors that need to be taken into consideration when designing a marine heat exchanger?
One is the velocity, if it is too low then there is a risk that sand and other particles will block the tubes.
What is the secondary heat exchanger in a condensing furnace?
In condensing furnaces, there is a secondary heat exchanger made up of small tubes that receive the exhaust gases once they have gone through the primary heat exchanger. Here, more heat is extracted, resulting in the gases that are cooled to the point that they condense into water and carbon dioxide.
What type of motor is used in a condensing furnace?
Condensing furnaces may have one of two types of blower motors: a standard permanent split capacitor (PSC) motor (the same type commonly found on conventional furnaces), or a variable-speed, direct-current electronically commutating motor (ECM). The latter is used with two-stage, or modulating, furnaces and is more energy-efficient than a standard motor.
What is the difference between a condensing furnace and a conventional furnace?
The main difference between a conventional and condensing furnace is how the furnace handles the exhaust gases from the combustion process. Both types of furnace have a primary heat exchanger, consisting of a combustion chamber where heat from gas burners is exchanged to the circulating air before it is distributed throughout the house. With a conventional furnace, the hot exhaust gases from the combustion chamber go directly into a metal flue and are vented to the outdoors. Because the exhaust gases are still very hot, all of that heat is wasted.
What are the two types of gas furnaces?
The two main types of gas furnaces in the home are the conventional furnace and the newer high-efficiency condensing furnace. The technologies used in these furnaces directly impact the difference in their energy-efficiency, as represented by their AFUE (Annual Fuel Utilization Efficiency) ratings. Only condensing furnaces are able to achieve ...
What are the components of a condensing furnace?
Condensing furnaces are similar to conventional furnaces when it comes to fuel combustion—the standard components include a gas burner, electronic ignition, and a combustion chamber. However, there are some differences in how air is delivered for combustion as well as in burner gas valve technology.
Why is exhaust heat wasted?
Because the exhaust gases are still very hot, all of that heat is wasted. With a condensing furnace, on the other hand, the combustion exhaust gases are also passed through a secondary heat exchanger that absorbs much of the remaining heat from the gases.
What is the purpose of air filters in a furnace?
Air Filter. Most condensing furnaces (and some conventional furnaces) use high-efficiency air filtration media to improve indoor air quality. These filters need to be changed regularly in order to work effectively. Different classes of filters are available, depending on your needs. If someone in your family suffers from allergies, for example, ...
