Full Answer
Is plenum return or ducted return an option?
if it is really return air (not merely exhaust) and you have the mentioned stratification, it appears that plenum is not an option in case that you have no conditioned space above that ceiling - that would be waste of energy. RE: Plenum Return or Ducted Return? Thank you all for your valuable input.
Do I need a return air plenum on my air conditioner?
Usually, air conditioners which are designed to use ceiling plenum for return air will not need to have a separate return air plenum box on the air conditioner itself. The outside air is introduced into the ceiling plenum to mix with the return air before flowing back to the respective air conditioners.
Can you use non plenum cable in a plenum?
Since non-plenum cables are less fire-resistant and release more smoke, they should not be installed inside plenum airspaces. However, depending on your building code requirements, you may be able to install non-plenum cable in plenum areas if it’s run through a plenum conduit.
Is roof load accounted for in plenum return?
If you ran your loads as insulated roof and conditioned space, all of the roof load is accounted for. You would just need to make sure that all materials in the plenum area are plenum rated and that the plenum is air tight. RE: Plenum Return or Ducted Return?
Is a return plenum needed?
1:313:35Titus Timeout Podcast - What is Plenum Return? - YouTubeYouTubeStart of suggested clipEnd of suggested clipThere are a couple benefits to using plenum return plenum return has less ductwork. So it costs youMoreThere are a couple benefits to using plenum return plenum return has less ductwork. So it costs you less to install. And there's less material.
Is a plenum necessary in HVAC?
The state of your ductwork and the plenum are vital to the functionality and efficiency of your heating and cooling systems. If the plenum or air ducts are too dirty, it can restrict airflow and force your HVAC system to run longer to try to reach the desired temperatures on your thermostat.
What does a return plenum do?
What is a return plenum box? The return plenum box receives used air from the return vents and distributes it to your HVAC unit to be heated or cooled again. The used air must pass through a filter before entering the return plenum, ensuring that it's clean before it reenters your AC, heat pump, or furnace.
How big does a return air plenum need to be?
Single plenums should not exceed 24 ft in length. Double plenums should not exceed 48 ft in total length.
How do I make a return air plenum?
0:0516:43Furnace Return Air Plenum Fabrication - YouTubeYouTubeStart of suggested clipEnd of suggested clipProbably gonna be a 3-piece box. You can make them a five-piece you can make them you know three-MoreProbably gonna be a 3-piece box. You can make them a five-piece you can make them you know three-piece there's numerous ways that they can be made. And ain't none of them wrong necessarily.
Do you need a plenum box?
Plenum boxes are used to distribute heated or cooled air throughout your home's interior. After producing heated or cooled air, the HVAC system must move that air through the ductwork. Plenum boxes take in this air so that it can be pumped into the ductwork and, therefore, distributed throughout your home's interior.
What is the advantage of having supply and return plenums in duct systems?
Protecting the System Against Dirt If you have a forced-air heating or cooling system, then you need to keep the ducts clean to prevent small particles from getting into the system. A plenum can help prevent dirt and other debris from getting into your HVAC system and into your home.
What is HVAC return plenum?
The return plenum connects the return ducts in your duct network back to your HVAC system. Many return plenums contain filters to remove bacteria and other contaminants from the indoor air that passes through them. The air is then sent back into your HVAC system for another cycle of cooling.
Should an AC plenum be insulated?
Supply and return air ducts and plenums shall be insulated with a minimum of R-6 insulation where located in unconditioned spaces and where located outside the building with a minimum of R-8 insulation in Climate Zones 1 through 4 and a minimum of R-12 insulation in Climate Zones 5 through 8.
Does every room need a cold air return?
Does Every Room Need Air Return Grilles? While it is a myth that air return grilles are required in each and every room in the house, it is definitely necessary to have more than one of these grilles installed at strategic places in the house. The most important place to have these would be the bedroom.
What happens if there is not enough return air?
If there is not enough return air available, your HVAC system will not heat or cool properly. They must be properly sized — Return air ducts must be large enough to carry a sufficient amount of expended air back to your furnace, air conditioner, or heat pump.
Can you have too many return air vents?
Having several return vents (ideally one in every room, but even two or three is better than just one) creates consistent air pressure. If you have one return vent, your home is fine. Keep the doors to each room open so air can properly circulate.
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What Is a Plenum?
The plenums, or plenum boxes are responsible for moving heated and cooled air through the house and back through the unit. Nearly all HVAC units have two boxes, the supply and return.
Signs of Problems with a Plenum Box
The plenum box is more of a storage container for air as it moves into and out of the unit, so having the proper size box along with air hoses at the proper angle going into the boxes is necessary to keep air flowing as it should.
Can I Replace a Plenum Box Myself?
If your plenum box has failed, you may want to save some money by repairing or replacing it yourself. While the component doesn’t look complicated, if it’s not installed properly to allow proper air flow, your unit’s coils can freeze, the furnace can trip, and over time the compressor itself may malfunction.
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1. Supply Air Plenum
The plenum box on a supply air diffuser helps to distribute cold air equally across the diffuser. Besides, the plenum box act as an adaptor to connect the diffuser and flexible duct. Furthermore, a plenum box can have a damper to regulate the airflow of the diffuser.
2. Return Air Plenum
The plenum box on a fan coil unit or ducted air conditioner helps to mix the return air and thus, averaging the return air temperature so that the air conditioner can regulate its cooling power appropriately.
3. Ceiling Return Plenum
Many buildings use the space above the ceiling as a plenum for their air conditioning system. Typically, return air grilles are installed on the ceiling without connecting to any ducts.
4. Room Return Plenum
Air handling units (AHUs) often use their own room as the return air plenum. These AHUs connect duct only at their supply air outlet. The room itself also has a fresh air opening with a damper to introduce outside air. The entire room act as a return air plenum for the AHU.
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Should I Use Plenum or Non-Plenum Rated Cable?
Whether you’re a professional installer, a DIY kind of homeowner, or just curious, knowing when to use plenum or non-plenum rated cable is extremely important. Using the correct cables when installing a signal booster or any networking system will keep commercial and residential buildings up to code and most importantly… keep occupants safe.
What is Plenum?
Plenum is an HVAC term used to identify open airspaces – usually above drop-down ceilings or below raised floors – which facilitate airflow circulation for heating and cooling. In most plenum airspaces, air ducts are used to connect the HVAC unit and the supply vents to distribute the air supply throughout a building.
What is Plenum and Non-Plenum Rated Cable?
Plenum and non-plenum cables can be any type of cable – coaxial, Ethernet, HDMI, fiber optic, etc. The term “Plenum” and “Non-Plenum” simply refers to the outer jacket/cover that protects the cable.
When Should Plenum Cable be Used?
Article 800 of the National Electrical Code (NEC) states that plenum cable should ALWAYS be used in plenum airspaces and air ducts to slow down the spread of flames and reduce smoke and toxic fumes from circulating throughout the building.
Do I Need Plenum Rated Cable in My Home?
While it's definitely acceptable to use plenum-rated cable in your home to install a signal booster, a WiFi network, or something else, more often than not, it’s not necessary. Most residential buildings don’t have plenum airspaces. Plenum areas are more common in commercial buildings.
How do I Know if a Cable is Plenum Rated?
The numbers and letters printed on the cable’s jacket will usually tell you everything you need to know about the cable, such as the jacket rating, who manufactured it, who verified it, temperature rating, reference number, and more. Here is a great and easy read on how to read a cable’s jacket legend.
When Should Non-Plenum Cable be Used?
Non-plenum cable (CMR and CM) can be safely installed inside walls, across open ceilings, and any non-plenum area.
Do RA plenums have a roof load?
With RA plenum, the space does not see the roof load (well most of it), the coil does. With a ducted return, you will need more air flow, thus larger ducts, larger fans, etc..and you will need much more ceiling space since now you will have supply and return ducts crossing at the ceiling.
Can you balance a plenum with a RA load?
If you don't really know the RA load, it's hard to size the unit with a plenum. Plenum systems are also almost impossible to balance because what was the lowest RA pressure path to the fan today will not be the same tomorrow after ceiling tiles are removed/altered.
Do all electrical devices have to be plenum rated?
However all the electrical devices will have to be plenum rated. The problem is if you are going with a plenum return system you must be able to guarantee that the build is constructed air tight and that there are no leaks above the ceiling space. So you will have less control over where the air travels.
