What Is a Plenum in an HVAC System?
Jan 23, · Plenum is a lot more than hollow space. It's a space where the air returns from the ac (basically an AC system without return duct). So that air gets back in the air handler and gets pumped right back into the rooms. Not sure how many have seen how . 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.
Hollow: empty plennum ,void 50kva transformers and iss are allowed in such areas. Why 50kva limitation? Because the buildup of heat in such an unventilated area on higher rated transformers may cause them to fail and burn up.
Plenum: A compartment or duct to which one or more air ducts are connected and forms part aid the air distribution system. Although these areas may appear similar, they are two distinctively different portions of a building. A hollow space will not communicate to an environmental air passageway and likewise. Electrical Equipment in Plenum?
Low Smoke Producing Type. It is my contention that above grid return air plenums are a hollow space, but should not be considered as such, as they do indeed contain something: Environmental air, The Article in does not apply to transformers in environmental air, otherwise we would allow transformers to be installed in metal ducted plenums which are void and empty as defined by the term hollow.
All equipment installed in return air above grid plenums must be rated for this purpose, not just electrical equipment. The accessibility requirements prescribed in are just that a matter of accessibility. If the hollow space communicates with and environmental air passageway, that hollow space now becomes an approved form of duct work as prescribed in the 03 International Mechanical Code. Which also address the installation of electrical equipment in environmental air return plenums in article The code writers intent in article Not to allow the installation of a piece of equipment in return air plenums.
Although Transformers are not tested for the plenum rating as the body of the code already address their approved installation in a hollow space up to 50kva? Herein lies the problem. Am I wrong? Should we what is adjusted gross income irs allowing transformers in environmental air plenums knowing that such equipment has not or ever been tested for such an installation?
Location Massachusetts. Dang old king said:. This section applies to space used for environmental air-handling purposes other than ducts and plenums as specified in It does not include habitable rooms or areas of buildings, the prime purpose of which is not air handling. Exception: This section shall not apply to the joist or stud spaces of dwelling units where the wiring passes through such spaces perpendicular to the long dimension of such spaces.
Electrical equipment with a metal enclosure, or with a nonmetallic enclosure listed for the use and having adequate fire-resistant and low-smoke-producing characteristics, and associated wiring material suitable for the ambient temperature shall be permitted to be installed in such other space unless prohibited elsewhere in this Code. Exception: Integral fan systems shall be permitted where specifically identified for such use. Npstewart Senior Member. Transformers are not allowed in the air plenum, most of the transformers like optimus prime are like 50 feet tall!
How go they aif all fit in there??? So we cant put them in a metal duct that conveys environmental air. But we can put them in an above grid os that performs the same function? Is that correct? But we can put them in an above grid ceiling that performs the same function? Location Palmer, MA. But I wouldn't say a transformer has a "low smoke producing charateristic".
I've seen a lot of smoke come out of one them things. I agree with you on the listing. Mellow Has mad a statement in regard to this issue.
What would you say to that? Location Logan, Utah. Strife Senior Member. Plenum is a lot more than hollow space. It's a space where the air returns from the ac basically an AC system without return duct. So that air gets back in the air handler and gets pumped right back into the rooms.
Not sure how many have seen how much smoke couple grams of PVC can generate. It's a LOT. Just a whiff. I left a heat box unattended for let's say more than I should havewhen I got to it to pull the pvc out the whole 3 feet of it there was enough smoke to knock plemum an elephant. Last edited: Jan 21, Strife said:. I appreciate how to animate stick fights the response to this topic.
It certainly appears to be one of confusion. This forum has stated that the transformer must be listed for the location was touched and concluded on not so long ago. And now it has changed. Metal enclosure: Yes indeed transformers are in metal enclosures but they have vent opening to dissipate heat so much so that the combined measurement of the opening equals one of what is a return air plenum transformers 6 sides.
In essence you have a 5 sided cube. I don't think that's what the code writers were talking about when they spoke of metal enclosures. Its not completely enclosed that's pretty simple Hollow Space.
I think the code writers intent here is pretty obvious as well. Is an above grid return air plenum hollow? Not so much in most cases those areas are used as plumbing, communication and ventilation chases those three items themselves disallow the definition of Hollow. I'm being a bit persnickety.
The code does not allow transformers. So why cant we put a transformer larger than 50kva in a hollow space that is used to convey conditioned air. In a quandary. The only thing we can stand behind is code in w effort to provide said protection. I would rather error on the side of caution and protect a building and it's occupants from possible exposure to the noxious fumes and vapors that are emitted by burning transformers than to plenjm approve them in such how to break in grishko pointe shoes. Thanks again for all the input.
Cheers DOK. Sierrasparky Senior Member. I have been in Mechanical rooms that are plenums the have enough area that you could place 20 of those size transformers. Boy the noise and the constant hurricane wind inside.
Location Chapmansboro,Tn. I wonder what building codes in your area would say about this one? I came how to backup files from iphone to computer this years ago.
It seems to me from what I can remmember from 15 years or so back that the G. C had to wrap a dry wall box around wwhat and duct the box out of the ceiling. I recall this becuase I remmember the G. Its not completely enclosed that's pretty simple. Hollow Space. We are obligated as building officials and qualified people to protect the public from this thing we call electricity. You are also as much obligated to enforce the adopted code not your own ideas about what is righ or wrong.
Location Austin, TX. I'm going to take an uneducated guess on why the code does not allow any transformers over 50kVA to be installed in a plenum what is the islamic way of intercourse ceiling. I think its not so much that the whah put off by the transfomer will affect the transformer, but since the plenum rated space is the return air for the HVAC system,seems like the heat that a transfomer expecially a large transformer or transformers that would be put off would be hard on that system.
Guide to Cable Ratings
A plenum space is a part of a building that can facilitate air circulation for heating and air conditioning systems, by providing pathways for either heated/conditioned or return airflows, usually at greater than atmospheric pressure. Space between the structural ceiling and the dropped ceiling or under a raised floor is typically considered plenum; however, some drop-ceiling designs create a. Feb 18, · In homes and businesses, a plenum chamber is an alternative to traditional duct-based ventilation systems. Instead of relying on two separate networks of ducts to supply and return air, plenum systems utilize only a set of supply ducts. As these ducts pump fresh air into the room, stale air naturally exits through exhaust grills in the ceiling. ing return air plenum that has been used for a few years could have substantial dust accumulation on plenum surfaces. But return air ducts could have a similar or even thicker layer of dust. The dust “challenge” for both are particles drawn from the conditioned space and the source strength of these particles is the same whether.
Sign me up for the newsletter! What in the world is a plenum, you ask? The return plenum is a box that connects the return ducts in your ductwork back to your HVAC system. The air is then sent back into your HVAC system through a return inlet to be put through another cycle of cooling or heating.
In any case, it is well worth your penny for peace of mind. Especially with ductwork , we recommend getting your installation from a seasoned expert.
Your supply and return plenums must be properly fitted in order to effectively distribute air throughout your home. Also, proper fitting will help to reduce risks of air leaks and other potential problems within your system. Check out the list below to see a few of the issues that could arise from improper plenum installation. If you have any ductwork needs, whether they involve your supply plenum, return plenum, or other aspects, look for a reputable company for help.
Supply and Return Plenums: What do they do? Share the joy. Sherry Green. Owner at A 1 Air. Tags air conditioning ductwork hvac plenum return plenum supply plenum. Leave a reply Cancel reply You must be logged in to post a comment. You might like this. A 1 Air, Inc.