AC Runs

Wow, we only charge $125 per run... A cold air return would work well... If you have forced air, you have cold air returns. A wire fish would work fine to pull it...

The entire system is inside the house. the air handler is inside a closet inside the front door. The return is at the bottom of the unit. None are anywhere else in the house. Which reminds me, I need to buy filters.

Strange. Every room should have a cold air return so that proper ac and heat can be pushed into the room. The only room that wouldn't have a cold air return are bathrooms (for obvious odor reasons)

The return is the suck in side or the blow out side?

Suck in. Takes existing air, regardless of the temp and brings in to the basement to the HVAC. Summer it helps remove the moisture, winter helps add moisture (unless you don't have a humidifier hooked up)

That's generally not how HVAC systems are installed down here.

Conditioned air is ducted through the attic and into each room. The return air is pulled in through a large grill under the air handler, which usually houses the filter as well. In effect, the entire living space is the return. In larger or multi-floor houses you will often have multiple systems. I've never seen ducted returns down here.

In systems that are designed correctly, there will be "jumpers" in rooms that have doors, such as bedrooms. There will be a register on either side of the doorway connected by a short piece of insulated duct (the "jumper") in the attic or ceiling. This allows air circulation through the room even if the door is closed.

Things might be more conventional further north and maybe in the center of the state, but you'd be hard pressed to find a basement anywhere along either coast.


Welcome to Florida.

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Attic or basement it shouldn't matter. Strange that there would be no cold air return in a bedroom leading back to the HVAC (again doesn't matter the location) especially with AC as you would want to draw air out of that room to remove moisture and pump it back into the room. @aaiyar you're in a somewhat temperate climate. Isn't that how yours is set up?

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NC resident here and all the apartments and houses I have lived in have 1-2 large returns per floor and 1 or more vents per room/space. The returns typically have 20” x 15/20” vent boxes where filters are installed. Upstairs returns are in ceilings and downstairs they are in walls within a closet type space since the boxes are large and need depth. The return vents are usually located near the air handler.

In my current house I have a return above my crawl air handler in a void below the stairs and another in my kitchen in a space below the back staircase. Upstairs has one at the top of the central stairs and one in the room above the garage.


Also, from North Carolina. In my two-story house, we have a return in the hallway upstairs, return in the central area downstairs, and a third return in the master bedroom.
All of the returns are in the ceiling, as we are on a concrete slab.


The short answer is that our houses are setup like @ritchierich's and @dcaton1220's. One large return register per floor. One or more supply registers per room (or area). We're also on slabs like @TArman described. Or raised on pilings. But there are no basements.

The long answer is that many/most houses here were built before central A/C became prevalent. Also most of these older houses were single-story houses.

So, when they were retrofitted for central A/C, ducting was all in attic space, and most often, the air-handler was also installed in attic space. Thus, it became common to put a single large return register in the ceiling, with supply registers in each room; this setup being easier to implement than running multiple return air ducts. It also changed the position of the return air filter from being at the air-handler to being at the single large return register.

Most older two-story houses use a single large condenser (5 or 6 ton). The air-handler is often placed in a closet on the 2nd floor, with ducting run along the edge of a ceiling and concealed.
for the first floor. Ducting for the second floor was run through the attic. The exception being for "raised" houses, where first floor ducting was run underneath the house and second flood ducting run in the attic.

Newer constructions have stuck to this style. The only exception being that rather than using one large condenser, they typically use one condenser for each floor - which is more efficient.

Is insulating the underside of the roof a thing now? Last I read, a while ago, it seemed to be all the rage. Maybe I mis-remembered. Maybe people reconsidered the concept, ie, complexities of future roof maintenance, etc.

I have 6" of closed cell spray foam in my roofline. It's fantastic. Yes, insulation of the roofline is awesome. If you use batting though and have a roof vent, you will need to use breathers though.

It is. And I know a horror story that happened last year. A single shingle nail on a friend's roof was hit by lightning. The energy was so high, that it caused the spray foam insulation on the underside of the roof to start smoldering and house filled with thick black smoke.

Anyway, firefighters ended up soaking the house with water. And their rebuild process took about 7-8 months.

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Wow.... That's a rare occurrence. Closed cell foam usually is also a fire retardant

I understand, our homes up north that I lived in were all like that. It's just not done that way down here. Why, I don't know as you could certainly have returns in the same attic space that the supply ducts are located in.

And it's not just older homes that didn't originally have air. Our new house was built in the early 90's and it's the same way. One large system with the air handler in a closet in the laundry room, with the return through the wall into a hallway that's more or less centrally located. There's also a smaller 1.5 ton system for the master bedroom and bath.

I'm guessing here, but perhaps the cost of running insulated returns would not provide much, if any benefit. They returns would have to be insulated because they would be in the attic and still handling cool air, whereas the temp in the attic could be well over 100 degrees in the summer.

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Is running ethernet through the HVAC returns a common thing? Does it meet code? I get that it may be easier, but you would be drilling holes in your ducts, and would have a bunch of loose cables running through them.

Not against any code I know and it's pretty common. Hell in my old house it was balloon framing so they just used the framing as the return from all rooms on the second floor.

You really should use plenum-rated cabling if you're using airducts as 'conduit'.


I seriously question how much of that horror story was caused by the spray foam insulation -- you'd need a control case, such as a lightning strike to a house without spray foam insulation under the roof.

My guess is that the spray foam smoldering was a good thing -- rather than an active fire.

It's no surprise that the water damage was greater than the smoke/fire damage. I understand that's extremely common in residential fires.