Running network wiring in a cold air return vent?

mcvane

Hi All.

Basically, I'm in the midst of laminating a bedroom above a porch. I've taken out the carpeting and have had to insulate it with some 'stuff it' at the base of the floor/walls as well as bought some nice felt underpad which will keep cold air out for the most part.

I also think this is the perfect time to run network cabling from this room and other rooms on this floor to the basement to setup a 'wired' home.

In order to minimize the damage I will cause to existing walls and drywall when running cable, I have found a 'cold air return' area on the top floor, which actually has at least one electrical wire inside stapled to the wall. I figured I could strategically use this 'vent' area to run more cabling down into the basement.

I couldn't stick my head in there, but I used an interesting technique (in case you want to know). I held a powerful flashlight with one hand and stuck in my camcorder to 'film' what was in between the wall with the other hand. That helped me figure out and see what was down there. This method worked pretty well to at least see what was going on

Does anyone have any opinions on my plan to run cable to this vent and run it down to the basement? I followed the vent from the top floor to the main floor to the basement and it appears to me to be 'ok'. I might have to find a way to drill a hole to allow the wires to get through.

Any feedback would be appreciated!

handy man88

I guess in theory, that works. Just make sure when you're pulling cable that the cable doesn't get ripped by the jagged edges of the ducting hole that you just drilled through.

jwhite

Per code, you are not allowed to run wires inside duct work, unless the wires are needed for the proper operation of the HVAC system.

This is intended to limit the wiring inside a duct because if it catches fire it will flood the rest of the home with poision gasses.

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joed

The wire must be FT6 rated to run in ductwork. That is it won't burn or give off toxic gases that will spread through the ventilation system.

jwhite

If in the USA, even plenum rated wire is not allowd in the duct work, unless it is needed for proper operation of the HVAC system. This does not mean that the t-stat wire can be snaked in there cause it is easier. If there is nothing in the section of the duct where the wire is running that requires wiring, do not run wires in there.

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RippySkippy

Make sure to use plenum grade cable you'll be fine, and be very careful when pulling through metal.

mcvane

Hi All.

Apologies if I didn't say it a bit clearer, but the wires actually won't be in the ducts themselves. Our HVAC furnace system has (in addition to the typical ducts which blow in warm or cool air depending on season) additional vents which are supposed to be the cold air returns (from what people seem to call it).

Basically, it allows the air to flow through the house. I would be running the cables through this cold air return, which actually 'sucks' air through the house, which then feeds into the furnace and pushes air out. Where these air passages are, there is simply the wooden frame and drywalls of the typical floor. I will attach a few pics to illustrate.

This particular section appears to go from the upper floor to the main floor to the basement.

How does this look to you?

Thanks in advance!

Attached Thumbnails

   

space_coyote

I ran some speaker wires through mine if it makes you feel any better...I ran them next to the thermostat wire that was already there.

As far as code goes, I have no idea...

mcvane

Thanks for your input...I do feel a lot better...

joed

Same rules apply for cold air returns as hot air ducts. The air still goes through the furnace and gets dispersed around the house. You don't toxic fumes from combustion being spread around the house.

jwhite

Yup, duhhhh huuuhh... I was speeding, but I was speeding right next to another guy who was speeding... ahuh a huh....

Explain it to the judge.

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jwhite

You should not feel any better from knowing that some other person hacked it up and his house has not burnt down YET>

If you really think that your job is worth doing, then it is worth doing right.

Wires cannot be run in duct work.

Notice I did not put anything after the . in my previous line.

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jwhite

Thanks for the lesson in HVAC terminology. I have been doing HVAC controls for over 10 years. I know what a supply duct is, what a cold air return is, and a bunch more stuff about the systems too...

When a hole is cut in the wall to allow air flow, and then the air is channeled later to or from the unit, it does not matter that the walls of the duct are wood and drywall.. they become the duct. The duct is the channel for the air, not the material use to make them.

Wires may not be run inside the ducts.

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jwhite

Let me add that I could care less who hacked it up before and hasnt been killed by it yet. That does not make it the right way.

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RippySkippy

In duct work, plenum grade...still