Is this return plenum legit?

[silver8ack]

I'm looking for places to run Ethernet from my basement to attic. I happened to look in my cold air return upstairs and found it's just a giant empty cavity.

There's pipes, drains, spray foam, electric wires and phone wires in it. I know you're not supposed to run non-plenum cabling here but this doesn't look right at all to me! Haha.

I'm not sure if I'd be adding any harm by running cables here to be honest. It's like they forgot to put a duct in.

Anyway, besides what's already in there would their be any issue with running CMP cables here?

See below for pics.

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[KenZ71]

Is there any air flow through there? Turn on hvac system and check.

Assuming it is just dead space I would say you have a great way to run electric, ethernet, coax, etc. Add access panels then cover with framed pictures.

 

[silver8ack]

There is definitely air flow. I traced to to the return duct in the basement that it connects to. There are also two holes in that duct on the bottom covered by duct tape. So I was able to get a look inside from the bottom.

The thing is, I planned on using the wall next to this area... but it's going to be exposed to this plenum space because it's not sealed off. I'm just wondering if it's really any safer using the wall next to the plenum or just use the plenum because it's wide open. Someone already decided to run a phone cable there! Hah


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[silver8ack]

Also, in the last pic... that little 'landing' on the right is the duct from the downstairs cold air return. Not sure why they put a duct there!


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[L&LD]

I'd use it, directly. And as KenZ71 mentions, easy to put access panels as needed too.

 

[degrub]

The ROMEX and phone cable (or is that the thermostat cable ? ) are against code. You could solve most of the issue by enclosing with HVAC duct board and sealing. Get a contractor to do it. The phone cable would need to be moved to the inside the studs. Right now your HVAC is pulling air and dirt from all the adjacent rooms and from between the floors - outside air and dust/dirt. If you want to run Cat 5e, put it in the stud cavity and do it before you seal up the studs. Run at least 2 sets of cables. Clean your evaporator coils and heat exchanger (if centrally heated) after you finish. Looks like you need fire stop caulking at the top plate penetration with the ROMEX as well.

 

[degrub]

Also, in the last pic... that little 'landing' on the right is the duct from the downstairs cold air return. Not sure why they put a duct there!


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That may be a flow restrictor to pressure balance the system. It is fairly common to use a partial sheet of plywood to do that.

 

[silver8ack]

The ROMEX and phone cable (or is that the thermostat cable ? ) are against code. You could solve most of the issue by enclosing with HVAC duct board and sealing. Get a contractor to do it. The phone cable would need to be moved to the inside the studs. Right now your HVAC is pulling air and dirt from all the adjacent rooms and from between the floors - outside air and dust/dirt. If you want to run Cat 5e, put it in the stud cavity and do it before you seal up the studs. Run at least 2 sets of cables. Clean your evaporator coils and heat exchanger (if centrally heated) after you finish. Looks like you need fire stop caulking at the top plate penetration with the ROMEX as well.

I'm pretty sure it's a phone cable. I didn't get to the attic to trace it yet, but it doesn't go to the HVAC system in the basement. I'm not 100% sure what that cable is but it's been there a while judging by the dust.

Also I do have a filter of course, at the end of the cold air return before going into the HVAC blower.

But yea, I didn't think this was to code.


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[degrub]

I'm pretty sure it's a phone cable. I didn't get to the attic to trace it yet, but it doesn't go to the HVAC system in the basement. I'm not 100% sure what that cable is but it's been there a while judging by the dust.

Also I do have a filter of course, at the end of the cold air return before going into the HVAC blower.

But yea, I didn't think this was to code.


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believe it or not, the filter doesn't catch the dust from the space between the floors and the room leakage. Seal off any returns with plastic and see how much flow you get out the registers. If it is a lot, then you have an opening somewhere on the return path. There will be some just from porosity of the sheetrock edges and imperfect sealing.

 

[silver8ack]

believe it or not, the filter doesn't catch the dust from the space between the floors and the room leakage.

Interesting... are you saying that the dust is too fine for the filter? I don't see how any air could get to the blower on my setup without going through the filter.


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[degrub]

I'm pretty sure it's a phone cable. I didn't get to the attic to trace it yet, but it doesn't go to the HVAC system in the basement. I'm not 100% sure what that cable is but it's been there a while judging by the dust.

Also I do have a filter of course, at the end of the cold air return before going into the HVAC blower.

But yea, I didn't think this was to code.


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The pipes are fine. No power carried through them. It is the power carrying cables.

 

[degrub]

Interesting... are you saying that the dust is too fine for the filter? I don't see how any air could get to the blower on my setup without going through the filter.


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it is bypassing the filter completely unless you have an electrostatic filter at the blower inlet. Ordinary return air filters, only catch the cat hair and vary large particulate anyway.

 

[silver8ack]

The pipes are fine. No power carried through them. It is the power carrying cables.

Ok thanks for the info.

However I thought the issue was what the pipes/cables are made of, not what they carry inside. I thought these things weren't supposed to be in the return in case of fire, they produce toxic fumes... not just because they carry electric or whatever.

Thanks.


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[degrub]

Ok thanks for the info.

However I thought the issue was what the pipes/cables are made of, not what they carry inside. I thought these things weren't supposed to be in the return in case of fire, they produce toxic fumes... not just because they carry electric or whatever.

Thanks.


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Flame initiation and propagation are the primary issue. A wire carrying current that can overheat due to load and ignite its insulation and jacket or other adjacent combustible is the concern. i don't know if PVC pipe would pass the flame spread test or not. The air velocity in the duct would accelerate the combustion if the flame can be maintained ( local heat produced greatly exceeds heat removed ) . Any carbon based material is going to produce toxic gases in the presence of sufficient high heat either as decomposition or partial combustion products. With man made materials there are likely Nitrogen or Sulfur atoms present resulting in partial oxidation products (CO, SOx, NOx), cyanides, and other combustion products that are potentially toxic. If the material does not propagate a flame, that will be reduced. With materials that resist flame spread, you have more time to detect and evacuate. And possibly the material will self extinguish once the heat source is removed.

 

[sfx2000]

There's pipes, drains, spray foam, electric wires and phone wires in it. I know you're not supposed to run non-plenum cabling here but this doesn't look right at all to me! Haha.

I'm not sure if I'd be adding any harm by running cables here to be honest. It's like they forgot to put a duct in.

Anyway, besides what's already in there would their be any issue with running CMP cables here?

Lot of folks will scare you with things being "not to code" - and I agree to some point - this series of pics, however, is more common than not, and it really depends on local regulations... in many ways though, this is just shoddy workmanship...

Plenum rated cable isn't likely going to add to any additional problems that are already not present - low voltage wiring like telecom/ethernet is low risk compared to the HV side with the romex cluster - and that would be a bit of a concern being next to the wet wall present (bathroom?)... in any event, the house hasn't burned down yet... and likely won't...

Ducting would be nice for the HVAC side, but many "McMansions" are built cheap, so we see this often...

Honestly - it's a situational thing, but to protect the forums here from any kind of liability, I would not recommend a DIY solution and get someone knowledgeable and qualified to take a look and do the work.

 

[KenZ71]

What about getting some HVAC duct?
http://m.lowes.com/pl/HVAC-duct-fittings-Heating-cooling/4294512241

I'll betcha once sealed up you will see much better system performance i.e. lower energy bills.

 

[degrub]

What about getting some HVAC duct?
http://m.lowes.com/pl/HVAC-duct-fittings-Heating-cooling/4294512241

I'll betcha once sealed up you will see much better system performance i.e. lower energy bills.

Wrong end of the system. This is on the suction side of the blower.

 

[Samir]

Once it's yours, code doesn't really matter until you have to replace the system and it has to be up to code. So use your own judgement on safety and what you're comfortable with.

 

[degrub]

I know what you are saying about 'as-built' versus current code, but any modifications or additions after original can matter if there is a fire investigation or insurance claim.
As SFX2000 mentioned above, please don't create potential legal liability for the forum.

 

[Samir]

I know what you are saying about 'as-built' versus current code, but any modifications or additions after original can matter if there is a fire investigation or insurance claim.
As SFX2000 mentioned above, please don't create potential legal liability for the forum.

I forgot about the fire investigation or insurance claim--that's true. They would definitely look at any way to legally wiggle out of paying out. Definitely consider that before you do anything. And even doing nothing, consider what you've found. The contractor that originally did that work might also be exposed to some liability (lose their license?), so you might be able to twist their arm to fix it for free/cheap.

As far as legal liability of the forum, I own a forum and investigated liability heavily before turning my site on. Case law states that § 230 of the Communications Decency Act prevents courts from entertaining claims that would place an interactive computer service in a publisher's role. Thus, lawsuits seeking to hold an interactive computer service liable for its exercise of a publisher's traditional editorial functions -- such as deciding whether to publish, withdraw, postpone or alter content -- are barred. By its plain language, § 230 creates a federal immunity to any cause of action that would make Interactive computer services liable for information originating with a third-party user of the service. U.S. 4th Circuit Court of Appeals, ZERAN v AMERICA ONLINE INC.

While this is the case law, I also like to error on the side of caution. The OP will hopefully consider both of my posts together as any action by anyone reading something on the Internet and getting themselves into trouble is purely the reader's fault, especially with respect to discussion forums.