InterNACHI


Go Back   InterNACHI Message Board > Specific Inspection Topics > HVAC

Notices

HVAC Topics include heating, venting, and air conditioning.

Reply
 
LinkBack Thread Tools
  #1  
Old 11/8/07, 11:54 AM
Mark Nahrgang's Avatar
Mark Nahrgang Mark Nahrgang is online now
InterNACHI Member
 
Join Date: Apr 2007
Location: Saint Peters, MO
Posts: 4,609
Default Oxidation on Ductwork

This is not from an inspection but from a friends home. He's got what looks to be oxidation on his ductwork. Can anyone tell me what might be causing it? His HVAC guy didn't know either. From looking at it, it almost LOOKS like it is galvanized. Could it be?
Thanks
Mark

Last edited by mnahrgang; 11/27/07 at 3:05 PM..
Reply With Quote
  #2  
Old 11/8/07, 2:10 PM
cbottger's Avatar
cbottger cbottger is offline
InterNACHI Member
 
Join Date: Apr 2004
Location: Marland, OK
Posts: 2,738
Default Re: Oxidation on Ductwork

Quote:
Originally Posted by mnahrgang
This is not from an inspection but from a friends home. He's got what looks to be oxidation on his ductwork. Can anyone tell me what might be causing it? His HVAC guy didn't know either. From looking at it, it almost LOOKS like it is galvanized. Could it be?
Thanks
Mark
Mark am I looking at bare duct in your pic's If I am it appears to be rusting from the inside out as is very common for duct with high humidity levels during the cooling mode and could also be a humidifier problem in the heat mode if one is installed. One of the reasons that I squeeze a duct in the crawl space when inspecting especially if insulation is installed have had them crush with just a gentle squeeze. Galvanized sheet metal ducts do not have excessive longevity when exposed to high moisture.



Freedom Express Inspections LLC
CMOR Thermography Certified Level 11 #2097
freedomexpressinspections.com
freedomexpress495@att.net
NACHI Member
Okla. State DEQ Environmental Phase One Certified
Master HVAC Mechanic (Retired)
Certified Universal Freon by 40CFR 82 Sub-part F
Professional Home Inspector State License # 130
Reporting system by Home Inspector Pro

Serving the State of Okla.
Reply With Quote
  #3  
Old 11/8/07, 2:55 PM
Mark Nahrgang's Avatar
Mark Nahrgang Mark Nahrgang is online now
InterNACHI Member
 
Join Date: Apr 2007
Location: Saint Peters, MO
Posts: 4,609
Default Re: Oxidation on Ductwork

Yes they are bare. The gray ashy color you see is what I am referring to. I don't know if it's galvinization, or if it's oxidation. I can't say that I squeezed them, but I did touch them, and they seemed firm. Also, notice in the pictures the support brackets. They've got the same "coating".
Reply With Quote
  #4  
Old 11/8/07, 3:11 PM
cbottger's Avatar
cbottger cbottger is offline
InterNACHI Member
 
Join Date: Apr 2004
Location: Marland, OK
Posts: 2,738
Default Re: Oxidation on Ductwork

Quote:
Originally Posted by mnahrgang
Yes they are bare. The gray ashy color you see is what I am referring to. I don't know if it's galvinization, or if it's oxidation. I can't say that I squeezed them, but I did touch them, and they seemed firm. Also, notice in the pictures the support brackets. They've got the same "coating".
Mark have observed that many many times on galvanized duct with and without insulation. High moisture causes galvanized metal to turn whiteish to gray looking. Check the humidity level in the crawl space probally find it excessively high most of the time what kind of ventilation does it have. I have been in crawls where water was actually dripping from the floor joist and not a water leak just humidity.



Freedom Express Inspections LLC
CMOR Thermography Certified Level 11 #2097
freedomexpressinspections.com
freedomexpress495@att.net
NACHI Member
Okla. State DEQ Environmental Phase One Certified
Master HVAC Mechanic (Retired)
Certified Universal Freon by 40CFR 82 Sub-part F
Professional Home Inspector State License # 130
Reporting system by Home Inspector Pro

Serving the State of Okla.
Reply With Quote
  #5  
Old 11/8/07, 3:29 PM
mberman mberman is offline
New User
 
Join Date: Nov 2003
Location: Mt. Clemens, MI
Posts: 89
Please Note: mberman is a non-member guest and is in no way affiliated with InterNACHI or its members.
Red face Re: Oxidation on Ductwork

Im with Charley, Very high moisture area where ducts are run,Matt
Reply With Quote
  #6  
Old 11/8/07, 3:31 PM
Mark Nahrgang's Avatar
Mark Nahrgang Mark Nahrgang is online now
InterNACHI Member
 
Join Date: Apr 2007
Location: Saint Peters, MO
Posts: 4,609
Default Re: Oxidation on Ductwork

This was in a basement. I wasn't doing an inspection, but it didn't appear wet, and I didn't notice any signs of moisture intrusion. I'll have him check his humidity. Thanks guys! Learn something every day )
Reply With Quote
  #7  
Old 11/8/07, 4:15 PM
cbottger's Avatar
cbottger cbottger is offline
InterNACHI Member
 
Join Date: Apr 2004
Location: Marland, OK
Posts: 2,738
Default Re: Oxidation on Ductwork

Quote:
Originally Posted by mnahrgang
This was in a basement. I wasn't doing an inspection, but it didn't appear wet, and I didn't notice any signs of moisture intrusion. I'll have him check his humidity. Thanks guys! Learn something every day )
As an after thought where was the dryer vent venting



Freedom Express Inspections LLC
CMOR Thermography Certified Level 11 #2097
freedomexpressinspections.com
freedomexpress495@att.net
NACHI Member
Okla. State DEQ Environmental Phase One Certified
Master HVAC Mechanic (Retired)
Certified Universal Freon by 40CFR 82 Sub-part F
Professional Home Inspector State License # 130
Reporting system by Home Inspector Pro

Serving the State of Okla.
Reply With Quote
  #8  
Old 11/8/07, 4:45 PM
Mark Nahrgang's Avatar
Mark Nahrgang Mark Nahrgang is online now
InterNACHI Member
 
Join Date: Apr 2007
Location: Saint Peters, MO
Posts: 4,609
Default Re: Oxidation on Ductwork

I didn't notice. I'll be sure to ask.
Reply With Quote
  #9  
Old 11/8/07, 9:04 PM
Brian A. MacNeish Brian A. MacNeish is offline
Active Poster
 
Join Date: Apr 2007
Posts: 2,527
Please Note: Brian A. MacNeish is a non-member guest and is in no way affiliated with InterNACHI or its members.
Default Re: Oxidation on Ductwork

Quote:
Originally Posted by cbottger
Mark have observed that many many times on galvanized duct with and without insulation. High moisture causes galvanized metal to turn whiteish to gray looking. Check the humidity level in the crawl space probally find it excessively high most of the time what kind of ventilation does it have. I have been in crawls where water was actually dripping from the floor joist and not a water leak just humidity.
There's a switch going on. Unvented and properly prepared crawl spaces are being seen to be drier than vented crawl spaces!
Reply With Quote
  #10  
Old 11/8/07, 9:41 PM
cbottger's Avatar
cbottger cbottger is offline
InterNACHI Member
 
Join Date: Apr 2004
Location: Marland, OK
Posts: 2,738
Default Re: Oxidation on Ductwork

Quote:
Originally Posted by Brian A. MacNeish
There's a switch going on. Unvented and properly prepared crawl spaces are being seen to be drier than vented crawl spaces!
Don't believe then I have ever seen a properly prepared crawl then. You have to have something to start with.



Freedom Express Inspections LLC
CMOR Thermography Certified Level 11 #2097
freedomexpressinspections.com
freedomexpress495@att.net
NACHI Member
Okla. State DEQ Environmental Phase One Certified
Master HVAC Mechanic (Retired)
Certified Universal Freon by 40CFR 82 Sub-part F
Professional Home Inspector State License # 130
Reporting system by Home Inspector Pro

Serving the State of Okla.
Reply With Quote
  #11  
Old 11/9/07, 8:54 AM
sparksnmore sparksnmore is offline
Active Poster
 
Join Date: Oct 2006
Posts: 158
Please Note: sparksnmore is a non-member guest and is in no way affiliated with InterNACHI or its members.
Default Re: Oxidation on Ductwork

I've seen basement ducts sweat like those obviously have been doing when a basement window was left open during the cooling season.
(Naturally they wont sweat during the heating season.)
Reply With Quote
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Information on failed ductwork in a slab Kevin Luce HVAC 2 8/23/07 10:06 AM


All times are GMT -4. The time now is 12:39 AM.


Popular Sections

:

All Sections

Popular

Membership

Inspection Standards

Education

Chapters & Members

Articles & Links

Other Organizations

 

 

 

NACHI.ORG Statistics

 

 

no new posts