Go Back   InterNACHI Inspection Forum > Specific Inspection Topics > Inspecting HVAC Systems

Notices

Inspecting HVAC Systems Topics include heating, venting, and air conditioning inspections.

Reply
 
LinkBack Thread Tools
  #1  
Old 4/26/08, 8:52 AM
Erich Kelter's Avatar
Erich Kelter Erich Kelter is offline
InterNACHI Member
 
Join Date: Dec 2007
Location: Barrie, ON
Posts: 149
Default High Eff. Gas Furnace - Intake Air

Did an inspection yesterday on a home with a 1 year old high eff. gas furnace. The fresh are intake was pulling air from directly in the house, not from a fresh air intake outdoors. This is the first time I have seen this before. Obviously there will be some loss in efficiency since the furnace is using indoor air for combustion but I am wondering how many of you have seen this before and what are your thoughts?
Reply With Quote
  #2  
Old 4/26/08, 8:57 AM
gbeaumont's Avatar
gbeaumont gbeaumont is offline
InterNACHI Member
 
Join Date: Jan 2003
Location: Clearwater, FL
Posts: 6,255
Send a message via AIM to gbeaumont Send a message via MSN to gbeaumont Send a message via Yahoo to gbeaumont
Default Re: High Eff. Gas Furnace - Intake Air

hi Erich,

most high efficiency furnaces draw combustion air from the outside, I would look up the manufactures installations instructions online and see what they call for.

Regards

Gerry



"To realize our true destiny, we must be guided not by a myth from our past, but by a vision of our future."
(Mark B Adams)

Commercial property Inspection Tampa, Orlando, Sarasota, Jacksonville, Ft Launderdale, Miami, Florida.
NACHI cell 484-429-5466
NACHI02121106

Reply With Quote
  #3  
Old 4/26/08, 11:19 AM
James E. Braun, CMI's Avatar
James E. Braun, CMI James E. Braun, CMI is offline
InterNACHI Member
 
Join Date: Jan 2005
Location: Jefferson City, MO
Posts: 8,520
Default Re: High Eff. Gas Furnace - Intake Air

see this a lot. You will loose about 1-2% efficiency. We did not do that when I owned my heating and cooling company, but some people are just lazy.
Reply With Quote
  #4  
Old 4/26/08, 2:20 PM
Erich Kelter's Avatar
Erich Kelter Erich Kelter is offline
InterNACHI Member
 
Join Date: Dec 2007
Location: Barrie, ON
Posts: 149
Default Re: High Eff. Gas Furnace - Intake Air

This is what I figured. I made a note of it in my report but didn't consider it a major defect seeing as how the furnace would still function ok, the efficiency would just be down a bit.
Reply With Quote
  #5  
Old 4/26/08, 3:49 PM
Bob Elliott's Avatar
Bob Elliott Bob Elliott is offline
InterNACHI Member
 
Join Date: Aug 2006
Location: Chicago
Posts: 30,875
Default Re: High Eff. Gas Furnace - Intake Air

They may be legal, but stupid.
They are pulling inside air and quite possibly setting up a negative house pressure situation.
If the place is newer it may be very air tight and for instance say they have a fireplace , may draw combustion by products back into the home.
Remember that water heater , which may be in the closet also needs combustion air.
Is it in a small utility room.Does it have vent openings at the top and bottom.
Back to that water heater it may have flue gas rising naturaly that could be reversed and pulled into the house.
I just did a place last week where they ran the schedule 40 out the wall.
(good deal right?)
Well it turns out the Polish speaking HVAC guy mis-heard the AHJ tell him the intake from outside was not needed.
Duh,...he went and cut all the intakes at the elboes hours before I arrived.
When I met him I said put them back up, right away please.
Water heater next to it had gas leaking at the same time but thats another story.
Reply With Quote
  #6  
Old 4/26/08, 9:24 PM
mthomas2 mthomas2 is offline
Active Poster
 
Join Date: Oct 2005
Location: Evanston, IL
Posts: 702
Please Note: mthomas2 is a non-member guest and is in no way affiliated with InterNACHI or its members.
Default Re: High Eff. Gas Furnace - Intake Air

BTW, when you see this at new construction and suspect that the furnace may have been used as a "construction heater", listen carefully for small pieces of construction debris tumbling around in the inducer fan housing.
Reply With Quote
  #7  
Old 4/26/08, 9:27 PM
Bob Elliott's Avatar
Bob Elliott Bob Elliott is offline
InterNACHI Member
 
Join Date: Aug 2006
Location: Chicago
Posts: 30,875
Default Re: High Eff. Gas Furnace - Intake Air

Hi Mike
Not to mention a dirty blower and filter , which can void the warranty
Reply With Quote
  #8  
Old 4/26/08, 9:42 PM
Bob Elliott's Avatar
Bob Elliott Bob Elliott is offline
InterNACHI Member
 
Join Date: Aug 2006
Location: Chicago
Posts: 30,875
Default Re: High Eff. Gas Furnace - Intake Air

From this afternoons Inspection
Notice lack of filter.
[ATTACH]high-eff-gas-furnace-intake-air-dscn0129-small-.jpg.JPG
Views:	1472
Size:	35.6 KB
ID:	20680[/ATTACH]
Attached Thumbnails
high-eff-gas-furnace-intake-air-dscn0132-small-.jpg.JPG
Views:	707
Size:	21.7 KB
ID:	20679  
Reply With Quote
  #9  
Old 4/26/08, 10:59 PM
Erich Kelter's Avatar
Erich Kelter Erich Kelter is offline
InterNACHI Member
 
Join Date: Dec 2007
Location: Barrie, ON
Posts: 149
Default Re: High Eff. Gas Furnace - Intake Air

Some good replies. Good points Robert, I wasn't too concerned about a neg. pressure or backdrafting since it was in a large open unfinished basement.
Reply With Quote
  #10  
Old 4/27/08, 7:22 AM
David A. Andersen's Avatar
David A. Andersen David A. Andersen is offline
InterNACHI Member
 
Join Date: Jun 2005
Location: Woodlawn, TN
Posts: 7,675
Default Re: High Eff. Gas Furnace - Intake Air

That is where they become radon gas suckers! Any leaks in the return air duct system and it gets pumped throughout the house. A good reason to add $10 worth of PVC pipe.
Reply With Quote
  #11  
Old 4/27/08, 9:42 AM
Kenneth R. Malone Kenneth R. Malone is offline
InterNACHI Member
 
Join Date: Apr 2005
Location: Sycamore, IL
Posts: 83
Default Re: High Eff. Gas Furnace - Intake Air

Depending on the furnace and the location. I will add this to my report.

Monitor: Ideally class IV furnaces with sealed combusting chambers should have combustion air intake vented to the outside for maximum efficiency.
Reply With Quote
  #12  
Old 4/27/08, 7:22 PM
Erich Kelter's Avatar
Erich Kelter Erich Kelter is offline
InterNACHI Member
 
Join Date: Dec 2007
Location: Barrie, ON
Posts: 149
Default Re: High Eff. Gas Furnace - Intake Air

Excellent note to add into a report. I made a similar note in my report.
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
980 Questions/Answers to the NHIE....Free! jbushart Legislation, Licensing, Ethics & Legal Issues for Inspectors 50 4/20/08 1:26 AM
Condemned Furnaces Spark Safety Issues Gary Reecher Inspecting HVAC Systems 7 3/8/07 8:17 PM
Furnace in attic (High Efficient) jcordell Inspecting HVAC Systems 14 2/10/07 6:02 PM
High Efficiency furnace rdean General Inspection Discussion 8 1/20/07 7:48 PM
Proper Vent - High Eff. Gas Furnace rkuntz Inspecting HVAC Systems 10 1/13/06 10:18 PM

All times are GMT -4. The time now is 6:58 AM.
no new posts