# HVAC Intake and Exhaust **URL:** \ **Category:** Inspecting HVAC Systems\ **Created:** [January 20, 2026, 7:58pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274 "2026-01-20T19:58:21Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![mgruenfeld](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/mgruenfeld/32/199314_2.png) [@mgruenfeld](https://forum.nachi.org/u/mgruenfeld)\ **Post date:** [January 20, 2026, 7:58pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/1 "2026-01-20T19:58:21Z")
Hi Everyone, Has anyone seen this before? I am not familiar with this. High efficiency furnace. Exhaust and air intake seem to be connected. See photos attached. I would appreciate it if anyone can help. ![IMG_0003](https://global.discourse-cdn.com/internachi/original/4X/8/c/1/8c161a9f27bbef6a250d00089f4bd0ebb93d8486.jpeg) ![IMG_9985](https://global.discourse-cdn.com/internachi/original/4X/c/a/d/cadb6b7bfda7512244a202e2c9418cfc544d17d9.jpeg) ![IMG_9949](https://global.discourse-cdn.com/internachi/original/4X/a/a/7/aa772415b0fbdc40e34aa6f7b7e4799db5ce10d7.jpeg) ![IMG_9869](https://global.discourse-cdn.com/internachi/original/4X/9/b/f/9bff2a99a2b1e64a8fc16ffceacf6b4edb2106ee.jpeg) ![IMG_0004](https://global.discourse-cdn.com/internachi/original/4X/3/9/9/399b6b7616cae424e5f23b6b3f074a8fc8a5a840.jpeg) ---
**Author:** ![jjonas](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jjonas/32/301755_2.png) [@jjonas](https://forum.nachi.org/u/jjonas)\ **Post date:** [January 20, 2026, 8:08pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/2 "2026-01-20T20:08:24Z")
Google “ **Concentric Vent** ”. ---
**Author:** ![mgruenfeld](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/mgruenfeld/32/199314_2.png) [@mgruenfeld](https://forum.nachi.org/u/mgruenfeld)\ **Post date:** [January 20, 2026, 9:12pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/3 "2026-01-20T21:12:36Z")
Thanks Jeffrey, this looks different than the other style I have seen before. Appreciate your help ---
**Author:** ![ryoung7](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/ryoung7/32/188798_2.png) [@ryoung7](https://forum.nachi.org/u/ryoung7)\ **Post date:** [January 21, 2026, 8:12am UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/4 "2026-01-21T08:12:44Z")
> [@mgruenfeld](#): > > High efficiency furnace. Exhaust and air intake seem to be connected. Concentric vent for a gas fired high efficiency furnace. A concentric vent, for a high-efficiency furnace, combines the intake and exhaust pipes into a single, streamlined unit, using a smaller inner pipe for exhaust and a larger outer pipe for fresh combustion air. Hope that helps. ---
**Author:** ![mgruenfeld](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/mgruenfeld/32/199314_2.png) [@mgruenfeld](https://forum.nachi.org/u/mgruenfeld)\ **Post date:** [January 21, 2026, 4:29pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/5 "2026-01-21T16:29:15Z")
Thank you Robert. Much appreciated. I guess this is just a different style than what I was used to. Have a wonderful day. ---
**Author:** ![dandersen](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/dandersen/32/59398_2.png) [@dandersen](https://forum.nachi.org/u/dandersen)\ **Post date:** [January 21, 2026, 9:43pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/6 "2026-01-21T21:43:41Z")
I don’t see it. I see two pipes and a furnace as well as a water heater. ![Screenshot_20260121_153835_DuckDuckGo](https://global.discourse-cdn.com/internachi/original/4X/7/d/5/7d52e73bb4eda15441376153aaa47a0eaecb0346.jpeg) The outdoor pipe is not a concentric termination fitting. Am i missing something? ---
**Author:** ![jjonas](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jjonas/32/301755_2.png) [@jjonas](https://forum.nachi.org/u/jjonas)\ **Post date:** [January 21, 2026, 9:51pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/7 "2026-01-21T21:51:20Z")
> [@dandersen](#): > > Am i missing something? “Exhaust pipe section” has been modified/extended, possibly due to local Regs/AHJ/Manufacturer requirements to accomodate for snow depths… ![CV modified](https://global.discourse-cdn.com/internachi/original/4X/6/c/2/6c2f22307e34572af74c9fbebdb3ef2910ad1ad4.jpeg) “Intake” remains behind the screen, flush with the exterior wall… ![image](https://global.discourse-cdn.com/internachi/original/4X/2/9/0/29064f3870dc25d044c54ad0a3d2d1c7937c2473.jpeg) ---
**Author:** ![dandersen](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/dandersen/32/59398_2.png) [@dandersen](https://forum.nachi.org/u/dandersen)\ **Post date:** [January 21, 2026, 10:00pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/8 "2026-01-21T22:00:01Z")
I don’t see what you posted on the picture on any of the pictures. You can not have an intake that close to the ground, because of the snow we see on the ground. I’ll go back and look again, again. 🤷 ---
**Author:** ![dandersen](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/dandersen/32/59398_2.png) [@dandersen](https://forum.nachi.org/u/dandersen)\ **Post date:** [January 21, 2026, 10:06pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/9 "2026-01-21T22:06:21Z")
![Screenshot_20260121_160210_DuckDuckGo](https://global.discourse-cdn.com/internachi/original/4X/8/a/6/8a62ad7c1049f33c082a77593477d473be03bd56.jpeg) This thing? It’s still wrong anyway. ---
**Author:** ![jjonas](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jjonas/32/301755_2.png) [@jjonas](https://forum.nachi.org/u/jjonas)\ **Post date:** [January 21, 2026, 10:12pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/10 "2026-01-21T22:12:20Z")
> [@dandersen](#): > > I don’t see what you posted Use your imagination. Have you never ‘fabricated’ anything on the job-site? I agree, the intake isn’t ideal, but I also know from experience living/operating in Minnesota, that unless the snow is wind-driven, there is typically about an inch or so of exposed wall from the snow accumulation due to the warmth of the structure… (the older the home, the bigger the gap). I have also observed actual Concentric vents totally encased in ice! Remember, this isn’t my inspection. I wasn’t there to see everything with my own eyes. I am simply applying what I have seen in other instances and making my own assumptions as to the what’s and why’s. ---
**Author:** ![jjonas](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jjonas/32/301755_2.png) [@jjonas](https://forum.nachi.org/u/jjonas)\ **Post date:** [January 21, 2026, 10:14pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/11 "2026-01-21T22:14:16Z")
> [@dandersen](#): > > This thing? Yes… that thing. ---
**Author:** ![dandersen](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/dandersen/32/59398_2.png) [@dandersen](https://forum.nachi.org/u/dandersen)\ **Post date:** [January 21, 2026, 10:15pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/12 "2026-01-21T22:15:25Z")
![Screenshot_20260121_160848_DuckDuckGo](https://global.discourse-cdn.com/internachi/original/4X/d/8/7/d87d8bfcc7edfc0426f4f0b32b658fed5f5f3e6a.jpeg) Put my glasses. 👍 ![Screenshot_20260121_160907_DuckDuckGo](https://global.discourse-cdn.com/internachi/original/4X/7/9/d/79d371358aaf6e4feb7fde32032bda57725aa3e8.jpeg) Guess they put this in for when intake makes a snowball inside. How’s that slope back to the furnace i wonder? ---
**Author:** ![jjonas](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jjonas/32/301755_2.png) [@jjonas](https://forum.nachi.org/u/jjonas)\ **Post date:** [January 21, 2026, 10:17pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/13 "2026-01-21T22:17:57Z")
> [@dandersen](#): > > Guess they put this in for when intake makes a snowball inside. It’s possible they open that cap for the winter. ---
**Author:** ![dandersen](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/dandersen/32/59398_2.png) [@dandersen](https://forum.nachi.org/u/dandersen)\ **Post date:** [January 21, 2026, 10:24pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/14 "2026-01-21T22:24:57Z")
I wasn’t responding at you directly at you. I just didn’t see what we were looking at. Confusing pics. Yes, even when done right, they fail. Intake has reduced air pressure, thus higher freeze temp. Pipe slope leaves water at the termination rather than going back to the furnace. = ice cube I was in the buisness when the Pulse furnace came out and got to see all the results of wrong install, even Pulse didn’t know about yet. ---
**Author:** ![jjonas](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jjonas/32/301755_2.png) [@jjonas](https://forum.nachi.org/u/jjonas)\ **Post date:** [January 21, 2026, 10:25pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/15 "2026-01-21T22:25:47Z")
> [@jjonas](#): > > I have also observed actual Concentric vents totally encased in ice! Example of similar setup: My neighbors home across from my kitchen window… ![IMG_20260121_161926489~2](https://global.discourse-cdn.com/internachi/original/4X/a/8/6/a864292ef4a8596a15aab35973b3c71a32e1ad82.jpeg) ---
**Author:** ![dandersen](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/dandersen/32/59398_2.png) [@dandersen](https://forum.nachi.org/u/dandersen)\ **Post date:** [January 21, 2026, 10:30pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/16 "2026-01-21T22:30:07Z")
Yea, when the furnace shuts down at 3:00 am when it’s in the single numbers. Hope they know how to get it back up and running w/o a service call. 😉 ---
**Author:** ![jjonas](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jjonas/32/301755_2.png) [@jjonas](https://forum.nachi.org/u/jjonas)\ **Post date:** [January 21, 2026, 10:38pm UTC](https://forum.nachi.org/t/hvac-intake-and-exhaust/264274/17 "2026-01-21T22:38:54Z")
> [@dandersen](#): > > when it’s in the single numbers. Well, the OP is in Toronto. I don’t think that their average temps get that low (Fahrenheit). They are actually warmer than my area in southern Minnesota! ![Cold](https://global.discourse-cdn.com/internachi/original/4X/4/4/c/44c72e84d0968f8439aaa682c964f45501662b09.jpeg)