exhaustfurnacelennox
We have a two year old house that has this heating season developed a vibration in the exhaust pipe that can be heard on the first floor of the house. It seems to have decreased as the season has progressed.
The exhaust exits the furnace with a 2” pipe has 2-45 bends in the first 2’ then transitions to a 3” pipe. It’s a Lennox furnace and this only occurs during the heat cycle.
Could I cut out a piece the 2” pipe and install a fern on fitting to eliminate the vibration?
I read this post last night when one of the blowers in my system started vibrating, shaking the entire house. The comments above encouraged me to look into it myself, and I wanted to share what I've found in my case for the benefit of anyone in a similar situation.
In my case, it seems the Installation Instructions were left inside the unit and pages of it got jammed on the blades, causing the imbalance.
After I removed these,
everything went back to normal. The AC is 6 years old, so these instructions must have been there since the installation, probably taped to a side panel internally.
Sounds like it's tripping out on high temp due to plugged filter or restricted air flow due to wrong filter or closed vents. Nest thermostats also cause this.
Best Answer
A couple of things- if it's started vibrating... you might have had a rodent or bug intrusion. That would create a 'dead zone' where air has to rush around (probably in the 3" section). The exhaust motor would work harder to overcome this, and that would shift things.
Your house could also have settled, and the wood could also have swelled slightly with moisture. As the winter dries out, everything goes back to normal and the pipe stops rubbing.
Vibration can be carried up the pipe as well, so you'll need to lay a hand on it (or a cell phone, say) and 'listen' to the pipe. Maybe you can track down where it's pinching at and causing the noise.
You could also download a spectrum analyzer app to see what's the main frequencies of vibration. Might be fun to see.
As for putting in a fernco, the answer I remember was 'no'. Basis being ferncos can not be used on pressurized systems, ever. And that won't necessarily fix the issue, either, depending on where the problematic sound is coming from. The manual should state the venting requirements of the furnace. And a quick call to your local code office should give you an idea too.
Here was a quick google- However: http://www.inspectionnews.net/home_inspection/heating-ventilation-air-conditioning-hvac-home-inspection-and-commercial-inspection/24693-fernco-furnace-vent-pipe.html