A supply vent in a child's bedroom and attached bathroom had been putting out a sewer smell for weeks. Duct cleaning did not stop it, and nobody who had been to the house could say where the odor was coming from.
The homeowner, Justin, lives in Plymouth, Minnesota, in a house where that bedroom and bathroom sit above the garage. The supply run serving those rooms is insulated flexible ductwork, which is common in spaces over unconditioned garages. By the time we got the call for HVAC service in Plymouth, he had lived with the smell for almost two months and had already paid other companies to look at it.
Key Takeaways
- THE CHALLENGEA persistent sewer odor came out of a bedroom supply register, and duct cleaning plus multiple service calls had not located the source.
- THE REPAIRWe opened the ceiling below the duct run, found contaminated insulated flex duct, and replaced that section of ductwork.
- THE RESULTThe odor was gone when we left, and the whole job took a little over two hours at a cost of $800.
Cleaning a duct system only helps if the problem is inside the part being cleaned. Our technician, Wayne, took the position that the odor had a physical source and that the source had to be seen before anyone could fix it. That meant opening the ceiling below the run rather than guessing from the register above.
Project Summary
| Client Profile: | Justin, a Plymouth homeowner |
| Project Location: | Plymouth, Minnesota — northwest Twin Cities |
| Primary Objective: | Locate and remove the source of a sewer odor coming out of a bedroom supply register, a problem that falls squarely under Air Quality Services |
| Ductwork Replaced: | The contaminated section of insulated flexible duct feeding the bedroom and bathroom over the garage, replaced as part of our HVAC Services |
| Key Outcome: | Odor source removed and new flex duct installed in a single visit of just over two hours |
Diagnosing the Plymouth Vent Odor
Before we arrived, the house had been through a duct cleaning and visits from other heating and cooling contractors. The smell kept coming back through the same register in the bedroom and bathroom over the garage. Nothing in the equipment itself explained it.
The homeowner was convinced his six-year-old daughter was not responsible, which is a reasonable place for a parent to start. What we could say with confidence was that the odor was coming out of a supply vent, meaning something was sitting inside the duct between the main trunk and the register. Cleaning had not removed it, so the section had to be opened and looked at directly.
Cutting In and Replacing Flex Duct
Wayne cut open the ceiling below the duct run to expose the flexible duct serving that bedroom and bathroom. Inside was urine and a gooey residue that had been introduced through the register above — kids at that age, possibly a friend, and no amount of cleaning was going to neutralize it. Since the run was insulated flex rather than solid metal pipe, the contaminated length could be disconnected and pulled out instead of tearing the ceiling apart in both directions.
"The only way I'm gonna be able to actually find out what's going on is to see where the problem actually is." - (Justin, Homeowner)
We made a run for new insulated flex, installed the replacement length, and reconnected it to the ductwork and the register so the room was back on supply air. That kind of call does not always come in labeled as a duct problem — homeowners in our Plymouth HVAC service area often describe it as a smell, a noise, or a room that feels wrong, and the diagnosis sorts itself out on site. The same thinking applies when a no-heat call turns into something other than what the thermostat suggests, which is why our Furnace Repair Services start with finding the actual failure first.
Odor Gone After One Visit
With the contaminated length out of the house and new flex in place, the smell that had hung around that bedroom and bathroom for roughly two months stopped. Total time on site was a little over two hours, including the trip for materials, and the invoice came to $800 for the exploratory ceiling work and the duct replacement.
The insulated flex also worked in the homeowner's favor over the long term. Had that run been solid pipe, reaching the fouled section properly would have meant taking apart far more of the ceiling. The replaced duct is new, insulated for the space above the garage, and the family told us they would be calling us with any future questions rather than going back to the companies that could not find it.
Smelling Something From Your Vents?
We handle plumbing and HVAC work for homeowners across Plymouth, Maple Grove, and the rest of the northwest and western Twin Cities. When something smells wrong and the usual answers have not fixed it, we would rather open things up and look than keep repeating a service that already failed. You get the diagnosis, the options, and the price before we start.
Dealing with a stubborn odor, a duct problem, or a heating and cooling issue nobody has been able to pin down in Plymouth? Give us a call or schedule a visit and we will take a look.
Frequently Asked Questions
Why does my bedroom vent smell like sewer in Plymouth?
A supply register that smells means something is sitting inside the duct or near it, since that air is being pushed into the room. In this Plymouth house the source was material that had been dropped and poured down the register itself, which collected in the flexible duct below. A duct cleaning will not always remove that kind of contamination, so the run may need to be opened and inspected.
Do you have to cut the ceiling open to fix a duct?
Sometimes, and we explain that and quote it before we cut anything. On this job there was no other way to see the inside of the duct run above the garage, so we opened the ceiling below it. Because the run was insulated flexible duct, the opening stayed small — a solid metal pipe would have required taking apart much more of the ceiling.
How do I take care of ductwork after a replacement?
Keep registers clear and make sure nothing gets poured or dropped into them, which is the issue that caused this repair in the first place. Change your filter on schedule so debris is not pulled through the system, and keep floor registers covered where small children use the room. If an odor or airflow change shows up again, call before it becomes a longer hunt.