Why the same part fails twice
The most frustrating call in this trade is the second one: an element replaced six months ago, the same fault back, and a customer who reasonably assumes the first repair was botched. It usually was not. A heating element in a dryer is a fuse of sorts, and if the air cannot get out fast enough the element cooks itself no matter how new it is. So the duct is the diagnosis, and the element is the symptom.
Your dryer is probably fine, and there is a code number for why
The North Carolina residential code adopts the IRC section on dryer exhaust, and it is unusually specific. M1502.4.6: the maximum exhaust duct length is 35 feet, measured from the connection to the transition duct at the back of the machine to the outlet terminal outside. And then Table M1502.4.6.1 applies the deductions:
- Each 90-degree elbow costs you 5 feet of that allowance.
- Each 45-degree elbow costs you 2.5 feet.
So a run of actual duct measuring 22 feet with four 90-degree elbows in it has an equivalent length of 42 feet, and it is over the limit by seven. It does not look over the limit. It looks like a short duct.
Here is why that is a Charlotte problem more than it is a general one. Roughly 3% of Mecklenburg County homes have a basement, so the laundry did not go downstairs. In the post-2000 two-storey subdivision stock that makes up an enormous share of Concord, Indian Trail, Stallings, Harrisburg and Huntersville, the laundry room went upstairs, next to the bedrooms. From there the duct has to travel through a joist bay, turn, climb or cross the house, and turn again to reach an outside wall or the roof. Four elbows is normal. Six is not unusual.
What happens next is mechanical rather than mysterious. The duct is sized so the air moves fast enough to carry lint along with it. Add length and add elbows and the velocity drops. Below a certain speed the lint stops being carried and starts settling on the duct wall, and every load adds a little more, so the run progressively closes itself. Airflow falls, the machine cannot shed moisture, the cycle takes two hours, and the thermal protection at the back of the dryer starts cutting out.
Then the element or the thermal fuse fails, and that is the part the symptom points at. Fit a new one into the same duct and you have bought the same failure on the same schedule. Which is why the duct is the first thing we measure and the number goes on your paperwork before any part is discussed.
The safety side is not a footnote either. The NFPA attributes roughly 14,000 home fires a year in the United States to clothes dryers, and identifies failure to clean, meaning lint accumulation in the duct, as the leading cause. A duct that is too long to keep itself clear is a duct that accumulates lint by design.
So on every dryer call we measure the run, count the elbows, work out the equivalent length and write it on your paperwork. Where it is over, we say so and quote the duct rework as a separate line you can see and decline. Where it is under and simply dirty, we clear it. Either way you get the number, which is more than the appliance itself will ever tell you.

The parts, and how to tell which one it actually is
It runs but does not heat at all
On an electric dryer: the heating element, the thermal fuse, or the high-limit thermostat, and they are frequently connected. The thermal fuse is a one-shot device that blows to protect the machine, so a blown fuse is almost never a random failure. It is evidence of restricted airflow. Replacing the fuse alone and leaving is the classic short repair.
On a gas dryer: the igniter, the flame sensor or the gas valve coils. Coils fail in a very recognisable way, where the dryer lights for the first cycle and then will not relight while warm.
It heats but the clothes are still damp after two cycles
Airflow, almost every time. The duct, the lint screen housing, or a blower wheel that has come loose on its shaft. Very occasionally a cycling thermostat. This symptom points at the duct more reliably than any other.
It squeals, thumps or rumbles
The drum support rollers, the idler pulley or the belt. Cheap parts, an hour of work, and worth doing rather than living with, because a seized roller wears a flat on the drum and that is not a repair.
It will not start at all
The door switch, the start switch, or the thermal fuse on machines that wire it into the motor circuit rather than the heater circuit. Again, if it is the fuse, the duct is the real question.
It shuts off partway through
Overheating, and the machine is protecting itself. Airflow again, or a blocked lint screen housing. The dryer is doing exactly what it was designed to do and the fault is upstream of it.
Gas or electric, and why it matters in this metro
Roughly three quarters of North Carolina homes are electric for major appliances, and the metro follows that, though Piedmont Natural Gas runs through most of it so gas dryers are far from rare. The distinction changes three things.
What can fail. An electric dryer has an element and a 240-volt supply. A gas dryer has an igniter, a flame sensor, valve coils and a 120-volt supply. There is very little overlap in the fault list, which is why the first question on the phone is always which one you have.
Who may legally touch it. The gas connection itself is licensed work in North Carolina under the plumbing and heating board. Disconnecting and reconnecting a gas dryer to service it is part of the job, but anything involving the supply line beyond that goes to a licensed trade, and we will tell you so rather than absorbing it quietly.
The 240-volt terminal block. On an electric dryer, the block where the cord lands at the back is a genuine failure point that gets missed constantly. Two hot legs at 120 volts each; lose one and the motor still turns on the remaining leg but the element, which needs both, does nothing. So the dryer runs, tumbles and does not heat, and the diagnosis reads as a dead element. It is worth looking at the block before buying anything, and it is the same failure we describe on the stove page for exactly the same reason.
What the job covers in Charlotte
What we cover
Electric and gas tumble dryers, stacked laundry centres, and the exhaust duct they are connected to.
Target outcome
The duct measured against its code equivalent length, the failed part named, and the actual cause of a repeat failure identified rather than replaced twice.
Decision point
We publish the duct arithmetic, because a heating element fitted to an over-length run is a repair with a return date attached to it.