Why a New Clothes Dryer Won’t Heat Up
My brand new electric clothes dryer won’t heat up, yet everything else seems to work – Help! Recently I had a question from a site visitor regarding a problem with an electric dryer. They had moved into a new home with new appliances, including a brand new dryer. When they went to use it, however, they found that the electric dryer would cycle correctly, but not heat up to dry their clothes. They even took the dryer back and tried another one, and still experienced the same problem.
This is a fairly common issue that can happen with a certain type and style of electricalpanel and breakers. When installing slim-line style breakers into a Schneider (FPE, Sta-blok, etc.) panel, you have to ensure that the breaker gets into the correct position in the panel. The breaker will fit just fine, but if it isn’t across the divider between hot buss bars, you will only have one side of the 120 volts on each of the load terminals. If the breaker is in positions 1,3…., down the left side of the panel, or 2,4…, on the right side, you will have this problem. It needs to be in position 3,5…, or 4,6… to correct the issue.
To check if this is the problem you will need to use an electrical meter or tester. At the receptacle (30A, 125/250V), test from one of the hot wires to neutral or ground, and then test the other. Each should read somewhere close to 120V.
Then test from one hot to the other hot. The reading will be 0 volts if the breaker is indeed installed incorrectly.
When the breaker is in the correct position you will have somewhere around 240 volts between the two hot wires. If not, the dryer won’t heat. The heating element uses 240V. The reason the controls, light, motor, etc. Continue to work is that these components use one side or the other of the 120V to neutral for a supply. I am using an actual picture of the inside of a small load center just to give you a clear picture of how this problem can occur.
This is an issue that really presents no safety hazard, only that if the installer isn’t paying attention when using this type of breaker and panel, it can cause a lot of unnecessary grief. Hauling a dryer in and out of a home is enough of a job to do once, let alone two or more times.
However, the most costly mistake of this nature that I’m aware of comes from my own experience. While working for a large oil company as a contractor, another installer made this mistake while connecting an electric heater for a small equipment shack, so the heater wasn’t working. That’s when they called me in to troubleshoot the problem. This wouldn’t be such a big deal, only that the equipment shack was for radio communication equipment, and was right on top of a Limestone Mountain in the Canadian Rockies. The only access to this site in the winter is via helicopter! While this provided me with a grand tour of the Rockies, with an exciting climb using 95% of the chopper’s power to the maximum height this machine can climb, and landing on a pad not much larger than the helicopter itself, it also provided the oil company with a rather large bill as you can imagine!
So if this situation ever comes up again, an electrical meter or voltage tester, and knowing how to use it can save you a lot of time and effort in correcting the issue without trying several new dryers in the process.
Do you need help understanding how to use and interpret a digital multi meter? Check out this helpful instructional e-book that explains this essential troubleshooting tool!
The latest in my series of ‘Internet Electrician’ E-Books covers the use of a digital multi meter.
This is one of those ‘tried and true’ tools of the trade that electricians can’t imagine doing their job without.
Should I Connect My Motor to 120 or 240 Volts
I am going to wire an outlet for a compressor in my shop. Should I connect to 120V or 240V? I’ve had a few questions regarding the topic of what is best, 120 or 240 connection when you have a choice on a motor, like on a compressor or a pressure washer. One particular question from one of my website visitors involved a situation where a new larger compressor was purchased to replace the old one that had a single voltage motor rated at 120V/7A, and the new one was more than double the size. The old unit was connected to a dedicated 15A/120V circuit, and he was quoted a healthy sum to upgrade this circuit to larger wire, and a larger breaker. The simple solution to this would be to change the existing circuit from a 120V to a 240V supply as the new motor was dual voltage.
Here is a link to an article that deals with this particular situation: How to Convert an Outlet or Receptacle from 120v to 240v.
The current draw on the new motor was 16A on 120V. This would require supply conductors of #12AWG, up from the existing #14AWG, and the breaker from 15A up to a 20A (could be allowed to be up to 40A for a dedicated motor circuit). By switching the motor to 240V, you can keep the same wire size – simply make the required changes to the connections inside the panel, and install a 2-pole breaker. You would also need to change the receptacle and compressor plug (if cord connected) to a 240V configuration. This is a much better solution than running new wire, especially if the panel isn’t close to where the compressor is, and if the walls are finished.
If this is a new installation, it is always best to run a supply of 240V instead of 120V if it is a dual voltage motor. With 240V, you will have a little more torque, and it will come up to speed a bit faster, but the biggest advantage is less line loss and voltage drop, thus saving some operating costs. You may also realize some cost savings on the size of the supply wire or cable that you need to run as well.
A motor running at 240V will consume half of the amps that it will draw while running on 120V. We pay for electricity by the kilowatt hour (KW/hr.) so if we consider a motor that draws 16A on120V, this is 1920 watts. (Volts x amps = watts). The same motor on 240V draws 8 amps, for the same total of 1920 watts (neglecting power factor, a little more technical than we are going to get here). However, the difference is in line drop (volts lost) and line loss (power lost) in the conductors.
This motor running at 120V will have twice the amount of line drop (amps x resistance of the wire = volts) because it is drawing twice the current, and it will experience four times the line loss (power in watts), because amps(2) x resistance of the wire = watts. This is wasted power that is lost in the form of heat. The longer the wire, the more significant these losses become.
The other consideration and potential cost savings here is that you can use #14AWG wire to run the motor on 240V, but you will have to buy at least 12 AWG to run it on 120V. This would be a cost savings, however the breaker may cost you more as you need a 2-pole breaker for the 240V motor, but only a single pole for the 120V set up.
Remember that you will have to know and understand how to make the correct splices in the motor junction box so that you don’t put 240V on a motor wired for 120V (likely damaging the motor), or 120V on a motor wired for 240V (may not start, or be very sluggish).
In conclusion, it is always best to use 240V if the option is available to you.