Being the bearer of truth hurts and takes a lot of time. Consider seriously what you are getting into when you eat from the Tree of Knowledge of Good and Evil.
I have a bathroom vent fan that blows hot air down and keeps me warm when climbing out of the shower. The heater element has a thermal cutoff switch for safety reasons in case the unit gets too hot (maybe the fan breaks while the heater remains on and starts to cook your insulation in the attic). My cutoff switch broke, so my heater quit working. I ordered a new one, sold by a different company since they bought out the original company, and available through a parts distributor.
I tested the new thermal cutoff switch when it arrived. It was open circuit at room temperature. That is incorrect. It’s just a bimetal relay contact that snaps open when it gets more than 278F. I thought maybe there’s something I don’t know so I plugged it in the circuit and, sure enough, the heater element would not come on. I tested the voltage across the cutoff to be sure – it would have zero volts across it if it was internally closed. It would have the full 110 VAC across it if it was internally open. I measured 110 VAC.
I called the distributor and to their credit, they were going to send a new one. Before doing so, I asked to speak with their tech person to test it. Again, they were willing. They found that a small sample all behaved the same as the one I have. At this point, I am trusting their motor technician’s ability to test the resistance of a contact relay (probably a good assumption, but a point to remember as things get more weird). So, the distributor customer service department decides “It’s supposed to be open circuit at room temperature.” When I pressed the issue that this is backwards for a thermal safety cutoff switch, their order clerk changed her mind and decided she didn’t want to send me one but rather just refund my money and end the relationship.
If I accepted her offer, then 1) they’re left with a problem of bad parts in the supply chain, and 2) I could have the same problem repeat from the next supplier I buy from. So I continued the conversation with the tech person, and he suggested I could call Broan.
Calling the new company yielded a Tech Support person 3 layers deep in the phone tree. He did confirm that the switch is supposed to be closed circuit at room temperature and confirmed the part number. Well, okay, but that leaves no solution because what we agree should happen is not what the new parts are doing. He offered to send me a part direct. But how do I know that HIS part would work? A little bit more research on his end and me with a magnifying glass looking at the little black part confirmed the part manufacturer number. But neither of us has a decoder ring to know if that’s a normally open or normally closed part number. We agreed that he would internally order one from his own company and measure it himself.
- If it’s open circuit at room temperature – both the new company and the distributor have a big problem to talk with the manufacturer, fix the supply chain, and flush their parts inventory.
- If it’s closed circuit at room temperature – I’ll ask him to mail me that specific tested switch, and then the new company and the distributor have a problem to flush their distributor inventory.
At the distributor, the order clerk said she has mailed out dozens of these. Why have they heard no complaints? My guestimate answer: An electrician buys the $6 part for a customer’s $280 fan. Installs it and the fan still fails. Electrician assumes the cutoff switch is okay and tells customer that the heater element and fan deeper in the system are broken (they do not make a profit if they habitually debugging further). Customer pays $280 for a new unit, old unit goes into the land fill.
So, you choose:
- Know and live the truth: spend $6 and days of effort to fix your fan and a huge supply chain problem that other people have, or
- Keep your blinders on. Pay the $280 and get a new bathroom fan.