Norman at Nor-Mon

Failed Furnace Igniter Control Relay

I've had a spate of electrical problems recently. The hot water heater I replaced a few years ago has gone out and I had to relight it three or four times in the last month. Since it seems to work fine most of the time, I suspect a connection in the wires that lead to the temperature sensors is at fault. The weather turned cold about a month ago, the water heater is in the garage, so it's going to feel those temperature changes. The best I can imagine right now is the change in temperature caused the metal in the connectors to contract just enough to lose contact. I unplugged the sensor wires from the the controller today and then plugged them back in. This might have dislodged any insulating oxide that had formed (i.e. corrosion) that could affect this connection. Remember these are very low current, very low voltage circuits so even the slightest barrier to conduction could easily cause failure.

Reliability has always been a bit of a black art to me. To make a machine is a pretty straight forward business. There are numbers and laws for strength and pressure and power, so if you do your math right you can make a machine that will run. How long that machine will run is another matter.

According to one theory of business, reliability is a key feature for gaining sales. If the business leader subscribes to this theory, at least some money is going to be spent on investigating reliability. The longer a product is around, and the more popular it is, the more it will improve. It may take a while, but electro-mechanical devices have been around for 100 years now, and I think they could do better with electrical connections. I am a little aggravated by this, I had to take a cold shower this morning.

A few days ago I fired up the furnace for the first time this fall. It didn't turn on. It's not a big deal, we use the gas fireplace for most of our heating. We only use the furnace when it gets really cold. But if we're going to have a furnace, we should keep it in working order. We might really want it one of these days. The furnace has failed twice before. Both times I called a furnace guy to come take a look at it. Once the only problem was that the filter was clogged. Cost me $100. That was embarrassing. The other time the igniter had burned out. This time Osmany and I opened it, poked around and discovered that the controller was kaput. Specifically the relay the supplies current to the igniter had failed. If I could have found a relay with a 24 VDC coil and 10 Amp, 120 VAC rated contacts, we could have replaced it ourselves. But I looked on Mouser and Digikey and couldn't find one. Maybe I wasn't holding my mouth right.

I looked on the Internet for a 50A50-112 furnace controller, but didn't find anything. Found an outfit in Pennsylvania selling something similar, but when I called them the couldn't find anything that would work. So now I look for furnace parts in Portland and I find two. I think this tells you something about the reliability of furnaces right there. Everyone has a car and there are hundreds of repair shops in Portland. I think furnaces might be a tad more reliable than cars. Of course, furnaces are much simpler than cars.

I called Nor-Mon with my part number and he tells me to bring it in and he'll match it up. So today Osmany and I drive into Portland and visit with Norman at Nor-Mon. The man talked incessantly about everything under the sun, his family, vacations, furnace controllers, devices you strap on your shoes that let you walk on ice (they have little carbide studs, kind of like studded snow tires for your car), the hardware business. I had to drag Osmany away or we might still be there.

There used to be thousands of different furnace controllers. Imagine with a population of 330 million people, we probably have somewhere in the neighborhood of a 100 million furnaces. If a production run of furnaces had 10,000 units, and each production run had their own unique controller, you would need 10,000 different controllers to control all those furnaces. A lot of them were probably minor variations of previous models. Somebody wanted a new feature, or they wanted more or different connection points, or they just wanted it to look different. Anyway,  a few years ago, White-Rodgers saw all this madness and decided to do something about it. They figured out what difference were and made a controller that can be configured as any one of a hundred different models. Now they only need a hundred different controllers to ensure that they will have viable replacement on hand to cover the 10,000 different controllers that have been deployed all over the country. (All these numbers are just supposition on my part.)

Anyway, Norman looked in his file of index cards. He had hundreds, maybe even a thousand, all arranged in cardboard trays and taking up six feet of valuable counter space. He looked in his file and found a replacement that ought to work. It has the model number of my controller, along with about a hundred others, printed right there on the box.I bought it for $200, which included a 5% surcharge to cover whatever tariffs are going to be coming into effect as part of Trump's trade war with China.