Pic of the Day

Miss NASA in Apollo 8, 1971

HSI

Furnace Start up Hot Surface Ignitor
69colbyt
Messing about with our furnace I got to wondering about the ignitor (Blogger wants to spell it with an e, not an o, but o is correct). I kind of sort of thought that it was a spark ignition device, but when we pulled ours out, I could see that it was not. It's just a resistance heating element. Okay then. So it must get pretty hot, but we use resistance heating in toasters and small room heaters, and you need to careful with them because they can set stuff like clothes and curtains on fire, so sure, you could use a resistance heater to ignite the gas in the furnace.

Hot Surface Ignitor

So how hot does it need to be in order to ignite the gas-air mixture?

Natural gas has a high ignition temperature, approximately 1163 degrees Fahrenheit. - ERPUD

That's a little warm. Paper, as we all know, thanks to Ray Bradbury, ignites at Fahrenheit 451. So our Hot Surface Ignitor (HSI) must likewise get pretty hot.

The HSI heats up to around 1,800°F to 2,500°F and glows red-hot. - The Spruce

That's almost hot enough to melt steel (2500 degree F). So what are these things made of?

In 1993, the furnace industry moved away from the standing pilot light ignition system in all furnaces. One of the most popular styles of ignition used today is a Hot Surface Igniter (HSI). The first HSI’s looked like a “fork” and were a silicon carbide material. While this type of igniter is very dependable, they are fragile. The newer style HSI is made out of Silicon Nitride, which is a more durable material. This is the type of igniter that our technicians stock on their trucks. While they are more expensive to purchase up front, you can expect a longer life out of them. - Santa Fe Air

Update October 2025 replaced missing video with a different one.

Efing Whirlpool

Water heater flamed out again this morning. Fine, time to see if Whirlpool has a solution for this problem that has been going on for years. Call customer service and the first thing Robo-cop wants me to do is tell them my phone number. WTF? Everybody and their dog all over the world has caller ID and these clowns can't figure out what my phone number is? This isn't good. I get to a person in short order, who transfers me to 'water heater technical support' where I get to listen to some horribly distorted muzak. Why do they do that? Is it because they are too cheap to buy a decent radio? Or is it a deliberate attempt to drive people away?

Whatever. After a few minutes Robo-cop comes back on the line and asks if I would like to have them call me back instead of just waiting. Sure, that would put a stop to the noise coming out of my phone. And hey, it appears Robo-cop knows my phone number after all. Bozos.

A few minutes later I get a call back and the operator starts interrogating me: name, rank, serial number, address, blah, blah. I answer her first couple of questions, but then I tell her no more, I want to talk about the water heater. We exchange a bit more and then it becomes apparent that they still don't have a solution for this problem. Call me when you have one.

I suspect there is a 'weak' electrical connection somewhere between the controller and the sensor and any little change in temperature causes the connection to fail which causes the controller to flag the sensor as bad. Then I come out and glare at it, and the connector contracts in fright, contact is restored and the water heater lights up again.

I could be wrong about all this, but I can't imagine what else could be causing these intermittent failures. I suppose it's time to get out the soldering iron and make some new connections.

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.

All I want for Christmas

Gifts for the Handyman

Shopping for new tools is one of my favorite pastimes. It's kind of pointless though if you aren't actually going to buy anything. Just about every day that I work on my son's house I find I need another tool, which gives me an excuse to go shopping, so I've been having some fun. Even picked up a garden hose at Harbor Freight. It wasn't the combo model with the built in extension cord. Too bad, that would have been exciting.

Pic of the Day

Steam locomotives of the Chicago & North Western Railway in the roundhouse at the Chicago rail yards (December 1942)

I haven't been reading much, mostly, I suspect, because I haven't been sleeping all that well. But when I sit down for lunch today I pick up a book that's been sitting on a pile that's due to be sold to Powell's and it pretty much captivated me.

The books is methland by Nick Reading and it is about the methamphetamine craze (epidemic) that swept the nation, especially the way it has affected small town America. The first town he focuses on is Oelwein, Iowa (I'm still reading the prologue.), which has a roundhouse. Cool! I like roundhouses, so I go looking for pictures, but I don't find much. The photo above is the best of the lot and it has a tenuous connection to Oelwein: The Chicago & North Western Railway extended to Oelwein Iowa.

Looking at Google Maps, it looks like there is still a big rail operation there. There is a big yard with 100's of cars. Looking at the Open Railway Map, you can see that the only active line goes to Des Moines, all the other tracks heading out of Oelwein have been abandoned. I suspect the only reason they are keeping the track to Des Moines open is that Oelwein has a big yard where they can store a large number of railroad cars.

Pic of the Day

F-16 Pilot