Year: 2011

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How to troubleshoot a gas burner

Trouble shooting a gas burner

While there is a lot of mystery surrounding flame safety circuits, gas burners are actually quite easy to trouble shoot. They really only need three things to operate: a fuel supply, combustion air and an ignition source.

In a forced are furnace, the combustion fan will come on first to purge the chamber. After a predetermined time, the flame controller will open the gas valve and provide an ignition source. If the flame is not detected in a few seconds, the gas will shut off and a new cycle will be required to relight.

The gas will be controlled by an electric solenoid valve. It opens and closes with an audible click.

The first step in trouble shooting the system is to determine if the combustion fan is running. There is often a time delay before the fan begins to run after the system is energized. Check the time control relay if the fan will not start or does not start at the correct time.

Next there will be some kind of air proving mechanism. Often this is a simple as a paddle in the air steam connected to a switch. It may also be an air pressure switch. Make sure that the air proving signal is present before moving forward.

Once the controller is satisfied that there is sufficient air and the combustion chamber is purged, the gas valve will open and the ignition source will fire. You can usually tell if the gas valve is opening by listening for it to click or feeling for it to open.

The two most common types of ignition are the pilot light and the electronic ignition. The pilot light is a separate flame that runs all the time. The electronic ignition consists of a spark rod and a high voltage coil. The coil provides the voltage end to make a spark at the gap on the spark rod. A neon lamp can be held near the wire to ensure high voltage is present during the spark cycle.

If the controller does not sense a flame within a few seconds of opening the gas valve, it will close the valve again and purge the system.

If you are having trouble lighting the burner after the gas valve opens, verify the gas pressure and make sure the gas orifices are clean.

If the valve fails to open, suspect a problem with the gas control circuit. Often this is a printed circuit board. Filed repairs or modifications are not generally allowed to these boards for safety reasons. If the board is bad, you will have to replace it with an approved unit.

If the burner lights but goes out with in a few seconds, there may be a problem with the flame sensing mechanism. In many burners this is simply a rod that generates a voltage in the presence of a flame. If bad it will need to be cleaned or replaced. Some systems use an optical flame sensor. These need periodic cleaning and eventual replacement as the voltage from the flame eye decays with age.

If the flame is unstable check the gas source for proper pressure or contamination.

Understanding how a gas burner works can make trouble shooting relatively easy. However, it is often hard to access the components in an enclosed furnace. It may be possible to remove the burner form the duct work and bench test the unit. If you find that the air proving switch works o the bench but not with the unit installed, check for blockages in the duct work.

Never attempt to relight a burner that has not been properly purged. Never do anything that will shortcut or bypass the purge cycle. Using these steps you should be able to isolate the cause of a gas burner problem quickly and possible save an expensive service call.
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A Process Improvement Story

A Process Improvement Story.

Back when I worked at Westvaco we had a need to change large heavy rollers called impression rollers. These impression rollers were changed about once a day and there were eight of them in a machine.

The process used for over 20 years was the one recommended by the printing press manufacturer. The process involved using a hand crank lifting table to raise and lower the rolls into place. Since the table lifted form directly under the roller, the paper web had to be cut in order to remove the roller. The web had to be taped back together afterwards. These tape splices were always difficult to get through the remainder of the printing press on start up.

We knew that on another brand of machine, they used a tray to catch the roller and the press had more travel in the impression roller mechanism so that the roller could be raised and lowered out of and into the tray. The tray was cantilevered so that it could slide between the roller and the web.

We decided to try to mimic the design of the other machine and provide a way to avoid cutting the paper. However, our machine was not capable of raising and lowering the rollers so we still had to have the capability of lifting the rollers.

We designed a hydraulic lifting table that was cantilevered from the operator end. The lifting bars rolled up and down on a post using roller bearings. The hydraulic cylinder was foot operated so that the operator could use his hands to align the roller into the bearing caps while he lifted it with his foot.

The lifting bars were narrow enough to slip between the web and the roller. We used webbing between the bars to support the roller so that it could be handled without damage.

The first prototype was very large and cumbersome as we were unsure of the strength needed to handle the rollers. Future versions were scaled down to make them more maneuverable and easier to handle.

These machines cost less than $2000 each to build. They were very simple to operate and completely reliable.

Down time on the machine cost about $1000 per hour so these machines paid for themselves almost every day they were used due to the time saved form not having to cut and splice the web.

I still have one of these machines in my shop and I use it for all sorts of lifting applications. It makes a great transmission jack. It is especially good for handling a heavy Jeep Transfer case transmission combination.

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Wicked – book review

Wicked by Gregory Maguire

Wicked is Gregory Maguire’s back story of the life of the wicked witch of the west from OZ. Watching the movie in TV growing up, I was always scared of the green skinned wicked witch. She represented pure evil to me. I never stopped to think that she had a mother and a father. I never even gave much thought to the fact that her sister is killed at the beginning of the movie and that a valuable family heirloom was lost when Dorothy stole the ruby slippers. She had reason to be upset.

Gregory Maguire must have considered all those elements of the story that most of us just pass over. So he created an entire history for the wicked witch. He even gave her a name. I never realized that we never know the witch’s name in the movie. I have never read the book by Frank Baum but apparently he did not give her a name either. She just went by her title.

Maguire creates parents for her. She is a preacher’s child. I thought that was funny, having known a few preachers children in the past. They did always seem to be the evil ones. Of course they decide that her green skin is a curse upon the family.

The West Witch is the first born and the East Witch is her younger sister who also has a birth defect. The story of how they both overcome their physical limitations is a great character study in the beginning of the book. The briefest mention of her parent’s polyamary lifestyle was also interesting to me. Her actual biological father hood is held secret until near end of the story.

I found the story of her being college roommates with Glinda the good witch to be quite an interesting twist. The fact that they might have been good and close friends until she gave away the slippers had never occurred to me. I had just assumed them to be life long enemies.

The Wicked Witch’s life story seems to be one of failures and near misses. She seems to get very close to achieving her goals and then is thwarted in some way. Even her famous death scene in the movie is more of an accident than an assignation.

I loved how Maguire worked important elements of the original story into his story as well. For example you get to read how her sister was the one who enchanted the axe that turned the tree cuter into the tin woodsman. Possibly it was one of her dear college friends that built the scarecrow. And the lion was one she had helped rescue as a cub.

The wicked Witch is portrayed as an animal lover and a strong supporter of animal rights. The flying monkeys were her biological creation based on her study of life sciences in school. I almost cried when the Tin Woodsman killed her dog that she had sent to welcome Dorothy to the castle.

The troubled life of the Wicked Witch resonates with many people I am sure. Reading the story made me think of my own failings and near misses. There are a lot of religious question posed by the characters in the book as well. These resonate with me also.

I got the feeling that Maguire’s own religious beliefs changed as he was writing the book. Or maybe he was afraid to pose the questions early it in the work for fear of alienating the readers. There is a strong metaphysical tone that underlies all of the religious discussions. My favorite part was the creation theory that involved a Dragon dreaming OZ into existence. I assume Maguire was posing his own personal questions about the nature of life through the voices of the characters.

Overall, I really enjoyed reading the book. One drawback was the vocabulary. Maguire used a lot of words I am not familiar with and I had to infer the meaning from the context or be distracted from the story to look them up. Then there was his tendency to make up words. So sometimes I was faced with not knowing if it was a word I did not know if it was one he simply made up. I felt like I missed some of the intricate details of the story because I tended to just skip those parts after a while.

I think my favorite part of the story was the time when the Wicked Witch was involved in a rebel movement to help restore the rights to Animals. The thought of the Wicked Witch having a passionate love affair had never entered my mind before reading Wicked. But I was confused by the story of her child. I am not sure why Maguire chose to be so vague about the child. I felt more confused than mystified by the description.

Now, I have to read the original Baum version of OZ. I am sure that when I reread Wicked it will seem like a completely different book. I also thought it was funny that the next book I picked up to read began with a story of someone comparing his boss to the Wicked Witch of the West. I so wanted to yell at this fictional character to tell him that there may be much more to this person’s personality that you see.

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Stars

Stars

Last night as I walked the trash can out our long driveway, I was amazed at how bright the stars were. I had not seen such brightness in the stars since I was last at Harlan.

I walked very slowly back to the house enjoying the view of the sky. I saw both the big and little dippers. I have never been able to recognize any of the other constellations. I just enjoyed the brightness of the little points of light contrasted against the cold black sky.

Back in the yard in the dim light of the icicle lights still n our front porch, my dog Smash took on a sudden playful urge. I had tried to get him to play chase with me when I first got home in the afternoon, but he was not interested then. I almost walked on into the warmth of the house and ignore his playfulness.

But inspired by the stars, I zipped my coat and began chasing Smash around the yard. He was very playful. He would drop the stuffed sheep and pretend to look away. They just as I reached for it he would scoop it up and run off in a circle around me. We played until I could no longer catch my breath.

Later that evening as I was getting ready for bed, I decided to sit up and read a bit. Just as I picked up my book to read, Smash started barking and whining.

I went down to see if he wanted out. He has been staying in the garage on cold nights but he often wants out to go puppying. But instead he went back to the rear bedroom. I lay down on the bed and picked up the book. Smash began barking at me. So, I went back to petting him.

In a few minutes he began to get antsy again. He paced around the room and then put a paw up on the bed. I tried to get him to jump but he would back away. I finally scooped him up and placed him on the bed beside me. He settled right down as I continued petting him. He calmed right down and went to sleep.

I was beginning to drift off to sleep when I felt the bed move. I looked up and saw the cat crawl up o the foot of the bed. Soon I was snoozing between the dog and the cat. It was very peaceful just laying there enjoying the warmth of my furry friends. All my cares, worries and fears seemed to melt away in to their fur.

I lay there a while before Janice finally came to check on me. She laughed when she saw me snuggled up between the cat and the dog.