Sunday, February 26, 2017
Slow Times
I believe most of the United States is experiencing unseasonably warm weather right now. Here it is the end of February and friends in Chicago are going to the zoo, people are gardening in New Jersey, and here in Georgia folks are running around in shorts and tees. So, what are you doing with all the spare time? The warm February weather is nice, but it is not very good for business! I have a suggestion for your down time. When you get tired of cleaning up the shop and the truck, how about investing some time into education? Now that you have time, invest some time studying those things that you never have time to get to during a busy season. You can take classes or just do some self-study and research. It is very easy to get information now, so take advantage of your time. Studying during slow times is a great way to prepare for the future.
Saturday, February 18, 2017
Furnace Door Switch
One of the first things most technicians do when troubleshooting a gas furnace is to disable the blower door switch. The blower door switch kills power to the furnace when the blower door is removed. Since the controls and blower are in that compartment, it is impossible to work on the electrical controls with the blower door removed if you do not jump out or physically disable the door switch. Many folks use duct tape to keep the switch closed. Many techs don’t know why the switch is there, and some make their life easier by just removing the door switch altogether. This is a bad idea.
The door switch is there to prevent the blower from sucking in vent gasses and circulating them through the house. The suction created by the blower can be stronger than the draft created in the vent. If the furnace is operating in an enclosed space and with the blower door off, the fan can literally suck vent gasses out of the vent. This can cause two problems. One, the negative room pressure can interfere with the furnace getting enough combustion air, and two, the vent stops working – dumping combustion gasses into the room. This creates a situation where carbon monoxide can be created, dumped into the room, picked up by the blower and circulated through the house. This is especially true for furnaces that get their combustion air from space in where they are installed.
What about sealed combustion systems which draw combustion air from outside through a PVC pipe? Although the combustion air for a sealed combustion furnace normally comes from outside via the PVC combustion air pipe, if you remove the panel to the burner compartment, the furnace will be pulling air from the surrounding area. More to the point, the vent gasses could conceivably be pulled out through the burner area. Although not likely, if both panels are off it is possible for the blower to create a strong enough negative pressure to interfere with the combustion process even with a sealed combustion furnace.
So after working on a gas furnace make sure the door switch is functional before you leave. Do not leave it jumped out or mechanically defeated. You do not want to be responsible for a tragedy.
The door switch is there to prevent the blower from sucking in vent gasses and circulating them through the house. The suction created by the blower can be stronger than the draft created in the vent. If the furnace is operating in an enclosed space and with the blower door off, the fan can literally suck vent gasses out of the vent. This can cause two problems. One, the negative room pressure can interfere with the furnace getting enough combustion air, and two, the vent stops working – dumping combustion gasses into the room. This creates a situation where carbon monoxide can be created, dumped into the room, picked up by the blower and circulated through the house. This is especially true for furnaces that get their combustion air from space in where they are installed.
What about sealed combustion systems which draw combustion air from outside through a PVC pipe? Although the combustion air for a sealed combustion furnace normally comes from outside via the PVC combustion air pipe, if you remove the panel to the burner compartment, the furnace will be pulling air from the surrounding area. More to the point, the vent gasses could conceivably be pulled out through the burner area. Although not likely, if both panels are off it is possible for the blower to create a strong enough negative pressure to interfere with the combustion process even with a sealed combustion furnace.
So after working on a gas furnace make sure the door switch is functional before you leave. Do not leave it jumped out or mechanically defeated. You do not want to be responsible for a tragedy.
Friday, February 10, 2017
2017 National HVACR Educators and Trainers Conference
There is still time to register for the HVAC Excellence National HVACR Educators and Trainers Conference is this coming on March 27-29 at the Florida Hotel and Conference Center in Orlando, Florida. I will be speaking at the conference and will be at the Pearson booth at the Expo. Please come by and say hello. I love to talk with other HVACR Instructors. Not an instructor? No problem. Techs and contractors are welcome as well. You can pick up on many of the latest topics. Better yet, you can meet the dedicated people teaching HVACR. You really can’t find this amount of quality continuing education anywhere else for the price of these conferences. Come and fill up at the all you can learn educational buffet being offered.
If you can find a way to attend one of this conference you won’t be disappointed. They are well worth your time. Unlike generic teacher’s conferences that target all subjects, these are specific to our field. And unlike industry showcases like ComforTech or the AHR show, these are specifically for teachers. As a result, everything you see will have a direct application to teaching HVAC/R.
I know that times are tough and getting funding and permission to go is difficult. When presenting the idea to your school administrators be sure to forward a copy of the program from the conference. The sessions at the National Educators and Trainers Conference in Orlando are high quality, professional programs, not sales pitches. The presenters are nationally recognized speakers from respected HVACR organizations. Be sure to note the large number of educational sessions. There are literally more sessions than you will have time to attend. Point out that attending will keep you informed about emerging technology like communicating systems. Point out that by attending you will be better positioned to integrate green mechanical concepts into your curriculum as a result of attending the conferences. Your attendance is tracked, so you can prove the number of hours you attended. Finally, you can get enough free instructional material and tools to help your program. Come gorge yourself at the all you can learn buffet! Here is a link for more information about the conference
If you can find a way to attend one of this conference you won’t be disappointed. They are well worth your time. Unlike generic teacher’s conferences that target all subjects, these are specific to our field. And unlike industry showcases like ComforTech or the AHR show, these are specifically for teachers. As a result, everything you see will have a direct application to teaching HVAC/R.
I know that times are tough and getting funding and permission to go is difficult. When presenting the idea to your school administrators be sure to forward a copy of the program from the conference. The sessions at the National Educators and Trainers Conference in Orlando are high quality, professional programs, not sales pitches. The presenters are nationally recognized speakers from respected HVACR organizations. Be sure to note the large number of educational sessions. There are literally more sessions than you will have time to attend. Point out that attending will keep you informed about emerging technology like communicating systems. Point out that by attending you will be better positioned to integrate green mechanical concepts into your curriculum as a result of attending the conferences. Your attendance is tracked, so you can prove the number of hours you attended. Finally, you can get enough free instructional material and tools to help your program. Come gorge yourself at the all you can learn buffet! Here is a link for more information about the conference
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