Project, well done. a good ending. Don ----- Original Message ----- From: Max Robinson To: Blind Handyman Sent: Tuesday, December 19, 2006 2:25 PM Subject: [BlindHandyMan] Changing the fan thermostat.
I have a forced air gas furnace. The blower is delayed by a thermostat that is near the heat exchanger. When the burner comes on the thermostat senses the temperature rise and turns on the blower when there is some heat to blow into the house. After the burner is turned off the blower continues to run until the temperature has lowered to the point where the air would feel cold. This keeps heat that is stored in the mass of the heat exchanger from being wasted up the chimney, instead it is put into the house where it does some good. Also there is a high limit. If the blower should stop due to a malfunction, the power to the gas valve is interrupted if the temperature gets above 200 degrees. The blower turns on at 130 degrees and off at 100 degrees. Mine started sticking on. My wife complained that the furnace was blowing cold air. At first I thought she had felt it just before it was due to be turned off when the air is not very warm. I soon found that it was running continuously. I went under the house having no idea where the thermostat was or what it looked like. I turned off the switch and opened the electrical box. I had to trace the wires to find the thermostat. There was a length of flexible conduit from the main junction box to another smaller box. I pulled off its cover and there was the thermostat dial. I pulled out the wires, there is a little slot next to where the wire goes in that you have to press on to release the wire. There were four wires. Then I removed four screws that were holding the box to the side of the furnace. To my surprise there was a long tube extending back from the box into the innards of the furnace. That tube is half of an inch shorter than a foot long. The bimetal is in the end of it formed into a helix, that's a cork screw for those who might not know. It doesn't stick into the burner compartment but into the air stream. I couldn't tell exactly where it was located relative to the heat exchanger but I assume it was close to it. Now with the old thermostat in hand and much trepidation in my heart I had Sue drive me into town to try to find a new one. The first place I went said they didn't have furnace parts. They directed us to another place. I expected laughter and the statement quote, I haven't seen one of those in 25 years. Our house is about 45 years old and the furnace is the original. But no laughter, He checked his computer which told him they had one in stock but they couldn't find it. On to another place where they brought out a replacement without batting an eye. 77 dollars but we had to have it. Working in a 30 inch crawl space isn't easy or fun and it takes a lot longer to do simple things that we take for granted. I got it done, all the wires connected correctly and it worked. Then there was just enough time to take a shower and get dressed to meet another couple for dinner and a trip to Nashville to see the Christmas decorations at the Opry land hotel. After we returned home I slept really well. Regards. Max. K 4 O D S. Email: [EMAIL PROTECTED] Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Music site: http://www.maxsmusicplace.com To subscribe to the fun with tubes group send an email to, [EMAIL PROTECTED] [Non-text portions of this message have been removed] To listen to the show archives go to link http://acbradio.org/handyman.html or ftp://ftp.acbradio.org/acbradio-archives/handyman/ The Pod Cast address for the Blind Handy Man Show is. http://www.acbradio.org/news/xml/podcast.php?pgm=saturday The Pod Cast address for the Cooking In The Dark Show is. http://www.gcast.com/u/cookingindark/main.xml Visit the new archives page at the following address http://www.mail-archive.com/[email protected]/ For a complete list of email commands pertaining to the Blind Handy Man list just send a blank message to: [EMAIL PROTECTED] Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/blindhandyman/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/blindhandyman/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
