JJkizak Posted July 14, 2015 Share Posted July 14, 2015 What are you gonna do with all of those thermostat controls? JJK Well I am going to sell them to you of course. Perfect condition, no ghosts involved (unless you consider random excursions 10 degrees below set point an issue). Forum discount $50 a piece shipped. Ready to go as I just dug them out of the thrash can. Send me your address and I'll send paypal info. How old is the unit? Carrier parts carry a 10 year warranty. 10 years 6 months Man tells me that I should have un-plugged the 120 before changing tstat. I tell him that I did, the unit was off line. He asks if I un-plugged both sides of the house (two independent units). Eh no, you got me there I only un-plugged the one I was working on. He writes up the receipt that H/O burned out transformed by failing to unplug unit before changing thermostat. Screw it, the kids rooms are cold and I am having livations. My assumption is that there is indeed an intermittent short between Common and Red which caused this. Common was not used prior to new tstat install. I verified that "Common" at air handler was blue as it was at tstat before connecting. The system worked for 24 hours +/- prior to failure. Such is life. NEXT issue............ oh, it's here now. Anyone want to buy a house in the surburbs of Dallas, GA 30157? Well my furnace man just installed a new Emerson with the blue screen about 3 months ago replacing the Honeywell. And since I am near the end of my tenure on this planet and I have not figured out how the thermostats can correct for a bad back and sore thumbs I have no need for 5 good thermostat controls. JJK Quote Link to comment Share on other sites More sharing options...
oldtimer Posted July 14, 2015 Share Posted July 14, 2015 Short sighted. Quote Link to comment Share on other sites More sharing options...
minermark Posted July 15, 2015 Share Posted July 15, 2015 (edited) Man tells me that I should have un-plugged the 120 before changing tstat. I never have. Guess I've been lucky. I've seen them change several here at work without shutting anything off. Me Neither, and we BOTH know that is BULLSHIT, god i hate people in the "Trade" that have that "I know everything Mindset". Iv trained more than one NOW lic electrican, its our option as to turn off power. In socal, i grew out of the local bar after a days work real quick, because when the cops showed up they just ask me who i set straight and where are they are laying, too dam many punks kill familys cuttin corners, i did NOT put up with it. Edited July 15, 2015 by minermark Quote Link to comment Share on other sites More sharing options...
USNRET Posted July 15, 2015 Author Share Posted July 15, 2015 (edited) Now now boys. It is perfectly true that you SHOULD secure the power before working, that is a given. However, I take issue that he assumed and documented that I did not do that even after I told him I did. With that said, I feel perfectly capable of separating 12 volt wires (low amperage) one at a time being careful but that is not what I did. After many, many searches on the interweb I read and understood the risk of shorting the transformer's secondary wires so I took the safe route and climbed the hot stairs and shut her down. I have had several years working on aircraft 270 VDC power and am leary about it all. That doesn't mean that I discount a "measly" 12 volts. But then again, I am guilty of not wearing an anti-static wrist band when I build a computer. I simply look at my surroundings taking into account carpet, etc. ESD mats and tools are a booming business. and I might add that I got WAY more posts toward my 5K mark with this than I intended. Peace / Out. Edited July 15, 2015 by USNRET 1 Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted July 15, 2015 Share Posted July 15, 2015 Now now boys. It is perfectly true that you SHOULD secure the power before working, Agreed, but that didn't cause your problem, if that's where he was going with that comment. Quote Link to comment Share on other sites More sharing options...
minermark Posted July 15, 2015 Share Posted July 15, 2015 "he assumed and documented that I did not do that even after I told him I did" These are the kind of guy's i would weed out of electrical training, and i did a few. Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted July 16, 2015 Share Posted July 16, 2015 I wait with baited breath for the "all good now" from you Mike! Quote Link to comment Share on other sites More sharing options...
USNRET Posted July 16, 2015 Author Share Posted July 16, 2015 Been good for 48 hours; fingers crossed and wooden head knocked 1 Quote Link to comment Share on other sites More sharing options...
babadono Posted July 16, 2015 Share Posted July 16, 2015 and he didn't even kiss me! Replaced the transformer that was 'bad' and suspected that common wire was shorted somewhere in the structure. Disconnected common (only loss is constant display light). I had to leave and come back to work prior to completed troubleshooting but he only charged me $195.00 for the $6.00 transformer plus the $75 service charge of course. I want a BEER! He charged you $195 and it is not completely fixed?(No display light). That is BS. As far as checking the 24VAC 50' from the transformer, put a 1k resistor across your meter leads to make sure the circuit will draw current out of the transformer. If there is something wrong with the transformer or wiring you will read 0 volts or damn close. Sounds to me like when the thermostat was calling for 'COLD' and 'FAN' one of those was shorting out the 24 volts. Quote Link to comment Share on other sites More sharing options...
Guest thesloth Posted July 17, 2015 Share Posted July 17, 2015 (edited) Am I misunderstanding what happened? The service tech said you broke the transformer? If you left the secondaries shorted for a while they would get very hot, was there any melting or burning, or a fire? You don't have to turn off power to replace thermostats, even shorting the secondaries for short periods of time won't do any harm. It would be really hard to kill yourself with that voltage too. As some of my electrician friends would try and be smart and counter with "it's the current that can kill you not the voltage"? I would answer well why doesn't a AA battery kill you which can deliver several amps of current for short durations of time (OSHA says only 70mA of current is needed to stop your heart)? Even that small transformer for the thermostat can deliver enough current to stop your heart. So why doesn't it? Resistance. Your bodies resistance would have to be extremely low to deliver enough current to stop your heart. Remember I = V/R So back the the transformer. I use a small transformer to step down my line voltage (120Vrms @ 60Hz) to 2.5Vrms to heat my heating element in my vaporizer. The heating element is a metal screen which as far as the transformer is concerned is more or less a peice of wire, or a dead short with very small intrinsic resistance until it starts getting warm and then the resistance will rise. The transformer itself, the secondaries have a "source resistance" that when modeled with the screen/heater element's resistance creates a potential divider. These intrinsic properties are what will limit the actual current being drawn. The vaporizer pretty much pulls 12 amps for short periods of time all day long Yeah I vape a lot. If you did break the transformer from shorting the secondaries my guess is it would take a while and there would have been some signs of burning, melting, fire etc........Electrical fires smell too. I am glad MInerMark is keeping those electricians in line! I have known several licensed electricians including my brother in law. None of them remotely understand the basic principles of electricity, it's kinda scary. Edited July 17, 2015 by thesloth Quote Link to comment Share on other sites More sharing options...
Guest thesloth Posted July 17, 2015 Share Posted July 17, 2015 (edited) IF you place a 1k resistor as a dummy load place your meter in series and read AC current. You should get 24mA. Also if you do this use a 1 watt resistor, a 1/2 watt resistor will get very warm. You can use a 1/2 watt .024*24=.576 watts just don't leave it connected very long, like I said it will get warm. Edited July 17, 2015 by thesloth Quote Link to comment Share on other sites More sharing options...
wstrickland1 Posted July 17, 2015 Share Posted July 17, 2015 carrier units have a 5 amp automotive style fuse. Shorting out the transformer will pop that fuse.....unless it's already bypassed. Quote Link to comment Share on other sites More sharing options...
USNRET Posted October 31, 2017 Author Share Posted October 31, 2017 It's b.a.c.k. last night the thermostat decided to drive itself down to 61 degrees. Woke up at 0100 freezing. Went to bed with thermostat in its usual setting of cool / HOLD / 78 degrees. Quote Link to comment Share on other sites More sharing options...
oldtimer Posted October 31, 2017 Share Posted October 31, 2017 Have you ever watched a horror flick and asked "why don't they just move?" Quote Link to comment Share on other sites More sharing options...
USNRET Posted October 31, 2017 Author Share Posted October 31, 2017 20 minutes ago, oldtimer said: Have you ever watched a horror flick and asked "why don't they just move?" 23 months left here; no moving to be done Quote Link to comment Share on other sites More sharing options...
JJkizak Posted October 31, 2017 Share Posted October 31, 2017 Remember about critters eating the insulation off the wiring and also in my case when the oil furnace air filter plugs the furnace will shut the 24ac off for a brief period until the overtemp resets. JJK Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted October 31, 2017 Share Posted October 31, 2017 39 minutes ago, USNRET said: It's b.a.c.k. last night the thermostat decided to drive itself down to 61 degrees. Woke up at 0100 freezing. Went to bed with thermostat in its usual setting of cool / HOLD / 78 degrees. I have an old mercury bulb thermostat I can send you. If that thing moves during the night, you need to move. Quote Link to comment Share on other sites More sharing options...
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