Re: [MBZ] OT Furnace gig
I forgot to add that I did have the power transformer in a tube audio amp over heat and die in the 1980's (new in 1964). As it was before the internet, I never did find a replacement (solid state low voltage having replaced those inefficient tube devices). On Thu, Feb 21, 2019 at 11:26 AM OK Don wrote: > The one other factor I can think of is a defective connection to the > terminals - becoming loose due to heat and vibration over the years. > > On Thu, Feb 21, 2019 at 8:55 AM Jim Cathey via Mercedes < > mercedes@okiebenz.com> wrote: > >> > [Ugandan pile of dead motors...] >> >> An electric motor is NOT a transformer! They can easily be toasted, >> because they depend >> upon back-EMF to limit current, and cooling from the embedded fan. If >> you run substandard >> voltage to a motor it won't spin at rate, causing massive overheating due >> to both of the >> above factors. (Even worse if there's an actual starting winding and a >> centrifugal cutout >> switch that can't disengage.) Substandard _frequency_ can also do it, >> because if the core >> saturates the back-EMF stops building, and the current goes up... >> >> You can only kill a transformer two ways: punch a hole through the >> insulation due to a >> massive (?) voltage spike, or overheat it causing wire burn-through or >> insulation failure. >> Making it overly small/cheap makes the transformer more susceptible to >> both of these. >> Vibration could also cause issues over time, if there were flexure and >> work-hardening >> of the copper windings, and/or abrasion of the insulation. >> >> Supplying control voltage for a furnace isn't a stressful task, unless >> the transformer is >> actually under-designed. >> >> -- Jim >> >> >> ___ >> http://www.okiebenz.com >> >> To search list archives http://www.okiebenz.com/archive/ >> >> To Unsubscribe or change delivery options go to: >> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com >> >> > > -- > OK Don > > *“Travel is fatal to prejudice, bigotry and narrow-mindedness, and many of > our people need it sorely on these accounts.”* – Mark Twain > > "There are three kinds of men: The ones that learns by reading. The few > who learn by observation. The rest of them have to pee on the electric > fence for themselves." > > WILL ROGERS, *The Manly Wisdom of Will Rogers* > 2013 F150, 18 mpg > 2017 Subaru Legacy, 30 mpg > 1957 C182A, 12 mpg - but at 150 mph! > -- OK Don *“Travel is fatal to prejudice, bigotry and narrow-mindedness, and many of our people need it sorely on these accounts.”* – Mark Twain "There are three kinds of men: The ones that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves." WILL ROGERS, *The Manly Wisdom of Will Rogers* 2013 F150, 18 mpg 2017 Subaru Legacy, 30 mpg 1957 C182A, 12 mpg - but at 150 mph! ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT Furnace gig
The one other factor I can think of is a defective connection to the terminals - becoming loose due to heat and vibration over the years. On Thu, Feb 21, 2019 at 8:55 AM Jim Cathey via Mercedes < mercedes@okiebenz.com> wrote: > > [Ugandan pile of dead motors...] > > An electric motor is NOT a transformer! They can easily be toasted, > because they depend > upon back-EMF to limit current, and cooling from the embedded fan. If you > run substandard > voltage to a motor it won't spin at rate, causing massive overheating due > to both of the > above factors. (Even worse if there's an actual starting winding and a > centrifugal cutout > switch that can't disengage.) Substandard _frequency_ can also do it, > because if the core > saturates the back-EMF stops building, and the current goes up... > > You can only kill a transformer two ways: punch a hole through the > insulation due to a > massive (?) voltage spike, or overheat it causing wire burn-through or > insulation failure. > Making it overly small/cheap makes the transformer more susceptible to > both of these. > Vibration could also cause issues over time, if there were flexure and > work-hardening > of the copper windings, and/or abrasion of the insulation. > > Supplying control voltage for a furnace isn't a stressful task, unless the > transformer is > actually under-designed. > > -- Jim > > > ___ > http://www.okiebenz.com > > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > > -- OK Don *“Travel is fatal to prejudice, bigotry and narrow-mindedness, and many of our people need it sorely on these accounts.”* – Mark Twain "There are three kinds of men: The ones that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves." WILL ROGERS, *The Manly Wisdom of Will Rogers* 2013 F150, 18 mpg 2017 Subaru Legacy, 30 mpg 1957 C182A, 12 mpg - but at 150 mph! ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT Furnace gig
> [Ugandan pile of dead motors...] An electric motor is NOT a transformer! They can easily be toasted, because they depend upon back-EMF to limit current, and cooling from the embedded fan. If you run substandard voltage to a motor it won't spin at rate, causing massive overheating due to both of the above factors. (Even worse if there's an actual starting winding and a centrifugal cutout switch that can't disengage.) Substandard _frequency_ can also do it, because if the core saturates the back-EMF stops building, and the current goes up... You can only kill a transformer two ways: punch a hole through the insulation due to a massive (?) voltage spike, or overheat it causing wire burn-through or insulation failure. Making it overly small/cheap makes the transformer more susceptible to both of these. Vibration could also cause issues over time, if there were flexure and work-hardening of the copper windings, and/or abrasion of the insulation. Supplying control voltage for a furnace isn't a stressful task, unless the transformer is actually under-designed. -- Jim ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT Furnace gig
A transformer _should_ be just about the most reliable device out there. It's nothing but wire, after all. But, trust the bean counters to find a way to shave things to get the cost (and MTBF) down anyway. Shades of Henry Ford! -- Jim ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT Furnace gig
Bravo! -- Max Dillon Charleston SC On February 21, 2019 12:20:50 AM EST, Curley McLain via Mercedes wrote: >Nothing stops a trainexcept a dead transformer! > >a few days ago the thermostat quit. (figgered it out on Monday, a >holiday. NOT good) Lights had been flickering, so I figgered the >low >volts fried the thermostat. Pulled it off a few days ago. (Monday) no > >volts at the thermostat. So, up to the furnace. Volts into the >transformer, no volts out. H. HVAC forums are like Dr Booth >and the Klima relay. "They NEVER fail" Ooops! I've had salvaged >transformers for years and never needed one. Well, they went up Nort. > >none here. tried several places to buy a new one. no dice. Fleabay >was about $20, HD was $35 but none in stock. On Tuesday I went to >Johnstone (HVAC supply) and paid $32 for a new one. Ole one has spade > >terminals, 1/4 for high, 3/16 for low. new one has wires. Tried all > >over to find 3/16 male spade terminals to crimp on the wires. No dice. > >tonight I decided to cut the low voltage terminals off the wires and >use >wire nuts on the low voltage side. > >got it installed. put the thermostat back on the wall. It works! >turned up the temp to make the furnace go on. > >No heat! What? > >back up, looked at the board. two flashes. > >Restarted. Igniter glowed, but no gaz. > >reset, started again. Same thing. HI didn't hear or feel the gaz > >valve open or click. > >look around. On the gaz solenoid, there is a marking ON and OFF and > >a little black plastic stub. H Pushed the stub toward ON. >It moved! Restarted: Far in the hole! > >Success! Furnace is heating again. > >Beware the 24v transformer on your furnace! In spite of what the >"experts" say, they DO burn out, and WILL leave you in the cold! > >Fortunately the days here have been fairly warm. Otherwise finding a >transformer would have been a VERY HIGH priority! > >This one was a trane, but the 24V thermostat is standard on all >furnaces. > >___ >http://www.okiebenz.com > >To search list archives http://www.okiebenz.com/archive/ > >To Unsubscribe or change delivery options go to: >http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
[MBZ] OT Furnace gig
Nothing stops a trainexcept a dead transformer! a few days ago the thermostat quit. (figgered it out on Monday, a holiday. NOT good) Lights had been flickering, so I figgered the low volts fried the thermostat. Pulled it off a few days ago. (Monday) no volts at the thermostat. So, up to the furnace. Volts into the transformer, no volts out. H. HVAC forums are like Dr Booth and the Klima relay. "They NEVER fail" Ooops! I've had salvaged transformers for years and never needed one. Well, they went up Nort. none here. tried several places to buy a new one. no dice. Fleabay was about $20, HD was $35 but none in stock. On Tuesday I went to Johnstone (HVAC supply) and paid $32 for a new one. Ole one has spade terminals, 1/4 for high, 3/16 for low. new one has wires. Tried all over to find 3/16 male spade terminals to crimp on the wires. No dice. tonight I decided to cut the low voltage terminals off the wires and use wire nuts on the low voltage side. got it installed. put the thermostat back on the wall. It works! turned up the temp to make the furnace go on. No heat! What? back up, looked at the board. two flashes. Restarted. Igniter glowed, but no gaz. reset, started again. Same thing. HI didn't hear or feel the gaz valve open or click. look around. On the gaz solenoid, there is a marking ON and OFF and a little black plastic stub. H Pushed the stub toward ON. It moved! Restarted: Far in the hole! Success! Furnace is heating again. Beware the 24v transformer on your furnace! In spite of what the "experts" say, they DO burn out, and WILL leave you in the cold! Fortunately the days here have been fairly warm. Otherwise finding a transformer would have been a VERY HIGH priority! This one was a trane, but the 24V thermostat is standard on all furnaces. ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
