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I’m becoming hot and bothered…

Clive Maxfield
11/21/2011 07:02 PM EST

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PH Eng
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re: I’m becoming hot and bothered…
PH Eng   12/7/2011 5:14:14 AM
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Years ago, I noticed my car's speedometer was reading 3 mph too high at 70 mph. (This was the days before GPS, and I used highway mile markers and stopwatch to do the calibration.) So the next time I needed new tires, I opted for 195 instead of 185 size. That corrected the speedometer error. The only inconvenience was that, each time I bought new tires (that car lasted 20+ years) I had to convince the guy at the shop to sell me the "wrong size" instead of what his computer said my car should use.

Max The Magnificent
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re: I’m becoming hot and bothered…
Max The Magnificent   12/5/2011 8:33:32 PM
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## Solution [...] grab a beer and walk away... I'll drink to that!

TFlynn
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re: I’m becoming hot and bothered…
TFlynn   12/5/2011 8:16:23 PM
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I have a similar problem. (I'm still alive from the hot flash comments ;^) ) I went from 1 stage heat & 1 stage AC system to a 3 stage heat, 2 stage cool heat pump system. Problem was I only had 4 wires in the walls. And difficult to rewire the house! So found modules that "communicate" over the 4 wires to run all these modes. But the modules generate a bit of heat right behind the thermostat. I moved the thermostat to the other side of the wall and dropped these modules lower down within the wall to help prevent the heat getting to the thermostat. I'm still sure I could tune this setup to 0.5 degree accuracy. But I would still have the problem of wife & daughters complaining about it either too hot or too cold or both! Solution: moving up or down, grab a beer and walk away, wait for next complaint. ;^)

Max The Magnificent
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re: I’m becoming hot and bothered…
Max The Magnificent   12/5/2011 2:18:21 PM
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There were a lot of clever inventions like this -- I presume that micro-controllers have taken over these days...

Max The Magnificent
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re: I’m becoming hot and bothered…
Max The Magnificent   12/5/2011 2:17:26 PM
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Re the light source -- we ran into this problem a year or more ago... My wife put a small wooden table in the alcove outside our bedroom door and put a light on the table... In the middle of the summer one evening we were freezing, but the Thermostat said the temperature was on the warm side... It took me ages to realize that it was the light on the table under the thermostat on the wall that was heating the thermostat up and causing it to run the air conditioning full blast...

bcarso
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re: I’m becoming hot and bothered…
bcarso   12/4/2011 5:27:05 PM
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This reminds me of an invention of years back, which was a bimetallic circuit breaker with a lamp filament in the vicinity. It opened the circuit for sustained overcurrent, and then the filament across the contacts glowed and prevented the breaker from resetting unless the power was interrupted externally. This meant that certain transformers which had this in their primary windings could be overloaded and open the circuit, but then rather than cycling endlessly simply remain off until someone independently removed the power for a little while. My father thought it a great idea, but no one seemed to be interested in qualifying it for agency-sanctioned use.

bcarso
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re: I’m becoming hot and bothered…
bcarso   12/3/2011 9:23:33 PM
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Do you remember the Read-Rite meters? They were usually spring-loaded permanent magnet-based, and were usually terrible. Naturally they got to be referred to as Read-Wrong meters. On the subj of constant temperature, the UCLA photodiode array spectrometer required quite stringent constant temperature operation, because in my zeal to have lowest noise I used a single JFET for each video line, and its gate-source voltage at a constant drain current as the diode bias. The 2N4416's used had as mauch as a 12mV/degree Kelvin tempco under those conditions (about -100mV Vgs. The system that regulated the temperature even while suffering the fluctuations of a telescope dome ambient during the course of the night managed few-millidegree stability over an hour, using thermistor feedback and Peltier coolers, coupled to a liquid ethanol heat exchanger, with the cooling coils immersed in a dry ice/isopropyl slurry. The operating temperature was near that of dry ice, sufficient to make JFET gate leakage about 1fA and enhance transconductance (thus reducing thermal channel noise) a little. What a kludge!

zeeglen
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re: I’m becoming hot and bothered…
zeeglen   12/3/2011 3:22:54 PM
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Remember the Heathkit thermostat programmer? It had a 24 hour cycle (can't remember if it had a weekly cycle) that controlled a small incandescent bulb (#47 or similar IIRC) which the user attached to the wall thermostat under the temperature sensor, often a coiled bimetallic spring with a mercury switch back then. The lamp intensity was controlled with a pot adjustment, the idea was the heat from the lamp would fool the thermostat into a temperature setback at the programmed times. It took a bit of tweaking the pot to get the lamp intensity right for the desired degrees of temperature drop, but it worked.

tomkinsr
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re: I’m becoming hot and bothered…
tomkinsr   12/3/2011 6:17:50 AM
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Follow up to Part 1 and Part 2, Possibly, you may be experiecing some influence on your thermostat, from a nearby heat source. I just added up all the lights in the candleabra, 6 times 50W,300W, wow.

tomkinsr
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re: I’m becoming hot and bothered…
tomkinsr   12/3/2011 6:12:52 AM
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Part 2 of 2 The second issue with cold is that the lights generated significant heat to influence the thermostat, when on in the winter, the thermostat was always warmer so it kept the furnace off, which made the house colder and in the summer, it kept the AC on, which made the house colder. We have trained ourselves to keep the lights off all the time, unless having dinner. Back to the furnace. In Ottawa, our electrical supplier was offering a $300.00 (price verified at Canadian Tire) thermostat to reduce energy consumption. The deal was, they would install it, for free, the thermostat, was free, they would come out any time and ensure it was working, if I complained, for free, and they paid me $25.00, to get all this free stuff. I had to remain in their program for one year; they had the right to turn off my air-conditioning during the summer, for 15 minutes, once per day, during peak demand. They turned my AC off twice last year, and I only noticed it because I looked at my electrical usage summaries. We all have smart meters now and the thermostat is also a smart device, that is how they control it, and I can control it and program it from work over the Internet. Oh, the new furnace that went with the thermostat or vice versa, a matched pair of Furnace and AC, with a claimed, better than 95% efficiency. My electrical bill is almost 50% lower and my gas bill is almost 45% lower.

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