god damn thermostat!

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we have a honeywell programmable thermostat for a water-based heating system. it often gets much hotter in the house than I se the thermostat to, and I always attributed this to the fact that the baseboard heaters are located at the extremities of the house while the htermostat is in the middle of the house, with no heater close to it.
today, however, I woke up to a temperature of 73 fahrenheit while the thermostat is set at 71. I just saw the thermostat turningon the heating system, even though the temp has been a constant 73 since this morning, it's not too cold outside and the temp is still set at 71.
what on earth could possibly make this thermostat turn the heating on when it's set at 71 and the temp reads 73?
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the anticipator is off, or the thermostat is out of calibration. or maybe its bad. A pro will come along with the correct answer, Im guessing. My digital I can recalibrate. How old is it.
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1 year
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Is your stat electronic or analog (mercury bulbs)? If it's analog, make sure it's level and calibrate it with a calibration wrench and an ACCURATE thermometer.
If it's electronic (digital), it could be a couple of things. First, make sure that the anticipator is set for baseboard heat. You don't say whether your baseboard is oil or gas fired. Makes a difference. Consult the owners manual. Remove the stat from the sub-base and look on the back.. You'll see at least one, maybe two or three set screws. These set the anticipator. Follow the instructions molded onto the back of the stat for proper settings. While you have the stat off the base, stuff a good-sized wad of insulation into the hole that the wires go through. Make sure no drafts are coming up BEHIND the stat and throwing off the reading. Also, blow any dirt/dust off the thermistor (sensor) on the stat.
Second, check your programming. Honeywell takes the liberty of programming adaptivity into its electronic stats. In other words, setting a 6-degree increase in temperature at 6:00 AM might cause the stat to begin "ramping up" as early as it needs to in order to have the temperature up BY 6:00 AM. This could mean several hours if the system is undersized or in high-load situations. Even though the SETPOINT might be 71, the stat is "looking ahead" at having the temp at 75 in a couple hours. Rather than blast the heat for a half-hour to get there, it brings it up a quarter-degree at a time over a 2-hour period. It varies, too. The stat "learns" how long it need to accomplish the feat, and adjusts seasonally. Nice feature, but takes some getting used to. On the back of the stat, there should be another screw which will turn off the adaptivity, making the stat operate like a mechanical setback model most people are accustomed to.
I've also seen spark ignitions make digital stats go haywire. The ignitions in some gas furnace/boilers, and all oil-fired equipment, is very high voltage and may cause spikes to reach the stat. Although this was an issue which was addressed long ago, some older equipment may still cause problems for newer stats. An isolation relay in the circuit usually cures this.
Good luck and post the results.
--
C.J.

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J J:
JJ> we have a honeywell programmable thermostat for a water-based heating JJ> system.<snip> JJ> what on earth could possibly make this thermostat turn the heating on when JJ> it's set at 71 and the temp reads 73? It's going to become pretty obvious I don't know a thing about water- based heating systems but I'll say it anyway. Any possibility it's the wrong type of thermostat or it's set to 'cool' instead of 'heat'?
- barry.martinATthesafebbs.zeppole.com
* All must be held accountable, but don't quote me on that.
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Don't most stats have a plus or minus 3 degrees or so in latitude in when they turn off or on ?
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"barry martin" < snipped-for-privacy@rime.org> wrote in message
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I don't know about most, but that is my experience with mechanical thermostats and it makes for a miserable house. OTOH, my Honeywell digital never varies more than 1 degree when it is stabilized and running automatically. This thermostat was a huge improvement from the mechanical one. OTOH, if you manually boost the temp, it can take sometime before the furnace comes on and the thermostat manual indicate that is normal. If it doesn't come on immediately I just boost the temperature up another 3 or so degrees and as soon as it starts I move the temp down to where I wanted it. Again, after it stabilizes (goes through one on cycle), it won't vary by more than one degree.
Steve Stone wrote:

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CBHvac wrote:

I bought our digital to control an electric furnace and it has now controlled our gas furnace for the past 2 years. It facinated me, so I've watched it closely and often hung both regular and other digital thermometer right next to it to check temperatures. As I said in an earlier post, it doesn't vary more than a degree and the difference in comfort, both for heat and cooling is amazing. May be one of a kind , but that's my experience.
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The RobertShaw thermostat that came with my house was +-1 (2 degree F spread) at best, and usually overshot 1-2. It had no anticipator setting, just gas/electric switch.
I changed to Honeywell CT3500 (should have gotten CT3600) with 1 degree spread, and by comparing air and wall termperature learns to electronically anticipate temperature rise to shut off before it reaches setting if necessary (since steam radiators retain heat), and ramps up from setback instead of all at once. It only rarely overshoots slightly if the weather suddenly turns very mild. The only reason I would have liked the CT3600 is because it logs total run time to tell most effective setback.
I don't know if the original poster gave a model number or whether it was wired or set properly for their hydronic system. But my Honeywell electronic works great for single-pipe steam, although, I my old home has plenty of thermal mass (drywall over plaster), so temperature changes are never sudden.
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I too, have one of the Honeywells. I can't seem to find the model number on the unit, but I remember that it was something like the previous poster's 3500 or 3600. It has the "electronic anticipation" and has worked extremely well with my gas furnace. I have also checked it with both termocouples and traditional mercury thermometers and found it to be right on. Occationally, and very occationally at that, I do get an anticipator failure. By this I mean that the furnace fires up and then, before the blower comes on, it shuts down. This seems to be related to the temperature and temperature changes. As I said, it only happens extremely rarely. BTW, one of those "smart" furnace guys came into my house and said "the Honeywell is junk." He's junk. This is why I do most of my own rebuilding/repair. BTW, I once bought a digital thermostat that advertised a +/- 1/2 degree accuracy. It had no anticipator. It, combined with the gas furnace, overshot by 6 or 8 degrees. I returned it right away. It had a bunch of big C batteries in it. BTW, the Honeywell batteries (I think they're AAs) last for years. I don't know when I last changed them and they are still going strong. Great Product!
David Efflandt wrote:

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I hate to "reply" to my own post, but I just remembered some additional info. I originally bought a 3200, which has an electronic switch (triac) to turn on the gas valve. Well, on my old furnace (1970 model) it would not let the gas valve close completely due to some minute leakage of the switch device. On warmer days, where little heat was required, I noticed a very slight smell of gas right in front of the burners. Honeywell tech people responded that this can sometimes happen and sent me a new model that has a relay in it. It was a 3400 (I just pulled off the front to check) which solved the problem and is still working perfectly. BTW, the old 3200 is still being used for AC as a 2nd thermostat for pseudo zone control.
Art Todesco wrote:

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Really. How is the resistor connected and what is it supposed to do? Is it just a shunt to divert the leakage current? I guess it was just easier to send me a whole new unit. BTW, I don't recall there being any resistor in the original box ... but that was a long time ago.
CBHvac wrote:

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CBHvac thinking his shit don't stink wrote:

And if you had your swollen head outa your ass you'd snip the extra crap out of your replies.
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And merry fuck you too...sorry...did you say something? I think you had your head up Stormys ass when you posted..
If you dont like it, you know how to set filters..and if you dont, perhaps when you get done reaming Chris out, you can learn about it.
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CBHvac wrote:

Child..
I remember when you first hit the scene here. You gave good advice for the most part and steered clear of arguments and nonsense. It appears you relish in it now. Everyone can see ole Stormin Moron is a yutz. So what? You're no better anymore.
It's one thing to blast a guy for giving stupid or lousy advice, but you follow this guy around with your nose so far up his ass there's no way anyone could give him a reaming without going through your ear canal.
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Nah...tired of the crybabys like you... Waaa...you got me all teary eyed...
Deal with it, or dont...it matters to me about as much as if you wake up in the morning...hint...it doesnt.
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CBHvac wrote:

As I said... 'child'.
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CBHvac Spilled my beer when they jumped on the table and proclaimed

After reading a few of his messages, I realized that it's just the standard garden variety troll, and plonked him... <G>
Yanno my theories on this...
NOI
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