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?
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.
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.
JJ> we have a honeywell programmable thermostat for a water-based heating JJ> system.
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.martinþATþthesafebbs.zeppole.com ®
All must be held accountable, but don't quote me on that.
They do. There is a reason for this, and a good Honeywell mercury switch stat, can be better than a Chronotherm model when it comes to comfort. Its called a dead band, and since MOST people can not actually feel the 3F difference in temps, you never know.
Personally, the 1F deadband on the digitals is a misleading thing. Some have been suckered into the hype, that its better, but depending on the system, it can actually be more than that. You figure in the built in time delay on some, (up to 5 min) and then, if its a heat pump for example, the 5 min delay on the defrost board for start, and some homes can drop a couple more degrees on a harsh day in that time..so....its cycled and thrown the adaptive recovery into a tizzy.
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.
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.
And if you had talked to someone at Honeywell that knew what he was doing, he could have sent you for free the resistor that should have been in the box to start with...
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.
(it's a honeywell MagicStat or something like that, BTW. digital programmable thermostat. it's supposed to be +/- 1 degree from temperature) well I followed their instructions. I set the metal screws behind the stat for a hot water boiler (or furnace, same settings)
the set temp doesn't change in the future as someone suggested, it's always set at 71F but for some reason, in the morning, it shoots up. this morning it was at 74. in my room I had 26 celcius instead of 22.
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