Question about Air Conditioners

1 Answer

Thermostat set at 71 deg overshoots to 74 deg

Posted by on

  • Anonymous Dec 06, 2008

    the thermostat that over shoots from 71 to 74 is honeywell T8865A Chronotherm (wireless).the heating system is steam.

  • serco 2000 May 11, 2010

    What king of heating do you have?

×

1 Answer

  • Level 2:

    An expert who has achieved level 2 by getting 100 points

    MVP:

    An expert that gotĀ 5 achievements.

    Novelist:

    An expert who has written 50 answers of more than 400 characters.

    Governor:

    An expert whose answer gotĀ voted for 20 times.

  • Expert
  • 124 Answers

If its a mercury bulb stat it must be perfectly level. or it will overshoot or under shoot depending on which way it is out of level. the heat anticipator under the cover if its an older stat should be .4 to .6 or it will over shoot. that is what lets it know that by the time it shuts off burner or strips and cycles down the fan it should be at the desired temp. if its digital be sure the hole in the wall behind it is sealed 100 percent. even a little cold or warm air leaking into the back of the stat can cause faulty readings and over or under temps. if this doesn't correct the stat itself may be bad and in need of new. good luck.

Posted on Dec 05, 2008

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

WHY DOES MY FURNACE SHUT OFF BEFORE REACHING TEMP


Hi Demetrio
Furnaces turn on and off based on what they're told by your thermostat. The thermostat, in turn, will control the furnace based on:
  1. The temperature AT the thermostat.
  2. What the internal heat sensor thinks the temperature of the air is.
So, if your idea of 68 degrees is what the thermostat thinks is 71 degrees (thermostat reads three degrees high), then when the air by the thermostat gets to about 65 degrees (by your account), it'll think it's 68 degrees and shut the furnace off.

Also, if the thermostat is, say, near a source of local heat, like a lamp, a big piece of electronics, a fireplace, or that place that you habitually set down your coffee, then the air right next to the thermostat may be warmer than the rest of the room, and fool it into thinking it's at it's target.

The sensor is usually inside the housing for the thermostat. If it hasn't been dusted in a while, then it can be hard for air to get inside to affect the sensor, though this would generally cause it to lag on readouts and run the temperature higher than you wanted.

If you have a digital readout, and the system is saying , hey, target is 68, and the readout gets to 66 and the system cuts off the furnace.... my only other guess is that the unit may have features that are trying to prevent overshoot - i.e. by the time the temp at the thermostat actually gets to 68, most of the room is more like 73. That'd depend on your particular thermostat. At that point, you may want to call customer service with the manufacturer and tell them the issue. There may be ways to adjust the unit to get behavior closer to what you seek.

Good Luck!

DH

Jan 25, 2016 | Air Conditioners

1 Answer

When in the heat mode the system will start and rune only a few seconds then stop. After a short pause the system will re-start and run ubitl the set temp is reached


Bruce, what you may be hearing is a short cycling of the fan and not a short cycling of the system. The fact that you indicate it only does it once per cycle kinda suggest that. If the ENTIRE unit was shutting down, it could indicate an adjustment in the 'heat anticipation' circuit on the thermostat sub-base was required. The heat anticipator is an adjustible resistor on non-digital thermostats that warm the spring that rotates the mercury bulb to cause it to shut off just a little bit before attaining setpoint...thus 'anticipating' the shut down temp and not 'overshooting' the setpoint.

Too low of a setting and the system will short cycle, too high of a setting and the system will overshoot the setpoint. The typical setting is .4 amp which is where the majority of sub-bases are set at from the factory.

Nov 12, 2015 | Hunter 44860 H Univ. Touchscreen...

1 Answer

My thermostat show 74 degrees as a current room temp...but we have it set at 70 and it's probably 65 in the house. ..the only way it will turn on is if I put it 74 or 75????


The old white-rogers thermostats with a mercury switch are adjustable. snap the face off. In the center you will find a plastic slot screw. set the indicator to the actual room temp.
Other type ? Replace the thermostat

Mar 01, 2015 | Air Conditioners

1 Answer

Set thermostat at 74 heat pump will not cycle it will cycle at 75 degrees ?


check stat calibration. see if you can measure temperture at stat. the thermostat cover temperture reading is not that accurate.

Jun 01, 2014 | Goodman CLQ36AR49 Air Conditioner

1 Answer

What are the numbers on the metal strip on the inside of my thermostat from 1.0 @ the bottom too .2 at the top it has a bronze sliding clip with point on it I moved it and not sure if my temp setting


You shouldn't be messing around inside the thermostat. You have now changed the setting on the heat anticipator.This control is used to set the heat, so the heat shuts down before and in anticipation of the heat reaching its set point so it doesn't overshoot it. This thermostat will have be to reset by a pro. I believe it would be cheaper to just buy a new digital thermostat.

Jun 21, 2013 | Intertherm Heating Cooling System 15kw...

1 Answer

Unit will not heat, change batteries controller cleaned filters etc. Still blowing COLD air


Check the thermostat setting...in the auto machines, with a reversing valve, there is no heating or cooling, generally, in the sensing temperature band of 19 Deg C to 22 Deg C and it only works on blower mode, re-circulating the room air. When the sensing temperature goes below 17 deg C, it works on heating and when the sensing temperature goes above 24 deg C, it works on cooling

Sep 05, 2011 | Air Conditioners

1 Answer

I have a White-Rodgers programmable thermostat. I have it set to go to 74 degrees at 11:00 PM. It has started going to 74 at between 10:00 and 10:30 PM. If I press run it goes back to the daytime temp...


Hello I assume its cooling program.Probally the thermostat has a recovery mode.In another words the thermostat will come on EARLY to make sure you are at (74*f at 11:00).Maybe try 11:30 start time and see if that helps or disable energy recovery mode.

Jun 17, 2011 | Air Conditioners

Not finding what you are looking for?
Air Conditioners Logo

Related Topics:

45 people viewed this question

Ask a Question

Usually answered in minutes!

Top Air Conditioners Experts

Dan Webster
Dan Webster

Level 3 Expert

8147 Answers

Bill Long

Level 3 Expert

577 Answers

Tim Whalen

Level 3 Expert

3056 Answers

Are you an Air Conditioner Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...