Trouble Shooting Poor Temperature Regulation

This page lists problems that may affect the temperature performance of your Lux programmable thermostat with suggested resolutions.
 

For more detailed information please refer to the instructions that came with your thermostat.

Those instructions can be viewed in PDF format here.

 

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TEMP REGULATION
Model DHP2110
Problem Resolution
Fan On continuously
  1. Move Fan switch from ON to Auto
  2. Remove the "G" wire. If fan continues to run, then either the system is miswired, or the problem is in the system, not the thermostat.
   
Indicates incorrect room temperature
  1. Refer to thermostat manual to verify that your set temperature is what you expect it to be. The set temperature is always visible with "SET" below.
   
Heats or cools more than 5 degrees past
its displayed set temperature
  1. Refer to thermostat manual to verify that your set temperature is what you expect it to be. The set temperature is always visible with "SET" below.
  2. Remove thermostat body from the wall, leave the backplate in place. Verify that Heating and cooling switch off within a few minutes.
  3. Replace the units batteries with fresh Duracell ® or Energizer® alkaline batteries.
  4. Set unit to heat mode. Adjust set temperature to at least 5 degrees below room temperature. Then adjust set temperature upward one degree at a time. Listen carefully for a soft click from the thermostat. This click should be heard near room temperature.
  5. Refer to your units manual to decrease the units swing setting to a narrower setting.
  6. Verify that your units placement and mounting are optimum per the installation section of it's manual.
  7. Refer to wiring to verify that it is according to the wiring diagram for your system.
   
No heat or cooling when expected.
  1. Note that in Cool Mode the thermostat may not activate a cooling stage until its compressor protection time has elapsed this may be a long as 5 minutes.
  2. Refer to thermostat manual to verify that your set temperature is what you expect it to be. The set temperature is always visible with "SET" below.
  3. Replace the batteries with fresh Duracell® or Energizer® alkaline batteries. Press reset with small Phillips screw driver. It may be necessary to reconfigure some settings after a reset.
  4. Set unit to heat mode. Adjust set temperature to at least 5 degrees below room temperature. Then adjust set temperature upward one degree at a time. Listen carefully for a soft click from the thermostat. This click should be heard near room temperature. Adjust set temperature down one degree at a time. Again listen carefully for a soft click from the thermostat near room temperature.
  5. The brass contacts in your thermostat may need to be cleaned and/or tightened. Each contact is comprised of a pin protruding from the rear of the thermostats circuit board, and two V shaped two contacts on it's wall plate. These contacts are located above each screw terminal. Insert a small regular screw driver at one side of a "V" contact. Turn the screw driver to slightly bend the top of each "V" contact toward it's mate.
  6. Refer to wiring to verify that it is according to the wiring diagram applicable to your system.
   
Advanced Trouble Shooting
  1. If your system is a low voltage system having 24VAC or less, and you are technically inclined, you may jump terminals as given below out to detect a malfunction in your system. If your
   

Fan Test

  1. FAN TEST: If your system has a fan, test it first.
  2. If the system is Heat only, or if there is a jumper between the "RH" and "RC" terminal of your thermostat, then with the power ON at the fuse box, touch the "G:" wire to the "RH" terminal. The fan should come on immediately and stay on. The rush of air is usually easily heard.
  3. If the system is Cool only, or if the system is Heat and Cool and there are separate wires to "RH" and "RC", and there is no jumper between them: then with the power ON at the fuse box, touch the "G:" wire to the "RC" terminal. The fan should come on immediately and stay on.
  4. If the fan does not come on it is an indication that there is a problem with your system. Check any breaker o fuses that fed the 24VAC transformer that powers your system
  5. If persists, contact qualified service personnel for aid in determining the fault.
   

Heat Pump Test

  1. To test a heat pump system with an "O" wire, three wires must be connected together with the power terminal. The power terminal is "R". "RH" and "RC" with a jumper between them my also be consider to be a single "R" terminal. With the power ON at the fuse box, connect the "O" and "Y" or "Y1" and "G" wires to the "R" terminal for a couple of minutes and the unit should provide cool air. Wait at least 5 minutes and repeat this test without the "O" wire. The unit should provide Heat.
  2. To test a heat pump system with a "B" wire, three wires must be connected together with the power terminal. The power terminal is "R". "RH" and "RC" with a jumper between them my also be consider to be a single "R" terminal. With the power ON at the fuse box, connect the "B" and "Y" or "Y1" and "G" wires to the "R" terminal for a couple of minutes and the unit should provide warm air. Wait at least 5 minutes and repeat this test without the "B" wire. The unit should provide cool air.
   
 
  1. Contact your HVAC service company or our Technical Assistance
    Line if not resolved.