Honeywell Heat Pump Thermostat Troubleshooting. Hello Richard! We have a Honeywell VisionPro (8000) thermostat with a Carrier heat pump that has two stages for heating and cooling. We are having problems with the staging of the system, especially in heating mode.
I know the problem also occurs in the cooling mode but it seems worse in the heating mode. The house seems to get uncomfortable even though the system is running and then finally after the thermostat gets to a certain point the second stage will turn on and we feel the difference. It doesn’t matter where we set the thermostat to for temperature. A friend of mine suggested I had a problem with a limit switch.
We also notice sometimes the outside temperature reading on the thermostat is incorrect sometimes and rarely matches the reported temperature from our News sources where we live. Just wondering what your thoughts are and if you can guide us in the right direction. We found your site by doing a search for Honeywell thermostat problems. Anyhow, can you help us, please? Thanks in advance!!!
Carrier Heat Pump Staging | Honeywell Heat Pump Thermostat Troubleshooting
Honeywell Heat Pump Thermostat Troubleshooting - Now for the staging of your Carrier heat pump. There are some settings in the thermostat that need to be looked at. The installation manual that came with the thermostat should give you instructions on these settings. If you do not have the installation set-up instructions the try Honeywell.com. Each thermostat is different so make sure you get the installation manual for your model of thermostat.
There are many different variations for various thermostats for the settings. These settings must match the type of system that you have installed for HVAC equipment. If they are not set correctly then you will definitely have the problems you are describing here.The first setting I want you to look at is the following:
- Setting 0170
It is imperative that this is set to option 11 (if you have no backup heat source such as electric heat strips) or option 12 if you do. This setting controls staging for a heat pump. It is possible someone installed your thermostat and did not include staging in the installation settings.
You may also want to check the wiring to make sure it is correctly wired. We have several thermostat wiring diagrams here in the thermostat category for you to browse.
Find the heat pump wiring diagram page and check it. For your convenience, I’ve screen captured a wiring diagram from the Carrier Two-Stage heat pump installation manual. What Carrier calls a Thermidistat is actually your thermostat.
A thermidistat controls humidity and temperature at the same time. It looks like a thermostat but has additional controls and settings inside to control a humidifier. See the Carrier two-stage heat pump control wiring diagram below.
Temperature Staging Settings P + I Control | Honeywell Heat Pump Thermostat Troubleshooting
This thermostat has what Honeywell calls P + I control. Here is what Honeywell says about this feature:
Second Stage Heat and Cool Control
“While maintaining setpoint, several factors affect when 2nd
stage energizes such as load conditions, environmental
conditions, P+I control, and home insulation. The second
stage energizes when the thermostat senses 1st stage is
running at 90% capacity. This operation is “droopless” control”
Essentially, in layman’s terms, this means the thermostat is intelligent and can learn. It takes into account the time and the temperature and compares it to the setpoint. If the system is falling back and losing ground, within a specific time frame as determined by the program, it will energize stage two. For heating mode, it will also energize stage 3 or auxiliary heat if you have it installed based on the same parameters.
What is Droopless? | Honeywell Heat Pump Thermostat Troubleshooting
You may be asking what Droopless control is? Time to scratch the back of your head and go “hmmm”???? Because this gets a little complex. Basically, it is a method of controlling staging in the thermostat that is different than older methods. It is a method Honeywell has patented. It uses Proportional and Integral (P + I) control methods. This takes a smart thermostat to process by the way.
In Layman’s terms, it is time and distance where distance, in this case, is measuring the temperature variable. The time is how long the system is running in single-stage, temperature swing, and the CPH or Cycles per Hour. It learns the ability of your system to keep up based on input information it keeps inside the program of the thermostat. This is not something you can change in the thermostat program but rather something the thermostat program learns on its own. Essentially, in the patent, it states:
I would say this is not your problem but the previously mentioned settings and wiring is your problem. That’s just a gut feeling and I could be wrong. If you check the other settings and wiring and find no problems then I would try to use a two-stage thermostat that does not have the P + I control feature. Those thermostats will give you the option of setting a temperature variance to make the stages kick in. In other words, you can have a 2° F temperature offset from one stage to the next.
Recovery Settings | Honeywell Heat Pump Thermostat Troubleshooting
- Setting 0680 (heating)
- Setting 0690 (cooling)
These settings have the following tweaks or options for your thermostat control of the heat pump.
- less aggressive temperature control (could cause the temperature to undershoot)
- Standard temperature control in heating (factory setting)
- more aggressive temperature control (could cause temperature overshoot)
For you, I would make sure it is set to option 3 for both 0680 and 0690. These settings actually apply to recovery ramping of the system meaning when the thermostat has been set back on the program this feature will allow a more aggressive recovery.
Dual Fuel Carrier Heat Pump Systems Troubleshooting
What is dual-fuel? Dual fuel is when your heat pump uses a gas furnace for back up heat rather than electric heat strips for backup heating. I think your particular problem doesn’t really have anything to do with any furnace controls so it will not require and furnace troubleshooting. Furnace systems troubleshooting or heat pump systems troubleshooting will likely require a professional to check for any problems. The depending on the type of gas furnace system you have will depend on the type of furnace controls. This includes limit switches as your friend suggested.
A limit switch is designed to turn the heating source off of it exceeds a set limit temperature. The gas furnace controls will also depend on the level of efficiency you have if you have a dual fuel heat pump system. Where higher efficiency gas furnace systems have more complex controls. Again, I doubt your problem is related to any problem with your furnace or furnace controls if you have a dual fuel system. Anything from basic heat pump troubleshooting should be done by a professional. Heat pump troubleshooting requires a thorough knowledge of heat pump components and sequence of operation for various heat pump heating systems.
Outside Air Temperature Sensor | Honeywell Heat Pump Thermostat Troubleshooting
I know some of the legacy Honeywell VisionPro thermostats do not have WiFi capabilities so if you have the WiFi version this part will not apply to you. The older VisionPro’s have terminal connections S1 and S2 on the sub-base or wall plate of the thermostat and if these are connected to thermostat wire on your thermostat then you have an outside air temperature sensor. Here are two things to check if you have this temperature sensor hooked up.
Honeywell Heat Pump Thermostat Troubleshooting: Outside Air Temperature Sensor Installation
- Check the location of the temperature sensor. As the illustration shows it should be installed in a shaded area away from any heat sources. The heat sources include radiant heat sources such as asphalt or other things that absorb and give off heat. You only want the temperature of the outside air and not some other temperature influence. A dryer vent can also cause problems with this. A temperature sensor installed over a condensing unit can cause abnormal temperature fluctuations also. An attic fan blowing hot air on it will also cause issues.
- The thermostat wire used to connect the outside air temperature to the thermostat. This wire needs to be a special thermostat wire. It should be shielded wire. The shielded wire prevents interference from other electrical wiring and appliances. Other electrical wire gives off an electrical/magnetic field. This electrical/magnetic field can cause abnormal temperature readings because it interferes with the signal in the wire if it is not shielded wire. The shielded wire has an outer insulation jacket and an inner jacket made of a foil that reflects electrical/magnetic interference.
Importance and Purpose of Shielded Wire | Honeywell Heat Pump Thermostat Troubleshooting
If you do not have this sensor connected with shielded wire then it is possible interference is occurring throwing off the temperature. Checking this will require removing the thermostat from the sub-base. If the thermostat wire is different than the regular thermostat wire then it has a dedicated wire to the sensor. The wire should also have a foil-like aluminum foil around the conductors. The foil is under the outer jacket of the thermostat wire. When removing the thermostat from the sub-base give it a gentle pull and it should release easily. Removing the thermostat from the sub-base is not super difficult.
Conclusion | Honeywell Heat Pump Thermostat Troubleshooting
You can troubleshoot the heat pump for additional problems but I only recommend a professional do this as the condenser unit and air handler unit has high voltage and many moving parts that you likely will not understand. As with any heating system whether it is a gas furnace or a heat pump or other type of heat system there are also safety issues that you may not be aware of.
With heating systems, there are limit switches, furnace controls, and other technical things in the condenser unit and gas furnace or air handler that sometimes need to be checked. And the type of heat pump system troubleshooting or even gas furnace troubleshooting should be checked by a professional who is familiar with these things.
I hope that helps you solve all your Honeywell thermostat staging issues with your Carrier heat pump. Troubleshooting a thermostat can be a bit complex with the newer types of thermostats and heat pump systems with two stages. I try to slice through the technobabble and so you can better understand what’s going on. This will, hopefully, help you solve your thermostat problem! Don’t forget to share us on social media. Thanks!!
Honeywell Heat Pump Thermostat Troubleshooting