# My Honeywell Vision Pro 8000 TH8110 is inaccurate and its acting up



## Electric_Light

I had the thermostat set to 69F before I left home. I first turned it down to 64, but since I was going to be gone for a while I decided to turn it "off". 

It was just installed, so its still being carefully monitored. So, I come home and it reports indoor temperature as 69F. I have a reference thermometer that is known accurate within 0.5F and it was reading 66.7F. 

I turn the thermostat on and turn it up to 68F and heat comes on, yet its reporting 69F currently. WTF? :furious:

Once its in on mode and let it run for a while, the reference thermometer and displayed temperature agrees within 1.5F. When it is in run mode, the display temperature is never different from set temperature, so I think it is filtered to show you what they want you to see to give you the impression that its holding the temperature as you set exactly. 

Internally I have no clue what its doing. How is it that actual temperature is 66.7F, report 69F and turn on the heat when its turned up from 64 to 68? 

It will often change in reading by two diegrees to. I've seen it jump straight to 68 from 70, with no transition and room temperature was not rising or falling rapidly.


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## flashheatingand

I would call the tech department at honeywell. Off hand, I would want to check out the configuration. Maybe to many button pushes or something. Having said that, I am not sold on the Honeywell touch screen stats. I am have had issues. I switched to an April-Aire stat which, so far, has been trouble free and cost about 40% less.


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## Electric_Light

beenthere doesn't know???!


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## beenthere

Was your reference thermometer mounted on the wall the same as the 8000?


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## Electric_Light

beenthere said:


> Was your reference thermometer mounted on the wall the same as the 8000?


Close as realistically possible. The gap between the wall and thermostat wire is caulked to keep the draft out. Reference thermometer sits right on top of the TH8110.

It still doesn't explain why Vision Pro reads 69, then heat comes on when it is set to 68...


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## beenthere

The display reading is rounded. The stat senses both ambient and radiant heat. A low radiant heat will cause it to come on even if the displayed temp is above set point.

Your reference thermometer doesn't read radiant heat separately. So its not a 100% accurate device to use.


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## Heritage Mt

It could be in the initial setup. There is an intelligent recovery setting in there. Is it on or off? I have had a similar problem before and replaced the thermostat and it was all good.


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## Electric_Light

Heritage Mt said:


> It could be in the initial setup. There is an intelligent recovery setting in there. Is it on or off? I have had a similar problem before and replaced the thermostat and it was all good.


It's off. It's being used as non programmable. It's no better than Hunter it replaced, to be honest.



beenthere said:


> The display reading is rounded. The stat senses both ambient and radiant heat. A low radiant heat will cause it to come on even if the displayed temp is above set point.
> 
> Your reference thermometer doesn't read radiant heat separately. So its not a 100% accurate device to use.


It's built just like my reference thermometer. It uses a thermistor on board. There's even an option for installing an external thermistor. It DOES NOT have a special radiant heat sensor.


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## beenthere

Electric_Light said:


> It's off. It's being used as non programmable. It's no better than Hunter it replaced, to be honest.
> 
> 
> It's built just like my reference thermometer. It uses a thermistor on board. There's even an option for installing an external thermistor. It DOES NOT have a special radiant heat sensor.


The 8000 series and 9000 series both sense radiant.

You can research it.


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## costello

have you checked the temp offset in the programing, This might explain the difference from what the display says and what the software is doing. I currently have one in my home and it works perfectly and have installed them all the time.


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## Electric_Light

costello said:


> have you checked the temp offset in the programing, This might explain the difference from what the display says and what the software is doing. I currently have one in my home and it works perfectly and have installed them all the time.


Offset is set to 0. I bought this brand new, so the settings are factory default, except for the ones I changed. 

I'm not exactly pleased with it, but it works. It cycles too often. Swing is not directly adjustable. 

I should have just kept my Hunter, which really didn't have any problems to begin with.


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## costello

Do you remember what changes your made.

Did you set it up to the correct type of system?
Also there is a adjustment in the later programing entries on how aggressive the tstat is, and you can also set up how many cycles per hour you will allow the tstat to turn the heat/cool per hour.

I have one of those in my house and i don't have the issue of the temp difference but i will say it does keep the temp excactly what i keep it on and does cylce the heat on when the tstat says what it is set for. Which in my case is fine since i have a multistage furnace. If you just bought it take it back and get anonther one they do have a year warranty you might just have a bad one.

Hope that helps


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## Dr Heat

Honeywell Has just released the latest in the world of precision thermostats it is called T87F it is round and is the best stat on the market.


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## beenthere

Dr Heat said:


> Honeywell Has just released the latest in the world of precision thermostats it is called T87F it is round and is the best stat on the market.



LOL...

Use to make good money from those stats.


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## Azpipe

So many questions. First let me say, I have installed many of these stats and many others by other manufacturers as well and these are by far some of the best stats out there. There are several things that should be looked at. Was the stats temperature calibrated by the installing contractor, or someone else? I haven't had one yet that needed to be field calibrated but the installation instructions say how to do it in the unlikly event that it needs it. Also If the dead band is set to close that could explain the early turn on. Trust me, Honeywell is a world leader in HVAC controls for a reason and it's not BSing their customers. These are great thermostats. Like any control if it is not set up properly it's going to act weird. The fact that it is turning on and off your unit suggests it is okay but not set up properly. Make sure this guy installed it right. You can be sure if there is a problem with the stat it will be replaced for free.


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## Electric_Light

The thermostat calibration is not field adjustable. The only setting is "offset" which allows field adjustment of display temperature up to 3 degrees in either directions. If you do mess up the settings, there is an option to reset, which brings back factory default. 

Dead-band is not relevant in my setup. It's only enabled for automatic transfer between heat and cool, which is not enabled by default. The only purpose is to prevent thermostat from hunting between cool and heat. Under default setting, the thermostat needs to be manually transferred between cool and heat. 

If I turn on the heat and set it to a temperature, the built-in screen will always read the same as the set temperature once the target is reached. Once you leave it at that, the reference thermometer usually reports within a degree of set temperature.

Still the touch screen is  and I'm debating if I should install that Rite-Temp. There's a lot of brand hate on that one, but the user interface seems really awesome.


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## Azpipe

*Go with the cheaper one pocket the money.*

Since you have such a deep understanding of these stats then why are you asking questions? if you really think the Rite Temp is better then the Honeywell,... that's fine, it's really about what works for you.

However, you can adjust the amount of drift between the set points. And it does effect the operation of the device even if your not using it in Auto. I know you think you are right on this, but you can field calibrate the temp read out, if that's the problem. I think it's interesting that you said you have a standard that is within .5 degrees (of something) and then you show a pocket thermometer. Make your life easy, install the one you like better and that's that. 

Good luck, and Happy New Year!


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## Electric_Light

Azpipe said:


> Since you have such a deep understanding of these stats then why are you asking questions?


What the software is doing inside is beyond my understanding. 



> if you really think the Rite Temp is better then the Honeywell,... that's fine, it's really about what works for you.


I haven't had the chance to try it, but I love the scroll wheel on my mouse. The scroll temperature setting is a great user interface in my opinion. 



> However, you can adjust the amount of drift between the set points.


There is "deadband" setting described in manual, but it is only shown if you enable automatic switchover. I think what you're talking about is "swing". Honeywell thermostats don't let you adjust "swing" directly. 



> I think it's interesting that you said you have a standard that is within .5 degrees (of something) and then you show a pocket thermometer. Make your life easy, install the one you like better and that's that. Good luck, and Happy New Year!


It's a "field standard". happy? It is checked against NIST traceable mercury standard and it is within 0.5F and the thermometer is NSF which ensures quality over some non-listed crap.


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