Honeywell T8600 D Stat Problems?

Neil Andrews

Thanks for your reply Bill,

I understand how the adaptive recovery is suppose to work, and that is really, why I purchased the Chronotherm 4 and would like to keep the adaptive recovery feature enabled.

What I am having a difficult time in understanding as why as mentioned in my previous post:

The stat was programmed to have the room temp at 70 at 6:00PM & at 6:30 I checked the stat and it displayed “Recovery” with room temp at 65 & NOT calling for heat.

Shouldn’t the room temp have been at the 70 by 6:30, if not the stat should have still been calling for heat?

This morning with the stat programmed to a Leave time temp of 62 at 8:00 AM it was 8:30 and the stat displayed “Leave” with room at 72 and it was still calling for heat with flame icon on.

Why was the stat still calling for heat when it was already 30 min past the Leave Time & the temp was past 70?

This is why I am questioning if there is a functional problem with the stat. It has operated this way in the past. It’s almost acting as if the electronic logic has been locked or zapped.

Thanks

Nick

Neil Andrews

I have a Honeywell T8600D IV power stealing stat that is less than 2 years old, which seems to be operating erratically.

For example last night, with the stat programmed to have the room at 70 at 6:00PM it was at 6:30 that I checked the stat and it displayed “Recovery” with room temp at 65 & not calling for heat.

This morning with the stat programmed to set back temp to 62 at 8:00 AM it was 8:30 stat displayed “Leave” with room at 72 and it was still calling for heat with flame icon on.

The stat does have a good 24V supply, the time is set correctly and I double-checked the set back settings for each day, all are set to factory settings and are fine. I ran through the Self Test programs and everything works properly ???

I am wondering if I have a flaky stat, or maybe the stat logic has been zapped.

Is there an alternate way to reset the logic on the stat, or do I need to disconnect power from it for a period of time ??

Maybe I need to replace the stat; I certainly would have expected it to last more than 1.8 years that is why I bought a Honeywell in the first place??

I look forword to hearing your comments.

Thanks

Nick Andrews

Mike T., Swampeast MO

Not certain of that exact model but you might want to try removing the thermostat (and batteries if they're not in the sub-base) and letting it sit for about half an hour.

You will probably have to reprogram the clock, but the setback program will likely remain intact. It should also clear the "Intelligent Recovery" memory.

I had a Honeywell t-stat with the "Intelligent Recovery" feature connected to a system where the A/C compressor was going bad and kicking out on high heat after it had run quite a while. This caused some sort of problem in the t-stat as it would appear to be working and the cooling and fan symbols would show, but the condensing unit would not start even after the compressor had cooled.

It almost seemed that the thermostat "knew" there was a problem because the temp wouldn't fall when the A/C was on and it "locked out" the A/C afterwards. Honeywell technician said that it "didn't do that" but it still seemed the effect.

Clearing the "Intelligent Recovery" memory as described above fixed the problem--until the compressor kicked out again on heat that is...

BillW@honeywell

There is probably nothing wrong with your stat...

Your Chronotherm 4 stat has what is called "adaptive intelligent recovery". It doesn't just turn the system on at the end of one period like the old mechanical stats did, it gradually ramps the temperature up, based on what the average room temps have been for the past 3 days, until it reaches the setpoint. While it is doing it, the display shows "recovery". For example, say your "sleep" setpoint is 60 degrees, and your "wake" setpoint is 70 degrees, and your "wake" time is 6:30 am. Depending on the heat loss of your house, and what the room temps have been over the past 3 days, the stat calculates when it should start ramping up the temperature at say, 5:45, so that it will be AT 70 degrees at 6:30, not just come out of setback at that time. It works that way for cooling as well. It is also a proven energy savings strategy. If you do not like that feature, it can be turned off by going into Installer Setup and selecting item 13, them change the 0 that's on the display to 1 by pushing the up or down key. Details are in your owner's manual or instruction sheet that was in the box with the stat. However, I don't recommend doing that, since it defeats the purpose of the Chronotherm 4.

You also can get instructions by going to http://hbctechlit.honeywell.com and type in T8600 to download all info on this product.

Neil Andrews

Batteries not included

Thanks for your reply Mike,

Its a power stealing unit, so I guess try pulling it off the base and let sit for a while with out any power as you suggested. Maybe any gremlins that are inside will get erased!! If that doesn't do it I guess I am looking at a new stat

Thanks

Nick

Mike T., Swampeast MO

Question for BillW

Does the Intelligent Adaptive Recovery system still use wall temperature as one of its' inputs?

The first Honeywell stat I used with that system stated such in the manual, but I don't recall reading such in subsequent.

Just curious. NOT "knocking" it AT ALL--I really like the system and have verified that it does what it claims--and does it with surprising accuracy.

Mike T., Swampeast MO

Computer Programs

Even if it is contained on a chip, the Intelligent Adaptive Recovery system is a computer program.

The most difficult task of a computer programmer is to anticipate EVERY possible occurrence. That problem is GREATLY magnified with a program that "learns".

If a single bit/byte/paragraph of "bad" data is stored in the "history" as valid it can easily send the program off into machine infinity...

Just as weatherstripping the meeting rails of double-hung windows is the holy grail of window restoration, identifying and preventing bad historic data from ever being stored is the holy grail of "learning" computer programs. Both are WAY more difficult than they appear on the surface.

John Mills_3

One question:

we ran across a couple times. I understand these are designed to shut off 2 degrees before final goal to see if residual heat in the furnace/boiler will bring it the rest of the way. True? We had a customer with a 2 stage using the timer on the board for staging. Every time the stat shut off at 68 while heading for 70, it started the furnace on low again and took forever to hit 70. We had to replace with a different brand going to a 2 stage stat. Also had a service call last week from a customer who thought her furnace had a problem because of it.

BillW@honeywell

Mike's post is a good one...

Try removing the stat from the subbase for 1/2 hour, you won't lose your program, but you will need to reset the clock & day. Also, check to be sure that the hole in the wall that the wires go thru is sealed, so the stat isn't picking up the wall cavity temperature. Check the stat location. Ideally, it should be away from any heat/cooling vents, on an inside wall and out of drafts or sunlight. Power surges effect all electronic products, and it's concievable that you stat has been damaged by one, but usually a surge powerful enough to damage the stat fries other components as well. Let me know how you make out.

BillW@honeywell

2 degree throttling ranges...

were common on electro-mechanical stats like the T87 or T8090. All the new electronic units are +-1 degree accurate. I'll check it out.

BillW@honeywell

Hi, Mike...

The temp sensor is mounted on the body of the stat, and senses air temperature. Wall temp wouldn't be accurate, due to the flywheel effect that sheetrock or whatever would have.

Neil Andrews

Removed

the stat last night since the weather was mild in our area. I let it sit for about 2 hours. Re-installed it and reset the time, so far the unit has operated properly both last night & this morning. I will keep an eye on it & keep you posted.

One question, I noticed that the stat has a software revision number, just curious as to what the latest rev level is in current production? Maybe the software designers have modified the software to prevent this kind of glitch?? We see this on almost every electonic controlled product these days.

If thats the case I would go out & purchase a newer stat just because I like this one so much.

Thanks for all your help

Nick

John Mills_3

Recovery

This was on recovery only. The HO would set it for 70, on warmup the stat would stop at 68 and wait a bit to see if residual heat would take it up to 70. If not, it would fire the furnace back up. Nice idea for hot water or steam heat but today's modern furnaces don't have much residual. This drove the HO & me crazy til we finally had a conference call with a sharp Honeywell customer service rep who explained it.

Tony Gatto

thermostat problems

It seems almost every application where we have run across this thermostat ,,,, sad to say we end up taking them off the wall and replacing with another,( sorry honeywell) and the w/r two stage heat and cool have totally repaired most of the problems. So kick it to the curb
Tony

BillW@honeywell

What kind of problems were you having?

> It seems almost every application where we have

> run across this thermostat ,,,, sad to say we end

> up taking them off the wall and replacing with

> another,( sorry honeywell) and the w/r two stage

> heat and cool have totally repaired most of the

> problems. So kick it to the curb

> Tony



If you could tell me what problems you were having, maybe I could find a solution for you. For wetheads & steamers, I usually recommend the T8602D version, (battery powered) That seems to minimize the few compatibility problems we have. I'd be interested in getting some of the "bad" stats back, so I can get them tested to find out what is wrong.

BillW@honeywell

What kind of problems were you having?

Let me know what problems you were experiencing, and I'll see if I can find out what is wrong. Did you keep the stats, or return them to the distributor? If you still have them, email me back, and I'll have them sent in for testing. Can you get me a date code? For wetheads & steamers, I usually recommend using the T8002 or T8602 battrey powered stats. Were these what you had? Let me know.

iunbears

fix current stealing for chronotherm III stat

If your Chronotherm III has a tiny Transformer on it you need to add a resistor between W and C at furnace! I don't remember what resistance it should be? Got into this site to find out? The power stealing will actually bring your furnace on when not calling