I installed a new programmable digital thermostat in my house a few
days ago, a Honeywell RTH7600D. It has a feature they call "Smart
Response Technology", which is supposed to "continually learn when to
pre-heat and cool your home so you are comfortable at your programmed
time". The feature seems to be included all but their most bare-bones
products. I'm not sure it's working correctly.
I have it currently set to be 70 at 8:30 AM. The first morning after I
installed it, I woke up at about 7:15 because it was so warm, and by
that time it was already at 70, so it obviously had been on for a
while. The next night I woke up at about 5:30 - I think I may have
heard the furnace blower kick on, and sure enough, the heat was on. I
managed to doze and wake enough times to guess that it reached 70 in
about an hour. Since then, I know it started heating early, but haven't
been able to rouse myself to know exactly when, only to know that
reaches 70 well before 8:30. This seems way too early - it's costing me
money to heat the house for as much as 3 hours or more when I don't
I called the 800 number on the box and talked to someone who didn't
really know that much about it. She was familiar with the feature and
understood my complaint, but she couldn't tell me if it was coming on
unusually early, or how long the thing takes to "learn" it's task.
The feature is turned on by default, but I can disable it, which I
probably will anyway. However, I don't want to have spent my money on a
defective machine, even if I don't use that feature. If it seems that
it's not working the way it's supposed to, I'll return it.
So, for anyone who owns a Honeywell or other brand stat with this or a
- is this normal behavior, for it to come on several hours earlier than
the programmed time? That seems excessive.
- will it really, as they claim, "continually learn" to turn on at a
reasonable time (for me that would be 1 hour or less), and how long
should I expect that learning period to take?
On Thursday, January 15, 2015 at 7:28:50 PM UTC-5, Nil wrote:
I have two different models of the Honeywell VisonPro series which
have the same kind of adaptive response for recovery from setback.
I've never seen them come on anywhere near that early. They do err on
the side of getting there a bit early, but overall, it works very well
and if it's early, it's by more like by 20 mins. I really like the
feature and would want it in any thermostat I buy. For example,
recently it went from outside nightime temps in the 30s, to temps
around 12F, resulting in the inside temp dropping more over night.
The thermostat correctly started the furnace about an hour earlier
and got it to the correct temp just prior to the time it was supposed
Mine were never anywhere near that far off, right out of the box.
They do learn and
adjust though based on experience. I would give it a week and see
what happens. If you're worried about it getting there too early, you
could temporarily set it for a later time and see how it behaves. If
it starts getting closer, zeroing in on that time, then you could reset
the time again. But
given that it's off so much, it sounds more to me like something is
wrong with it.
Are you sure it's installed correctly? IDK what has to be set on yours,
but mine you had to set whether it was a heat pump system, furnace, etc.
If it thought it was a heat pump for example, it might fire it up
sooner, IDK. I'd review all the install settings.
What is the temp. you set for sleep? 'stat needs some time to learn the
pattern. After a few days it'll learn how much it takes to bring up the
temp. from sleep to wake and gradually adjusts it. Isn't it logical,
is it? I always used Honeywell 'stats and my favorite is Pro 8000
series. I am using wireless one at home now. You are a bit impatient,
decay time from 70 to 60 and back from 60 to 70.
First tells you how much heat you're losing. Second tells you how much
you're adding. The difference should tell you something about the thermal
mass of the house.
My thermostat has the smart predictive on-time to get the house at the
right temp at the right time.
I have a running graph of the on-time of the furnace.
It's sensitive enough that I can see the % on-time throttle back
when I get up and turn on my computer.
After watching it for a while, I convinced myself that the amount
I saved during the setback interval was only slightly more than the
energy it took to heat all the thermal mass back up.
I turned off all the automagic stuff and set the thermostat for 66F.
The better your insulation, the less you save with setback.
The more you're home, the less you save with setback.
Then maybe you can answer another question I've been wondering about:
If I reprogram the times and temps, will I also have to go through this
painful training period all over again? What about if I lose power?
That's a big difference - 3+ hours vs. 20 minutes.
I installed it 10 days ago, but I only programmed it to my schedule not
quite a week ago. I guess I have to get up very early to know for sure
how much it's adjusted itself, if at all. Maybe it's getting better, I
don't really know, I just know it's not there yet.
I did check out all the fine-tune settings a couple of days after I
installed it. All the out-of-the-box settings were appropriate except
that it was originally set up for a low-efficiency gas furnace. I
changed it to high-efficiency. Otherwise, I think the other settings
I guess I'll give it a couple more days and monitor it more closely. I
just hate to think of all that expensive heat going up the proverbial
On Friday, January 16, 2015 at 1:25:49 AM UTC-5, Gz wrote:
The thermostat doesn't have to know btu output, dwelling size, etc. It
has all the basic info from experience. The thermostat quickly learns
how long the furnace has to run to raise the temp one degree, or two or
5 degrees. That will vary somewhat based on whether it's 10F outside or
40F. If it can raise the temp 5 deg in an hour when it's 40F outside, maybe
it can only raise it 4 deg/hr when it's 10F outside.
But it also knows if it's closer to 10F outside or 40F. How?
If it's been maintaining the temp, then it knows how many mins the furnace
ran in the last hour. If it's in set back, then it knows how much the
temp has dropped in the last 6 hours, the last hour, etc. That's the
And I don't see why any adaptive recovery program couldn't get the
recovery temp and time close after just a day or two. Just the fact
that it started 2 hours too early the day before, like the OP is
saying happened is a huge input.
It ain'r rocket science to have an algorithmn that say, OK tomorrow
cut that time in half. Adaptive recovery isn't worth spit if it's
On Thursday, January 15, 2015 at 11:43:12 PM UTC-5, Nil wrote:
With regard to changing times and temps, no, it doesn't affect what
it's learned regarding the adaptive recovery. It just learns how long
it takes to raise the temp. It knows that it has to raise it X degrees.
It also knows how fast and how far the temp dropped during the setback
time, how much the furnace had to run, if at all during the setback
period. From that it can calculate how long it's going to take to get
the temp back up.
Losing power has no effect, it has batteries. IDT even changing batteries
matters. It probably stores the learned parametet in flash memory with
the settup parameters, etc.
I'd take it back. A week is more than enough for it to be close to
correct. Like I've said, I've got two of them, neither did anything
like what you're seeing, even first day.
I highly recommend the Honeywell VisionPro. This is similar
to the one I have:
They also have a wifi model. If that was available when I bought mine,
I would have gotten it. I have enough times when I don't know for sure,
when I'll be back. With wifi, you can have it resume it's normal temp
from your smartphone when you're on your way back from the airport, etc.
They also just showed a new round, stylish thermostat that looks like
the Nest at CES. IDK anything about it, just mentioning it in case you
have any interest.
The only big negative about Honeywell is that with the better thermostats,
eg VisionPro, if you're a consumer, they won't answer any questions about
how to set it up, install it, etc. They just tell you to F off and call
a contractor, even if you just want to ask how to change one of the basic
settup parameters. The documentation is good, but if you have an install
problem, you're on your own. You can find them on Ebay, that's where I
You're not really wasting much in terms of heat by it getting the temp
back up to normal 2 hours early. Like someone said, during the night,
when it's set back, you're slowly depleting the thermal mass of the
house, all it's contents. The vast majority of the energy it's burning
during recovery is to put that heat back in. It has to do that whether
it starts at 5, 6, or 7. The savings come from the fact that while the
house is at 65, during the night, it's losing a bit less energy per hour
than if it were at 70. Let's say it was set at 70 and over 6 hours, when
it's set back, the temp drops to 60. That's an average temp of about
65. So, what you're saving is about the difference between having had
it set at 70 for those 6 hours versus 65. It makes a difference,
but it's not even close to the hour of constant running that the furnace
does in the AM to get it back up. It's just a small percentage of that.
The temp loss due to heat conduction is proportional to the temp difference.
Let's say it's 20F outside, 70F inside. That's a delta of 50F. At night,
if you set it back to 60F, let's assume it gets there after 6 hours,
about the time it's going to go back up. That means you had an average
temp of ~65 for 6 hours, that would be a 45F delta over outside. So,
instead of a 50F temp delta, or driving force for heat loss, you had a
45F one. That's a 10% difference. So whatever fuel you would have
used during those 6 hours, you probably saved ballpark 10%. Even if
you're spending $400 a month for fuel, when you get down to it, the
difference tha set back makes is definitely worth it over long periods,
but the furnace starting back up 2 hours early, for a week with that
thermostat is probably only a buck.
I'd just return this one now. From what I've heard, something is very
wrong. Even if it started up 2 hours too soon day one, by the next
day it should be down to an hour, then maybe a half hour, something
like that. It doesn't take a week+ to figure out it's way off.
experience is that even temporary overrides of a learned program will
require the thermostat to relearn the original program. As an example,
when I want to keep it somewhat warmer than usual on a particular winter
night (guests visiting) and use either the "temporary" feature or the
"hold temp" feature overnight, after resuming the program with "run
program", for the next 3-4 days the furnace will come on at least an
hour earlier in the AM than it would prior to the temporary override,
even though the outside temps are about the same.
changing a setting - either by override or by changing the programmed
setting. However, the more modern models may learn more quickly - my
Honeywell Chronotherm III is more than 10 years old.
It also depend on what kinda furnace. ie. single stage vs. two stage.
variable speed ns. single speed blower, etc.
I seldom see 2nd stage coming on. Having wireless thermostat I moved it
around to find a sweet spots as well for winter or summer.
On Friday, January 16, 2015 at 10:24:05 AM UTC-5, Peter wrote:
Well, maybe the lower part of their product line is junk. IDK.
All I know is how the VisionPro implementation of adaptive recovery
works and it works very well. And if the other ones work
as you say, they are indeed junk. Because changes like that should
have nothing to do with the thermostat having to learn all over again.
If it already knows that given the past history, it takes 1 hour to get
it from 65 to 70, then it can surely predict with good accuracy
about how long it's going to take to get it to 72 or 75. Changing the
time by an hour or two, similarly shouldn't require learning anything
No such problems here with the VisionPro. I can set it to any override
temp, change the programmed times, and it takes it to that temp, at that time, etc. So, maybe that's the difference, he needs to buy the better model.
But if they work anything like he says, I would think they would be
returned in bucket loads.
During that one week period was the outside weather steady?
My house is R2000 spec.'d pretty air tight, outside weather
does not impact much to maintain indoor comfort. Mine is set at 17.5
and 20.5 in Celcius I usually get up at 7 AM, furnace comes at around
6 AM every day. Give or take few minutes.
Well, mine is brand new, though with a 2012 copyright on the manual.
But it may be acting like yours, where if I adjust the settings it has
to learn all over again. That makes the feature just about useless,
especially if it responds that way to touching the temporary change
In any case, I decided that mine is either defective, or of a poor
design (if what you claim is true.) I'm going to return it for a new
one and that should tell me if the first case is true.
As you say, it shouldn't be that dumb or slow or hard to deal with. It
should just work, and if temporarily changing the temperature throws
its whole learning off and requires a new week of adjustment, that
makes it useless.
I don't know if that's the case, but I'm pretty sure mine is defective.
I got up 3 1/2 hours early this morning, and the furnace was off. Then
I got up again an hour and a half after that and the furnace was on and
the stat read "Recovery". That means it started up at least two hours
early. If it is, indeed learning, it's learning too slowly to be
I'm taking it back to Home Depot to exchange for a new one. If that
doesn't fix things, I'll have to look for another brand or model.
Thanks very much for your feedback. I had nothing to compare it with,
so this was valuable to me.
On Friday, January 16, 2015 at 2:53:17 PM UTC-5, Nil wrote:
The missing part is when did it reach the set temp? If it was
set way back, the house
temp went down 10 degrees and it took it took 2 hours to get to the
new temp, then it might not be off that
much and with some learning it may improve. If it got to the temp in
under an hour, then I think something is probably wrong with it.
The only strange part is it's hard to figure what kind of defect would
cause that. It's not a sensor type issue. It seems to me if it is
defective, it would have to be an error in the algorithhn, bug in the
Mine typically comes on about an hour before. If it's real cold out,
so the temp has dropped a lot more, then it can come on an hour and
a half or more before. It obviously depends mostly on how far it has to raise
the temp. When it's not very cold, that might be 3 deg. When it's
colder, could be 5 deg. When it's real cold, it's been setback for
a long time, it could be 10 degrees.
I've done a lot with PID temperature controllers. One learning cycle should
get you pretty close. I have no idea what current learning thermostats use.
I've stopped using automatic features. The house heats up pretty fast, and
I'm retired. The only thing that offsets adjustment is how cold that couch
or seat is, and floors.
I got at least three old honneywell stats. I just threw away an old
programmable that someone gave me, in the 90s. It was so difficult to
program. I forget the name. And I really hated walking toward it, touching
it, and a spark would reset everything!! I think it also had a hard fail
safe limit on temperature, separate mechanical switch, which I have not
seen on current models. So important.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.