ReplyArgghhh! The posting system needs to warn you if you put double-quotes in the subject line! The subject line was SUPPOSED to read VisionPro "Adaptive Recovery"... isn't.
SirWired
Regular Guest
After reading this board I had my installer put in a 8321 VisionPro last fall. Well, the setback bit doesn't seem to be working just right. One thing I thought this T-stat was supposed to do is to look at how long setback recovery took on previous days, and use that to make sure that the temp is at the setpoint AT the schedule time. (The cheapo setback I used before STARTED the unit at the schedule time.)
Well, with the recent heat here, I find that the durned thing can't recover until hours after the schedule time.
Evening setpoint is 78 @ 6:30, daytime is 85. By the time I get home, it is reading 83. It doesn't seem to get it down to 78 until 10PM or so.
I know that 85 is a high daytime setback, but I thought the thermostat was supposed to be smart enough to figure this out and start recovery at the correct time.
On a not-scorching-day, I looked at the stat @ 6PM, the inside was 81, and it STILL hadn't turned the unit on. No way is a properly sized-unit going to cool by three degrees on a hot day in half an hour. Right?
I went ahead and put the thing on perm. hold for the past few 100+ days because of this.
Is there some setting my installer forgot to turn on, or is the "Adaptive-ness" limited to .5 hr or so?
It seemed to work okay in the winter...
SirWired
Regular Guest
Argghhh! The posting system needs to warn you if you put double-quotes in the subject line! The subject line was SUPPOSED to read VisionPro "Adaptive Recovery"... isn't.
SirWired
Professional Member*
On properly sized HVAC systems you probably won't have the capacity to recover in that kind of heat, especially that much of a setback. The thermostat doesn't know the size vs load of your system. It's an air conditioner, not a refrigerator. We warn customers to be careful the amount of the setback and when to use it, especially with heat pumps in the heat mode. Maybe a 2-stage system would be the ticket for you.
Professional Member*
Sirwired, your tstat is doing what it's programmed to do. Nothing's wrong - operator error. It's a tstat not an A.I.
Global Moderator
I put mine on hold on the last heat wave. Stat was trying to cool the house down but with high heat & humidity, the cooling unit just couldn't. Also, intelligent recovery looks at past days too. If you suddenly turn hot, it may not turn on soon enough even if the unit is oversized enough to recover.
Professional Member*
Your temperature swing in cooling mode is too much.
It is much more cost effective to choose a milder temperature and setback. I choose 80 during the day and 77 at night. It is much easier for the system to cool an additional degree or two if needed.
Proper Prior Planning Prevents Piss Poor Performance
"There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper, and the people who consider price only are this man's lawful prey. It's unwise to pay too little.
When you pay too much, you lose a little money -- that is all. When you pay too little, you may lose everything, because the thing you bought was incapable of doing the thing it was bought to do.
The common law of business balance prohibits paying a little and getting a lot -- it can't be done. If you deal with the lowest bidder, it is well to add something for the risk you run. And if you do that, you will have enough to pay for something better."
John Ruskin
Professional Member*
Any energy savings you are hoping to achieve with this wide of a range of setback setpoints is self defeating. Narrow the range and you'll actually be spinning the meter a lot less than now. I would go no higher than 80 as your unoccupied temperature setpoint and then stay with the 78 as the occupied temp if that is your comfort level (too warm for me, but YMMV).
Psychrometrics: the very foundation of HVAC. A comfort troubleshooter's best friend.
Regular Guest
Not true....the greater and longer the setback, the larger the savings.Originally posted by neophytes serendipity
It is much more cost effective to choose a milder temperature and setback.
http://www.energy.ca.gov/efficiency/...HERMOSTATS.PDF
Professional Member*
travisfl
I don't care what the government says about setback tstats. If you set it back more than the system can recover you will be running your unit constantly and be at an uncomfortable temperature level as well. There is a point beyond which you can setback your temps and save money as well as acheive the desired comfort level. I would say in A/C mode you should not look for swings of greater than 2 degrees. Usually you are bringing the air back on upon arival home after work, this is also in the hottest part of the day and most systems begin to lose ground at this time. So now you are asking the system to recover a large temp difference as well as overcome the heat of the afternoon. This is not a realistic situation for a properly sized system. Your system is designed to maintain a set temp level not recover vast temp differences. So even if you do save a couple of bucks by large setbacks it will be at the cost of comfort.
"Go big or Go Home"
Professional Member*
I wouldn't believe this to be true in this circumstance.Originally posted by travisfl
Not true....the greater and longer the setback, the larger the savings.Originally posted by neophytes serendipity
It is much more cost effective to choose a milder temperature and setback.
http://www.energy.ca.gov/efficiency/...HERMOSTATS.PDF
I personally designed sir's system.
The design temps in Raleigh, NC are 75 inside @ 92 outside.
It was reaching 105 during the peak of the days when he was having most problems recovering.
This was the hottest July Raleigh has had in 50 years!
My systems never shut off except maybe 4-5 hours at night.
I made the same mistake of setting my tstat back to 77 while I'm at work and 74 when I get home.
The temps in my house even climbed to 78 until after midnight!
How tall are you Private???!!!!
Regular Guest
[QUOTE]Originally posted by Yellow Dot
Note that I'm not referring to comfort or the amount of time required to return the conditioned space to the design temperature. Having said that, the statement relative to setback energy savings is true, it is a matter of physics.I wouldn't believe this to be true in this circumstance.
Professional Member*
It's like argueing evolution against creasion theory, until you can give some definitive data on energy saving by setting back as opposed to maintaining temps on A/C I will not be convinced. As far as I am concerned customer comfort is the reason that we install systems, not energy efficiency. If I can save $50 per month and sweat my bag off it is pointless to have an a/c system. I can also save $.05 by pissing in the dark and not turning on the light. But any savings are returned by cleaning materials needed. There is cost involved in comfort, I leave it to you to decide which is more important to you. I say if you can afford to run the a/c and maintain comfort levels go for it. If cost saving is more important you are welcome to sit in the heat.
"Go big or Go Home"
Regular Guest
Yes, that would be the case exactly. Science vs non-science.Originally posted by Black Adder
It's like argueing evolution against creasion [sic] theory
Professional Member*
That government literature didn't give any hard numbers, just percentages.
Obviously, it costs money to operate the HVAC system.
Forced air heat seems to be able to recover an ambient temperature relatively quickly. My home is 72 degrees for about 8 hours a day in the heating season.
Cooling doesn't seem to work that way, and I have found about a 3 degree swing to be about it, otherwise, the equipment is on for a much longer time to recover the temp.
My home is shaded and on a slab, so if it is cooled to 77 at night, it takes a while for the AC to kick on at 80 during the day.
I bet that if everyone raised their t-stat by 1 degree in summer and lowered it the same in winter, the energy savings would be much more than a setback stat.
Proper Prior Planning Prevents Piss Poor Performance
"There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper, and the people who consider price only are this man's lawful prey. It's unwise to pay too little.
When you pay too much, you lose a little money -- that is all. When you pay too little, you may lose everything, because the thing you bought was incapable of doing the thing it was bought to do.
The common law of business balance prohibits paying a little and getting a lot -- it can't be done. If you deal with the lowest bidder, it is well to add something for the risk you run. And if you do that, you will have enough to pay for something better."
John Ruskin
Regular Guest
I'm surprised no one's posted this yet, but...
Do you have the dehumidify control (overcool) enabled? (If you hit the More button, do you get an option to change humidity levels?) If so, the adaptive recovery features gets disabled. Why, I'm not sure, but Honeywell confirms this is what it does. If you disable the humidity control, it will still show humidity % on the screen, but won't respond to it, and you'll have adaptive recovery working. Also, the stat can be configured for conventional recovery (just does exactly what the program says) or adaptive recovery (reaches the set points by the programmed times).
The recovery algorithm in the Honeywell stats is pretty good about "learning" how well the system functions and usually won't let the temperatures get so far out of range that it wouldn't be able to recover on time. On my place, I have the set-back set to 85F, but never have seen it rise that high b/c the stat calls for recovery well before then.
Also, when you first start running the adaptive recovery, it may take it a couple of days before it learns about how the system performs and how it needs to control it. It seems to take about a week before it gets into its usual pattern.
[Edited by tpa-fl on 08-02-2005 at 08:08 AM]
Regular Guest
tpa-fl,
Thank you! That is EXACTLY what I was looking for! I may give Honeywell a call myself to confirm, but that could explain what is going on.
SirWired
Regular Guest
I'm still not sure why Honeywell chose to let the thermostat function like this. I called them when I first put the TH8321 in my place. They insist this is "normal" for it... but to me, adaptive recovery should work regardless of the overcool setting.
Professional Member*
Why the switching is so damn noisey. Can't hear my system kick off and on but can damn sure hear the switches make. "Click-click on, click-click off".
Regular Guest
The noise is from the relays, there are triax.
Professional Member*
cuz they've always been that way. my xt500c is made by hwell. i can hear it click long before the blower ramps to high.Originally posted by Stamas
Why the switching is so damn noisey. Can't hear my system kick off and on but can damn sure hear the switches make. "Click-click on, click-click off".
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