Programmable thermostats

[snow_monkey]

I am continually confused on how to manage my programmable thermostat. On a hot day and just the dog at the crib I set the temp at 77. One hour before I return for the day I have it set at 72. In the evening it took the system 3 hours to reach the set temperature. I know it is super hot but my house is on a slab. The air most likely does not come on until noon or 1 oclock in the afternoon when most systems have already been running full tilt. The unit is the appropriate size for the house and works very well. At the peak of the afternoon my neighbors unit runs non-stop while mine continues to cycle properly. Thoughts?

 

[doomsman]

The properly sized ac unit will hold 15 degrees below the exterior temp.
3 hours to recover is not unreasonable, you may need to feed in a little more lead time before leaving and returning.
ALSO be sure that the condenser coils outside are clean and unobstructed.

 

[wags]

Just a note: The standard design criteria in the HVAC industry at least in the Chicago market is 90deg - 10deg so anything outside that range is up for grabs.

I run a 460,000sq. ft. class "A" office building and no matter what you do once your OAT's exceed the design criteria everything is out the window. I'm running two York Centrifugal Chillers totaling 1,400tons of cooling 24/7 just to meet lease requirements.

My condensing units for the Chillers (Cooling Towers) also cover several other A/C units and they total 2,000tons, these unites are running 100% of their capacity.

It's not just the OAT'S it's also the higher humidity levels.

I have my home T-stat set up like you but what the conditions are like they are today there's nothing you can do but turn the set-point down. I know, I know it will raise your utility bill, that's a personal decision if you want to be comfy or not I guess.

 

[BluByU]

I read that to be the most efficient and cost effective the thermostat should be set 10°F higher when not home for a min of 8 hours. I typically set mine to be 80°F from 4am to 5pm. Then 75° from 5 pm to 9pm then 72° from 9pm to 4am. Remember the times you set are not when the A/C will first turn on but when the house needs to be at that temp. So if you have your unit set to 72° 1 hour before you return home it will actually start cooling 4 hours before you get home.

 

[Admin]

Also, insulation is not just for winter. It helps to keep a building cooler in the summer (think of a cooler). Might want to make sure you are properly insulated.

One last thing might be to make sure that your attic is properly vented.

-John

 

[snow_monkey]

Also, insulation is not just for winter. It helps to keep a building cooler in the summer (think of a cooler). Might want to make sure you are properly insulated.

One last thing might be to make sure that your attic is properly vented.

-John

X'2 have the ridge vents but not enough soffit vents. Thought about that last night!

 

[yamahauler]

Blu: You must have a unique system that can somehow calculate how long it is going to take to cool the house down, thus know when to turn on. Min programmable works that it turns on at the time I set it to and it is trying to cool it down to the temp I set it at.

If I build again, I am going to do as my father did in his new house. Run separate thermostat for upstairs and downstairs. This way when the downstairs doesn't need the cooling, it isn't dumping cold air down there to sit. Vice versa for the winter.

 

[yamahauler]

One more thing, keep the curtains closed to keep the sun from heating up the things on the inside of the house.

 

[polarisrider1]

On the tube last night they had a very reputable Heating contractor on to discuss how to keep AC from breakdowns during this time of year. He said that it is best to leave temp at 1 setting as to not run air for a several hour "catch up" when you get home at night. It can ice up the duct work and put a strain on all components of the AC. 2. clean all the leaves and debris off the unit outside and to clear away shrubs and other plants to within no less than one foot from unit. 3. check your air filter and change as needed. 4.close blinds, drappery and check that windows are latched shut. 5. close off unused rooms and the registers to those rooms. Basically treat the situation as you would to keep the cold out in winter like john said.

 

[snow_monkey]

Were sending one of our desciples to the dairy queen for slushies as we speak! The parking lot is hotter than the exhaust manifold of a thunder cat after running the Raco Strongs railroad grade!

 

[BluByU]

Blu: You must have a unique system that can somehow calculate how long it is going to take to cool the house down, thus know when to turn on. Min programmable works that it turns on at the time I set it to and it is trying to cool it down to the temp I set it at.

The thermostat has a feature called Adaptive Intelligent Recovery(AIR) or Smart Response or Early Start. This allows the thermostat to "learn" how long the heating and cooling system will take to reach the programmed temperature settings. So the temperature is reached at the time you set. For example: Set the Wake time to 6am, and the temperature to 70F. The heat will come on before 6am, so the temperature is 70F by the time you wake at 6am.

 

[frnash]

[FONT=Verdana,Arial,Helvetica][FONT=Verdana,Arial,Helvetica]Two years ago [/FONT][/FONT]—[FONT=Verdana,Arial,Helvetica][FONT=Verdana,Arial,Helvetica] long overdue [/FONT][/FONT]—[FONT=Verdana,Arial,Helvetica][FONT=Verdana,Arial,Helvetica] I switched to a "Timed Advantage" electric rate schedule:

<table border="1"><tbody><tr><td><center>Time period</center></td><td><center>Summer rate (May-Oct)</center></td><td><center>Winter rate (Nov-Apr)</center> </td></tr><tr><td><center>"On Peak" (12N-7P, M-F)</center></td><td><center>21¢/KwHr</center></td><td><center>16¢/KwHr</center> </td></tr><tr><td><center>"Off Peak" (all other times)¹</center></td><td><center>2.6¢/KwHr</center></td><td><center>2.6¢/KwHr</center></td></tr></tbody></table>(¹ And all day on six holidays per year; if a holiday falls on Saturday, Friday is Off-Peak and if a holiday falls on Sunday, Monday is Off-Peak.)

During the summer, my programmable thermostat sets the target temperature thus:

<table border="1"><tbody><tr><td><center>Start time</center></td><td><center>temp (degF)</center> </td></tr><tr><td><center>9:00AM</center></td><td><center>60°F</center> </td></tr><tr><td><center>12:00N</center></td><td><center>85°F</center> </td></tr><tr><td><center>7:00PM</center></td><td><center>82°F</center></td></tr></tbody></table> (Among various additional time periods/settings.)

Of course it will never really get the house down to 60°F by noon, but it does cause the A/C to run continuously, at full tilt, from 9AM until 12 noon, when the programmable thermostat sets the temperature to 85°F, effectively shutting the A/C down completely during the "On Peak" rate schedule from noon until 7:00PM (or until the indoor temperature reaches 85°F).

This is essentially "banking" the maximum "coolth" (the opposite of warmth ) at the considerably lower "Off Peak" rate. Of course the house does slowly warm up during the afternoon, but only rarely does it reach [/FONT][/FONT][FONT=Verdana,Arial,Helvetica][FONT=Verdana,Arial,Helvetica]85°F, and my on-peak usage is typically only 3-4 KwHr/day![/FONT][/FONT]
[FONT=Verdana,Arial,Helvetica][FONT=Verdana,Arial,Helvetica]
Since re-insulating the attic and adopting this tactic, my "Equal Payment Plan", based on a 12 month rolling average electric bill has gone from $302.00 in October 2007 to $99.00 today! (You can imagine what additional savings I could possibly attain if I ever get these severely leaky casement windows replaced!) [Corrected "Equal Payment Plan" numbers.]

I have had a number of programmable thermostats over the years. I have been most pleased with my current one: a RiteTemp model 8082C (sadly it is no longer available), it gives you a choice of either two or six time periods for each day. The time periods must be set when the 'stat is set to heat, then the same time periods are also used when set to cool (or automatic). Of course there are different temperature settings for each of those time periods for heating and cooling. I am using six periods x 7 days, with the same temperature settings in the various periods on all weekdays, and I use a second set of six temperature settings for Saturday & Sunday. The six periods per day for each of seven days has been the most versatile and useful for me, although that does make it a bit tedious to set.
[/FONT][/FONT]

"The thermostat has a feature called Adaptive Intelligent Recovery(AIR) or Smart Response or Early Start. This allows the thermostat to "learn" how long the heating and cooling system will take to reach the programmed temperature settings. So the temperature is reached at the time you set."

Mine has a similar feature, but fortunately I can turn it off! I prefer for the 'stat to set a new target temperature at the time I have programmed, rather than trying to reach that setting at a given time when it "thinks" I want that target to be reached. It just would not do for it to start running the A/C "early" — before the end of my "On Peak" period, for example!

 

[frnash]

The properly sized ac unit will hold 15 degrees below the exterior temp.

Oboy, that would never cut it in Phoenix: 115-122°F outdoors = 100-107°F indoors?

ALSO be sure that the condenser coils outside are clean and unobstructed.

And the evaporator coils indoors as well! Especially if you have one or more four legged furry creatures in the house, even if you do change the filter(s) frequently!

 

[favoritos]

If I build again, I am going to do as my father did in his new house. Run separate thermostat for upstairs and downstairs. This way when the downstairs doesn't need the cooling, it isn't dumping cold air down there to sit. Vice versa for the winter.

We did that in our home. One thing to remember though, both zones are using the same return ductwork, so cover the areas you do not want to cool.

On the tube last night they had a very reputable Heating contractor on to discuss how to keep AC from breakdowns during this time of year. He said that it is best to leave temp at 1 setting as to not run air for a several hour "catch up" when you get home at night. It can ice up the duct work and put a strain on all components of the AC. 2. clean all the leaves and debris off the unit outside and to clear away shrubs and other plants to within no less than one foot from unit. 3. check your air filter and change as needed. 4.close blinds, drappery and check that windows are latched shut. 5. close off unused rooms and the registers to those rooms. Basically treat the situation as you would to keep the cold out in winter like john said.

The coil can ice over if it does not have proper airflow. Make sure the air filter is clean. Watch for icing if you start to shut down areas of the home. It reduces airflow. Newer furnaces run high fan speeds on cooling to keep from icing over. Humidity in the air is a problem too. One way to help prevent that is keeping the air inside as dry as possible. Do not keep opening the windows.

Geo is very efficient in cooling mode if you do not run a water storage based system. The plenum coil systems are great in the summer. They are not as efficient in the winter though.

 

[yamahauler]

I would like to do geothermal if I could afford.

favoritos, they actually installed a second set of ductwork so upstairs and downstairs are independent.

 

[yamahauler]

Blu: What make/model thermostat do you have, I am interested in looking that.

 

[anonomoose]

[FONT=Verdana,Arial,Helvetica][FONT=Verdana,Arial,Helvetica]...[/FONT][/FONT]
[FONT=Verdana,Arial,Helvetica]
[FONT=Verdana,Arial,Helvetica]Since re-insulating the attic and adopting this tactic, my "Equal Payment Plan", based on a 12 month rolling average electric bill has gone from $302.00 in October 2007 to $99.00 today! ...[/FONT]
[FONT=Verdana,Arial,Helvetica]I have had a number of programmable thermostats over the years. I have been most pleased with my current one: a RiteTemp model 8082C (sadly it is no longer available), it gives you a choice of either two or six time periods for each day. The time periods must be set when the 'stat is set to heat, then the same time periods are also used when set to cool (or automatic). Of course there are different temperature settings for each of those time periods for heating and cooling. I am using six periods x 7 days, with the same temperature settings in the various periods on all weekdays, and I use a second set of six temperature settings for Saturday & Sunday. The six periods per day for each of seven days has been the most versatile and useful for me, although that does make it a bit tedious to set.[/FONT]
[/FONT]Mine has a similar feature, but fortunately I can turn it off! I prefer for the 'stat to set a new target temperature at the time I have programmed, rather than trying to reach that setting at a given time when it "thinks" I want that target to be reached. It just would not do for it to start running the A/C "early" — before the end of my "On Peak" period, for example!

Okay, I'm ratting out Nash.....he got one of those crazy foreign guys to climb the pole and by-pass the meter....What's the name of the Lectric company in AZ??

Now with all that fancy zones and time switches...all I can say is NEVER change the batteries...or you will be days trying to reset that puppy!

SnowMonk.....don't forget that here in the Midwest, as in the south, we FEEL the heat because the humidity is so high....UNLIKE Mr. NASH....who only suffers from dry heat....yeah, right......

You need to get the humidity out of the air in your home to FEEL comfortable. It is not just the temperature....it is the reduction of humidity. So setting the dial to run for one hour after the house has become humidified will mean that this is more a problem of "run-time" than one of getting the temps to reduce. You FEEL the heat more because the humidity hasn't been extracted from the air...and that simply takes time. You can learn how this works very well, by going for a ride on a hot day and instead of turning the AC on in the car, run the defroster only, and bump the temp up to the middle of the dial not warm not cold...and as the car gets dehumidified, notice how much more comfortable you feel without lowering the inter temperature one degree. It is amazing how much more comfortable this makes the car. I often turn on the defroster on damp days with high humidity just to reduce the humidity in the car, and it makes for a much more comfortable ride without adding heat or air.

The other thing is the fact that being on a slab handicaps your unit because the "mass" heats up during the day....and will actually work as a heat-sync absorbing HOT and given your AC unit a bigger work out than had it been running all day long.

Once that attic and cement slab gets warm it can take much longer to cool down.

My first house which did NOT have AC used to heat up because the attic was not vented correctly. You could open all the windows in the evening after the sun was down and that plaster would radiate the heat for hours afterwords. You walked outside and it was much cooler, and when you wanted to head for bed it was like walking into an oven....

Needless to say I invested in one of those window units that worked well, but always had an up hill struggle to get the temps down. I am not a big one for noise when I want to sleep...it has to be quiet....no fans droning on for me...and that was always a problem because you could not sleep even stock naked without the window unit running.

 

[BluByU]

Blu: What make/model thermostat do you have, I am interested in looking that.

It's a pretty basic Honeywell, not sure of the model as my contractor was the one who installed it but I think it's the Pro 4000.

http://yourhome.honeywell.com/home/products/thermostats/

 

[snow_monkey]

I closed off the 2 extra bedrooms and vents today. I think I would die without ac! If I could have it my way 58 degrees year round. When I retire I will be headed north for sure.

 

[peter]

I am continually confused on how to manage my programmable thermostat. On a hot day and just the dog at the crib I set the temp at 77. One hour before I return for the day I have it set at 72. In the evening it took the system 3 hours to reach the set temperature. I know it is super hot but my house is on a slab. The air most likely does not come on until noon or 1 oclock in the afternoon when most systems have already been running full tilt. The unit is the appropriate size for the house and works very well. At the peak of the afternoon my neighbors unit runs non-stop while mine continues to cycle properly. Thoughts?

set it to one temp and leave it or press hold button.