My last house came with a Nest thermostat where I loved the airwave feature that would circulate air for about 5 min after the AC (compressor) has turned off. Pipes are still cold for a few minutes after AC turning off, thus saving me energy. In my new house I have installed the z-Wave Trane tzemt400bb3nx. Now the fan turns off right when the compressor turns off. Two questions:
Can I have my fan run for a few minutes after my AC turns off (aka Nest Airwave feature)? I am not looking at the cycle mode because its feature is different than my need.
Would the fan turning off right away (as is the case now) would cause harm to my HVAC? There used to be a time when system had to run for a few minutes so that freon gas can settle in the compressor. New systems do not seem to have this problem. MY HVAC is 8 years old (Trane as well)
Running the blower after the temp has already been reached seems questionable on energy savings. Sure there might be a bit of cold air left in the tubes, but how much? Running the blower (especially if the air is just cool and not COLD) is using electricity, and after your setpoint has been met it sure isn’t saving rather been being off. If the tubes are in attic and it runs for 5 mins… Is there cold air for the whole 5min or you just running the home air threw the hot attic and back down? I personally wouldn’t worry to much about it. Either it’s going to save you pennies or it’s going to cost you pennies.
Not in the thermostat, but Some Airhandlers have this feature built in or you can set some Scenes to do this in VERA.
The fan has nothing to do with this.
Your compressor should not be cycled on and off fast as this will create problems. These settings are set in the thermostat and I think its a min. or 3 min off and 5 min on is your lowest option in the trane thermostat, but don’t quote me on it.
[quote=“dealser333, post:1, topic:181554”]My last house came with a Nest thermostat where I loved the airwave feature that would circulate air for about 5 min after the AC (compressor) has turned off. Pipes are still cold for a few minutes after AC turning off, thus saving me energy. In my new house I have installed the z-Wave Trane tzemt400bb3nx. Now the fan turns off right when the compressor turns off. Two questions:
Can I have my fan run for a few minutes after my AC turns off (aka Nest Airwave feature)? I am not looking at the cycle mode because its feature is different than my need.
Would the fan turning off right away (as is the case now) would cause harm to my HVAC? There used to be a time when system had to run for a few minutes so that freon gas can settle in the compressor. New systems do not seem to have this problem. MY HVAC is 8 years old (Trane as well)
No, The blower delay function is a function of the thermostat in non variable speed blower motor AHU’s. If you have a unit with a VS motor, then you should be able to set the VS profile to “enhanced” to achieve what you are looking for.
Thank you for your reply. Unit is sitting in basement and it stays colder for a while. I have set the minimum run time and the minimum off time to 9 min–maximum the thermostat would allow so that my HVAC unit does not cycle very quickly.
Could you please point me in the direction of creating a scene in vera to accomplish this? Primarily, my concern is how would I have vera tell the thermostat to turn only the fan?
Running the blower after the temp has already been reached seems questionable on energy savings. Sure there might be a bit of cold air left in the tubes, but how much? Running the blower (especially if the air is just cool and not COLD) is using electricity, and after your setpoint has been met it sure isn’t saving rather been being off. If the tubes are in attic and it runs for 5 mins… Is there cold air for the whole 5min or you just running the home air threw the hot attic and back down? I personally wouldn’t worry to much about it. Either it’s going to save you pennies or it’s going to cost you pennies.
Not in the thermostat, but Some Airhandlers have this feature built in or you can set some Scenes to do this in VERA.
The fan has nothing to do with this.
Your compressor should not be cycled on and off fast as this will create problems. These settings are set in the thermostat and I think its a min. or 3 min off and 5 min on is your lowest option in the trane thermostat, but don’t quote me on it.[/quote]
Thank you for your insights. I called the customer support and they were not of much help. I think they primarly deal with installation questions and not many configuration questions.
Being a novice, I am not sure I understand your #2. How would I tell if my unit has a VS motor. I went to my HVAC unit in my basement and could not find anything that would indicate that. Perhaps I was looking in an incorrect location. Any pointers?
No, The blower delay function is a function of the thermostat in non variable speed blower motor AHU’s. If you have a unit with a VS motor, then you should be able to set the VS profile to “enhanced” to achieve what you are looking for.[/quote]
I personally would accomplish this in PLEG, but it might be a little difficult for you if you never used it. Bottom line is on your z-wave thermostat and in your VERA UI for this thermostat you have the option to run fan in manual. Right now it should be set to auto so a/c or heat kicks on so does the fan.
What I would do in Vera is set a scene to:
when A/C is running for more then 5 min, then turned off to switch the fan to Manual on.
2nd scene to turn it off would be after min. after manual fan on turn back to auto.
[quote=“dealser333, post:5, topic:181554”]Thank you for your insights. I called the customer support and they were not of much help. I think they primarly deal with installation questions and not many configuration questions.
Being a novice, I am not sure I understand your #2. How would I tell if my unit has a VS motor. I went to my HVAC unit in my basement and could not find anything that would indicate that. Perhaps I was looking in an incorrect location. Any pointers?[/quote]
Post the full Model number (from the nomenclature plate) of the Indoor unit, and should be able to let you know
You are right. I have never played with PLEG and would be lost. I tried creating a scene as you have suggested but run into the same problem again. How to control my fan, AC separately. I have attached a copy of my Vera scene create section where it lets me pick options. I appreciate your help.
[quote=“integlikewhoa, post:6, topic:181554”]I personally would accomplish this in PLEG, but it might be a little difficult for you if you never used it. Bottom line is on your z-wave thermostat and in your VERA UI for this thermostat you have the option to run fan in manual. Right now it should be set to auto so a/c or heat kicks on so does the fan.
What I would do in Vera is set a scene to:
when A/C is running for more then 5 min, then turned off to switch the fan to Manual on.
2nd scene to turn it off would be after min. after manual fan on turn back to auto.[/quote]
[quote=“dealser333, post:8, topic:181554”]You are right. I have never played with PLEG and would be lost. I tried creating a scene as you have suggested but run into the same problem again. How to control my fan, AC separately. I have attached a copy of my Vera scene create section where it lets me pick options. I appreciate your help.
[quote=“integlikewhoa, post:6, topic:181554”]I personally would accomplish this in PLEG, but it might be a little difficult for you if you never used it. Bottom line is on your z-wave thermostat and in your VERA UI for this thermostat you have the option to run fan in manual. Right now it should be set to auto so a/c or heat kicks on so does the fan.
What I would do in Vera is set a scene to:
when A/C is running for more then 5 min, then turned off to switch the fan to Manual on.
2nd scene to turn it off would be after min. after manual fan on turn back to auto.[/quote][/quote]
The buttons in the middle “Auto” “on” and “cycle” those are to control the fan only. in the first pic you have it set to “on”. That means its running 24/7 even if the compressor is off. Auto is where it normally should be.
OKay, I think I get. I would have to create a series of triggers to do it. It would be complex but I might still be able to do it. I will play around with it tonight. Many thanks for your help.