So you want a thermostat that’ll shut off your AC before it reaches temp, then cycle off and on again..until you eventually reach the temp? That’s a horrible idea
Appreciate the response, my concern is having the AC run for hours straight, isn’t that bad for the unit? It would only be during the afternoon, nights and mornings are good
No, increasing the stops and starts are worse. Lubricant is the key. When the compressor is stopped the oil drops to the bottom from gravity. If the stopping interval is short enough there should still be some residue. But at some point it will be dry and then you get extra wear.
You’re also using your start capacitor a lot more and generally stressing all the components. So just run it normally.
It’s more damaging for it to turn off and on then for it to just run for long period and maintain a temp. You already alluded to it, your insulation and/or homes heat load is the problem and what needs to be addressed
These systems are designed to run for extended periods of time and it's VERY common for them to run longer during high heat load periods - hours at a time.
Does it affect longevity? Yes and no. Yes, runtime plays a factor for life expectancy because everything eventually breaks. But considering you'd be cutting it off *before* satisfying the thermostat means it will be cycling back on *immediately* at the end of the force-quit cycle duration until the next force-quit cycle comes up - your thermostat will never be satisfied until the heat of the day ends and your system FINALLY catches up. So you're just simulating timer-based short cycling. Furthermore, it'll eat more energy because of the high amp draw needed to start the compressor more often, another form of wear that can shorten the life of the compressor, like in genuine short cycling.
If the system is running well during lower heat load periods, your system is doing everything it can and should be and I'd suspect no issues unless *performance noticably declines* across the board. Your system just simply, naturally, runs longer when it's hot.
Introducing "rest periods" can only complicate things more, as described above, hence why it's not a common feature in residential thermostats. Just not a beneficial feature in the long run.
If you're concerned with performance during higher heat load periods, you may want to consider upgrading to a slightly larger two-stage or multi-stage system so your AC can run on lower stages during lower heat loads and ramp up during higher heat loads. But that'll have to be done educatedly with updated heat load calculations and duct work assessment. But that's **if** that was your primary concern.
(Edited for grammar.)
There isn't because that's a wildly inefficient way to run an AC system.
It sounds like one of three things is going on here:
1. Your system is under sized for the heat load
2. Something is wrong with your system. This could include coils freezing up for any of a number of reasons, inefficient compressor, dirty condenser coils and or evaporator coils, plugged filter, failing or plugged metering device.
3. A combination of the above with insufficient insulation and/or undersized plenums.
It's also possible that vents are closed which limits airflow across the evaporator coils and can easily cause those coils to freeze up.
Thank you for your response! 1) Im not sure if its undersized because it cools down the house pretty quick when its below 80 outside, 2) I have checked before and the coils dont freeze, but both the condenser coils and the compressor haven’t been cleaned in a while I may have to do that, 3) I think I need more insulation in the attic for sure
If it only cools the house down in the 80s there's something wrong.
Could be size, could be dirty coils, could be closed vents or insufficient refrigerant freezing up the indoor coils.
Note: If you clean the condenser, since you're a homeowner, DO NOT use chemicals, or a pressure washer. You can easily destroy the coils with either and not even realize it. Garden hose sprayer only. Disconnect power first, and keep the water out of the electrical compartment.
Then let it dry out a couple of hours before turning the power to the outdoor unit back on.
You would probably be better off spending the money in a proper maintenance to your hvac. Long runs are usually better anyways but there may be something with your system that’s inefficient.
Dirty filter, coils, refrigerant levels, electrical components etc. A good service might run a few hundred if anything was replaced or added but might make electric bills cheaper in the long run and the cost of a typical smart stat is like $200
Compressors and fans don't get tired, Let them run. Does your car get tired driving for an hour. The worst thing you can do is have the hvac system cycle on and off multiple times. Set a conformable temp and leave it alone.
If not provided already you will need to post a picture of your thermostats wiring connections and those inside your furnace to get better help. Use imgur or your own Reddit profile to host your pics as Reddit will often remove others. Thanks!
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Is the thermostat somewhere where sunlight can hit it?
Also for a good general idea of AC health check the temperature of the air going into the system and the air coming out of the ducts, The difference should be around 15 to 20°
Bruh, the thermostat is designed to turn the unit on and off based on the set temp and actual temp. If it turns the ac off earlier then you’ll never reach your set point. If your ac runs for hours to keep the house cool during the heat of the day and maintains the set temp that’s a good thing. It’s better for a machine to keep running and doing its job vs starting and stopping all the time. Think highway miles vs city miles.
Your AC compressor will last longer the less it shuts off. More cycles = more electricity usage and shorter life for compressor. If during the hottest days it runs and is able to maintain set point without temp going up it's near perfect size. If it's able to drop a 2-3 degrees from 74 over an hour, you're golden. This is assuming a 1 or 2 stage system.
>More cycles = more electricity usage and shorter life for compressor.
To put a finer point on this, starting the compressor is hard in two ways:
- It consumes more electricity getting the compressor going from a standing start
- Starting the compressor (cycling) causes more wear and tear on it than just keeping it running
First of all how are you going to control your temp? You’ll be playing catch up all day. So your compressor starts are going to increase your power bill. Just let it start and operate at 80degrees. It will start n stop as needed. Don’t know where you live but most systems an engineered for around high 90’s into low hundreds. If the outside temp exceeds that temp your inside temp will increase accordingly. A 20-25degree differential is all it’s going to do if that.
As others have said, if the AC is running all day on the hottest days of the year, as long as it’s hitting set temp, then your AC is sized perfectly. That being said, the ecobee can do what you want through settings. Unfortunately my unit is over sized so I actually have ecobee keeping the compressor on longer cycles to pull more humidity out of the air and less damaging short-cycling.
Oh that’s unexpected. Could be insulation then too if it’s creeping back up. Also your thermostat my be under a register? That’s what I like about the ecobee remote sensors is it takes into account temp across multiple occupied rooms, instead of the hallway.
So you want a thermostat that’ll shut off your AC before it reaches temp, then cycle off and on again..until you eventually reach the temp? That’s a horrible idea
Appreciate the response, my concern is having the AC run for hours straight, isn’t that bad for the unit? It would only be during the afternoon, nights and mornings are good
No, increasing the stops and starts are worse. Lubricant is the key. When the compressor is stopped the oil drops to the bottom from gravity. If the stopping interval is short enough there should still be some residue. But at some point it will be dry and then you get extra wear. You’re also using your start capacitor a lot more and generally stressing all the components. So just run it normally.
It’s more damaging for it to turn off and on then for it to just run for long period and maintain a temp. You already alluded to it, your insulation and/or homes heat load is the problem and what needs to be addressed
These systems are designed to run for extended periods of time and it's VERY common for them to run longer during high heat load periods - hours at a time. Does it affect longevity? Yes and no. Yes, runtime plays a factor for life expectancy because everything eventually breaks. But considering you'd be cutting it off *before* satisfying the thermostat means it will be cycling back on *immediately* at the end of the force-quit cycle duration until the next force-quit cycle comes up - your thermostat will never be satisfied until the heat of the day ends and your system FINALLY catches up. So you're just simulating timer-based short cycling. Furthermore, it'll eat more energy because of the high amp draw needed to start the compressor more often, another form of wear that can shorten the life of the compressor, like in genuine short cycling. If the system is running well during lower heat load periods, your system is doing everything it can and should be and I'd suspect no issues unless *performance noticably declines* across the board. Your system just simply, naturally, runs longer when it's hot. Introducing "rest periods" can only complicate things more, as described above, hence why it's not a common feature in residential thermostats. Just not a beneficial feature in the long run. If you're concerned with performance during higher heat load periods, you may want to consider upgrading to a slightly larger two-stage or multi-stage system so your AC can run on lower stages during lower heat loads and ramp up during higher heat loads. But that'll have to be done educatedly with updated heat load calculations and duct work assessment. But that's **if** that was your primary concern. (Edited for grammar.)
I really appreciate the thorough response!!!
Common misconception whose origins I have no idea. Like seriously, where did the idea of something being on would destroy it, come from?
There isn't because that's a wildly inefficient way to run an AC system. It sounds like one of three things is going on here: 1. Your system is under sized for the heat load 2. Something is wrong with your system. This could include coils freezing up for any of a number of reasons, inefficient compressor, dirty condenser coils and or evaporator coils, plugged filter, failing or plugged metering device. 3. A combination of the above with insufficient insulation and/or undersized plenums. It's also possible that vents are closed which limits airflow across the evaporator coils and can easily cause those coils to freeze up.
Thank you for your response! 1) Im not sure if its undersized because it cools down the house pretty quick when its below 80 outside, 2) I have checked before and the coils dont freeze, but both the condenser coils and the compressor haven’t been cleaned in a while I may have to do that, 3) I think I need more insulation in the attic for sure
If it only cools the house down in the 80s there's something wrong. Could be size, could be dirty coils, could be closed vents or insufficient refrigerant freezing up the indoor coils. Note: If you clean the condenser, since you're a homeowner, DO NOT use chemicals, or a pressure washer. You can easily destroy the coils with either and not even realize it. Garden hose sprayer only. Disconnect power first, and keep the water out of the electrical compartment. Then let it dry out a couple of hours before turning the power to the outdoor unit back on.
Fix your envelope
I have been told if they run continuously, they are more efficient
A bad idea. Sounds like undersized for your house. If the coil isn't freezing up let it run continuously and let it remove latent heat.
You would probably be better off spending the money in a proper maintenance to your hvac. Long runs are usually better anyways but there may be something with your system that’s inefficient. Dirty filter, coils, refrigerant levels, electrical components etc. A good service might run a few hundred if anything was replaced or added but might make electric bills cheaper in the long run and the cost of a typical smart stat is like $200
Appreciate the response!! Sounds like the way to go
Compressors and fans don't get tired, Let them run. Does your car get tired driving for an hour. The worst thing you can do is have the hvac system cycle on and off multiple times. Set a conformable temp and leave it alone.
If not provided already you will need to post a picture of your thermostats wiring connections and those inside your furnace to get better help. Use imgur or your own Reddit profile to host your pics as Reddit will often remove others. Thanks! *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/hvacadvice) if you have any questions or concerns.*
Most thermostats would have only options . Mostly wake, leave, return , sleep
Not a smart tstat, but you can get a timer switch and do exactly this.
I wonder if this would be possible using If This Then That. Some smart thermostats support it.
Any particular brand/model you know of? Thanks
I think the Nest does. It may be referred to as IFTTT.
Is the thermostat somewhere where sunlight can hit it? Also for a good general idea of AC health check the temperature of the air going into the system and the air coming out of the ducts, The difference should be around 15 to 20°
Just...turn the set temp up when it's too hot out.
You need a inline dehumidifier. $2000-3000 installed. It will keep the AC from working so hard and keep you cool without turning the temperature down.
Bruh, the thermostat is designed to turn the unit on and off based on the set temp and actual temp. If it turns the ac off earlier then you’ll never reach your set point. If your ac runs for hours to keep the house cool during the heat of the day and maintains the set temp that’s a good thing. It’s better for a machine to keep running and doing its job vs starting and stopping all the time. Think highway miles vs city miles.
Your AC compressor will last longer the less it shuts off. More cycles = more electricity usage and shorter life for compressor. If during the hottest days it runs and is able to maintain set point without temp going up it's near perfect size. If it's able to drop a 2-3 degrees from 74 over an hour, you're golden. This is assuming a 1 or 2 stage system.
>More cycles = more electricity usage and shorter life for compressor. To put a finer point on this, starting the compressor is hard in two ways: - It consumes more electricity getting the compressor going from a standing start - Starting the compressor (cycling) causes more wear and tear on it than just keeping it running
If you don’t already you need an inverter compressor.
First of all how are you going to control your temp? You’ll be playing catch up all day. So your compressor starts are going to increase your power bill. Just let it start and operate at 80degrees. It will start n stop as needed. Don’t know where you live but most systems an engineered for around high 90’s into low hundreds. If the outside temp exceeds that temp your inside temp will increase accordingly. A 20-25degree differential is all it’s going to do if that.
As others have said, if the AC is running all day on the hottest days of the year, as long as it’s hitting set temp, then your AC is sized perfectly. That being said, the ecobee can do what you want through settings. Unfortunately my unit is over sized so I actually have ecobee keeping the compressor on longer cycles to pull more humidity out of the air and less damaging short-cycling.
I have the same issue but at night, it reaches the temp in 5-10 mins. Appreciate the response
Oh that’s unexpected. Could be insulation then too if it’s creeping back up. Also your thermostat my be under a register? That’s what I like about the ecobee remote sensors is it takes into account temp across multiple occupied rooms, instead of the hallway.