4 ms·

$25? I live in a northern, Midwestern state and our coop (part of MISO) offered a one time $1500 and continued discounts (11%) per month on electricity for the

$25? I live in a northern, Midwestern state and our coop (part of MISO) offered a one time $1500 and continued discounts (11%) per month on electricity for the capability to control utility curtailment (power control to the unit, no ability to adjust set-point or collect any other data). For winter it can only be in buildings that are non-primary living and can only shut off power to an electrical heating appliance (heat pump, boiler, etc). In the summer they can curtail your heat pump / AC for up to 15 minutes at a time. I see the curtailment notification on my thermostat on hot days. But the house never gets warm. I have a newer heat pump that is rated up to 22 SEER2 and compared to my old on/off AC unit the variable speed unit makes a huge difference in performance, cost and noise levels. I never hear it running when it is and so during curtailment I don't notice it unless I see the notification.

mindslight 3y ago
Is it really only 15 minutes at a time, or is it 15 minute units with possibly multiple in a row? Heat pump efficiency requires long cycles, so turning it off, on, off, on within the course of an hour to make some "never off more than 15 minutes" guarantee would be counterproductive.
- windexh8er 3y ago
  The unit basically runs all day during the day on hot days. The difference is, as you state, it runs long cycles. The 15 minutes it's off is the break in the cycle itself. The unit I have is a communicating unit that "learns" the house in terms of all the internal and external changes. So it knows what fan speed and compressor rate to run to get to the setpoint - it doesn't just ramp up to the highest rate after a curtailment event. So it's basically running at a very low rate all day long, curtailment happens, and it ramps slightly if there's a need to bring any zones back to setpoint - but the thermostat is aware of the curtailment event and, as I was told, responds different after the curtailment is lifted. I talked to both the installer and the manufacturer regarding whether or not curtailment would negatively impact the system (performance, cost, longevity) and the consensus was that unless the curtailment events happened every hour there wasn't any downside to cooling. Heating would be another story, but I don't have any curtailment contract for heating in my home. And I believe the contract states curtailment events can only happen up to 4 times in a given day and cannot happen more than once an hour.
  - mindslight 3y ago
    Ah, so basically the variable speed and feed-forward PID make it so the unit is running all the time, so it's not like the 15 minute curtailment will come right after it kicked on to satisfy cooling demand. Rather your house is continually cooling, stops for 15 minutes, then goes back to it. That makes a lot of sense! I do find it interesting that these terms are still valuable to a power company. Obviously being able to shed the load for 15 minutes is fantastic, but I would think the system would then just use more energy (say for the next 45 minutes) to make up for it. But perhaps staggering the curtailment times, and paying the debt of more draw from the units that were curtailed by doing even more curtailments, can kick the can down the road enough for the few hours they need to smooth peak load? Also just a guess: is the story with heating that your heat pump is sized based on your max heating load, and so losing up to 25% of its capacity on the coldest days means it would never be able to catch up?
    - windexh8er 3y ago
      > Also just a guess: is the story with heating that your heat pump is sized based on your max heating load, and so losing up to 25% of its capacity on the coldest days means it would never be able to catch up? The unit I have has a HSPF2 rating of 10.5. It's very efficient at the transfer of the heat available. Heat pumps can extract more energy than the consume. New heat pumps can operate over 300% efficiency. The best furnaces are generally in the mid-90 percentages. I have a dual-fuel system and can set where the heat pump locks out. The system is rated to a COP of 1.75 at 5F. Meaning it's still over 100% efficient at that temperature. The unit will operate down to -22F but would be at, likely, less than 50% capacity of output. To save on wear and tear of the unit, however I have my setpoint lockout at 15. It would have to be significantly below 0 for days on end to have a problem. But even then the furnace would be providing primary heat. There are people in my area that heat their entire home with ductless heat pumps [0]. My unit is rated at 48k BTU. The furnace at 100k BTU. I only really "need" the furnace for emergency. But we do have sub-zero highs rather often and during those days the heat pump would be running continuously. I also have an 80 gallon hybrid heat pump water heater which has saved us thousands over the last few years. 98% of the year it only uses the heat pump. [0] https://www.energyvanguard.com/blog/can-a-heat-pump-work-in-minnesota/ https://www.energyvanguard.com/blog/can-a-heat-pump-work-in-...
GenerWork 3y ago
>I have a newer heat pump that is rated up to 22 SEER2 Can I ask why you got a heat pump with such a high SEER rating? I look at flyers advertising heat pumps near me and the price differential between 16 SEER and 18/20 SEER units just doesn't seem worth it at all even accounting energy savings.
- windexh8er 3y ago
  Because it was a wash. I was paid a higher rebate from the state, the coop we have for power and the manufacturer. It didn't make financial sense to buy anything less.
  - GenerWork 3y ago
    Your manufacturer gave you a rebate on top of the state and coop rebate? So you have $1500 from the coop, what kind of rebates did you get from the state and manufacturer?
    - windexh8er 3y ago
      Yes. The manufacturer (Carrier) has a program called "Cool Cash" - the linked PDF is an example. The "Cool Cash" program I had was different [0]. The state also had passed a new energy law that provided rebates [1]. It's been so popular that they're expanding that even further in 2023 for air source heat pumps with, potentially, more money. [2] [0] https://yourallweatherhvac.com/media/2022-Carrier-Cool-Cash-Guidelines-REVISED-2-9-21.pdf https://yourallweatherhvac.com/media/2022-Carrier-Cool-Cash-... (PDF) [1] https://techxplore.com/news/2021-07-minnesota-energy-law.html https://techxplore.com/news/2021-07-minnesota-energy-law.htm... [2] https://www.minnpost.com/greater-minnesota/2023/03/dfl-energy-plans-include-incentives-for-heat-pumps-and-other-climate-friendly-technology/ https://www.minnpost.com/greater-minnesota/2023/03/dfl-energ... I got a $1400 rebate from the manufacturer at the time $2000 tax credit from the fed and another $1200 from the state.

mindslight 3y ago

Is it really only 15 minutes at a time, or is it 15 minute units with possibly multiple in a row? Heat pump efficiency requires long cycles, so turning it off, on, off, on within the course of an hour to make some "never off more than 15 minutes" guarantee would be counterproductive.

windexh8er 3y ago
The unit basically runs all day during the day on hot days. The difference is, as you state, it runs long cycles. The 15 minutes it's off is the break in the cycle itself. The unit I have is a communicating unit that "learns" the house in terms of all the internal and external changes. So it knows what fan speed and compressor rate to run to get to the setpoint - it doesn't just ramp up to the highest rate after a curtailment event. So it's basically running at a very low rate all day long, curtailment happens, and it ramps slightly if there's a need to bring any zones back to setpoint - but the thermostat is aware of the curtailment event and, as I was told, responds different after the curtailment is lifted. I talked to both the installer and the manufacturer regarding whether or not curtailment would negatively impact the system (performance, cost, longevity) and the consensus was that unless the curtailment events happened every hour there wasn't any downside to cooling. Heating would be another story, but I don't have any curtailment contract for heating in my home. And I believe the contract states curtailment events can only happen up to 4 times in a given day and cannot happen more than once an hour.
- mindslight 3y ago
  Ah, so basically the variable speed and feed-forward PID make it so the unit is running all the time, so it's not like the 15 minute curtailment will come right after it kicked on to satisfy cooling demand. Rather your house is continually cooling, stops for 15 minutes, then goes back to it. That makes a lot of sense! I do find it interesting that these terms are still valuable to a power company. Obviously being able to shed the load for 15 minutes is fantastic, but I would think the system would then just use more energy (say for the next 45 minutes) to make up for it. But perhaps staggering the curtailment times, and paying the debt of more draw from the units that were curtailed by doing even more curtailments, can kick the can down the road enough for the few hours they need to smooth peak load? Also just a guess: is the story with heating that your heat pump is sized based on your max heating load, and so losing up to 25% of its capacity on the coldest days means it would never be able to catch up?
  - windexh8er 3y ago
    > Also just a guess: is the story with heating that your heat pump is sized based on your max heating load, and so losing up to 25% of its capacity on the coldest days means it would never be able to catch up? The unit I have has a HSPF2 rating of 10.5. It's very efficient at the transfer of the heat available. Heat pumps can extract more energy than the consume. New heat pumps can operate over 300% efficiency. The best furnaces are generally in the mid-90 percentages. I have a dual-fuel system and can set where the heat pump locks out. The system is rated to a COP of 1.75 at 5F. Meaning it's still over 100% efficient at that temperature. The unit will operate down to -22F but would be at, likely, less than 50% capacity of output. To save on wear and tear of the unit, however I have my setpoint lockout at 15. It would have to be significantly below 0 for days on end to have a problem. But even then the furnace would be providing primary heat. There are people in my area that heat their entire home with ductless heat pumps [0]. My unit is rated at 48k BTU. The furnace at 100k BTU. I only really "need" the furnace for emergency. But we do have sub-zero highs rather often and during those days the heat pump would be running continuously. I also have an 80 gallon hybrid heat pump water heater which has saved us thousands over the last few years. 98% of the year it only uses the heat pump. [0] https://www.energyvanguard.com/blog/can-a-heat-pump-work-in-minnesota/ https://www.energyvanguard.com/blog/can-a-heat-pump-work-in-...

GenerWork 3y ago

>I have a newer heat pump that is rated up to 22 SEER2 Can I ask why you got a heat pump with such a high SEER rating? I look at flyers advertising heat pumps near me and the price differential between 16 SEER and 18/20 SEER units just doesn't seem worth it at all even accounting energy savings.

windexh8er 3y ago
Because it was a wash. I was paid a higher rebate from the state, the coop we have for power and the manufacturer. It didn't make financial sense to buy anything less.
- GenerWork 3y ago
  Your manufacturer gave you a rebate on top of the state and coop rebate? So you have $1500 from the coop, what kind of rebates did you get from the state and manufacturer?
  - windexh8er 3y ago
    Yes. The manufacturer (Carrier) has a program called "Cool Cash" - the linked PDF is an example. The "Cool Cash" program I had was different [0]. The state also had passed a new energy law that provided rebates [1]. It's been so popular that they're expanding that even further in 2023 for air source heat pumps with, potentially, more money. [2] [0] https://yourallweatherhvac.com/media/2022-Carrier-Cool-Cash-Guidelines-REVISED-2-9-21.pdf https://yourallweatherhvac.com/media/2022-Carrier-Cool-Cash-... (PDF) [1] https://techxplore.com/news/2021-07-minnesota-energy-law.html https://techxplore.com/news/2021-07-minnesota-energy-law.htm... [2] https://www.minnpost.com/greater-minnesota/2023/03/dfl-energy-plans-include-incentives-for-heat-pumps-and-other-climate-friendly-technology/ https://www.minnpost.com/greater-minnesota/2023/03/dfl-energ... I got a $1400 rebate from the manufacturer at the time $2000 tax credit from the fed and another $1200 from the state.