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Recall your entire house is a thermal battery too! In fact, all the four major energy loads in a house - Heating/Cooling, Water heating, EV Charging, House Bat

Recall your entire house is a thermal battery too! In fact, all the four major energy loads in a house - Heating/Cooling, Water heating, EV Charging, House Battery - are extremely flexible. But we're still lacking good standards for reliable control. Today we do stuff like tell your HVAC to stop via vendor X's cloud API. What happens if your router dies after we send a "stop" command in the middle of the winter? For many of the minisplits I see control code for, they'd just let the house freeze, waiting forever for another command that'll never arrive. For critical functions like "keep my water pipes from freezing" / "be able to drive to work in the morning", we need much better standards for reliable control and safe failure modes.

phh 3y ago
French's "fil pilote" to control electrical radiators is quite bullet proof in this regard: No power on command wire = comfort thermostat, full power = "eco" thermostat, and there are other more convoluted signaling for various modes (send only positive voltage, only negative, only a third of the phase) , including simple anti freeze mode. There is an off command as well, but you really can't send it accidently. If your IoT dies, you'll most likely get to the comfort mode. Only nit is that in 2023 the default mode would probably be "eco" rather than "comfort"
MostlyStable 3y ago
Tangentially related gripe: My biggest issue in making this work reliably is that my "smart" thermostat is trying to be too smart. Our power gets cheap at 10pm. I can't just set my HVAC to turn on at 10 and go full blast until power gets expensive again at 6am. I have to program a set temperature at a time. if I set that at 10pm, my thermostat tries to make sure that it _reaches_ that temp at exactly the time. So it will actually turn on an hour early. So I have to guess how long it will take my HVAC system to reach whatever temperature I have it set to, and then set it for that much time _after_ 10PM. It's inexact and annoying, and means that I am leaving performance on the table. I have idly searched a few times for a replacement thermostat that would interact locally with home assistant and have had zero luck (partially due to the fact that my system is complicated and seems to have a non-standard wiring setup). Everything else: hot water heater, EV, laundry, etc. are all trivially easy to make run during the desired periods. But the biggest use of energy I have (yes, larger than charging the car) is a PITA to make it play well with TOU billing.
- Scoundreller 3y ago
  What’s your “smart” thermostat?
  - MostlyStable 3y ago
    Lennox 7500 series.
- Symbiote 3y ago
  Check the manual for the thermostat. Mine has a setting to disable this feature.
- quickthrowman 3y ago
  Just buy a 240v DPST 24 hr mechanical time switch and wire it into the electric furnace circuit (or furnace fan circuit if you have a gas-fired furnace). Intermatic makes them. The ‘smart’ thermostat can call for heat all it wants, but nothing will happen if the time switch relay contacts are open. I’ve seen 50 year old 24 hour mechanical time switches operating just fine, and you won’t need to replace your thermostat. This one is $122 and comes inside a NEMA 1 enclosure: https://www.intermatic.com/Product/T104?setcontextlanguagecode=en https://www.intermatic.com/Product/T104?setcontextlanguageco...
AnthonyMouse 3y ago
> In fact, all the four major energy loads in a house - Heating/Cooling, Water heating, EV Charging, House Battery - are extremely flexible. The dominant energy load in existing houses is heating. EV charging is 100% new generation capacity and doesn't take any of the existing load off the power grid. House Battery isn't a load, it's the expensive thing you suffer when the actual loads are inflexible. Heating is slightly flexible, you can lower your thermostat at night, but it's also colder at night. And most existing heating is fossil fuels. Converting that to electricity is going to require more electricity consumption at night than we have now.
- jakewins 3y ago
  > EV charging is 100% new generation capacity and doesn't take any of the existing load off the power grid. All the more important to ensure this additional demand is flexible. Shaping it to match renewable production and low-usage hours in the distribution grid means higher capacity factors across the board and less new transmission+distribution need. > Converting <home heating> to electricity is going to require more electricity Yes.
  - AnthonyMouse 3y ago
    > All the more important to ensure this additional demand is flexible. It's inherently flexible. Shaping it to be that way isn't a particularly hard problem. The issue is that it's entirely new demand -- what you're really replacing is the petroleum burned in existing cars, not any part of the existing power grid. So how do you solve the demand currently served by coal and natural gas and home heating oil, rather than gasoline and diesel? > Converting <home heating> to electricity is going to require more electricity I feel like editing out the "at night" part hasn't actually provided a mechanism for supplying that electricity at night when it's cold and you need heat.

phh 3y ago

French's "fil pilote" to control electrical radiators is quite bullet proof in this regard: No power on command wire = comfort thermostat, full power = "eco" thermostat, and there are other more convoluted signaling for various modes (send only positive voltage, only negative, only a third of the phase) , including simple anti freeze mode. There is an off command as well, but you really can't send it accidently. If your IoT dies, you'll most likely get to the comfort mode. Only nit is that in 2023 the default mode would probably be "eco" rather than "comfort"

MostlyStable 3y ago

Tangentially related gripe: My biggest issue in making this work reliably is that my "smart" thermostat is trying to be too smart. Our power gets cheap at 10pm. I can't just set my HVAC to turn on at 10 and go full blast until power gets expensive again at 6am. I have to program a set temperature at a time. if I set that at 10pm, my thermostat tries to make sure that it _reaches_ that temp at exactly the time. So it will actually turn on an hour early. So I have to guess how long it will take my HVAC system to reach whatever temperature I have it set to, and then set it for that much time _after_ 10PM. It's inexact and annoying, and means that I am leaving performance on the table. I have idly searched a few times for a replacement thermostat that would interact locally with home assistant and have had zero luck (partially due to the fact that my system is complicated and seems to have a non-standard wiring setup). Everything else: hot water heater, EV, laundry, etc. are all trivially easy to make run during the desired periods. But the biggest use of energy I have (yes, larger than charging the car) is a PITA to make it play well with TOU billing.

Scoundreller 3y ago
What’s your “smart” thermostat?
- MostlyStable 3y ago
  Lennox 7500 series.
Symbiote 3y ago
Check the manual for the thermostat. Mine has a setting to disable this feature.
quickthrowman 3y ago
Just buy a 240v DPST 24 hr mechanical time switch and wire it into the electric furnace circuit (or furnace fan circuit if you have a gas-fired furnace). Intermatic makes them. The ‘smart’ thermostat can call for heat all it wants, but nothing will happen if the time switch relay contacts are open. I’ve seen 50 year old 24 hour mechanical time switches operating just fine, and you won’t need to replace your thermostat. This one is $122 and comes inside a NEMA 1 enclosure: https://www.intermatic.com/Product/T104?setcontextlanguagecode=en https://www.intermatic.com/Product/T104?setcontextlanguageco...

AnthonyMouse 3y ago

> In fact, all the four major energy loads in a house - Heating/Cooling, Water heating, EV Charging, House Battery - are extremely flexible. The dominant energy load in existing houses is heating. EV charging is 100% new generation capacity and doesn't take any of the existing load off the power grid. House Battery isn't a load, it's the expensive thing you suffer when the actual loads are inflexible. Heating is slightly flexible, you can lower your thermostat at night, but it's also colder at night. And most existing heating is fossil fuels. Converting that to electricity is going to require more electricity consumption at night than we have now.

jakewins 3y ago
> EV charging is 100% new generation capacity and doesn't take any of the existing load off the power grid. All the more important to ensure this additional demand is flexible. Shaping it to match renewable production and low-usage hours in the distribution grid means higher capacity factors across the board and less new transmission+distribution need. > Converting <home heating> to electricity is going to require more electricity Yes.
- AnthonyMouse 3y ago
  > All the more important to ensure this additional demand is flexible. It's inherently flexible. Shaping it to be that way isn't a particularly hard problem. The issue is that it's entirely new demand -- what you're really replacing is the petroleum burned in existing cars, not any part of the existing power grid. So how do you solve the demand currently served by coal and natural gas and home heating oil, rather than gasoline and diesel? > Converting <home heating> to electricity is going to require more electricity I feel like editing out the "at night" part hasn't actually provided a mechanism for supplying that electricity at night when it's cold and you need heat.