Re:Shocked to find smart thermostats raised remotely by “Sma...
by pdonis on Monday June 21, 2021 @10:49AM
(#27579703)
> If you cycle the AC on and off every few minutes, neither one will wander much.
The dewpoint will, yes. There's a lot more room for dewpoint to rise than for temperature to rise.
> It will work "harder" but for less time, so averaged over the entire 10 minutes it's probably about the same.
I don't think so.
> The different modes having different dew points was a core part of your original suggestion.
> If you're changing that, and now we're talking about a system where "full on" is an optimal dew point but high air flow, and "energy saving mode" is the same dew point but with low air flow
Neither of those is what I'm talking about. I'm talking about a system whose only mode (unless you want to have an "initial cooldown" mode as well, see below) is what you called "energy saving mode": the dewpoint is set higher than a current A/C unit's "full on" mode, so that it's just low enough for comfort, ahd the A/C runs at much lower power (lower compressor power and lower airflow) continuously to maintain that dewpoint, instead of running "full on" (high compressor power, high airflow) for a while at a lower dewpoint, then cycling completely off for a while and letting the dewpoint get higher than the comfort level.
The point of running in the above "energy saving" mode is that you do it all the time; you never shut the system off. But there might be cases where the system turns off for a while unavoidably (say a power outage) and the house gets well above the temperature and dewpoint target. For that case, the system would have an "initial cooldown" mode, where it does run "full on" for a while (high compressor power, high airflow, dewpoint below optimal) until it senses that it's back to its usual setpoint, then it goes back into "energy saving" mode described above.
Running at the same (low) dewpoint but lower airflow would save some energy (less fan power), but much less than running at a higher dewpoint, since that reduces the amount of dehumidification, and dehumidification is most of the work that the A/C system does.
The dewpoint will, yes. There's a lot more room for dewpoint to rise than for temperature to rise.
> It will work "harder" but for less time, so averaged over the entire 10 minutes it's probably about the same.
I don't think so.
> The different modes having different dew points was a core part of your original suggestion.
> If you're changing that, and now we're talking about a system where "full on" is an optimal dew point but high air flow, and "energy saving mode" is the same dew point but with low air flow
Neither of those is what I'm talking about. I'm talking about a system whose only mode (unless you want to have an "initial cooldown" mode as well, see below) is what you called "energy saving mode": the dewpoint is set higher than a current A/C unit's "full on" mode, so that it's just low enough for comfort, ahd the A/C runs at much lower power (lower compressor power and lower airflow) continuously to maintain that dewpoint, instead of running "full on" (high compressor power, high airflow) for a while at a lower dewpoint, then cycling completely off for a while and letting the dewpoint get higher than the comfort level.
The point of running in the above "energy saving" mode is that you do it all the time; you never shut the system off. But there might be cases where the system turns off for a while unavoidably (say a power outage) and the house gets well above the temperature and dewpoint target. For that case, the system would have an "initial cooldown" mode, where it does run "full on" for a while (high compressor power, high airflow, dewpoint below optimal) until it senses that it's back to its usual setpoint, then it goes back into "energy saving" mode described above.
Running at the same (low) dewpoint but lower airflow would save some energy (less fan power), but much less than running at a higher dewpoint, since that reduces the amount of dehumidification, and dehumidification is most of the work that the A/C system does.