Controlling a minisplit
fourforhome
| Posted in General Questions on
While “set and forget” is the best use of a mini-split thermostat, we like the house 2 or 3 degrees cooler at night while sleeping.
Is there a way to control a mini-split to utilize a lower output (and higher efficiency) while warming the house up to the daytime temperature? A longer ramp time is fine.
(Possible OAT range is 25-45°F)
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Replies
If you can find a way to gradually turn up the thermostat, then the mini-split may never switch to high power "catch up" mode.
You might also look at ways to differentially heat the bedroom and use the rest of the house to provide much of the morning catch up btus (ie, perhaps a simple as opening the door in the morning before the thermostat calls for a higher temp). Limited to a small space, comfort is likely to outweigh a small net energy effect.
Some thermostats permit many programmable set points and times (the ecobee3 that I use is one example). You could split the “ramp time” into several smaller temperature levels to make the overall temperature change more gradual with respect to time.
You might also try contacting a company like ecobee and ask them. I know that particular company tries to help the thermostat be energy efficient, so you might try suggesting a mini-split optimized operation mode to them to incorporate into their product.
Bill
Some manufacturers, I think Fujitsu does this, has a parameter where you essentially tell it whether you have high or low quality construction. If you set it to high quality, it is a lot less aggressive, in low quality it cranks itself up quickly. The actual verbiage is different though, I'm just going off what I remember.
Here is another thread where it was mentioned...
https://www.greenbuildingadvisor.com/question/remote-thermostat-for-fujitsu-mini-split
These are all good points. The "no heroics" setting sounds really close to what I would want to do.
If all you want is a 2 degree setback then setting the Fujitsu on "high insulation" as Josh suggests should not result in a significant loss of efficiency as the startup will be gradual. Because the warm up will be gradual it will take some time to get those two degrees back. If you want a larger setback or if you want the house back up to temperature when you get up in the morning, then you can get a product like Flair that lets you set a schedule to gradually change the temperature in the morning. Flair also lets you monitor the actual temperature over the internet.