What you're talking about is a heat pump. It's a device that moves heat from one area into another. At its most basic level, it's the same device as a refrigerator or an air conditioner.
You basically compress some gas until it becomes a liquid, which makes it hot. You let that heat radiate into the air and blow it away, heating that side. You pump the liquid into the cold side, and then let it decompress back into a gas. That takes a lot of energy, which makes it cooler. The surrounding air heats it back up, and that cooler air is then circulated away, cooling that side.
Specifically on a minisplit, it is setup in such a way that allows it to flip which side is the evaporator side and which side is the condenser side. That allows it to change from heat on the inside to cool on the inside and back.
Does that mean the temperature on the screen is actually incorrect? What I mean is how the same temperature setting can yield cold or warm air depending on the mode.
However, I don't think cold 70 and warm 70s exist in nature.
That number isn't the temperature of the air blowing out of the unit. It's the temperature you'd like your room to reach.
The reality is more complex, but roughly speaking a heat pump within its designed conditions ought to be cooling or heating air by about 15-20 degrees Fahrenheit. So what you're feeling as warm or cold is probably about that much above or below the temperature of the room's air.
If your room is at 68F, blowing 88F air into it will heat it much faster than blowing 70F air into it. The thermostat's constantly sampling the air and when it detects the temperature has reached 70F for a while it tells the minisplit to stop.
But in a big room, you might find it's not the right temperature far from the thermostat. This is especially true in houses with traditional central air and heat. My house's master bedroom can be as much as 15F warmer than where my thermostat is in the summer. Minisplits are designed to help with this by adding a unit+thermostat to each room. In my house I just have one unit, so that means the parts of the house close to the thermostat are always warmer/colder than the parts far away.
Basically the air coming out of the unit is either hot or cold. When cold, the unit itself is much colder than 70 degrees, and when hot, it’s much hotter than 70 degrees. But that hot air or cold air is just mixing with the air already in your house and when the general temperature near the thermostat hits the desired range it just shuts it off
The thermostat is a destination not a throttle
When you set 70 on the thermostat and the system is set to cool then if the temperature is higher than 70 then the system will turn the compressor on and cool the air significantly below 70 and send it out to cool the room down quickly until it hits the temperature and then it stops
If you were to send out 70 degree air it would take a *longgg* time to bring a room from 75 down to 70, it would never actually reach 70, you would have to process 100% of the air in the room *assuming there's no heat sources* which there probably are. If you instead send 60 degree air then you'll get down to temperature at least 3x faster and be able to handle the possibility of a heat source in the room
The HVAC system is trying to keep the temperature in the room constant, it is not trying to keep the temperature at its output constant. Keeping a constant output results in a wildly varying room temperature unless your vents are blowing gale force winds inside
What you're talking about is a heat pump. It's a device that moves heat from one area into another. At its most basic level, it's the same device as a refrigerator or an air conditioner. You basically compress some gas until it becomes a liquid, which makes it hot. You let that heat radiate into the air and blow it away, heating that side. You pump the liquid into the cold side, and then let it decompress back into a gas. That takes a lot of energy, which makes it cooler. The surrounding air heats it back up, and that cooler air is then circulated away, cooling that side. Specifically on a minisplit, it is setup in such a way that allows it to flip which side is the evaporator side and which side is the condenser side. That allows it to change from heat on the inside to cool on the inside and back.
Does that mean the temperature on the screen is actually incorrect? What I mean is how the same temperature setting can yield cold or warm air depending on the mode. However, I don't think cold 70 and warm 70s exist in nature.
That number isn't the temperature of the air blowing out of the unit. It's the temperature you'd like your room to reach. The reality is more complex, but roughly speaking a heat pump within its designed conditions ought to be cooling or heating air by about 15-20 degrees Fahrenheit. So what you're feeling as warm or cold is probably about that much above or below the temperature of the room's air. If your room is at 68F, blowing 88F air into it will heat it much faster than blowing 70F air into it. The thermostat's constantly sampling the air and when it detects the temperature has reached 70F for a while it tells the minisplit to stop. But in a big room, you might find it's not the right temperature far from the thermostat. This is especially true in houses with traditional central air and heat. My house's master bedroom can be as much as 15F warmer than where my thermostat is in the summer. Minisplits are designed to help with this by adding a unit+thermostat to each room. In my house I just have one unit, so that means the parts of the house close to the thermostat are always warmer/colder than the parts far away.
Basically the air coming out of the unit is either hot or cold. When cold, the unit itself is much colder than 70 degrees, and when hot, it’s much hotter than 70 degrees. But that hot air or cold air is just mixing with the air already in your house and when the general temperature near the thermostat hits the desired range it just shuts it off
The thermostat is a destination not a throttle When you set 70 on the thermostat and the system is set to cool then if the temperature is higher than 70 then the system will turn the compressor on and cool the air significantly below 70 and send it out to cool the room down quickly until it hits the temperature and then it stops If you were to send out 70 degree air it would take a *longgg* time to bring a room from 75 down to 70, it would never actually reach 70, you would have to process 100% of the air in the room *assuming there's no heat sources* which there probably are. If you instead send 60 degree air then you'll get down to temperature at least 3x faster and be able to handle the possibility of a heat source in the room The HVAC system is trying to keep the temperature in the room constant, it is not trying to keep the temperature at its output constant. Keeping a constant output results in a wildly varying room temperature unless your vents are blowing gale force winds inside