How can the aircon be at the same temperature for both heating/cooling modes and feel different?
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There are a lot of good answers here. Another thing to remember is that when you heat air, the mass of water stays the same, so the relative humidity drops. Cool air is significantly drier (in terms of water mass) than warm air.
As an example, if you maintain 74 degrees, air conditioning should drop the dewpoint to approximately 52 degrees, which is a relative humidity of about 46%. But if it’s 35 degrees outside, your dewpoint can’t be higher than 35, and is probably much lower. This means the relative humidity is only 24% or lower, a very noticeable difference that will certainly impact comfort.
There are a lot of good answers here. Another thing to remember is that when you heat air, the mass of water stays the same, so the relative humidity drops. Cool air is significantly drier (in terms of water mass) than warm air.
As an example, if you maintain 74 degrees, air conditioning should drop the dewpoint to approximately 52 degrees, which is a relative humidity of about 46%. But if it’s 35 degrees outside, your dewpoint can’t be higher than 35, and is probably much lower. This means the relative humidity is only 24% or lower, a very noticeable difference that will certainly impact comfort.
Because the air is unlikely to be fully mixed, and you’re feeling the stratification
In a room with the ceiling fan running on reverse (pulling air) it’ll feel more similar
Because the air is unlikely to be fully mixed, and you’re feeling the stratification
In a room with the ceiling fan running on reverse (pulling air) it’ll feel more similar
One thing that a lot of the replies have missed also is the fact that how the AC determines when to turn off is very imprecise.
Example: if you set the temp to 70 F and the room is currently above that, say 72 F, the AC will blow Very Cold Air until after the temp is Below 70 F. So it basically blows cold until it is pretty close to 69 F. But if the temp is set to 70 F and it’s currently lower than that, say it’s 68 F, the Heat will turn on and blow Very Hot Air until it’s Above 70 F so that it doesn’t actually turn off until it’s pretty much 71 F.
Also, our bodies are very sensitive to temp, as that is one of the things that can kill us is low or high temps. So just one or two degrees is very noticeable. This all combines with what others have been describing about how your body detects changes in temp rather than detecting a specific temp. Like your body has no clue whether it’s currently 70 F or 65 F. It only knows that it’s either colder or warmer than it was. And the faster the temp changes, the more alarmed your body gets, and it will feel like a greater change in temp if it happens very quickly.
One thing that a lot of the replies have missed also is the fact that how the AC determines when to turn off is very imprecise.
Example: if you set the temp to 70 F and the room is currently above that, say 72 F, the AC will blow Very Cold Air until after the temp is Below 70 F. So it basically blows cold until it is pretty close to 69 F. But if the temp is set to 70 F and it’s currently lower than that, say it’s 68 F, the Heat will turn on and blow Very Hot Air until it’s Above 70 F so that it doesn’t actually turn off until it’s pretty much 71 F.
Also, our bodies are very sensitive to temp, as that is one of the things that can kill us is low or high temps. So just one or two degrees is very noticeable. This all combines with what others have been describing about how your body detects changes in temp rather than detecting a specific temp. Like your body has no clue whether it’s currently 70 F or 65 F. It only knows that it’s either colder or warmer than it was. And the faster the temp changes, the more alarmed your body gets, and it will feel like a greater change in temp if it happens very quickly.
The temperature our bodies feel it’s a very complex matter that a 21C on a thermometer in a wall barely reflects. There’s heat index (windchill) that is temperature with humidity which measures estimated perceived temperature. Then there are air currents, that draw heat from your skin so the same ambient feels colder. There’s radiation from objects: you could be in a 21C room yet being hot because a wall of bricks exposed to sun is emitting radiation to you. There are also studies that bodies have season cycles so what 21 feels in summer is not the same as 21 in winter.
The temperature our bodies feel it’s a very complex matter that a 21C on a thermometer in a wall barely reflects. There’s heat index (windchill) that is temperature with humidity which measures estimated perceived temperature. Then there are air currents, that draw heat from your skin so the same ambient feels colder. There’s radiation from objects: you could be in a 21C room yet being hot because a wall of bricks exposed to sun is emitting radiation to you. There are also studies that bodies have season cycles so what 21 feels in summer is not the same as 21 in winter.
When you’re cooling, the thermostat is one of the warmest things in your house.
When you’re heating, the thermostat is one of the coolest things in your house.
So any room with good airflow that isn’t close to the thermostat probably has 10 degrees of difference between summer and winter even with the thermostat set the same.
When you’re cooling, the thermostat is one of the warmest things in your house.
When you’re heating, the thermostat is one of the coolest things in your house.
So any room with good airflow that isn’t close to the thermostat probably has 10 degrees of difference between summer and winter even with the thermostat set the same.
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