It seems like I can hang meat in my hotel room pretty effortlessly but my home AC really can’t get my house as cold. Is there a fundamental difference between how the two ACs operate or am I just more likely to crank my AC down at a hotel?
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PTAC system vs a whole house system or VTAC
https://blog.totalhomesupply.com/ptac-vs-vtac/
Hotel rooms *generally* have a dedicated unit for each room (thought they can be ‘networked’ into a larger system). That unit is usually powerful enough to do the job.
Where it really matters is that the unit is cooling one room (plus a bathroom) with limited interface with the outside (usually one wall). Cooling one fairly well insulated room doesn’t take all that much effort. It’s a reasonably efficient/powerful A/C cooling a small space, so it doesn’t have a lot of work to do.
Hotels have to deal with a lot of different people who want a lot of different temperatures. Your house only has you (unless you ans your spouse/roommate fight over the thermostat, but that’s a different question). Empty rooms don’t get much AC in them, and the system has to respond quickly when you check in. As a result they need to make a large swing in temperature in a small space (your room).
Your house needs to keep a uniform temperature in a large space. As a result it can be much more energy efficient, and thus less expensive to operate.
There’s a couple of factors, it’s kind of subjective.
*Usually* we’re talking about a relatively large structure when we say ‘a house’. And often houses have relatively open floor plans. So there’s one big AC unit but it’s having to cool multiple rooms at the same time. AC units only come in a few “sizes”, but houses are built with a lot of different square footages and layouts. So it might cost a few thousand dollars more to have “too big” a unit and you might be right on the threshold, so technically you might have “too small” of a unit. But it’s probably something like “This size AC can cool 1800 square feet and you have 1825” compared to, “Is it worth $2,000 extra to buy the AC that is made for 2500 square feet?” and usually it’s not.
Cooling the entire house also means there are a lot of factors like how long your ducts are, if your ducts are insulated, if you have leaks in your ducts, if your air handler is operating as it should, insulation, windows, etc. There are a lot of factors that make it really hard to cool an entire house with just one unit. Some houses use multiple units to try and compensate.
On the other hand, hotel rooms are relatively small. It’s just one open space and it’s usually less than about 300 square feet. If you peek at window units at a hardware store you’ll see they’re most typically made in sizes for rooms about 150, 250, and 350 square feet. So the units in most hotel rooms are probably sized for about 300 square feet but the room might only be 250.
It’s also a lot less work to cool off one room as opposed to an entire house. I’ve been in houses that don’t have a central AC, they only have window units or mini-splits. They can cool off the individual rooms very quickly, too. But keeping the whole house cool takes more energy than if they had centralized A/C. This only really works, though, if your house is built with less of an “open” floor plan.
The funky part is we tend to measure the space we’re cooling in terms of the floor plan’s square footage, but what really matters is the VOLUME of air inside the house. A 250 square foot room with 8 foot ceilings will cool off much faster than one with 12 foot ceilings, and even if your living room is 250 square feet if it’s completely open to the rest of the house having a window unit in it won’t feel as cold as if it were closed off by doors.
Put really simply:
Refrigerators are usually relatively small because it takes more and more energy to cool bigger spaces. A hotel room is smaller than a house. So it’s easier to make it colder faster with less energy.
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Have you properly maintained your home AC, and is it properly sized for your home? If either of those are no, there’s your issue. If both are yes, you should be able to get cold air from it just like you would in a hotel.
You’re only cooling a few thousand cubic feet of volume in a small room in a hotel. In your house it’s magnitudes more Volume your ac has to cool. Add in small gaps in windows and doors for air to escape, you’ll never get it as cold as a hotel.
I said this on the last ELI5 about AC: I assume you live in a cooler climate? Moved from Texas to Boston and home AC units in Texas are next level. I regularly wear sweaters inside during summer. I have not once needed to wear a sweater indoors in Boston.
Cooler climates just don’t need the most recent AC technology. It’s too expensive for the net gain. A window unit does the trick for 46/52 weeks and the last 6 weeks the window unit still does a good amount. Hotels/commercial buildings are more likely to invest in the better technology because they have the money and they make more money if people are comfortable for those 6 weeks. Boston’s biggest tourist times are during those 6 weeks. A hotel has a lot more to gain from a $15k ac unit than someone just living in the area
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