Window A/C Units

[Volvohead]

Originally Posted By: Gary Allan

That's their advantage. A central air unit takes a long time to effect change from set point. A window unit does not. I an "open ended" max duty cycle, the window unit offers rapid cool down allow the unit to remain idle when that room or area is not in use.


I guess it comes down to what "change" one is after. There's heat, and there's humidity. There's BTUs, and there's pints per hour. There's cooling, and there's dehumidification. Any evaporator can only remove so much moisture from the air per hour. You can't quickly condition air in this regard. Window units are generally less efficient than central units at this. I don't live that far from you. Right about now, higher humidity is becoming a factor around here.

Most of the commercialized world lives in centrally conditioned spaces. It's there every time you walk into a store or office building or shopping mall. It does not feel as bitingly cold, but it doesn't have to, as it is usually much drier air than the typical overcooling window unit. IAQ folks will tell you that correctly conditioned air is both cool and DRY, and comfortable.

So why cranking a Haier to max output in a smaller space may bring the temps down in a hurry, it leaves a lot of humidity in the room. Humidity is half the comfort battle. When you do that, you HAVE to have it colder to reach a similar comfort index. More importantly, the oversized window unit NEVER lowers the humidity to the right "set point". That's their disadvantage. And the constant cycling is just plain uncomfortable.

This is NOT a statement against window units. I've used them for decades before getting lazy with central. It is just pointing out the disadvantages of using one with too much cooling capacity.

A properly sized window unit, with GOOD moisture removal rates (and that is the key spec that always gets ignored) can be the equal of central. A good Friedrich has solid dehumidification rates and can get pretty darn close to a Trane or Lennox, provided you give it some time.

It is a free country, which is why we are always free to disagree, hopefully with a smile.

 

[Gary Allan]

Quote:
So why cranking a Haier to max output in a smaller space may bring the temps down in a hurry, it leaves a lot of humidity in the room. Humidity is half the comfort battle. When you do that, you HAVE to have it colder to reach a similar comfort index. More importantly, the oversized window unit NEVER lowers the humidity to the right "set point". That's their disadvantage. And the constant cycling is just plain uncomfortable.


That assumes that you set it at a long cycle setting. Again, we're (I'm) talking "open ended". You're still viewing it from a given temp setpoint reasonably cycle producing the proper dehumidified air. While the same unit with no setpoint employed (evaporator temp limits) will reach the proper humidity level a "some temp". You may view that as an unusual way to look at it.


That is, a unit run continuously will always produce dehumified air at some variable temp depending on load from ambient sources.

You probably don't break into "sweating like a pig" @ 75F/50% just moving around. I was a sweater when I was 180lb and at 280lb. I like a nice dry meat locker.

 

[Volvohead]

I think we're saying the same thing.

The correct way to maintain dehumidification is to run the compressor continuously. A correctly sized evaporator, regardless of window or central design, does that without excessive cooling. That's what a correctly sized unit (central or window) should do - run relatively CONTINUOUSLY and not short cycle - and maintain temperature and humidity at comfortable levels.

The really good window units have timers, and can start a few hours before you arrive and gradually bring temperature and humidity to optimal levels. You can't speed up dehumidification - it always takes time.

You just seem to like meat lockers (and oversized window units).

I actually like being out in the 100+ temps. The hotter, the better.

 

[Tahoe4Life]

Originally Posted By: Gary Allan
While I agree on central air sizing being critical, I don't feel that way on window units. There is no central air unit that I've ever experienced that has an outlet temp like a window unit. That is ..my living room with the 13k btu unit is a meat locker compared to what most would set there central air thermostat.

A window unit is going to work out to a given temp at a given duty cycle. A central air unit is going to work out to a given duty cycle for a given thermostat set point.

Most condos in Fla have central A/C. I really don't like it cause its impossible to keep all rooms at the desired temperature. The living room and kitchen are ice cold and the bedrooms are warm unless I drop the temperature down to 70 degrees instead of usually 75 its usually set at. I put a wall unit in the back of the house to cool the bedrooms so at night I shut off the central unit and run the 10K BTU unit. The compressor never shuts off during the night and cools the bedrooms perfectly. That one is a Freidrich.

The most popular A/C's down here that hold up for years are Freidrich,G.E. and Kenmore.

Also with the central A/C every year the drain backs up and I have a flood in the house. That happens at least twice a year without fail. It happens to everyone in the building.

 

[Volvohead]

Originally Posted By: FORD4LIFE

Most condos in Fla have central A/C. I really don't like it cause its impossible to keep all rooms at the desired temperature.


I will say this about central air, as it was a brave new world for us (having lived with window units for decades) and we did a mountain of research about it before retrofitting a 40 yo split level with a complete system including metal ductwork (which no one does anymore):

The most important system factor, more important than the equipment, the ducting system, or anything else for that matter, is the skill and expertise of the installer in planning and executing the system. Many home systems are not correctly planned or laid out and there are a lot of hackers in residential HVAC. A bad HVAC install can be really BAD. The good ones are few and far between. What we wound up doing is finding a larger commercial HVAC firm that had a gap in schedule and was willing to take on a "quick" residential install. They spent a lot of time just planning and calculating loads. We have complete and even conditioning on every level and room (except one BR where I asked for a little cooler), and that is no easy feat in a large four level split.

The installer is everything with HVAC. And avoid fiberboard ductwork.

Looking back, I think we did the right thing. I don't have to haul around, clean and store window units every season, our resale value has gone up, the house is a lot quieter and more comfortable, and we actually have lower electric bills. Love the variable handler and the dual stages, and I can set temp AND humidity levels. Once a year I change a filter and that's it.