Central Air Conditioning

[elessar78]

I was just curious. Our home has the thermostat downstairs and it is much hotter upstairs (we live in the Northeast) and there is about a seven to ten degree difference between the two floors.

Is it cost effective at all to just install a window AC unit or two for the two bedrooms we actually sleep in at night, only running the AC units for the times we are sleeping?

[MonkeyMama]

I would say no, BUT then again maybe window units have become more efficient over the years.

I just wanted to add that we have a dual-zoned system, so two thermostats (one on each level) and each thermostat only controls one level. That said, not sure how much it would cost to install a system like that. But, it is extremely energy efficient.

[GrimJack]

Does your home have the duct work for the heating system? You could run your heating system fan which will pull all the air down through the basement where it is cooler and mixes with the cooler air from the floor with A/C. I know that this worked for me when I lived in a home with no A/C but central heating - I ran the fan on low all summer and it helped.

[scubatim84]

I would say no, BUT then again maybe window units have become more efficient over the years.

I just wanted to add that we have a dual-zoned system, so two thermostats (one on each level) and each thermostat only controls one level. That said, not sure how much it would cost to install a system like that. But, it is extremely energy efficient.

It would be outstanding to have a system like this. We don't even use our thermostat most of the time...no AC in our home, as Santa Cruz doesn't really need one except maybe 2-3 weeks out of the year. Still, it gets pretty damn warm upstairs sometimes.

The best advice I can offer is do your living downstairs during the day and early evening as much as possible. Even if you had independent thermostats for each floor, you're going to suck up a lot of juice keeping the 2nd floor cool. What about ceiling fans?

[elessar78]

I'm planning on installing a timed system, so we only cool when we're at home. I'm def interested in getting a dual zone system, wonder how long it would take to recoup the initial outlay of cash. I'm open to fans but ceiling fans dry out my sinuses. I've been doing research, and controlling the humidity also helps in the making it feel cooler/warmer than it actually is.

Link and diagram to 2-zone controlled home: HVAC 2-Zone Controller - Smarthome

[bjl584]

Probably the easiest thing to do is to make sure that your home has adequate ventilation so that the floors aren't closed off from each other. You may need to instal some ventilation fans here and there.

[JoeP]

We found two solutions to this problem. For summer, balance your blower output so that more cool air gets pushed upstairs. Reverse this in the winter. Also, try running your furnace fan manually while in "cool" mode. This will mix the air more frequently and even out the temperatures. Be sure you keep your furnace filter clean. If you have ceiling fans, run them to further mix the air (a couple basic fans can help if you don't have ceiling fans).

A more involved solution would be to install returns toward the tops of the walls. This would allow the blower to collect warmer air. The downside is that for summer the configuration would be high returns=open and low returns=blocked, and winter would be the reverse.

[Joan.of.the.Arch]

JoeP, are you saying you have multiple speed settings on your blower fan?

Elessar, I would probably just take the simple solution you asked about --using window units upstairs for summer. They probably wouldn't have to run much as you will only use them at night and they only need to cool things down perhaps seven degrees if you intend to keep the central AC running all night. I'm assuming you have central AC. If you don't, GrimJack's idea sounds like a good thing to try.

We have central AC with two floors. The cool air gets pushed into the upstairs bedrooms much better if we keep the bedroom doors open.

[elessar78]

We found two solutions to this problem. For summer, balance your blower output so that more cool air gets pushed upstairs. Reverse this in the winter. Also, try running your furnace fan manually while in "cool" mode. This will mix the air more frequently and even out the temperatures. Be sure you keep your furnace filter clean. If you have ceiling fans, run them to further mix the air (a couple basic fans can help if you don't have ceiling fans).

A more involved solution would be to install returns toward the tops of the walls. This would allow the blower to collect warmer air. The downside is that for summer the configuration would be high returns=open and low returns=blocked, and winter would be the reverse.

In the summer, close vents downstairs to push that air upstairs.

A friend also recommended putting in attic fan vents. He says it helps a lot with cooling his house.

[JoeP]

JoeP, are you saying you have multiple speed settings on your blower fan?

If you consider "off" and "on" to be multiple speeds, then yes.

Just flip the little switch over from Auto to On, and the blower fan will run continuously. The AC will kick on when the thermostat tells it to. You'll get better air mixture.

[apexair]

Undoubtedly, central air is one of the most effective and efficient ways to circulate cool air throughout the house in comparison to window air conditioning systems. However, central air conditioners offer one major benefit that individual window units cannot claim: these systems can improve your indoor air quality.

[Jillycd]

I do adjust my vents for the summer and the winter to force more air upstairs in the summer and opposite in the winter when heat rises. 2 summers ago I bought a portable air conditioner for my bedroom. ( I live in a 2 story house). Best $300 I have spent. It cools my bedroom when needed and has allowed me to not have to turn the ac on as early in the season when it is only hot upstairs. The portable unit has a timer so,I can just cool off the room and it shuts off or I can run it all night. I have not noticed any real impact to my utility bills either.

[elessar78]

Sometimes the timing of threads is amazing. Just yesterday we came home and it was pretty warm in the house, we concluded that the central air had gone out. WE had a guy come out to repair it and he said that our thing is on it's last legs (18 years old). But it's been a dutiful unit despite the guy referring to it as a very low-end model—at least we know that if we replace, we're happy with the performance of the lower end models for our home.

[disneysteve]

Sometimes the timing of threads is amazing. Just yesterday we came home and it was pretty warm in the house, we concluded that the central air had gone out. WE had a guy come out to repair it and he said that our thing is on it's last legs (18 years old). But it's been a dutiful unit despite the guy referring to it as a very low-end model—at least we know that if we replace, we're happy with the performance of the lower end models for our home.

If your unit is 18 years old, you should see a nice drop in your utility bills when you install the new one, especially if you choose something highly efficient.

[elessar78]

Thanks DS, that sounds like great news.

I want to save up for it. Since we live in a pretty cool climate and summer is ending, I hope I can buy myself a few extra months of saving and research.

Any recommendations/experiences as far as brands that are on the market?