A/C & fan usage

[msmith13]

Before I even ask my question, let me acknowledge that using central air is very anti-mustachian...I know, I know.  :-)  That said, for times that I do want to use it, I'd like it to be as efficient as possible.  Thanks in advance for any advice and/or suggestions!

So...am I doing it right?  Are there changes I can make?

We have a 2-story colonial with a finished, partly-exposed basement.  The 2nd floor gets so warm/hot if we keep the settings at normal (75^o F when we're home & awake).  We already use ceiling fans to help as much as possible.  I've looked into getting duct vents that are thermostat controlled but the cost was outrageous (sorry but this is not something I feel I could do myself).

• There is one return duct running from the unit to the 2nd floor.  In the summer, I put rigid insulation in the lower return opening on each floor.  [My theory is, this only permits the warmer house air to be drawn to the unit for cooling rather than the already-cool air.]

• I close all of the vents on the 1st floor.  [I'm trying to direct more of the cool/cold air to the upstairs.]  I also close all of the (few) vents in the basement since it's cool enough there already.

---

Moving to a different, yet related, topic.

Am I doing something wrong?

• I find that using a fan (granted it's not a window fan but rather, a typical oscillating one) when it does get cooler out at night doesn't really cool the house down as much as it seems like it should.  I put it in our bedroom (front-right of house) and open a window on the 1st floor (back-left).  The only path for the air to travel is up the (mostly enclosed...meaning not a 2-story ceiling height) stairwell. 

[catccc]

I don't have central air, but your moves make sense to me in theory.  The only thought is maybe it takes more work for the A/C to cool the warmer air rather than a combo of the two?  Keep in mind I know nothing about HVAC...  Also, if you are just turning a little dial to "close" the vents, maybe something more effective might help?  The magnetic vent covers or something similar?

Here's what we do:
We have deep windowsills and put box fans in the windows.  Our 2nd floor bedroom is on the "cool" side of the house.  In the summer it's cooler.  (Also, in the winter it is warmer.  I don't really understand it, but I'll take it.)  During the day we turn the box fan so it is blowing out.   I like to think that this is creating some sort of current that pulls cool air from the first floor upstairs.  Then at night we flip it around and blow cool air in.  The kids' room gets a window unit that is turned on at nap time and night time only.  The first floor has one big (old, probably quite inefficient) window unit, and I try to keep it off until July, as a fun game to play every year that results in a lot of semi-nudity.

[ShoulderThingThatGoesUp]

Do you have a whole-house fan in your roof that you could run? When I had a split-level near Philadelphia that was very helpful to cool the house down at night.

[MsPeacock]

How is your attic insulation? Is the heat coming from the inside of the house (e.g. rising up) or coming from the heat of the roof?

My basement is always much cooler than the rest of the house. I use a box fan at the bottom of the basement stairs and tilt it pointing upwards and then another box fan at the top of the stairs,  to move cool air upwards (my house is only basement and first floor).

Would an energy audit be helpful? In our area they are available through the electric company at a significantly reduced cost (e.g. $100 vs. $500). I had one done and found it very helpful and they also connected us w/ all sorts of rebates and deals for making upgrades.

Is your A/C old and is it working correctly? Have you had someone out to evaluate it? Could it be underpowered for the amount of space you are trying to cool?

There are many 2-story colonials and cape cods in my neighborhood. The cape cods are notorious for being extremely hot upstairs (houses were all built in the 50s). Many people have installed window units or second A/C units in order to get effective cooling on the second story.

[TheLazyMan]

I usually keep the whole-house fan running constantly to distribute the area around.

If it gets cool at night in your climate, open some windows downstairs and upstairs and let the hot air out that way, no  fan required.

When I had a two story house with a hot upstairs, what I found to help the most was to keep the bedroom doors all closed during the day so the hot air couldn't get into them.

[msmith13]

Our bedroom is the hottest room upstairs (all year 'round) and considering it has east-facing & south-facing walls, I'm not surprised.  The other bedrooms are in the rear of the house (north-facing) and/or have less linear wall space which I feel contributes to their more consistent temperatures (albeit not ideal).

We don't have a whole-house fan but I've wondered about the merits of one in the past.

We had an energy audit about 2 years ago and it came back pretty good.  They had some suggestions but we opted to save the money seeing that the numbers were already good.

The house is only approaching 6 years old.

I'll have to play around with doors closed to see how that helps.

[TheLazyMan]

I forgot to mention solar shades on the outside of windows can help keep down solar gain, or you could plant a tree to provide some shade to the affected windows.

Here's where I got my solar shades from http://www.qualitywindowscreen.com/
Usually darker ones are easier to see through if that's a consideration, though they will all reduce visibility.

[blueridge]

I'd like to weigh in on this . . . thanks for posting!

First, you're not making it any better by choking off all of the airflow, both on the return and on the supply side.  When you cut the airflow drastically below the design airflow, you force the compressor to work much harder and to possibly fail prematurely.  Most duct systems already suffer from poor airflow characteristics as-is already . . . the main problem is usually poor duct design coupled with trying to put too many spaces on a single thermostat . . .

Next, though, I'll second the whole-house fan suggestion.  The window box fan will work in the meantime.  Try this: stick it in the upstairs window, but exhausting outwards.  Don't just open one window downstairs; open three or four and let the fan pull in cool outside air through those windows whenever the outdoor temperature is at least a couple of degrees colder than inside the house (to account for humidity effects). 

Last, "mini-split" DX systems are great for cooling smaller areas like your bedroom, and are extremely efficient.  Probably between $2k and 4k to install but it depends on your area. 

[TheLazyMan]

We don't have a whole-house fan but I've wondered about the merits of one in the past.

What I meant was just putting the central air fan to the 'on' position using the thermostat.  I don't know if there's another meaning.

[TheLazyMan]

Last, "mini-split" DX systems are great for cooling smaller areas like your bedroom, and are extremely efficient.  Probably between $2k and 4k to install but it depends on your area.

I got a quote last year for $7k for a single zone mini-split. Yikes!

[epipenguin]

I see you had an energy audit done already, but did you specifically ask them for help on cooling the upstairs? When I had my energy audit, that was one thing I asked for help with as half my house was a lot cooler than the other half, plus I had a hot area in the south west corner that was somewhat unbearable in summer. Where certain things were not up to code (like the attic insulation), they provided me with some rebates to help remedy the situation. It might be worth having someone come to the house to take a good look at your situation for that specific thing, and offer ideas. And not a company that sells A/C units.

In my case, because of uneven attic insulation, in one part of the house I was losing a lot of cooling straight upwards into the attic. UV window films helped to cool the dining area, which is the hottest part of my house - they may help in your bedrooms. I also had a short extra run of ducting and an extra a/c blower thing put in to help cool the hot spot.

[ShoulderThingThatGoesUp]

We don't have a whole-house fan but I've wondered about the merits of one in the past.

What I meant was just putting the central air fan to the 'on' position using the thermostat.  I don't know if there's another meaning.

What I was talking about was a fan installed in the roof. Open some doors in the highest level bedroom (split-levels are weird) and flip a switch, and it'll suck air through the house. When it was nicer outside than in I would open windows on the lowest level first and turn that on. Really effective.

[Bob W]

When it is hot time of year you should run your HVAC fan 24 7 to keep the air close to even in temperature.

It won't do it all the way but will help.

Then sleep on the lower floor during hot time periods.   You may even decide to shut all vents to the upper floor and just live on the lower during hot months.

In the winter,  you can keep the thermostat low and the upper will be warmer.

This is the problem with not having independent units on multi story dwellings. 

[gotaholen1]

Have you considered a portable AC unit for the upstairs bedroom? 

We run ours only when it is really hot, and rarely turn on the main house AC.  We also feel that our upstairs bedroom is the hottest room in the house, and figured we only needed to cool that room in the summer. 

We considered putting in a split unit or zoning our duct work, but it was going to be 5 - 8 k.  Just not worth it to try to cool 1 room for about a month or so out of the year.

[Drifterrider]

I have a two story house.  The bedrooms are upstairs.  I have central A/C.  I run the central unit at about 76 degrees and I run window A/C units in my bedroom when I'm sleeping and in my TV room when I'm doing anything else.  Window units are about $150 each and usually last for five years.  Keeps my electric bill under control and allows me to be cool where I am (vice keeping the whole house cool).  I also run ceiling fans (keeps the air moving). 

I'm going to be comfortable at home.  Being uncomfortable because you don't have money is a fact of life for some (been there).  Being uncomfortable by choice is a poor choice IMO.

[GardenFun]

Make sure your basement vents in the duct work are closed.  No need to unintentionally A/C the basement. 

[catccc]

I forgot to mention solar shades on the outside of windows can help keep down solar gain, or you could plant a tree to provide some shade to the affected windows.

Here's where I got my solar shades from http://www.qualitywindowscreen.com/
Usually darker ones are easier to see through if that's a consideration, though they will all reduce visibility.

I just posted about putting taping mylar to the windows to cut down on the solar heating of my kids bedroom in the DIY category.  I've heard it works well and it is hardly costing anything to try (mylar emergency blankets are around $1 at Amazon if you buy multiples.)

[Forcus]

In our old house where the ducting design was poorly done and cobbled together, we ended up using vent fans in the rooms we needed cooled (living room and bedroom). These fans are placed over a standard floor vent and assist in pulling air in to the areas you want more flow. They worked incredibly well and were about $40 each. We ran then 24/7 and they'd last over a year like that (they can be turned on / off and sense flow, I didn't worry about that).

This is similar to what we got and looks like it can be used in vertical vents as well.

http://www.amazon.com/Suncourt-HC500-B-Flush-Register-Booster/dp/B001WT11Y2/ref=sr_1_1?ie=UTF8&qid=1433260289&sr=8-1&keywords=air+vent+fans