Pittsburgh: Hot Water + Whole House Fan + Transom Windows (+ Limited High Velocity AC?)

PittsburghRowHouse

Hi all,

First, I want to say I already owe a lot to The Wall -- you all are great. You've already set me straight and convinced me to go with hot water heat instead of steam for my gut renovation (http://bit.ly/2kA110P). I'm back again for advice. Also, if there are any professionals in the Pittsburgh area or who'd travel for my job, please send me a message.

The big breakthrough my wife and I had was we've decided to ditch central air for AC. We both realized we grew up in a house without it and turned out alright. It seems like a whole lot of money to spend for something we'd only turn on for six weeks (and then double your electric bill for). I now sort of think AC is the fallacy of forced air heat; the second biggest supposed pro for forced air--after it being cheaper--is that you "get AC with it." But if central air doesn't make sense for you, then it is sort of a moot point in favor of forced air.

Instead of AC, we're going with a whole house fan for our two story 2,000 sq ft main house (it's a duplex, so there is a ~600 sq ft studio on the first floor we'll rent out). We're also going to add the old fashioned transom windows above the doors for the four bedrooms on the 3rd floor, to allow some real nice air flow (and natural light to our interior hallway). We're up on a hill too, with south facing windows on the third floor not blocked by the house across the street, so I'm hoping that'll provide some good breeze.

Ironically--despite my knock against AC above--what we're struggling with is what we should do for cooling during those six brutal weeks of August and early September. To deal with the humidity, I am thinking we can put a really good dehumidifier in. That just leaves the temperature; I'm worried that a whole house fan (even with the transom windows) will leave us a little too warm during the dog days. My understanding is that a whole house fan just brings the interior temperature to match the outside temperature. When it's really hot in the summer in Pittsburgh, the temperature doesn't break until late at night, so that might get uncomfortable.

I just want a solution to bring the third floor bedrooms down to a cool temperature, when the whole house fan might not be fully up to the job. Is there some sort of minimal version of air conditioning that would work? I've got a few ideas; are any of them worthwhile?

1. Put in a high-velocity system just for the third floor (four bedrooms and two bathrooms). My GC says that cool will wind up drifting down to the second floor, so that's a plus. It'll cost a pretty penny I bet, though, once the quotes come in. It might be more money than we're willing to spend.
   
2. Put in a ductless air conditioner in the hallway that splits all the bedrooms and use the transom windows as a way to get the air into the rooms. If we used one of the ceiling units, we could plop it right in the center of the hallway (and third floor) and hopefully that would leave it well positioned enough to hit the bedrooms. My GC says Mitsubishi has some great products here, but he's worried it won't have enough kick to cool the whole floor.
   
3. Put a super-sized, 240 volt A/C unit at the end of the hallway and go for the same affect with the transom windows as option # 2. The benefit vs. # 2 I assume is that it would be significantly cheaper to install (and that it would technically stick out on my neighbor's alley...).
   
4. Just stick with fans. In addition to the whole house fan, equip all rooms with really high quality ceiling fans and during those hot months, sleep with a sheet on and just deal with it .
   

Let me know your thoughts! And if you're interested in the job, send me a message! Thanks again all.

Jamie Hall

"It's not the heat, it's the humidity". Which is absolutely true. If you do have a really good dehumidifier, it will make a huge difference in those few horrible weeks. So... if it were up to me, I'd go with your option 4. Your understanding of what a whole house fan can do is quite correct -- up to a point. However, there is no rule that says if it's really stinking outside (90 with 90 percent relative humidity) around noon and in the afternoon...) you can't turn it off and close the windows for a while. If the house is well insulated, it will be cooler than outside, and if the dehumidifier is up to snuff, it will seem a lot cooler. Then turn it on again in the evening, when it's nicer out.

EBEBRATT-Ed

Your going to die on the third floor without ac. Get some quotes on high velocity and ductless splits. You won't be happy with one ductless evaporator but you might get away with 2 if you keep the doors open

Tinman

I could not get through Chicago summers without air conditioning. Fans would do the trick for much of the time but I want to be comfortable in my own home and that won't happen without AC.

There are great applications for ductless splits but I prefer not having one hanging in my living room or bedrooms.

Properly installed, high velocity AC is a great choice and it won't impact the aesthetics of your home. I have 35 years experience with them and continue to be impressed. If you go that route, stick with one of the two major players, SpacePak or Unico.