Ducting

One of the advantages of the Carrier Infinity system is that it can calculate duct static pressure. Briefly, this has to do with the pressure of the air as it blows through the ducts. Like blood pressure, lower is better. The newer AC systems expect a reading of around 0.5 inches per water column. Our ducts are delivering a reading of nearly 0.9.

Why should we try to fix this? Well, the air blower is going to be working harder than it should, which is wasting energy and shortening its life span. Our installer told us for under $1000 they could add more returns to increase the amount of air entering the system, which should reduce the pressure. They also wanted to add some supplies to each room of the upstairs to help equalize the temperature in the house.

Before we had any energy improvements done the house, the temperature difference between the top and main floors was around 8 degrees. Afterwards it dropped to about 5 degrees. So doubling the AC vent numbers on the top floor should help!

Closet without the shelves, before any vent work

Where a return is going

Before the new supply was added

Cutting a hole in the closet to run the new ducts, which will connect with the existing duct, outside the wall

New return hole

Supply hole in the baby room

The return in the linen closet is the biggest problem. The air is being pulled from the hallway between the walls into the ducting. Only a couple of inches to fit a lot of air. So the plan is the put some proper ducts in. But we'll be losing quite a bit of closet space. Which is probably why the previous install ran INSIDE the wall. They are also adding a return next to the Chinese painting in our room. .

Results of the finished work:

New supply on the right

Much tighter closest. We lose a lot of shelving on the right

So, did we hit 0.50? Drum roll........

No we did not

Not even close. A bummer, really. From reading around the internet it seems that getting below 0.7 is just fine. So 0.73 is pretty close? Our AC guy says this is fine, but what would you expect him to say?  We are pretty disappointed but we have dropped way too much money on this project to do anything more now. It's not even clear what can be done - we are running out of space to install returns.

The system should be fine. I just need to stay on top of the filter cleanings to make sure the pressure doesn't build up too high. The doubling of the vents upstairs has also reduced the temperature difference between the top floor and main floor from around 5 degrees to 2-3 degrees. A noticeable difference.