HVAC Questions

[Cherokeekid88]

We replaced our HVAC system 2 years ago and the other day I come home and the house is hot...after doing some digging, I realize that our power had went out shortly before I got home and was just trying to catch up. Checked the condensation line outside at the condenser to make sure it was draining and not clogged, no lines were frozen over or anything. It got my looking around at things and realized some issues with cooling certain parts of the house, specifically my daughters room.

So we have the one return downstairs in our dining room (that honestly, probably needs to be bigger) and then at the top of our stairs we have what I am guessing is a vent (is bigger than a normal vent, but its def not a return) that is on the wall near the floor. There is barely any air coming out of this thing, then of coarse, we have vents in the 3 bedrooms upstairs. The vent in my daughters bedroom just doesn't seem to blow air like the other upstairs rooms do.

I understand that have a single zone heating/cooling and having a 2 story home, that the upstairs is always going to be hotter, but I feel like there is some sort of restriction problem going on.

Its got me wondering about that vent at the top of our stairs and if that should be blowing out cool air at a more powerful rate?

One of the things that I am going to do this weekend is insulate our attic in hopes that makes a difference in keeping that cold air upstairs longer.

 

[tsconver]

The larger vent up stairs might be a return vent. It could be using the spacing in the wall cavity as a return. Would need to look at all the lines and see where they go. Might have a section that has come loose and is blowing air into the attic or a stud cavity.

 

[Cherokeekid88]

The larger vent up stairs might be a return vent. It could be using the spacing in the wall cavity as a return. Would need to look at all the lines and see where they go. Might have a section that has come loose and is blowing air into the attic or a stud cavity.

This particular vent/return does not have a filter and it actually is blowing a bit of air out of it. Def not pulling air in. From what I can see, the duct goes straight down after the elbow bend.

 

[Wes]

You could check to make sure all of your dampers are open. I hade a zoned system in my last house. It had a hard time keeping my upstairs cool/warm. It had electric dampers. They would open and close to regulate. If you have those you could manually open them. Might not be your issue though. I have an up and down unit in my current home and I still have 2 rooms upstairs that don’t cool and heat well. Hvac guy said they’re the furthest away from the handler and that’s all I’m going to get with the long run. Might be your issue if it’s a really long run.

 

[skyhighZJ]

So I’ll ask a question on the HVAC topic. Or House was fitted with central air at some point prior to us. The upstairs “feed and return” go up through a wall cavity into the attic and then the upstairs is all fed through the ceiling. As it is now the “piping” “tubing” or whatever that supplies the heat/air is above the attic insulation, should I buy more insulation to cover it up to prevent heat or cold escaping and give it some extra insulation properties?

 

[paradisePWoffrd]

So I’ll ask a question on the HVAC topic. Or House was fitted with central air at some point prior to us. The upstairs “feed and return” go up through a wall cavity into the attic and then the upstairs is all fed through the ceiling. As it is now the “piping” “tubing” or whatever that supplies the heat/air is above the attic insulation, should I buy more insulation to cover it up to prevent heat or cold escaping and give it some extra insulation properties?

You could measure the temp of the duct compared to things around it. But insulating it from the unconditioned space can't hurt.

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[Fabrik8]

So I’ll ask a question on the HVAC topic. Or House was fitted with central air at some point prior to us. The upstairs “feed and return” go up through a wall cavity into the attic and then the upstairs is all fed through the ceiling. As it is now the “piping” “tubing” or whatever that supplies the heat/air is above the attic insulation, should I buy more insulation to cover it up to prevent heat or cold escaping and give it some extra insulation properties?

It sounded tricky to do properly in our hot/humid climate zone without potentially causing condensation problems, from what I remember. The R-value of the duct insulation, and the amount and ratio of attic insulation above/below the duct seems to be very important. Basically you're decreasing the temperature loss from the duct to the attic with the added insulation, which then increases the temperature delta inside/outside the duct, creating the condensation danger if not buried properly. Duct leakage always makes things worse too.

It's worth doing some research before committing to do it, just to avoid unintended consequences. Google something like "duct insulation burying" or similar. I'm no expert on this stuff, I just remember reading that it's not as simple/easy as it sounds.