HVAC Question

[kroberts2131]

I asked this awhile but I thought I would ask one more time before I end up calling someone. I have a 1500 sq ft home. When we use the ac or heat the front two bedrooms almost no air flow from the vents. We keep the doors open and we bought some of those thermal curtains. Now that its getting cold, the rooms are starting to get too for a baby. I got up in the attic and followed all the duct work but couldn't find anything at all. The only thing I realized was those two bedrooms share one line. It Y's off in the middle and goes to each room. I could have explored the rest of the attic to verify but from what I could see every other vent in the house had its own line.

So my question is.....If i get someone out to look at it would they be able to do anything for the weak airflow besides maybe run a duct for each room? The curtains helped but not enough to eliminate the problem by any means.

 

[swampratt]

I have installed lots of duct pipe..commercial and residential...
In my own house if i have to Y off a single duct there is certain sizes to play with...
Bathrooms usually can get by with 4" single...and you can Y off a 6" into 2 4" ducts....
bedrooms i like to have 2 6" ducts....an 8" can supply enough air for 250sq feet...you can Y off an 8" into 2 6" ducts...
Flex duct can be purchased at lock supply....it is insulated and much quieter than solid....any better nah...measure your plenum box hole where they have the duct in question hooked up....if you are feeding rooms and Y ing off it should be an 8"....minimum......you will actually get less air flow if you block off other registers...weird how those squirel cage fans work....it will actually cavitate if you do not let it flow out...

How is the intake side of the system...got a good filter...and is the A coil clean and free of dusty matted debris...or can you even acess it to check

Hope that helps ..Jeff

 

[victor152]

Is the duct in the attic supply or return? Sounds stupid, but if this is just a return duct, changing it won't do anything. Where are the supply air registers in the room? Are they high mounted in the wall or mounted in the floor?

My house has underfloor supply registers with high mounted returns.

Just a question.

 

[kroberts2131]

I have no idea about any of this stuff but I called a local company and they are coming out thursday to have a look. They will check it out and give me an estimate on how much it costs to fix it. They do it free of charge so I'm going to let them do thier thing and go from there.

 

[swampratt]

If you have a 6" duct feeding those 2 rooms and they Y off of it with 2 6's there is a problem.....
You can do that really easy and cost should not be more than 100 bucks for the supplies and about 1 hour in the attic max.....if the size is the problem that is.....time probably closer to 20 minutes