I just had my new A/C system turn on3 ton 18 seer two stage for 2200 one story building. I had two inches of closed cell on the underside of the roof and walls. My master bathroom is 19X9X9. is on the west wall, with one window. The HVAC installer put a 6 inch duct. Should this be a larger duct? It is a 20 foot run with 15ft of metal duct with 4ft of flex. He has the same size for an interior 5x6 closet. I am going to ask for his load workups, but I'm afraid be just put 6 inch ducts in bathrooms and closets regardless.

Not likely.

Though he should have used adjustable dampers to limit the airflow to smaller areas.

around here 5" of foam is the norm. ask to see his copy of his heat load calculations 

Sounds right.

All my ducts to all my rooms are 6 inch.

If there isn't enough flow to the room then I would think they would run one more.

sounds small.

But honestly, it's going to depend on how much heat gain that room receives.
South or west facing windows?
40" LED TV?
Connecting bathroom with a shower and insufficient ventilation?


I had a room in my house that was always under conditioned (hot in the summer, cold in the winter) even though the unit was replaced (increased from 1.5T to 2.5T about 3 yrs ago).
Turns out there just wasn't enough CFM hitting the room (it had 1 more window than the other bedrooms and the most western and northern exposure wall area (corner room).

I had the sub come back out and replace the 6" duct with an 8" supply to the room and it's made all the difference.

I'm a licensed general contractor in the Atlanta area.

Not enough info.

Long and short of it, you need a Manual J to tell you what goes where. If he didnt do that, that would make me question everything else he did.

I only say this because Im currently going through a dual heat pump replacement and my contractor did a Manual J. And then they compared it to MY Manual J. 

Im an engineer. 

But seriously, the load calcs will tell you everything. Anyone who does it based on sq ft and CFM, Id run.

I've had the ac on for a week and cant get to a 72 set point, even with outside temps below that.  I talked to the hvac installer Monday the conversation went south pretty quick. I asked him about load calculations and that seemed to piss him off. He said he had no idea what the r value  of the closed cell spray foam is. The building is just a big rectangle 60X36 12' walls with a 4/12 pitch roof. its just metal on wood 2x6 studs and purlins with the closed cell sprayed directly on the metal.  There is supposed to be 3" on ceiling and 2" in walls. I said 2" on the ceiling in the OP.  

He installed a electronic fresh air damper but no exhaust.

Sounds like you might have too much load for the system.  Check the temp drop across the coil, if it is too low with first stage and second stage cooling calling, it probably is undersized.  I would like to think that a 4 ton condenser and evaporator would have been a better choice (especially for you being in the very warm and great State of Texas).
You should get 15-20 degree drop from the return to the supply side.   Use a good electronic thermometer.  

Try to upgrade the bathroom vent and flex run to 8" and see how that works.  That is a pretty big area and return air vents are not allowed to be installed in bathrooms.  I think your HVAC guy done fucked up...

Yeh, they tend to get pissy when you ask to see some proof of work they didn't actually do...

If he had actually done the calcs, he would have either KNOWN what the R value is, or researched it until he DID know.

is that all the insulation you have?  3'' for roof and 2" in walls?  Does this even meet Energy Code requirements for your area?  Closed cell 2# rating is R-6 per inch.  So you only have R-18 on your roof and R-12 on the walls.


You need more insulation

Code here is 12 walls and 19 roof.


it all depends on the degree days you have based on your location.

could you post pictures of the outside and the install? what are the windows like? doors? what county you are located in? 3 tons sounds light 

my house has 2*6 walls and 2*12 ceiling joists and this is how the foam was done

 there is a perfect spot to ad one too.

I'm in central Texas. I had the bright idea to try in make a pole barn a house. I was told by the spray foam installer that 3" of closed cell in the ceiling and 2" in the walls was sufficient. The closed cell foam seems to have actually amplified the outside noises and popping metal sounds. I framed the inside 3/4 of the building for bedrooms and bathrooms, that area has sheetrock, and the attic space is decked. I put soundproofing insulation in interior walls but nothing extra in the exterior walls other that spray foam. The living area is going to have galvalume tin hung across the trusses. I have not hung the tin in the living area yet and don't know how much the tin would mitigate and cooling or heating. The HVAC guy knew what I was planning. I was thinking of blowing cellulose on top of the tin to soundproof and try and slow things down.  Not sure if that is wise as the roof underside is spray foamed.


Checked up in the attic, might be I got goat screwed on the foam. I don't think there are many spots that have true 3" coverage. The walls seem fine. THe foam cost me 12K.  I'm not sure how to correct this. I don't want to spray any more foam in the house,

Is that closed cell or open cell?

the foam guy just sprayed the underside of the metal?
that's not how it was supposed to be insulated.
(I assume you're talking about traditional pole barn construction with perlins running down the slope and furring strips running horizontally with a screwed down roof)

In that scenario, the insulation should have been kept off the back side of the metal using either plywood framing or styrofoam (preformed) baffles.

ETA:
and in the picture above, if those are 2X12 rafters then 8" of sprayfoam insulation (on baffles) is overkill by at least 2"   (but it would be correct if they are 2X10 rafters)

open cell

Look up code for insulation in your area. I think you have compounding problems!

Doing this off the books with no permit I take it?
Energy Code

Yes I guess. Out in rural Texas. I just went up in attic and the spray foam was warm to the touch from sun on the roof.  Not sure what to do at this point. I beleive the spray foam applied isnt sufficient.

Yes. spaying directly to the metal is pretty common here. It is 2x6 on hangers between the trusses.