New construction home - HVAC in attic?!

Do any of y'all know anything about house building/ building science?

I'm trying to figure out a way to tell the builder of the place I'm buying that they need to make the attic unvented and conditioned, because the air handler and ducting is up there. Right now, all of the roofs I'm seeing are vented and unconditioned, which is horribly inefficient when the attic inevitably gets to 140° in the summer and all the ductwork is up there. People have mentioned in articles that moisture could be an issue, but if the attic is properly sealed and the ceiling insulation is removed, the temp and humidity should be fine. A supply vent could be added to the attic just to be certain.


I'm wondering how to tell if the HVAC system pulls in fresh air. Because things I'm reading say that sealing the attic could cause air quality issues. A non issue if the HVAC pulls in fresh air, but I'm not sure how to tell. Here's some pictures if that helps.





And as you can see, the attic is totally vented. Stupid when the HVAC system is up there, especially in the south.







HVAC in attic
https://modernize.com/hvac/air-conditioners-in-attics
https://www.teegardenhvac.com/new-h...efore-deciding-to-install-an-attic-hvac-unit/
https://www.birdinsulation.com/blog/2018/april/wheres-the-ideal-place-to-locate-your-hvac-crawl/
https://www.energyvanguard.com/blog...Those-Air-Conditioning-Ducts-out-of-the-Attic
http://www.americancoolingandheatin...g-efficiency-are-attic-hvac-systems-efficient
http://www.ntcinsulation.com/the-insulation-lab/ducts-in-the-attic-a-very-bad-idea
https://www.osti.gov/biblio/988099

Insulated foam effects on roof shingles
https://www.retrofoamofmichigan.com/blog/does-spray-foam-damage-roof-shingles
https://homeguides.sfgate.com/spray-foam-insulation-effect-shingle-roof-105368.html
https://www.energyvanguard.com/blog/75042/Will-Open-Cell-Spray-Foam-Insulation-Really-Rot-Your-Roof
https://www.greenbuildingadvisor.com/article/insulated-rooflines-and-shingle-temperatures

 

Are you going to spray foam the rafter bays with 2lb foam ?

 

Basically, from what I've read, the attic where the HVAC is located should be an unvented and conditioned attic in order to be as efficient as possible. Usually this is either closed or open cell foam along the roof decking with no insulation above the ceiling area.

 

Yeah exactly , in the rafter bays

 

Correct.

 

You can actually still do a vented roof assembly if you use batt insulation and provide an air baffle from soffit to ridge vent . Depends on your local code requirements for R value in a roof assembly though

ie roof system is still a vented vs unvented system but attic is in conditioned space

 

This is a pretty standard building practice, and I wouldn't be concerned. . For example, my home in central Texas was built in 2016 and has the HVAC handler located in the attic, which is vented. There is a fresh air system tied into the HVAC as well, which is programmable and pulls fresh air into the system about 20% of the time its operating. The attic gets blazing hot in the summer, although all ducting is heavily insulated. There is about 18 inches of heavy insulation over all interior rooms.

The home is about 2400 sq ft, the thermostat stays at 74* 24/7, and I average a utility bill of around $85 a month across the year. That bill includes gas and electric (gas furnace.)

 

I've seen that as well as using spray foam with a baffle. Though I'm not sure that would make much of a difference when the main reason for making the attic unvented is due to the location of the air handler and ducts

 

Here's what the ducting looks like up there




I've seen some people just spray foam the ducting itself. I guess that would work too, not sure how effective it is but I haven't looked into it.

Do you know how to tell if an HVAC system pulls in fresh air? Or is this an industry standard by now?

 

I edited my post

2 different things there

The attic could be in conditioned space and still utilize a vented roof assembly

 

I dont know much about hvac, but from the pics it looks like my setup, the air handler is in attic with fan outside, vented attic. Works fine for the 200 or so houses in my neighborhood.

Found this

https://www.serviceexperts.com/blog/air-conditioner-versus-air-handler-whats-the-difference

 

Mine looks very similar. You should be just fine. HVAC has evolved quite a bit over the years. With that said, keep an eye on your builder. I found all sorts of half assery during my build, non-hvac related. I don't care how much you're paying, if you let them get away with it, eventually someone will start cutting corners.

 

Yep pretty much they're all like that, but just typing in "HVAC in attic" and you'll find a ton of articles saying how inefficient it is. Which seems obvious really. Studies showed a 40% difference in efficiency if the attic is sealed and conditioned. But I'm wondering about air quality and fresh air coming in - or rather how to tell if the HVAC system does this.

 

https://youtu.be/NOQJHZJdLxA

 

Something I learned: If its still in the building process id try to get someone out there to check the pressure at all the vents. I have one vent that pushes significantly harder/more than others.

 

Do we have a super in the house?

 

I haven't read anything about this - seems like they are mutually exclusive but I could be wrong. Can you explain or point me to some stuff I can read?