[electricblue]

My unit is up in the attic and I want to bring it down in the garage for a vertical configuration. My question is what size square duct made from duct board do I need? (3) return trunk lines 10,14,14

 

[2old2rock]

Are you going to tell us what size the unit is, or shall we just guess?
Air handler? Furnace? Model, serial?

 

[electricblue]

It will soon be a new Goodman ASPF426016E 4 ton heat pump

 

[hvacvegas]

It will soon be a new Goodman ASPF426016E 4 ton heat pump

I wouldn't put it in a garage.

Your going to have some big code issues.

Railing protection system, has to be so high off the floor, has to be sealed EXTREMELY tight. Your just asking for problems.

But:
12x32 would meet the requirement for a 4-ton heat pump.

 

[bluebinky]

A few questions from a non-pro...

1) Is this a DIY project?
2) Is duct board allowed to penetrate the wall into the garage?
3) Which is worse, furnace and ducts in attic, or furnace in garage and ducts in attic (and garage)?
4) Does manual J need to be redone for the entire duct system?

 

[dan sw fl]

Time for a Manual D review in order to develop an appropriate plan.

 

[electricblue]

A few questions from a non-pro...

1) Is this a DIY project?
2) Is duct board allowed to penetrate the wall into the garage?
3) Which is worse, furnace and ducts in attic, or furnace in garage and ducts in attic (and garage)?
4) Does manual J need to be redone for the entire duct system?

1 Just the plenum
2 Idn
3 I think ahu in attic sucks. Florida building code now requires carbon monoxide detectors if there is an attached garage. (good thing)
4 Idn

 

[motoguy128]

Better get that unit tight, really tight. I was at a place my brother in law was renting. A new construction duplex with builder grade junk installed. The flex runs were totally collapsed and half hte house was like a jet engine was running, the others were underconditioned. It was an electric furnace instead of a heat pump located in central Missouri. His first electric Bill in Dec. was $600. The unit was located in the garage. There was no cover over the furnace filter slot. He might as well have left the door to the garage open. The place was such a slapped up POS. I bet the vinyl window were already leaking in the panes. But it had pretty countertops and an "open" layout. Must have that open layout (ie. fewer walls and doors, which cost more money for the builder.... but it's better that way right?).

Are you sure you can't find a closet you're willing to give up? Could you build a utility closet that goes into the garage off the wall connecting to the garage? Building a utility closet is jsut a matter of some basic framing and and drywall. It doesn't even have to look pretty or be painted.

 

[electricblue]

How hard is it to do a tight install? I could build a closet...Why not just do a good job at sealing up the db?

 

[electricblue]

I wouldn't put it in a garage.

Your going to have some big code issues.

Railing protection system, has to be so high off the floor, has to be sealed EXTREMELY tight. Your just asking for problems.

But:
12x32 would meet the requirement for a 4-ton heat pump.

Any reason you wouldn't do 24x16? 24 being the depth of the unit.

 

[lafittejdubb]

Using a ductulator, you can create the deminsions of the mainline pretty much any way you want. I would recommend oversizing a little just so you won't need to replace the mainline12 yrs from now, but also because you'll reduce the air friction (Temp increase and Noise) in the mainline. 4 tons = 1600 cfm's (minimum). 1800 - 2000 cfm capacity would serve you well.

 

[hvacvegas]

Any reason you wouldn't do 24x16? 24 being the depth of the unit.

Unfortunetly for yourself, you've openly admitted your doing the ductwork.

I was already stretching myself by saying "maybe he just wants to make sure his contractor is doing it right."

sorry, no DIY.


What I will tell you, is that 24x16 is actually 22x14 in ductboard.

and if your going to try and cut ductboard yourself, good luck. The guy that works with me roughed houses for 20 years, and has no idea how to use ductboard. It's complicated, and is an old skill that only those that have worked with someone who has done it, learn it correctly.

 

[electricblue]

I am doing the the d work. I'm an electrical contractor. I work with a/c guys all the time. I've asked one that I work with alot if he can charge my lineset and exac my old one. I'm just doing the labor. I know the forum rules no DIY... Just fishin for info.

 

[genduct]

Since HVAC guys do electrical all the time

Seems like having "sparky" do some duct is OK
Duct dimensions about 2 sq ft of area is ok for initial discharge. Main concern is getting the return sized ( 2 sq ft plus ) good and tight.
Choice of ductboard is really good choice since it is inherantly sealed when you use the UL 181 A tape

 

[electricblue]

:cheers:

Seems like having "sparky" do some duct is OK
Duct dimensions about 2 sq ft of area is ok for initial discharge. Main concern is getting the return sized ( 2 sq ft plus ) good and tight.
Choice of ductboard is really good choice since it is inherantly sealed when you use the UL 181 A tape