Duct Branching

[pjsullivan]

I'm a home inspector and I'm seeing this more often. Essentially, there's a distribution branch run off of the main plenum of a forced air unit. This branch is then split into two (a "Y") without the use of a "triangle" junction box, AND the split is NOT equal in size (one large branch, and one small). Then further down the larger branch, there's another split without a junction box (again one large, and one even smaller branch). Many of my customers who complain of poor airflow have this configuration. Is this type of thing proper, and if not, what is a better configuration. I would think that no branching would be best. Any help appreciated.

Peter.

[Steve Wiggins]

Dude you are freakin cracking me up......hahaha

The junction boxes you speak of are the worst way to run a duct system. The wyes you see are the best.

[Irishmist]

Peter: don't know if you are referring to a new or old home, where you come across this. Where I am located (Ohio Valley) it is not at all uncommon to come across duct systems in older homes (vintage 50s and 60s) that I refer to as "graduated duct systems." On these galvanized duct systems each time a branch comes off the main trunk, there is a reduction. The transition at this point resembles a "y" in its configuration, but is really a reducer. At each branch the reducer transition is in place. These are actually excellent systems for air distribution as each time a branch lead comes off, the trunk size is reduced accordingly maintaining good pressure within the system. The only reason these systems are not used today is cost. With the number and type of fittings required, the new construction market makes it prohibitive. I couldn't tell if you were referring to round or rectangular duct, but all this duct in these systems is rectangular, even the branches. One thing to note. In these systems I am referring to, there is a volume damper at each one of the transitions to help balance the airflow throughout the system. I am curious. Is it normal procedure for inspectors in your area, or are you just that much more thorough in getting into the air distribution systems of the hvac system? Around here, the home inspectors some of whom have more background in mechanical systems than others usually look at the equipment and note, "yep, that there's a furnace all right."

[pjsullivan]

Dear Mr. Wiggins:
I'm glad I made your day. BTW, I'm just down the road from you in Round Rock. Perhaps I'll have the pleasure of inspecting your work some day ... then we'll see who has the last laugh. Anyway ... here's a picture. You tell me ... is this kind of thing proper?

[Steve Wiggins]

Yes that is proper and thanks for the pic. Some cities want to see mastic on the vapor barrier but I wouldn't ever recommend that.

As for inspecting my work let me let you in on a little secret. I am a design professional and you are not. Challenge me and you will lose.

[duc dowg]

Mr Wiggins,
I to am amused by you. Keep it up.We all know inspecters suck. If he was any good at his job he wouldn't have to ask a thing like that.lol lol lol lol

[Irishmist]

those pants seem to be a little short in the "rise."

[davidr]

Peter a lot of times that type of duct design has so much pressure drop over the various fittings it just can not properly deliver airflow.
We have gone in on jobs before & renovated duct systems where we had to remove this type of design.
It may be ugly but if it delivers airflow & BTU's in the proper quantity to where it is supposed to then no issues.
Problem is most of them don't even come close.
Irish,if you are ever in Frankfort look me up.

[tinner73]

[QUOTE]Originally posted by pjsullivan
Dear Mr. Wiggins:
I'm glad I made your day. BTW, I'm just down the road from you in Round Rock. Perhaps I'll have the pleasure of inspecting your work some day ... then we'll see who has the last laugh. Anyway ... here's a picture. You tell me ... is this kind of thing proper?


[/QUOT

now that's quality. i bet they can rough in the whole house in 5 hrs.

irish i completely agree with you. we have alot of the old graduated trunklines around here too.

[tin_fab]

Irishmist

That method is called the "static regain method" and I can tell you from experience that it is still used by people that want value rather than price (many still around, you just have to sell TO them). I only use rectangular, wrapped.

PJ

that system in the pic is junk. You are gonna have insulation failure where that lawn chair webbing and pan-ties choke that flex. Also if you instal flex systems you should at least stretch out the flex. I guess nowadays that type of install passes for cookie cutter homes.

[tin_fab]

Challenge me and you will lose

lmao

[Steve Wiggins]

[Steve Wiggins]

Originally posted by tin_fab

I only use rectangular, wrapped.

Hahaha .....what kind of dream world are you living in?