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?

[Backspin]

a lot of use of flex duct. Esp for a main trunk line. Poor quality of work, but yes some inspectors pass this kind of work.

[the_guru]

We have an inspector taking his job more serious than alot of other inspecters and u bash him =/.... he was asking for an answer to a legitimate question. dont get me wrong i think most inspecters are screwballs. but u cant knock him for asking,he's attempting to do more than most.last time i checked this was a useful site for learning

Appreciate his curiousity.

[tin_fab]

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

Dream world?? I am about 1500 miles and 180 degrees from texas

lmao

[pjsullivan]

Guys:

Thanks for the replies. However, there seems to be some minor disagreement in the group ...

Steve Wiggins said: 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.

davidr said: 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.

tin_fab said: 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.

It seems that although "proper", this design may not be the best alternative. Since the builder is likely to use the same materials, can anyone offer a solution to provide better airflow to the various trunks?

I'm way out of my element here, but I promised my customer that I would do my best to help. FYI, this is part of a pre-sheetrock inspection ... normally I would refer the client to a pro, but in this case, I have to provide convincing evidence that the builder's HVAC installer could have done a better job.

Thanks for your help.

[Steve Wiggins]

Wait a minute......you said you were a "home inspector". Do you mean you are an inspector for the city of Round Rock?

You were comparing the triangle juction boxes to the metal wyes and yes the metal wyes are better. I never said a flex system was better than a rigid metal pipe system.

Yes, the-guru, you are right this site is for learning and I apologize to PJ for coming across as a smartass. Learn we shall.

[GradyWhite244]

Originally posted by tin_fab

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

Dream world?? I am about 1500 miles and 180 degrees from texas

lmao

I agree with tin fab. You want chicken salad or chicken sh**? Sorry I don't deal in chicken sh** & most builders won't pay for chicken salad. That's why I stay out of new construction.

[trane]

I welcome a educated inspector. If you do everything the way it should be then the only ones getting hurt by him are your lowball competitors.