Any HVAC guys able to advise, this OK?

[lendaddy]

New build, duct was "modified" to allow clearance for the PVC vent of the (yet to be installed) hot water heater. I'll not give my take so I don't shade any response. Thanks guys!

[Sooner or later]

I think it sucks.

[cabmandone]

Looks like an oval to round fitting on each. I don't see any real issue with it. It might slow down the volume just a bit but no worse than those elbow to the left already do IMO

Is it supply or return air duct?

[icemann427]

I think I would reroute the vent instead of doing that to your HVAC

[rwest]

While it probably will work, it looks poor to me. Very should be the one that gets moved if it can- could be a height issue and then the duct routing is the best you can do.

[Hugh R]

Nope, your backpressure will rise and you'll strain on your blower motor.

[LWJ]

Not an expert. Did this restrict the sizing of the duct work? If so, I would reject it.

The gold standard for duct sizing is Manual D. This is published by ACCA. I have been on the board of my local ACCA association for over a decade. Get the opinion of a contractor who uses Manual D and you will have the correct answer. This is science. There are correct and incorrect answers.

[Baz]

Seems to me they "modified" the wrong component. Shouldn't the PVC vent have been the one "modified"?

Two 45's would have done it.

[lendaddy]

I agree with you guys, it probably isn't a real issue but it sure shows poorly. It's looks like an amateur afterthought to me.

It gets better though, how about this one. This is the AC ref line where it exits to the outside of the house. I'm still trying to wrap my head around this.

First photo for reference and the second is a close up. The red and blue tubing that's hanging is just yet to be connected PEX.

[BK911]

You have to look at the system, not just one duct run.
Is this the main, or just one branch to a grille?
Is this the longest run (critical path) or are there other longer runs?
Is the flat portion significantly less cross area than the round duct?
Airflow and duct sizes?
Static pressure of the fan?
Overall not a bad fitting, but if in the critical path I would be a little concerned.
If not in the critical path, I would not be too concerned. Unless area is significantly reduced.

[lendaddy]

Just to be clear, I didn't do this install

[rattlsnak]

Bernoulli's principle.. This will cause lower pressure but more velocity (in that section) -- up until the point where its back to normal sizing.. Then it's not going to matter.

[908/930]

I'm not in the industry but I did all the ductwork in my new build, about 700ft of pipe, just for that reason.

Will that work, probably, it will just add 10 or 20 equivalent feet to that run, and look like a hack job. What diameter is that pipe 6 or 8"?

Is there a reason he didn't want to run the PVC up and then over, two more elbows so he will possibly have to go up a size. How long of a run until the PVC gets through the wall? The PVC also requires slope back to the furnace for the exhaust.

[cabmandone]

On the refrigerant lines, some come pre charged so installers can't cut and braze fittings like they would using copper that just has a nitrogen holding charge. Many won't braze because to do it properly you need to flow nitrogen to keep impurities from forming while brazing. Does it look bad? Yep... does it hurt function? Nope. I was a painfully picky installer because I knew that something looking off leads a homeowner to look for more.

My guess on the duct is that he didn't want to end up going below the metal pipe because that would put the vent pipe below the main trunk and that would mess things up for framing a bulkhead and boxing the duct in for a drop ceiling.

[Geoz1]

It doesn't look good, but it won't hurt anything. It's simply oval to round fittings. As stated, the elbow to the left hurts air flow worse.

Add 10' to 20' to the run? You can't be serious. How much does a 90* elbow add?

[lendaddy]

Originally Posted by cabmando

On the refrigerant lines, some come pre charged so installers can't cut and braze fittings like they would using copper that just has a nitrogen holding charge. Many won't braze because to do it properly you need to flow nitrogen to keep impurities from forming while brazing. Does it look bad? Yep... does it hurt function? Nope. I was a painfully picky installer because I knew that something looking off leads a homeowner to look for more.

My guess on the duct is that he didn't want to end up going below the metal pipe because that would put the vent pipe below the main trunk and that would mess things up for framing a bulkhead and boxing the duct in for a drop ceiling.

Thanks guys, great info. In regards to the AC lines my concern is the butchering of the wooden framework that was completely unnecessary but I would have preferred he run it that high so I wouldn't have to box the line in to drywall the ceiling. Again it just looks amateurish and hack to me.

It does sound like I might be overthinking it though which is why I'm bouncing it off you guys. Sincerely, thank you all.

[Zeke]

Originally Posted by lendaddy

Thanks guys, great info. In regards to the AC lines my concern is the butchering of the wooden framework that was completely unnecessary but I would have preferred he run it that high so I wouldn't have to box the line in to drywall the ceiling. Again it just looks amateurish and hack to me.

It does sound like I might be overthinking it though which is why I'm bouncing it off you guys. Sincerely, thank you all.

2 things: the framing butchering is awful and needs some metal strapping to repair. Not sure if that's a bearing vertical member to the upper right. Anyone who did that on a job of mine would not be allowed on site again, ever. If this is inspected, if I was an inspector — fail.

The duct may be fine if you do the calcs. First the sq in of the round and then the sq in for the oval. If they match, it's pretty close that the flow won't be restricted enough to "burn up the motor." It seems like a short run to the boot from the oval, right?

The bigger crime is that the oval connection isn't centered over the PVC vent. Who in the hell is working there? Jezus in a handbasket!

[sammyg2]

Originally Posted by rattlsnak

Bernoulli's principle.. This will cause lower pressure but more velocity (in that section) -- up until the point where its back to normal sizing.. Then it's not going to matter.

From the picture it looks like the duct is flattened without increasing the width (maintaining overall volume).
If the ducting is over-sized and can flow more than the fan puts out with minimal restriction, then it'll be fine. But if the ducting is sized correctly for the fan, the restriction will reduce flow.

If that is the case and it is a true reduction in cross-sectional area, then he pressure will INCREASE right before the restriction, which will increase pressure, which will increase velocity. But the flow will be decreased.

[Zeke]

Originally Posted by sammyg2

From the picture it looks like the duct is flattened without increasing the width (maintaining overall volume).
If the ducting is over-sized and can flow more than the fan puts out with minimal restriction, then it'll be fine. But if the ducting is sized correctly for the fan, the restriction will reduce flow.

If that is the case and it is a true reduction in cross-sectional area, then he pressure will INCREASE right before the restriction, which will increase pressure, which will increase velocity. But the flow will be decreased.

It sorta does but if you follow the reflection of the camera flash, I see an angle indicating that the oval is wider than the diameter of the round.

[Gogar]

It looks great, unless you want air to come out of the end of it.