Home Furnace Air Handler Plenum Design help,, Anyone A GURU??

[2manyrocks]

I would guess air flow measurements would be okay, but I've yet to see an HVAC tech come out with a sound level meter or measure audio frequency response for rumble caused by not making a smooth transition from the air handler outlet to the duct system.

It just looks like the installer was concerned with trying to make an awkward transition at an angle from the air handler to the ductwork. So he went with a transition sized to the case instead of the outlet. The system evidently works, but CADplans is tired of the noise because he's the one that has had to live with it.

 

[ultrarunner]

Problem is it is ongoing day in and day out for decades...

Seen more than one new install with a do over... and the customer was right.

The system I put in my brothers was about as quiet as could be... it was 100% new ad previously only a wall furnace and window AC.

His neighbor had a 12k similar but it was like gale force wind and loud like a vacuum in the next room

Installer used much smaller duct work and one speed blower and that was just the start.

I have some commercial transitions not made with metal but more like a rubber coated canvas material that can flex and it is very quiet...

 

[CADplans]

OK, I have taken the "next step" in my heat pump install saga,,

I removed the plenum, which was easier than I thought it would be.

The flat top surface of the air handler can be seen here.
I decided to install an angled block off piece of sheet metal.

Since the plenum was removed, and the block off would be installed while the plenum was on the floor, the concern about drilling chips getting into the air handler was eliminated.

The last time I made a modification to a plenum was 50 years and 4 months ago.
(I remember the date accurately, it was when I went on active duty with the US Navy.)

So, after pulling up some files from my memory bank,, I cut, then bent, then installed the block off.
Here is a pic of it installed, ready to replace the flexible joint.

I simply bolted the block off to the insulated interior of the plenum.
I used 10-32 bolts, with washers and double locking nuts. I did not want the bolts to vibrate loose.

Then the flexible joint was re-installed,,

After the two drive clips were installed, I retaped all the joints,

The unit is now 90% quieter!! SUCCESS!! `~`

With the noise issue resolved, I still have a few other issues.
I need to replace the 220 volt wiring to the air handler, and purchase the correct size breakers.

 

[ultrarunner]

Thank you for posting the results...!

 

[ponytug]

Great memory banks! Nice job, and I am really glad it solved your problem. (Is 90% good enough?)

All the best,

Peter

 

[CADplans]

I started a new thread to help investigate a startup issue with the new heat pump,,

Heat Pump Startup Makes The Lights Flicker,,, Is That OK??​

Heat Pump Startup Makes The Lights Flicker,,, Is That OK??

Well, we have a new heat pump, I watched the tech monitor the running amps,, only about 17 amps. The compressor is a "screw type" rather than a piston of the old days,, The screw type should have lower startup amp demand.. no pistons to get moving,, ? What surprises us, is that the lights will...

www.tractorbynet.com

 

[m1garand762]

Make sure the motor is set for 350-400cfm per ton cooling the ahu should have an ecm motor. The dip switches should be checked and also make sure that it’s set to 2.5 tons that is all set through the board that funds the motor