A/C zone ducting question

[jerichorick]

Originally Posted by Cappy58

Joopy, I have been in the a/c installation business for 20 years mostly on multi-million dollar houses and the last thing they want to hear is noise from the AC sytem. My RV does not have a ducted system. Just two colman mark II units and both were extremely noisy but I think I can solve your noise problem. On the roof, remove the AC shrouds. This is an excellent time to clean everything and oil the fan motor and check bearings and wire connections as well. On a home system, we use a sound blanket that slips over the compressor to help kill sound. On my RV I used 1" fiberglass ductboard avaliable at home depot or Lowes or any AC supply shop. It can be cut to size with just a kitchen steak knife. Cut pieces to surround your compressor with the fiber side facing the compressor. Make sure to slightly over-sixe then so they fit snug. If need be, you can hold them in place with foil tape sold at the same places as the fiberboard(ductboard). You will have to slice the board to slide the wires through from the compressor. Them replace the AC shroud and your done on the roof.
I removed the interior shroud and used the same fiberboard to deaden the sound of the air rush and blower motor by lining the inside bottom of the shroud with fiberboard where it would not interfere with remounting and I cut pieces to "baffle" the air for the return and supply so there was not a direct "line of sight" to the blower motor. The fiber side of the ductboard needs to face in the direction of the sound and blower. Be careful not to restrict the airflow to much or your evaporator will ice up. All you want to do is create a sound deadining buffer. This works extremely well for mine as now all I hear is a very low hum and I do not need to turn the telly volume up at all.
Hope this makes sense... It will make a world of difference.
Cheers, Cappy

Great idea!

I just thought of heat dissipation for the compressor. Might there be a problem here when temperatures go to the extreme high -- triple digest?

Just a note of interest. The Colman units on a few model years of Winnebago products had a problem with the sound shroud tape falling off. The results was insulation being blown into the living quarters as the fan shredded it. This happened to me at the time I bought this coach in May. The fix was to remove the shroud. According to the manufacture it was not needed because my units have the "improved and quieter" fan.

Anyway. In every Winne coach I have been in with roof air running I have noticed the same thing. It sounds like being in the back seat of a 737. All you can hear is turbine noise. Also, the amount of air rushing from the vents is extremely and forceful to the point of being a distraction if you are standing near a vent trying to accomplish something.

Personally I feel the airflow rate is too great for the size of the duct channels. Even at low speed these units put out a force of air.

When we get to WA in June I will attempt to do as you say. I hope someone else has a go at it in the interim and post a report.

Thanks again for this idea.

Rick

[jerichorick]

Cappy, your unit is much different than mine. I have a horseshoe heat exchange and the compressor is in the front. Also, the profile is lower. I see that the principle is still the same.

Two questions: 1/ Is there any chance of heat dissipation being a problem for the compressor in extreme heat?

2/ Do you open up the "boxes" front and rear to put insulation in them?

Thanks for the great help.
Rick

[NeilV]

Originally Posted by bruceisla

82 "feels" very warm unless you are moving a lot of air ... ducted systems alone have difficulty with that. Just like a FL S+B, you really need ceiling fans.

A few small fans is all it takes to make up for it. I was not a big supporter of it at first but when you work with it 78/79 starts to feel chilly. I confess that at times I do cheat and leave the AC at 79/80 at night.

[bruceisla]

Originally Posted by NeilV

A few small fans is all it takes to make up for it. I was not a big supporter of it at first but when you work with it 78/79 starts to feel chilly. I confess that at times I do cheat and leave the AC at 79/80 at night.

I agree. I didn't state it well, but the difference is the paddle type ceiling fan is nearly silent vs. other type. In my case, the bedroom has a paddle ceiling fan and the other spaces have a Lasko tower fan.

[Jupiter]

All great tips again, folks. I'll take a look at the compressor sound insulation when we return home late March. Our bedroom ceiling fan really does help and is nearly silent.

As for cooling at 78 to 82 degrees … you don't know my wife! Or me as far as that goes. Our comfort zone during daytime is probably 74 / 75 and closer to 71 / 72 at night. Obviously, in extreme warm temps we live with interior temps several degrees higher. Sure, we support energy conservation, but we don't think we should live with conditions that feel (to us) to be quite uncomfortable.

Shade is your best friend!

cheers,
Joopy

[Cappy58]

Originally Posted by bruceisla

Of the 2 things you did (compressor wrap and blower baffles) which one reduced the noise the most?

Quote:
Of the 2 things you did (compressor wrap and blower baffles) which one reduced the noise the most?
__________________
1997 HR Endeavor 37, 1996 Geo Tracker


The compressor wrap will greatly reduce the "hum" and heat build-up is not a problem with the compressor. Lining the inside of the blower assembly greatly reduces the blower noise. The baffles in the duct decrease even further the blower noise down to a whisper.

[Cappy58]

Originally Posted by jerichorick

Cappy, your unit is much different than mine. I have a horseshoe heat exchange and the compressor is in the front. Also, the profile is lower. I see that the principle is still the same.

Two questions: 1/ Is there any chance of heat dissipation being a problem for the compressor in extreme heat?

2/ Do you open up the "boxes" front and rear to put insulation in them?

Thanks for the great help.
Rick

You only want to deaden the sound inside the interior blower. The other "box" is the evaporator coil (has one side of coil exposed to outside air) and you do not need to do anything to it. Heat dissapation of the compressor is not an issue.
Cheers, Cappy

[targaboat]

If one breaks you still have air through out the coach. If you want more in one area than the other shut the appropriate register.

[jerichorick]

Originally Posted by Cappy58

You only want to deaden the sound inside the interior blower. The other "box" is the evaporator coil (has one side of coil exposed to outside air) and you do not need to do anything to it. Heat dissapation of the compressor is not an issue.
Cheers, Cappy

Thanks, Cappy. I hope this works. The way Winnebago designed the roof duct I don't have high hopes.

I have read that the compressor vibration can be eliminated by adjusting screws. Is that the mounting screws of the compressor they are talking about? Any advise here? (See what happens by fessing up that you real know?)

[Cappy58]

Originally Posted by jerichorick

Thanks, Cappy. I hope this works. The way Winnebago designed the roof duct I don't have high hopes.

I have read that the compressor vibration can be eliminated by adjusting screws. Is that the mounting screws of the compressor they are talking about? Any advise here? (See what happens by fessing up that you real know?)

Yes Rick, Check the rubber bushings that the compressor mounting bolts go through. If they are worn and the compressor can move a lot, tighten the bolts or replace the bushings.

[NeilV]

Originally Posted by Cappy58

Yes Rick, Check the rubber bushings that the compressor mounting bolts go through. If they are worn and the compressor can move a lot, tighten the bolts or replace the bushings.

Just don't squash the rubber bushings so that they become solid and no longer absorb the compressors vibrations. They do need to stay resilient in order to work.

[jerichorick]

So, Cappy, hard or loose is not good. When I get to the BIG doing, getting on the roof in warm weather with my son, I will get a better idea of what is going on. I'll try to take some good pictures to share with folks. This will happen at the end of June. Don't think I have forgotten y'all. (Learnin to speak Texan.)

I look forward to this project. I do hope I can find a way to reduce the noise.

Blessing all,
Rick

[Cappy58]

Originally Posted by jerichorick

So, Cappy, hard or loose is not good. When I get to the BIG doing, getting on the roof in warm weather with my son, I will get a better idea of what is going on. I'll try to take some good pictures to share with folks. This will happen at the end of June. Don't think I have forgotten y'all. (Learnin to speak Texan.)

I look forward to this project. I do hope I can find a way to reduce the noise.

Blessing all,
Rick

Very cool! I linked this thread to alert my email so when you get around to it and post, I will get an email and respond if you need help.
P.S. We are going to be in the mid to upper 70's starting tommorow... I feel for those of you further north.

[LadyFitz...]

Originally Posted by Cappy58

...I cut pieces to "baffle" the air for the return and supply so there was not a direct "line of sight" to the blower motor. The fiber side of the ductboard needs to face in the direction of the sound and blower. Be careful not to restrict the airflow to much or your evaporator will ice up. All you want to do is create a sound deadining buffer...

Thank you for your suggestions to quiet an AC. I'm not able to wrap around my little mind exactly what you mean by the baffles. Could you give an idiot's version of that description or, even better, a picture or drawing of the baffles?

[Cappy58]

Originally Posted by LadyFitz...

Thank you for your suggestions to quiet an AC. I'm not able to wrap around my little mind exactly what you mean by the baffles. Could you give an idiot's version of that description or, even better, a picture or drawing of the baffles?

Below is a rough drawing(I used windows paint) of the baffles I did on mine. Ductboard has a foil side and a fiber side... The baffles needs to be inserted with the fiberglass side facing toward the blower motor in order to deaden the blower noise. It seems restrictive to "air flow" but in AC systems the forced air willl build up inside the duct to a "static" pressure so it will not impead airflow noticably but will decrease the noise from the blower motor. Don't place baffles to close to the air outlets or the diffusers will not "spread" the airflow effectively. If your ducts are bare metal on the inside, I would glue in a 1/4 inch fiber mat to help decrease noise. Bare metal will just "bounce" the noise out your air outlets. Home Depot or Lowes will have this and a glue made for this as well. Hope this helps.
Cheers, Cappy

[LadyFitz...]

Thank you!