A/C zone ducting question

[Jupiter]

I tried to find out an answer via the site search engine, but had no luck.

2013 Journey 36M with 2 Coleman rooftop units (very noisy I should add )

The units cool okay, but it appears as though they share a common supply air duct. Given that they are "zones" (front and bedroom), I would expect them to only distribute cooling to their respective zone. However, zone-1 (front) is a larger area and therefore runs longer to reach set point. When zone-1 is cooling and zone-2 is "off", zone-1 is also distributing cool air to zone-2 (bedroom) which is smaller and therefore will get cooler than its respective set point. Conversely, when zone-2 runs, it distributes air to zone-1.

Not a serious problem since we like a cool bedroom. But I would have expected them to have a segregated supply duct.

Have others experienced the same on this model Winnie?

cheers,
Joopy

PS - Did I mention noisy… I would love to have our basement air back. These Coleman roof top units are seriously noisy. We have to crank the TV volume near max when the cooling is on.

[HerbZilla]

Our 2013 Vista 35B is set up the same way. Does make for a cool bedroom as you say. And the funny part is the two thermostats are only a couple feet apart.

[Jupiter]

Thanks, Herb. Good to know. We have one thermostat mid-coach behind an access door. But each zone has a temp sensor. One on the bedroom inner wall and the other on the end of the kitchen counter base cabinet by the sofa arm.

[Jbmsr]

Originally Posted by Jupiter

I tried to find out an answer via the site search engine, but had no luck.

2013 Journey 36M with 2 Coleman rooftop units (very noisy I should add )

The units cool okay, but it appears as though they share a common supply air duct. Given that they are "zones" (front and bedroom), I would expect them to only distribute cooling to their respective zone. However, zone-1 (front) is a larger area and therefore runs longer to reach set point. When zone-1 is cooling and zone-2 is "off", zone-1 is also distributing cool air to zone-2 (bedroom) which is smaller and therefore will get cooler than its respective set point. Conversely, when zone-2 runs, it distributes air to zone-1.

Not a serious problem since we like a cool bedroom. But I would have expected them to have a segregated supply duct.

Have others experienced the same on this model Winnie?

cheers,
Joopy

PS - Did I mention noisy… I would love to have our basement air back. These Coleman roof top units are seriously noisy. We have to crank the TV volume near max when the cooling is on.

I feel you. If it is zone temperature it should adjust by zones. I took the ac vent out and stuck a piece of foam rubber in the duct to separate the two zones as they should be. I love it. DW can be 77 in the bedroom and I can be 68 in the living room.

Jesse

[Jupiter]

Very clever idea, Jesse.

Have you operated this way for some time without issue? Also, did you separate the return duct as well?

cheers,
Joopy

[Clay L]

I prefer having both ACs feed into the same duct.
One advantage is that the front can be turned on at night which is much quieter than having the bedroom one running.
Conversely if it isn't too hot outside during the daytime, the rear one can be run so there is less noise in the front.

[Jbmsr]

Originally Posted by Jupiter

Very clever idea, Jesse.

Have you operated this way for some time without issue? Also, did you separate the return duct as well?

cheers,
Joopy

Thanks Jupiter
We have have it this way for 10 months now without any issues and we didn't separate the return. One zone will still cool another zone if the door is open. Nothing to loose, just pull the foam out. Please let me know if you like it.
Jesse

[D Lindy]

While we have 3 AC units on the roof we have only 2 zones too. What we do is just close off the vents in the Bedroom when we cool the living area during the day, and vice versa at night. Usually we only run the middle AC on Zone 1 by tripping the breaker for AC1 Zone 1. Running the AC in the living area while sleep is a lot quitter.

[Jupiter]

Thanks for all the good feedback. I think I'll try the foam divider when I can get my hands on some material. I'll let you know how we like it, Jesse, when I get around to it.

I never gave a thought to adjusting the louvers and running the front unit at night and the bedroom unit during the day. Good suggestion I'll try experimenting with running one or the other during mild periods. I say during mild periods because having only two units in the hot Florida sun during temps in the 80's and 90's is a challenge. Both units work hard with brief downtime to maintain interior comfort. IMHO, Winnebago should have had three units on this coach, or a front unit with a larger BTU output.

In any event, thank you all for the suggestions. I now know that the common duct is typical, and I have some good ideas to try

cheers,
Joopy

[jerichorick]

We have been in our coach since May. The A/C is working fine with two zones and common ducts. When we are on propane during the day (cold here in TX) we close the bedroom door and set the zone 2 thermostat cooler than zone 1. This will keep the basement essentials warm but not waste propane. When we go to bed we open everything up and set both zones for around 63*. We also run a space heater and the fireplace to supplement the heat.

We use the roof units differentially. We try to heat and cool with zone 2 when we can. The noise we all detest is just too much from zone 1. We only use zone 1 when it zone 2 can't keep up. At that point the rest of the campground knows what we are watching on TV. You all know why.

A side note. I just volunteered with a couple that have a spanking new Adventure. The roof air noise is about half that of mine.

Back to the topic. Adjusting the output vents helps to get the air where you want it or don't. We often close the vents in the bedroom because it is not as critical as the front, for us.

So, there are my two cents.

Rick

[HerbZilla]

I do what Clay does also. Like you mentioned about the noise it helps reduce it if you run the opposite one of the space you are in. This is especially convenient at night because I do hate listening to the thing run above my head.

[Jupiter]

Thanks for your input Rick, Clay, Herb and Jesse. Good suggestions that I'll certainly experiment with. Really do appreciate your comments.

Just minimizing the noise will be a great benefit!!!

cheers,
Joopy

[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

[Cappy58]

this pic might help explain....

[bruceisla]

Originally Posted by Cappy58

this pic might help explain....

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

[bruceisla]

Originally Posted by HerbZilla

I do what Clay does also. Like you mentioned about the noise it helps reduce it if you run the opposite one of the space you are in. This is especially convenient at night because I do hate listening to the thing run above my head.

This is really the only solution unless the outside temp is so high you MUST run both A/C units.

Here's a few other things I've found that help in Florida summer:

1) use a floor fan to circulate air (I use a Lasko tower which is very quiet).

2) install a paddle type ceiling fan in bedroom (they are relatively quiet and keep air moving in the "dead" area of a bedroom).

3) park in shade (yes, you may lose sat TV).

4) use aluminum faced bubble insulation across the entire windshield.

5) deploy the awnings.

6) try to park so the setting sun IS NOT on the bedroom.

These all help and, in moderate temps, allow lower A/C blower fan speeds and use of one vs. both A/C units. But, when it's 95 outside, it's gonna' be noisy in your RV ...

RV A/C is far more like home window units than home central air ... there's only so much you can do when the noise (blower) is close to your head.

[NeilV]

The recomedation by many in Florida is to run the AC at 78 to 80 during the day and 82 while your sleeping. 84 to 85 when nobodys home as long as heat sensitive animals are not left behind. 68 would be an unreasonable expectation and waste a ton of energy. There is the need to conserve energy to be considered too.

I believe the ducts are linked to help equalize things when your on a 30 amp service and power management turns off the second AC unit when you have things loaded up with the convection over going or other high draw appliances running that are not managed.

The new Espresso, Charcol and other dark color schemes of the newer coaches isn't helping with cooling either. Pulling down the sunshades on the sunny side of the coach will also help keep things cooler.

For sound deadening as Cappy mentioned ductboard or wet location sound board/mat can help. Even some 1 inch single faced fiberglass insulation contact cemented to the flat surfaces inside the rooftop units can make a big difference.

Myself I think I will hold on to my 2001 with Basement Air a while longer.

[Jbmsr]

I too loved my basement air!

Jesse

[bruceisla]

Originally Posted by Jbmsr

I too loved my basement air!

Jesse

Unfortunately, the quest for more outside bay storage won that battle.

Personally, living in Florida, I'd rather have quiet, efficient, isolated A/C.

[bruceisla]

Originally Posted by NeilV

and 82 while your sleeping.

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.