A/C ducts send more air to bedroom

[dontay]

I always thought more air was going to bedroom because of fan direction but in looking at ducts they are located off to the sides of the a/c so fan rotation shouldn't matter and there is a styrofoam baffle in each that looks like it divides the air flow to front and back unevenly with more of an opening for air going to the rear. It is the same with both the left and right side ducts.
The baffle is only 3/8" styrofoam and would be easily removed. But heaven forbid I should find the baffle is necessary because it would be nearly impossible to put it back in the hole. Would probably have to remove the a/c unit to get my hands into that space.
Has anyone else seen this problem and removed the baffle I'm referring to? If so did it help with air flow to the front vents?
Thanks for any help.

[Thurman]

I'm going to take a stab at this using my "somewhat" experience with industrial A/C systems: An A/C systems duct work has to be "balanced" so that the air flow is equalized from all registers within a system. That's why you see A/C duct systems, which are sometimes square, rectangular, or round decrease in size as the run gets longer. I have worked on a few RV A/C systems with a friend of mine who owns/operates an RV repair service. I have not seen the particular baffles you have mentioned. Yes, all the ceiling placed A/C ducts in RV that I have seen are located to the sides of the A/C units output. On a ducted system if you look at the ceiling registers to the front and back of the A/C unit you will see that they are not in a straight line, they are offset as is the ductwork at the A/C unit. You are correct in that trying to work within that small height of the ductwork is not easy. As far as removing the baffle--I don't think I would do that just yet. It might be worth it to make an appointment with an RV service place to have them look at it. When/if you call make sure that you tell them you want an experienced A/C tech to look at this problem and make recommendations and pricing estimate before scheduling any service work. One thing I emphasize to anyone who owns an RV with ducted A/C units is to remove, one at the time, the ceiling registers to look for gaps between the Styrofoam duct material and the ceiling material. It's not surprising to find gaps ranging from small (1/16") to large (1/2") between the ducting and the ceiling. These gaps allow cooled air to go up in to the "attic" of an RV which is just wasting the cooled air. These gaps must be closed for an A/C unit to work efficiently. Use the silver/foil backed A/C ducting tape, not regular duct tape, to work around these outlets and seal those gaps off.

[A32Deuce]

It also helps to block the duct going away from the last ceiling vent. Air flow is much improved and the air is colder using an IR temp gun. Did that with mine and easier to maintain temp inside after it cools down after getting set up.

[Thurman]

Good call A32Deuce. I also found that each end of my ductwork was completely open to the attic. One can only imagine how much cooled air was escaping through this open duct work. It was quite a challenge to get my hand in there to stop this up. Due to the ductwork being small in height I used a piece of black pipe insulation foam, maybe for 1 1/2" or 2" pipe. I cut it to the correct length, test fit it to assure that it was snug, then put dabs of silicone on the top and bottom of the pipe insulation before placing it into the duct work. It's ridiculous that there is literally no quality control in the RV building industry.

[BillyBass]

Guys I'm lost .Bc On mind I just close the vents to the living rm or kitchen and the air goes back to my bedroom and it cools it down

[retiredcamper47]

My a/c duct vent covers are not adjustable. The a/c duct in my bedroom extends past the vent opening. I made a "dam/baffle" in the duct that blocks the air from going past the opening. Now the air hits the dam/baffle and comes directly thru the vent opening with more air flow. I used silver duct tape to create the dam/baffle.


Bob

[Thurman]

@BillyBass and others: Base on my experience with industrial air conditioning--closing off one or more registers, IF you have the type you can close off, is not a good thing. Air systems are balanced so that the entire duct run carries the output of the A/C unit, measured in Cubic Feet per Minute (CFM). By closing off one or more registers you create back pressure on the fan supplying the cooled air. This back pressure can, and will, cause the fan to strain to push air from it which will lead to premature fan motor failure. IF you were to close the dump gate and all the registers you should hear the fan motor change tune which is caused by this back pressure. The cooled air has no where to go. This is not the ideal way to operate the system, just an example of how to hear the change in the motor IF it cannot push the cooled air through the system. Before I added the 2nd. A/C unit to the front of my TT we used a small fan blowing from the living/dining room area to help cool the front bedroom. At times this was not enough to cool the bedroom so I added the 2nd. A/C unit and have never regretted it, , ,

[Bama Rambler]

Can you post a picture of that baffle?
It may just be something they didn't 'punch' out during construction.

[BillyBass]

Originally Posted by Thurman

@BillyBass and others: Base on my experience with industrial air conditioning--closing off one or more registers, IF you have the type you can close off, is not a good thing. Air systems are balanced so that the entire duct run carries the output of the A/C unit, measured in Cubic Feet per Minute (CFM). By closing off one or more registers you create back pressure on the fan supplying the cooled air. This back pressure can, and will, cause the fan to strain to push air from it which will lead to premature fan motor failure. IF you were to close the dump gate and all the registers you should hear the fan motor change tune which is caused by this back pressure. The cooled air has no where to go. This is not the ideal way to operate the system, just an example of how to hear the change in the motor IF it cannot push the cooled air through the system. Before I added the 2nd. A/C unit to the front of my TT we used a small fan blowing from the living/dining room area to help cool the front bedroom. At times this was not enough to cool the bedroom so I added the 2nd. A/C unit and have never regretted it, , ,

thanks for that info I won't do that again

[dannybye]

Thurman

Not trying to hijack Dontay's post about where and how easily air moves or doesn't in ceiling ductwork. Do you suppose the ceiling ductwork is truly engineered for volume? How can it be if they ship with one unit but claim it's ready for a 2nd unit .. How in the world is that balanced when you may have twice as CFM then if it only had one unit?

My 34 foot travel trailer came with one unit. It is pre-everything ready for a 2nd unit. In light of Dontay's question and your experience I'm tempted to install the 2nd bedroom AC and not connect it to the ceiling ductwork even though it's there ready and waiting to be connected if I want to. It seems to me that one moving the air from the back towards the front will cancel the other out or at the very least be totally inefficient.

Dontay, my feeling is that move the air with a circulating fan in your unit. Ductwork in these campers at best is putting cold air way to close to hot ceilings as it moves around and we campers lose more function/coolness then if they just gave us quiet fan systems in doorway corners to move air from front to back if necessary.

Billy Bass when you put your 2nd unit in did you tie it to the ductwork or just dump the air in the bedroom! I have a choice don't know which way would be more cool air for me in the unit not lost in ductwork that may be very leaky?

[Jughead]

Get a ChillGrill and you have the option of dumping or sending through the ducts.

[RVAV8R]

We have a 2016 Cardinal with 2 AC units, one in the living area and the other in the bedroom, on a common ducting system. Each air outlet can be directed or shut off. We routinely close vents to redirect air front to back. At start up when it is hot, both units on HI, all vents open. Once cooled down, the bedroom AC is typically turned off using only the living area AC. A couple hours before bedtime, the bedroom AC unit comes back on to cool things down but with a vent or 2 closed (bedroom gets too cold - smaller area). At lights out, the bedroom unit goes off, 2 bedroom vents get closed (drafts) and the living unit is set to continuous fan on LO with a couple vents closed to boost the flow to the bedroom.

Previously, we owned a toy hauler with separate garage and living area, 2 AC units with one over the garage drawing return air from the garage but feeding the common ducting. Any time we needed 2 AC units (initial cool down or really hot weather), all outlets in the garage were closed to direct cooling air entirely to the living area, with the connecting door cracked for return air to the garage AC unit. In spite of the garage AC getting fed "hot" air from the garage, the 2nd unit made major contributions to cooling.

In over 10 years of operating this way, we've never experienced any issues with fan problems or AC failures. YMMV

[BillyBass]

Originally Posted by dannybye

Thurman

Not trying to hijack Dontay's post about where and how easily air moves or doesn't in ceiling ductwork. Do you suppose the ceiling ductwork is truly engineered for volume? How can it be if they ship with one unit but claim it's ready for a 2nd unit .. How in the world is that balanced when you may have twice as CFM then if it only had one unit?

My 34 foot travel trailer came with one unit. It is pre-everything ready for a 2nd unit. In light of Dontay's question and your experience I'm tempted to install the 2nd bedroom AC and not connect it to the ceiling ductwork even though it's there ready and waiting to be connected if I want to. It seems to me that one moving the air from the back towards the front will cancel the other out or at the very least be totally inefficient.

Dontay, my feeling is that move the air with a circulating fan in your unit. Ductwork in these campers at best is putting cold air way to close to hot ceilings as it moves around and we campers lose more function/coolness then if they just gave us quiet fan systems in doorway corners to move air from front to back if necessary.

Billy Bass when you put your 2nd unit in did you tie it to the ductwork or just dump the air in the bedroom! I have a choice don't know which way would be more cool air for me in the unit not lost in ductwork that may be very leaky?

danny i didnt put another one in.

[dontay]

Picture of the baffle I am talking about. Left side leads to rear vents. This picture makes it look slightly worse than it is but it is best I can do sticking small camera and hand up through opening. There are 2 vents each on front and rear of both ducts (total of 8.) Air flow on rear vents is considerably stronger on both ducts.

Just got through checking the front vent openings to make sure ducts were blocked off past the last vent on each side and they are. Also saw no openings in the ducts that would allow cool air to escape ducts. Will do rear ducts after I send this.

BTW, when we get into a situation where the a/c can't cool down the rig or it can't seem to keep up we open the dump vent and allow the cool air to shoot straight down into the hall and push it to the living room with a fan sitting on the floor. This bypasses the ducts.

[Bama Rambler]

I can't see a reason why that piece is there. If it were me I'd tear it out.