Ac vents

[PARAPTOR]

Originally Posted by xrated

Something to keep in mind if you are seriously thinking of adding another A/C unit into existing ductwork, is the duct size itself. It's probably not large enough to support the amount of airflow generated by two units. And even if it was, if two A/C units are running at the same time, from opposite ends of the ductwork , they are effectively trying to push air against each other. Of course, some of the air will be coming out of the registers, but probably not enough to give you good airflow across the evaporator coil of each unit. Low airflow across the evaporator(s) will result in them freezing up because there is not enough of a heat load to boil off the refrigerant circulating through the evaporator.

I have no idea what you are referring to, seems to me you may be merely reemphasizing information in John's previous post in this thread. If your post is in any reference to my post also in this thread, I highly suggest you reread it. Real simple, my concept, which is identified in the referenced post,
identifies two separate A/C units feeding into two separate existing ducts.

Just want to clear up any possible confusion related to previous posts pertaining to this thread

[xrated]

Originally Posted by canesfan

Paraptor - I'm not understanding your last post. Are you getting into the "adult beverages" already?

jtrevill - I think yo may be right. Wait...look over there...

xrated - Most of the recent discussion is more "tongue in cheek" than reality. However, if it were to be done, if you read back through, the main ducting would be broken into two "sections", blocked off or not connected to each other, making a "front" duct and a "rear" duct, one for each AC. You are right, it would not work well to have them both connected to the same duct trying to blow air at each other, as well as the volumes not being adequate. However, I don't really see this as becoming "reality".

Got cha! I guess I totally missed the part about making "two separate ducts".

[JRTJH]

Laredo and a couple other Keystone products did, in fact, connect two rooftop units to the same ductwork. The way they did it is called "racetrack ducting". There were (may still be available in current models) two ducts, installed in a "circular" fashion. By doing this, one unit is actually "pulling" air toward itself while "pushing" air to the other unit and the unit at the "other end" is also doing the same. This allows them to work in unison, rather than to oppose each other.

You can see an example and an explanation in the 2015 Laredo brochure which can be downloaded here: http://www.keystonerv.com/brochure-archive

I've no doubt there are other ways to effectively install a dual rooftop system using the same ducting network, but considering that Keystone has already done this, using their ideas might save some of the errors in "trial and error installations"....

ADDED: For me, at least the way I visualize the A/C system, installing two separate ducting systems, one for the front of the trailer and one for the rear of the trailer is a significant limiting factor. In that type installation, there's no cooling in the front unless that system is on and there's no cooling in the rear unless that system is on. So, on "mild temperature days" the system would be limited to requiring both systems to evenly cool the trailer. There's no "alternative means" to reduce noise levels by using the front system when living in the rear of the coach and no way to use the system to cool both ends of the trailer when using a generator of "normal size"... Definitely, at least for me, considerations that would impact installing two separate systems in such a small trailer.

Just my thoughts, based on how we use our RV and certainly not any criticism of how others plan to use theirs.

[canesfan]

That's an interesting concept, John. Not sure how it works in real life, but interesting. Personally, I think just adding a separate non-ducted AC in the bedroom would suffice. I have a door into the bath from the bedroom and the "trickle down" effect of cold air sinking would help cool the downstairs.

[jtrevill]

well after several hours of internet reading - I'm going to go back up into the ducting and see if there are any blockages... and then I'm going to shut off the bedroom/bathroom ducts and see how well one unit cools just the garage and living area. If that takes care of the issue, a 2nd unit is in order for me.

[canesfan]

Originally Posted by jtrevill

well after several hours of internet reading - I'm going to go back up into the ducting and see if there are any blockages... and then I'm going to shut off the bedroom/bathroom ducts and see how well one unit cools just the garage and living area. If that takes care of the issue, a 2nd unit is in order for me.

If you shut off the living room and garage vents, how is the air flow into the bath and bedroom? I gained a "bunch" of airflow up there after I redid mine.

[JRTJH]

canesfan,

I'd guess that probably 90% of all trailers with a dual A/C setup are installed with a "gravity dump" interior shroud. Most have a simple rotary speed control and a built in thermostat next to the power switch.

While there are some "exotic installations", some "high tech" control features, some "intricate air systems" and lots of other "fancy gadgets", probably the most realistic installation is the one that's most common...

I don't think you can go wrong with your ideas. You might not have "the latest and greatest" that is in some "Cadillac brand" and you might find some things that you wish you could do better, but overall, I'd believe that the benefits of a simple installation outweigh the expense, effort and potential errors of trying to make a silk purse out of a sow's ear.....

[PARAPTOR]

Originally Posted by canesfan

Paraptor - I'm not understanding your last post. Are you getting into the "adult beverages" already?

jtrevill - I think yo may be right. Wait...look over there...

xrated - Most of the recent discussion is more "tongue in cheek" than reality. However, if it were to be done, if you read back through, the main ducting would be broken into two "sections", blocked off or not connected to each other, making a "front" duct and a "rear" duct, one for each AC. You are right, it would not work well to have them both connected to the same duct trying to blow air at each other, as well as the volumes not being adequate. However, I don't really see this as becoming "reality".

xrated; Good to hear you had an opportunity to read and understand my concept, Thanks

canesfan, jtrevill I hear you, may start working on my design drawings after I complete this far more difficult assignment to get the cover off this miniature light and replace the bulb with an led

canesfan; seriously , in regard to "I don't really see this as becoming "reality"" there is more of a chance of me taking on this concept than buying a second AC for solely the bedroom. Okay I will also include the bathroom, usually never spent that much time in there for cooling

I think this is a good time given canesfan, jtrevill, and I have been commenting back and forth and have similar Raptors. Another topic

"Should I buy a second AC" in this case you will notice that the three of us are in very different temperature zones thereby really different temperature extremes and our cooling needs will differ drastically. canesfan and I are in the East and jtrevill in the CA area. In my travels including down into the south central states I would say I experienced temps in the in the mid to upper 90's and have had no issues. I have to admit that I have played around with closing registers in areas not being used at that time as well as closed shades. Raptor windows 80% tint. To date, I have never been in the 100’s. Come to think of it, during the day when it was really hot out, I used think it is called the cool blast vents in the main ceiling. After a short time it will run your A…. out of there. After all this it seems like it comes down to location ….location

jtrevill; I agree with canesfan given your experiences in the temperature ranges you described, you may have other issues with your AC. There have been some interesting posts in the past addressing expectations of a RV AC, as well as, measuring temperature at the input and output registers, how to determine adequate feron/xxxx levels, etc If interested may want to do some searches

What am I going to do at my current age, probably nothing, again as discussed has not been a big issue with me at least up to now.

John, thanks thought I had seen a brochure on this concept. I am hoping the next generation of “configured for second AC” will include this raceway concept so when a second AC is added that it aids in cooling the entire rig rather than merely the bedroom. Oh YA, also the bathroom.

[Bigtphx]

I have Raptor 3712, has 2 ac units, frt bedroom unit is stand alone, close duct to Main when running bedroom unit. Works great, was in Glamis for Camp Rzr was 105deg ran both units in daytime had to shut bedroom unit off was freezing