Ducted A/C Unit - Bypass Ductwork for Better Cooling??
Bought a new 5th wheel with 2 Dometic Brisk II 13.5k a/c units a few months ago. As expected the front bedroom non-ducted a/c unit works extremely well due to the small area it has to cool. Not surprisingly, the ducted 2nd a/c unit, which is cooling a much larger area, doesn't cool as well. We've been on two camping trips with 100-112 degree ambient temps. Cooling, although not ideal in the main living area, has been "adequate". We've been using a squirrel cage fan to move the colder air from the front bedroom to the main living area to assist the ducted 2nd a/c unit when temps got above 100.
We're getting ready to go on an extended cross-country trip in a few weeks, so I figured I'd clean the air filters, remove the shrouds to make sure the a/c pan gaskets were torqued down sufficiently, and check the internal "partition" to make sure no hot intake air was leaking into the cold exhaust area. When I removed the shroud on the ducted unit (while it was cooling), I couldn't help but notice the DRAMATIC increase in air movement when I removed the shroud (which was adjusted for a maximum "direct flow" of approx. 50 percent).
This is my first ducted a/c unit, so I'm not sure how other ducted units work. The shroud on this Brisk II unit has a slider that enables one to adjust the amount of air that gets forced into the ducted outlets vs. direct flow downward out of the shroud. I'm estimating the adjustment goes from 100 percent ductwork (baffle completely closed), to 50 percent ductwork/50 percent direct flow. The baffle won't allow 100 percent of the air to flow directly out of the shroud.
Long story short, with the shroud removed, which allows 100 percent of the a/c unit's air to exhaust directly out of the a/c unit (little to no air into the ductwork), cooling increased dramatically. My estimate? It was almost like adding a 2nd 13.5K a/c unit in the main living area. With ambient temps around 103 degrees today, temps in the main living area dropped down to 76 degrees within 1-2 hours (IMO a pretty significant drop for a 33 ft. TH with very high ceilings; 13' 4" outside height). It never dropped below 80 degrees in the main living area with the shroud adjusted to 50/50 (ductwork/direct flow) when ambient temps were above 100 degrees.
Although I have nothing to compare it with, I don't believe the ductwork is obstructed---a "decent" amount of air was exiting each duct prior to removing the shroud.
Anyhow, the Brisk II shroud costs about $55. I decided to cut out the adjustable baffle to allow 100 percent air flow out of the shroud with the shroud installed (not a big risk if my gamble didn't pan out). So far, so good--simply amazed with the increase in cooling.
For those with a ducted a/c unit that won't allow 100 percent direct flow out of the unit (or minimal flow to ductwork) and aren't getting the cooling they desire, temporarily removing the shroud to see if cooling improves is something they may want to try. If it works better, hey great; if not, at least it gave you an excuse to check things out underneath your shroud--lol!
We're getting ready to go on an extended cross-country trip in a few weeks, so I figured I'd clean the air filters, remove the shrouds to make sure the a/c pan gaskets were torqued down sufficiently, and check the internal "partition" to make sure no hot intake air was leaking into the cold exhaust area. When I removed the shroud on the ducted unit (while it was cooling), I couldn't help but notice the DRAMATIC increase in air movement when I removed the shroud (which was adjusted for a maximum "direct flow" of approx. 50 percent).
This is my first ducted a/c unit, so I'm not sure how other ducted units work. The shroud on this Brisk II unit has a slider that enables one to adjust the amount of air that gets forced into the ducted outlets vs. direct flow downward out of the shroud. I'm estimating the adjustment goes from 100 percent ductwork (baffle completely closed), to 50 percent ductwork/50 percent direct flow. The baffle won't allow 100 percent of the air to flow directly out of the shroud.
Long story short, with the shroud removed, which allows 100 percent of the a/c unit's air to exhaust directly out of the a/c unit (little to no air into the ductwork), cooling increased dramatically. My estimate? It was almost like adding a 2nd 13.5K a/c unit in the main living area. With ambient temps around 103 degrees today, temps in the main living area dropped down to 76 degrees within 1-2 hours (IMO a pretty significant drop for a 33 ft. TH with very high ceilings; 13' 4" outside height). It never dropped below 80 degrees in the main living area with the shroud adjusted to 50/50 (ductwork/direct flow) when ambient temps were above 100 degrees.
Although I have nothing to compare it with, I don't believe the ductwork is obstructed---a "decent" amount of air was exiting each duct prior to removing the shroud.
Anyhow, the Brisk II shroud costs about $55. I decided to cut out the adjustable baffle to allow 100 percent air flow out of the shroud with the shroud installed (not a big risk if my gamble didn't pan out). So far, so good--simply amazed with the increase in cooling.
For those with a ducted a/c unit that won't allow 100 percent direct flow out of the unit (or minimal flow to ductwork) and aren't getting the cooling they desire, temporarily removing the shroud to see if cooling improves is something they may want to try. If it works better, hey great; if not, at least it gave you an excuse to check things out underneath your shroud--lol!
