Forkys front AC ductwork rework :)

Ok it's time. My old cheap/ broke ass has bubble gummed/ studied and repaired freon leaks and electrical connections and recharged my 15 yo front unit for the last time. And this determination was at the hands of a true professional.. More on that later.

And the only thing more embarrassing than my dragging out the inevitable verdict- are some of my approaches to maximize what I did have to work with. Case in point:

The original installation (I'm thinking about halfway through PL2's lifespan) by a marine service provider in the North East was very shoddy. And the worst portion of the install was the ductwork.

So... A couple of years ago I ripped out the crushed/ failing original flexible ducting and resolved to minimize any bends- as I had studied an installation guide and straight runs are what you need for the best airflow. The front cabin had one small vent over the bunk and the balance of the cool air ran through the ductwork to a register in front of the lower helm... Ineffectivley participating in cooling the salon. So my attempt at getting the best air flow resulted in the 1/2 full bed of sheet metal ducting and God knows what else in the back of my Ford truck.



Did I mention that the two 100 gallon water tanks below the fore cabin sole restricts me to a height of 2 1/8" inches maximum duct height?? That's right. Less than 2 -1/4".

So I'm plumbing in an upper/ lower bunk circular vents. This should keep the front cabin cool, and the remainder will feed a plenum (we are galley down) that will be placed where I can add a small register to the front head and then either one large register facing the sink (port side) about knee high and the plenum I have built will also allow for second large register if deemed needed. More later as this story unfolds...


Forky
1983 Present 42 Sundeck
Twin Lehman 135's

I have a similar project coming this winter but from the bunk room under the helm plan on using a y with damper to add some air to the salon coming up through the helm

you got more clearance than most rv roofs. The ducts in my rv are 2" tall. They (rv's) generally call for 10 inches sq. or better for the ducts.

Good info!
I haven't converted the 6" duct to square inches yet- but I have enough room to pull off the dimensions you have on the bus . And insulation needs to be considered as well.
I trade out work on a guy's old Ling tractor that will be building the ductwork. We swap hour for hour on skill set trades, and generally provide our own materials. It's still gonna have a couple of sections of 6" round heavy spiral round duct transitioning into the small flat runs.
I'm sure we will end up with either light gauge aluminum or SS.
Which # SS sheets would be necessary to live in this environment anyone??


Forky
1983 Present 42 Sundeck
Twin Lehman 135's

28.27"

Last year I bought some PVC type ducting and fittings from Webasto. I tried a few sizes but ended up with some flat oblong about 1 1/2-2" thick, about 6-8" wide. You can order a wide assortment of fittings like 2 styles of 90 turns, various transitions to 4" round etc. and the main duct in about 8' lengths, you can just cut length you need, it's all mix and match slip fit, works great.
Really moves some air, and easy to take apart to clean or can be made permanent.
I actually used it for 2 different clothes dryer ducts, I take them apart couple times a year to clean the lint.

Moonstruck said:

28.27"

Click to expand...

Pie r square?


Forky
1983 Present 42 Sundeck
Twin Lehman 135's

BerettaRacer said:

Last year I bought some PVC type ducting and fittings from Webasto. I tried a few sizes but ended up with some flat oblong about 1 1/2-2" thick, about 6-8" wide. You can order a wide assortment of fittings like 2 styles of 90 turns, various transitions to 4" round etc. and the main duct in about 8' lengths, you can just cut length you need, it's all mix and match slip fit, works great.
Really moves some air, and easy to take apart to clean or can be made permanent.
I actually used it for 2 different clothes dryer ducts, I take them apart couple times a year to clean the lint.

Click to expand...

Thanks for the info- I would like to look into that- any chance that you remember the brand that you were happy with??


Forky
1983 Present 42 Sundeck
Twin Lehman 135's

It's all Webasto, they just make different sizes. Looking at it this morning I see I'm using the 200 x 60mm size.

Check this catalog, top of page 104
http://techwebasto.com/redirect/marine_main/2011_Marine_Catalog.pdf

BR- what a great resource. Looks like a game changer- will study up with my laptop. Thanks!


Forky
1983 Present 42 Sundeck
Twin Lehman 135's

Fork:

My A/C duck redo involves the use of this simple insulated duct board from Lowes or Home Depot. With the aluminum tape, it's possible to make any width or height and is easy and fun to work with. Metal round to rectangle adapters were also in stock and simple to attach. Here I have a duct running vertical up my utility closet.

Forky-
I think you need more projects!

Larry that's a great idea. And it's insulated. Anything round is a space killer. Your set up still leaves a very usable locker.

CC- that's a fair analogy. . Admiral requests one more day before I get home. I think:

* There's a really happy young cowboy somewhere near Watson Louisiana..
OR
*She is finally about to catch up on paperwork- as she has been trying to achieve for several months.

End result is the same. Captain Steve gets another "unsupervised" boat day
(Thanks for letting me borrow your term Don!)

Still keep a sharp lookout- cause I'm gonna finish the transom shower and sew something. Soon.


Forky
1983 Present 42 Sundeck
Twin Lehman 135's

Thanks Larry for reminding me that I need to remove the round flex duct that takes up so much space on my new a/c unit that's in the same location. What size did you make the duct board rectangle ? Do you have a photo of how you did the transition from the blower discharge into the insulated duct board ?
Bill