duct diameters and their corresponding supply and return air grille minimum area in square inches. If a transition box is used, the total area of supply air ducts going out of the box should at least equal the area of the supply duct feeding the box. To calculate the square inch area of a round duct, multiply the radius by itself (r2) and multiply that number by 3.1416(π). See Figure 8.
The following is a summary of proper ducting connections:
1.Pull back the fiberglass insulation exposing the inner mylar duct hose.
2.Slide the mylar duct hose around the mount ring until it bottoms out.
3.Screw 3 or 4 stainless steel sheet metal screws through the duct hose into the transition ring.
Make sure to catch the wire in the duct hose with the heads of the screws. Do not use band clamps, as the hose will slide off.
4.Wrap duct tape around the ducting and ring joint to prevent any air leaks.
5.Pull the insulation back up over the mylar to the ring and tape this joint.
6.Remove excess ducting and use the same connection method at the supply air grille.
All ducting should:
•Be appropriately sized for each application.
•Run as smoothly and taut as possible.
•Have as few bends or loops as possible.
•Be securely fastened to prevent sagging during boat operation.
•Have all excess ducting lengths trimmed off.
•Not be flattened or kinked.
•Insulated when located in high heat load areas (hull side, mechanical compartments, etc.).
•Be properly protected against potential damage when routed through open areas.
Seawater Pump and Plumbing
Several guidelines should be followed during the installa- tion of the seawater system. Since the circulation pump is centrifugal and not
seawater speed scoop intake as far below the water
line and as close to the keel as possible in any application, but especially on a sailboat, to keep the intake in the water when the boat heels over so that air does not get into the system. (See Figure 7 for
proper installation.)
The speed scoop intake must face forward and not be shared with any other pump. A seawater strainer is mandatory between the shut off valve (seacock) and the pump to protect the pump from any foreign matter.
Failure to install a seawater strainer will void the
pump warranty. The seawater system should be in- stalled with an upward incline from the speed scoop & seacock, through the strainer, to the inlet of the pump and then up to the inlet of the a/c unit’s condenser coil. The discharge from the a/c unit should then run to the seawater outlet
1.Install the speed scoop
2.Install a bronze, full flow seacock on the speed scoop
3.Install a seawater strainer below the level of the pump with access to filter.
4.Mount the pump above the strainer and at least one foot below the waterline.
5.Connect the seacock and strainer with an uphill run of reinforced marine grade hose.
6.Connect the discharge from the pump uphill to the bottom inlet of the a/c unit’s condenser coil with 5/8" hose. Connect the discharge from the condenser coil to the overboard discharge
7.Avoid loops, high spots or the use of 90° elbows with seawater hose (each 90° elbow is equivalent to 2.5' of hose and a 90° elbow on the pump outlet is equivalent to 20' of hose).
8.Double clamp all hose connections with stainless steel clamps, reversing the clamps.
9.Use teflon tape on all threaded connections.
10.Connect all metallic parts in contact with seawater to the vessel’s bonding system including the speed scoop inlet, strainer, pump and the air conditioner. Failure to do so will void warranty.
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