Saturday, October 27, 2012

The Quest for Cool

LUX didn't have Airconditioning when we bought her. It is seldom needed in the BVIs with the trade winds there. But now that we're in Annapolis with the hazy, hot, and humid Chesapeake weather, A/C is now a requirement. Looking at Leopard 40s of various vintages, we found that the early models and the plans showed two 12,000 BTU units. Later models have two 16,000 BTU units. We wonder if experience showed that 16,000 BTU was more appropriate.

The layout drawings in the owners manual show the two units located under the main salon settee, port and starboard. Fortunately, we had pictures from other Leopards and were able to learn a few key tips about the installation. We considered having someone else do the installation, but the cost of nearly $13,000 plus haul-out put us off.

Several weeks later, we have two EnviroComfort 16,000 BTU units installed and a set of nice looking supply vents and return vents. We did the installation ourselves instead of having an installer hack on Lux, putting things where it was easy to install instead of where it made the most sense. The parts were ECD16K-HV 410A w/passport I/O Display, 16000 BTU, 115v Dometic/Marine Air, 6"MR, 15' display cable and March AC-3CP-MD 115V Sea Water Pump 630 GPH.
Unit Installed

We had several installation requirements. We wanted to limit the number of holes that had to be drilled or cut. We didn't want the salon vents to use precious shelf space. We also wanted to consider the option to have one A/C unit provide cooling to all four cabins (LUX is the 4-cabin, 2-head model). We also wanted to use the electrical system design, which looked very good. So we decided that we would do the installation ourselves and we are happy with the results.

The two units went under the main salon settee, just as in the original R&C plans. A 3/4-inch plywood base was put under the units to raise them slightly and to bridge the gap in the bases that already existed.

Cooling Water Plumbing

One of our goals was to limit the number of through-hull holes, we connected the cooling water supply to a Tee off the 3/4-inch raw water supply for the marine toilet, using a one-way valve on the head supply feed to keep from sucking water out of the head. Our reasoning is that the head use is infrequent and it doesn't use much water. On the starboard side, we created a 4-way manifold which we can use to supply water to an anchor wash-down pump as well. The cooling water exhaust goes to a Tee on the galley sink drain and the condensation drain goes to a Tee on the drain for the cooler that's outboard of the sink.

The cooling water exhaust is also ganged together into a 1-inch hose that goes to a Tee with the galley sink drain. That causes a bit of running water noise if the sink drain plugs are not in place, which may annoy some people. The condensation drains are ganged together on a 1/2-inch hose that goes to the cooler drain that is adjacent to the galley sink. One suggestion that we found is to not combine the cooling water drain with the condensation drain so that if the cooling water drain gets clogged, it doesn't pump water back up the condensation drain hose. Both hoses were wire tied to bases that we glued down with 5200. The condensation hose is particularly important to have a smooth run to make sure it drains easily.


Cabin Supply Vent
The ducting was the biggest challenge, particularly to the forward cabins. We found that Marine Systems Inc makes a nice set of vents that can be custom ordered. A variety of distributers handle their products at a wide range of prices. We ordered ours from Marine Discounters. Lux was built when the trim was beech, so we ordered soft maple, which is a reasonably close match to the beech wood.

Salon Supply Vent
The vents arrive unfinished so we used Minwax Polyurethane gloss finish and it did an excellent job. Finishing inside the vent requires a steady hand and a small artist brush. The vents in the aft cabins are close to the bunk because they have to avoid the wiring, tubing, and hoses that are behind the panel.

All vents except the return air vents have built-in dampers, which helps with directing the air where we want it. The additional directional blades in the front of the vents allow us to direct the air within each cabin.

We had to build custom venting to the forward cabins. Tech foil (available from Farm Tech and other suppliers - bubble wrap with aluminum foil backing) was used with 3M 77 spray adhesive to build insulated ducting between the forward cabin wall and the built-in shelving that's inboard, behind the cabin door. The Tech Foil will also keep the shelving from collecting condensation from the cool air on its back.
Plenum Box with Salon (to the left) and Starboard Cabin Feed

A 7-inch plenum box tops the A/C unit, with 6-inch hose adapters to feed to each side. The outboard feed goes to a 655 Y. The two 5-inch legs of the Y feed each cabin. The aft cabin gets fed by a long piece of 5-inch insulated hose purchased from Home Depot (only available via order - we couldn't find it in stores). We wished that we could find 5-inch plastic hose with 1/2-inch insulation like the foam pipe insulation that we found in Home Depot.
Hose End with Foil Cover Taped Inside
Passport Control and Return Vent, Stbd Hull

The second 6-inch feed off the plenum box feeds a short 6-inch duct that uses the space behind the R&C logo box as its plenum. We used the Tech Foil again to line the box. We made sure to not foul the electrical connections to the masthead. With both units running, anyone sitting in front of the salon vent gets a lot of air on the back of his/her head. The dampers and vents can be directed to minimize the wind tunnel effect.

A tip for running the 5-inch duct: Fold the external foil cover over the duct hose and tape it. This holds the hose, insulation, and cover all together and makes it much easier to handle. Also watch out for the random hose clamp or wire tie end that will rip the foil cover when you're pulling the duct into place.

The end result was a nice looking system.

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