FPB 78 HVAC and Engine Room Ventilation

Interior 302

Air conditioning, heating and ventilation are at the heart of all systems decisions. With the FPB 78 we are designing for the most efficient and comfortable environment yet.

In the lead photo you are looking at a locker which is centered in the great room. This has four 12,000 BTU evaporators, as well as a heater (which is plumbed to a Webatso boiler). The light colored “Y” shapes are plenums connected to each evaporator. We then have a choice of using one, two or all four units. Much of the time a single air evaporator will be sufficient to dehumidify the air and drop the temperature a touch. Occasionally we think that two units might be required. The four are there for unusually hot and humid conditions where it would be nice to get the boat chilled in a hurry – think tied to a dock with no breeze. In addition to housing the great room air conditioning system, this locker will also provide substantial storage.

Interior 303

The back side of this locker, showing where the return air grills go. These provide access to the service points on the evaporators.

Engineering 135

Staying with the HVAC theme, this is the engine room air inlet. There are three Delta-T 11”/275mm  fans pulling air into the engine room (one of the three fans is shown). Above the fans is a fire dampener. The fan/dampener assembly is hinged for service access, which also allows the engine room to be passively ventilated if this becomes desirable. These three 1400 CFM fans are intended to be run at half speed in most conditions (fan noise is thereby reduced or eliminated).

Engineering 124

At the forward end of the engine room, on each side, are another pair of openings to the outside world, these can be used as passive intakes or exhausts when the fans are running. The mechanism we are looking it here is the fire dampener. We don’t think these will be required in temperate or higher latitude environments, in which case the fire dampeners can be closed.

Engineering 212

The aft port corner of the engine room is a bit crowded but we still have reasonable access. The partially shown white barrel overhead is the secondary engine muffler (after the aqua lift), and bottom right you can see the shutoff valve for the engine exhaust, connected to the muffler with a pair of high temp silicone rubber fittings (hose clamps not yet installed).

The Webasto diesel boiler is upper left in the photo above. The key maintenance item here is the power head, which is easily accessed for maintenance or R and R should there be a malfunction (we will carry a complete Webasto heater in the spares department).

Electrical 35

One of the eight Dorade vents into the lower deck, this one ventilates the electrical cabinet outboard of the stairs between great room and lower deck. Each of these Dorades includes a 9”/225mm Delta-T fan, either blowing into or extracting ( in this case). To minimize the drip risk onto electrical components, the bottom of this Dorade pipe is sealed with a drain line (although we do not expect to ever have anything coming through the water shedding grill and baffle between this opening and the exterior). With the rest of these vents the bottom is open.

Posted by Steve Dashew  (June 1, 2015)

8 Responses to “FPB 78 HVAC and Engine Room Ventilation”

  1. Jono Frankfort Says:

    Steve, Your attention to detail is both truly amazing and one of the key selling points of your designs. I was impressed from the first look at “Wind Horse” and you continue to amaze me. I now know what is going into the 78’s great room cabinet. On land, 48,000 BTU = 4 tons of air, which is normally sized at 500SqFt per ton. I know the great room will live up to its name, but 2,000SqFt is a lot of space. Love the design of the engine room plenum (details, details). Are you intending to mount something onto the plate stock tacked to the plenum? The drain line at the base of the electrical room dorade to prevent a possible drip from causing havoc is both straight forward and genius. Sorry to keep tooting your Kahlenbergs. Please continue.
    Best, Jono

  2. Steve Dashew Says:

    Thanks Jono:
    Kudos is due the team who came up with these details. The vent drain trophy goes to Deon Ogden who suggested it. The plate is a temporary stiffener.

  3. Jono Frankfort Says:

    Must be both enlightening and heartwarming to be able to surround yourself with excellence. The kudos go to you for pulling such a great team together.

  4. chris Says:

    Dampers, dampers.

    Nitpicking aside, I love the attention to and explanation/ illustration of all these ‘little’ details. Thanks for taking the time (of course it’s marketing, but still). I’d hate to think what all this costs, and I’d hate to be the guy doing all that insulation. But if I could afford one…

    Please keep it up.

  5. RobS Says:

    I would have thought even with the expense of additional internal heat load in hot climates that avoiding water ingress and critical system failure would justify venting electrical/electronic cabinets internally.

  6. Steve Dashew Says:

    Other than a complete knockdown,Rob, there should be no water ingress. The water shedding grill is very effective and rare drip which gets past it has then to overcome a very tall inlet pipe. And the downpipe can be sealed from the interior as with the rest of the Dorades.

  7. Raj A.Narayan Says:

    Awesome as usual Steve.

    What prompted the switch from Kabola to Webasto?


  8. Steve Dashew Says:

    We switched back to Webasto, Raj, becaause of reliabilty and voltage issues.