Engine rooms ventilation and cool down

[Pascal]

I guess I m either trying to re invent the wheel or to think out of the box ...

Using a little DC blower to extract heat from the ER doesn't really do anything... blowing air directly from outside isn't a great idea as it just brings a ton of corrosion which I don't want to do on new reman engines and new air cons

So, I m thinking of using 120v squirrel blowers pulling air from the genny room into each ER. Even if in the 250/300 cfm range there is plenty of opening thru the ER vents so that the ERs don't get pressurized and leak ER air into the staterooms.

The air flow thru the genny room would also help cool it. What am I missing ?

Many larger boats use AC blowers to pump air into the ER, I like the idea

 

[racclarkson@gmail.com]

I use a squirrel cage to blow into ER from the cockpit after running. 137 degrees trumps corrosion (for me). It works because the blower is made by Dayton and not March.

 

[davidwigler]

I guess I m either trying to re invent the wheel or to think out of the box ...

Using a little DC blower to extract heat from the ER doesn't really do anything... blowing air directly from outside isn't a great idea as it just brings a ton of corrosion which I don't want to do on new reman engines and new air cons

So, I m thinking of using 120v squirrel blowers pulling air from the genny room into each ER. Even if in the 250/300 cfm range there is plenty of opening thru the ER vents so that the ERs don't get pressurized and leak ER air into the staterooms.

The air flow thru the genny room would also help cool it. What am I missing ?

Many larger boats use AC blowers to pump air into the ER, I like the idea

Won't that just move the corrosion to the generator room?

 

[MikeP]

Our 53 has a 120vac dual impeller squirrel cage blower at the ceiling of each engine room that exhausts air out via the engine intake vent. There is a sheet aluminum "duct" approximately a foot wide/a couple of inches deep from the blower exhaust outlet sealed to the top side of the vent, where the vent's Dorade box screen is mounted.

Seems to work pretty well.

BUT...don't expect too much; 3500 lbs of hot metal (DD 8v71TI+transmission) makes a really good heater!

To be honest, I don't use the blower very often unless I'm planning to be IN the engine room shortly after shutdown. Other than some attempt at creature comfort if you are going to be in there, there is no functional need for a blower. I guess it might help keep the boat a bit cooler after a run but I have never really noticed any engine heat warming the salon floor in our 53.

 

[Pascal]

Less stuff to corrode in the genny room... the genny is better protected in the sound shield and it gets hot in there with the genny running for days

Mike, I m sure hatteras improved the insulation in 10 years, and I will do that too but there is no doubt that my boat was hotter after a run. Even after shedding about 1400lbs of metal per side, keeping the ERs cooler has many benefits. Forced ventilation makes it more pleasant to work in there even when the engine are cold. Here in south Florida most of the year it's hot in there with no ventilation

 

[DCMY #92]

I added an AC squirrel cage blower in the engine room of our 41 DCMY many years ago. I added a second 3" exhaust duct in one of the engine room air inlets. It not only helped cool the engine room faster after a run (probably a marginal benefit), but more importantly keeps the engine room at a slightly lower pressure than the saloon when only the gen-set is running. The air swallowed by the Detroits prevents any fumes from the engine room entering the saloon when they are running, but with only the generator running heat and fumes (hot oil smell-not exhaust leak) entered the saloon.

I suggest you place your new blower in the engine room with its discharge exiting the air intake. If you have the blower discharging into the engine room it will slightly increase the pressure. If there are any leak paths (even very small ones) hot air will flow from he engine room into the passenger spaces.

 

[luckydave215]

On our 60C the engine air intakes are in the cockpit under the bolsters. The engines run at 173 degrees, so after a run if the ER is kept closed the temp is......173-ish. While running it's fine of course, twin 12V71's and a 20kw draw a lot of air.

I have large (10" x 10" outlet) 110v squirrel cage fans in the air intakes to force air through, after a run I open the cockpit hatch and run the fans for a couple hours, this cools down the ER surprisingly quickly. At least it makes it livable to go down there right after running. Without the fans running it's a sauna.

 

[SEVEN]

My surveyor recommended that I take the long plastic blower hose off. He said you're trying to get rid of heat. There are no gas fumes in there. Your thoughts?

 

[Scarlett]

Rusty, he is correct, hot air rises so why would you have a hose on the blower that goes to the floor of the engine room if you are trying to remove heat with the blower. That hose is correct for gas engines where you are trying to blow out any fumes in the bilge before starting, but for diesels not so. John

 

[MVCaprice]

it works because the blower is made by dayton and not march.

hahahaha!!!!! Any manufacturer would be better than March it seems!

 

[MVCaprice]

I think whatever you do will be fine as long as you have a negative pressure setup. Blowing air in will create a positive pressure situation where you are forcing some air underneath the floorboards forward and aft. After looking at this on our boat my gut feeling was that it's probably not sealed enough to do that without a little bit of work.

If I was going to open up the checkbook for this I would probably drop in a fan controller (http://www.deltatsystems.com/dtsp-T4_Auto_Manual_Fan_Control_System.aspx ) as well as a couple large radial fans such as http://www.deltatsystems.com/dtsp-Redneck_Axial_Fan_11to30inch.aspx .

I also thing the demisters would be another good option: http://www.deltatsystems.com/dtsp-Moisture_Eliminator.aspx . You can get the demisters with fans so that may be another alternative.

 

[Pascal]

Forced ventilation into the engine room is used on many newer boats. The 84 Lazzara i run (2009 vintage) has two big 240 blowers pulling air from the side decks into the ER. They are controlled by frequency drives and even have an atmospheric pressure sensor to keep the ER pressurized. The higher the RPM the faster they run to keep up with engine demand. A little too fancy for my ole hatt But after a run if I manually increase blower speed, the ER cools much quicker

On the hatt, with a reasonable blower size the ER can't get pressurized at the openings on the hull sides are pretty large. In any case I intend to seal as much of the holes and penetrations as possible at the end of the project

 

[Tim Powell]

FOR WHAT IT IS WORTH.
My 52 c draws air from right and left of the tackle lockers. I changed it all. I put tom Slane vents in the side and put two 24volt flush fans inside the engine room. They pull air from the engine room

Air comes in from the side vents and pulled out the stern by the two fans. The fans are on both thermostat and manual control. The fans are loud at the dock, They pull a lot of air and will bring the er room down quite a lot.
the fans look like radiator fans and are enclosed in a plastic case the fit is very neat inside the er room. I took out the dinkey blowers and nasty black hose, The fans are hooked to the old blower switches . Workes well. when the er room is hot it shure makes it nice but you gotta ware ear plugs
https://www.fisheriessupply.com/delta-t-systems-dc-axial-fans-ignition-protected.

 

[northshoreone]

I talked to delta systems last year about just this topic. Based on the engine room size of my 70 their quote for a system was just shy of $1,800, which included the control box, 4 fans two blowing in and two blowing out. That was parts only 24 volts system. It's still on my list to do at some point.