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19-01-2017, 09:30
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#1
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Registered User
Join Date: Mar 2016
Location: Ottawa, Canada
Boat: Jeanneau 409
Posts: 246
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Should the engine bay blower be always on?
Ever since I purchased the boat, the blower has never turned off when the engine is running. Is this normal?
The reason I am asking is because its starting to sound different and I am guessing it has more hours on it than it should.
My previous boat had the blower on a relay to shut off after a set period of time.
__________________
2015 Jeanneau Sun Odyssey 409 - 3 Cabin / 2 Head, Shoal Keel, Furling Main, Performance Genoa 135% with Tracks, Folding Prop, Bow Thruster, Air Conditioning, B&G Zeus2 Chartplotter, B&G Autopilot, B&G 4G Radar, B&G ForwardScan Sonar.
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19-01-2017, 09:36
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#2
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Moderator
Join Date: Feb 2010
Location: La Ciudad de la Misión Didacus de Alcalá en Alta California, Virreinato de Nueva España
Boat: Cal 20
Posts: 20,441
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Re: Should the engine bay blower be always on?
Even for a gas/petrol engine the blower only needs to run for 5min or so before starting then not at all.
Maybe there isn't a big enough air inlet to the engine compartment and the blower makes up for this.
__________________
Num Me Vexo?
For all of your celestial navigation questions: https://navlist.net/
A house is but a boat so poorly built and so firmly run aground no one would think to try and refloat it.
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19-01-2017, 09:40
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#3
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Senior Cruiser
Join Date: May 2013
Location: Oregon to Alaska
Boat: Wheeler Shipyard 83' ex USCG
Posts: 3,494
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Re: Should the engine bay blower be always on?
Unless you have a gasoline engine, heat problems or fumes, the blower doesn't need to be run at all. Some people run their blower for engine room cooling in warm climates or to solve a fume problem.
I have 4 diesels in my engine room and rarely run the blower. And then only to clear some unwanted smell, like curing paint.
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19-01-2017, 09:47
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#4
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Moderator Emeritus
Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,351
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Re: Should the engine bay blower be always on?
Some boats like mine use the blower to exhaust excess heat, if you blower inlet is at the top of the engine compt, that is what it is for, the ones to eliminate fumes of course draw from the lowest point in the bilge.
Blowers are real cheap, I run mine as the manufacturer intended, lower engine room temps have to be a good thing
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19-01-2017, 09:53
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#5
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Registered User
Join Date: Apr 2014
Boat: Beneteau Oceanis 45
Posts: 174
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Re: Should the engine bay blower be always on?
High engine room temps cause the air to be thin (less oxygen per cubic foot) and degrade engine performance. I don't recall the exact recommended max temp but I think it's 140 F. Run the blower all the time if needed to keep it cool in there. Maybe someone else can chime in on the exact max temp recommendation.
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19-01-2017, 09:58
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#6
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Registered User
Join Date: Apr 2007
Location: Marina del Rey, California
Boat: President 43 Sportfish
Posts: 4,105
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Re: Should the engine bay blower be always on?
Run it whenever the engine is running and for awhile after engine is shut off.
__________________
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
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19-01-2017, 10:02
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#7
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Registered User
Join Date: Aug 2006
Location: Skagit City, WA
Posts: 25,453
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Re: Should the engine bay blower be always on?
I like to run it to extract the heat, unless it's cold out. A separate switch is nice.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard
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19-01-2017, 10:12
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#8
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Registered User
Join Date: Jan 2011
Location: Cowichan Bay, BC (Maple Bay Marina)
Posts: 9,703
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Re: Should the engine bay blower be always on?
I've never run my blower. 18 years in San Francisco. Diesel engine. Runs great. Blowers were a holdover from gasoline engines. Useful to remove heat and smells. If you have smells you have other issues. Heat removal is good. I never had that issue.
__________________
Stu Jackson
Catalina 34 #224 (1986) C34IA Secretary
Cowichan Bay, BC, SR/FK, M25, Rocna 10 (22#) (NZ model)
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19-01-2017, 10:20
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#9
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cat herder, extreme blacksheep
Join Date: Jul 2008
Location: furycame alley , tropics, mexico for now
Boat: 1976 FORMOSA yankee clipper 41
Posts: 18,967
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Re: Should the engine bay blower be always on?
my diesel engined boats have never had one. my gasoline powered boats i left it on while running , prestarting and other times when fumes could well be an issue.
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19-01-2017, 10:43
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#10
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Registered User
Join Date: Apr 2004
Location: Southern Maine
Boat: Prairie 36 Coastal Cruiser
Posts: 3,080
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Re: Should the engine bay blower be always on?
At this point in this discussion, someone usually jumps in with equations showing how many CFM the engine moves, vs. the amount a blower moves.
At any rate, I'm convinced that my puny little blower doesn't make much difference one way or the other if the engines are running. If not, it's kinda loud and annoying. I might consider using it to cool the engine room faster after shutdown, but I'm not convinced it's a match for all the thermal mass in there anyway.
Also, a blower large enough to make a difference might compete with the engines for air, if the ventilation wasn't adequate.
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19-01-2017, 10:56
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#11
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Registered User
Join Date: Mar 2006
Location: Tampa Bay area, USA
Boat: Beneteau First 42
Posts: 3,961
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Re: Should the engine bay blower be always on?
Quote:
Originally Posted by epiic
Ever since I purchased the boat, the blower has never turned off when the engine is running. Is this normal?
The reason I am asking is because its starting to sound different and I am guessing it has more hours on it than it should.
My previous boat had the blower on a relay to shut off after a set period of time.
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In the same manner as is the case on our boat, on the 409 the blower, mounted in the transom is connected to a vent tube that runs to the upper portion of the engine bay while two "static" (i.e. unpowered) vent tubes run from the transom to the lower area. The blower is designed to extract hot air from the engine bay and ensure the engine, while in operation, is receiving relatively cooler ambient air. That ensures the engine runs cooler itself and combustion is more efficient. FWIW there are rarely "unnecessary" parts on a boat. Most are included by the designer/builder to fulfill a specific, intended, purpose.
__________________
"It is not so much for its beauty that the Sea makes a claim upon men's hearts, as for that subtle something, that quality of air, that emanation from the waves, that so wonderfully renews a weary spirit."
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19-01-2017, 10:58
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#12
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Registered User
Join Date: Oct 2007
Location: Urbanna, Virginia
Boat: Tartan 4100
Posts: 697
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Re: Should the engine bay blower be always on?
This is an interesting topic of discussion and perhaps a thermal/mechanical engineer may chime in but I am pretty sure that there is a direct relationship between the volume of the engine compartment and the effectiveness of the blower to remove heat, as well as the capacity of said blower. Also, air has to be able to enter the engine compartment too.
I personally will only use the blower when running the engine for more than an hour or so to remove unwanted heat. My engine compartment is not all that large and excess heat is probably not desirable. If I had a huge compartment like you find on large powerboats, or large center cockpit cruisers, than probably doesn't make that much difference. Of course, I am thinking diesels here.
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19-01-2017, 11:43
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#13
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Registered User
Join Date: May 2011
Location: San Diego CA
Boat: Liberty 458
Posts: 2,205
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Re: Should the engine bay blower be always on?
Quote:
Originally Posted by Adelie
Even for a gas/petrol engine the blower only needs to run for 5min or so before starting then not at all.
Maybe there isn't a big enough air inlet to the engine compartment and the blower makes up for this.
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A blower wont counteract a flow restriction issue. It's not a positive displacement pump.
There is usually enough leakage for this not to limit engine power. Any pressure tight engine room will have an inlet.
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19-01-2017, 11:55
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#14
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Registered User
Join Date: May 2011
Location: San Diego CA
Boat: Liberty 458
Posts: 2,205
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Re: Should the engine bay blower be always on?
Most engine rooms are not classified as explosion proof. The use of a blower is more about feeling safe.
However the ABYC calls for a ventilation blower where heating systems are fitted. No mention of a blower in the ABYC fuel system docs.
Our blower is most useful for clearing the engine room when our espar heater is not combisting correctly. I usually complete my preventative maintenance on the fuel misting mesh before this happens.
We also use our blower for a minute prior to staring our engine, generator or espar heater. If there was a combustible atmosphere present the electric arcing on the blower brushes would ignite them. Propane is the only flammable gas that would cause this.
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19-01-2017, 12:41
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#15
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Registered User
Join Date: May 2010
Posts: 673
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Re: Should the engine bay blower be always on?
I have a small blower that I hoped would remove heat from the engine compartment. I have a switch in that area and so forget to use it. I bought a button thermostat, the type used on hot water services and plan to attach it to the motor somewhere so that the fan turns on when the engine gets hot and off when it cools a little. One day I migt put it on.
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