engine room blower does not suck out but blows air in !

[haulnazz15]

Re: engine room blower does not suck out but blows air in !

The blower pulls the air/fumes from the bilge and dumps them outside. They DO NOT blow air into the bilge. there is no debate about this, regardless of what general rule you learned in some intro to engineering course.

 

[JoLin]

Re: engine room blower does not suck out but blows air in !

The blower pulls the air/fumes from the bilge and dumps them outside. They DO NOT blow air into the bilge. there is no debate about this, regardless of what general rule you learned in some intro to engineering course.

+ 1

 

[UncleWillie]

Re: engine room blower does not suck out but blows air in !

Thanks Guys,
I was starting to feel like the I was alone in the Wilderness.


The OP stated it is a "Centrifugal" Blower. (Radial)
Running the motor in reverse will NOT reverse the airflow, Not even a little!

The difference between the Radial blower and the much more common Axial blower.....

 

[generator12]

Re: engine room blower does not suck out but blows air in !

The blower pulls the air/fumes from the bilge and dumps them outside. They DO NOT blow air into the bilge. there is no debate about this, regardless of what general rule you learned in some intro to engineering course.

+2

The blower is an exhaust fan. The placement of the ducts on the bottom of the bilge enables it to remove the air/gas mixture at it's most volatile point. If its operation were reversed, it would simply disperse the fumes throughout the engine compartment, increasing the opportunities for combustion.

The only time an enclosure is positive-pressurized is when the explosive fumes are on the outside and must be kept out. Obviously not the case on an engine cover.

 

[Part-time]

Re: engine room blower does not suck out but blows air in !

Aerobat, are you a smoker, or someone near you? or find something that smokes, incense or something... Hold it in front of the blower in the boat and see if it really is blowing or pulling.

 

[UncleWillie]

Re: engine room blower does not suck out but blows air in !

Aerobat, are you a smoker, or someone near you? or find something that smokes, incense or something... Hold it in front of the blower in the boat and see if it really is blowing or pulling.

Or try it with a short piece of string or plastic.
Burning "Somethings" are not a good idea in a bilge with suspected ventilation issues.

 

[aerobat]

Re: engine room blower does not suck out but blows air in !

hey gents ! thanks very much for all you responses so far.

the blower blows into the engine compartment for VERY sure. but not really into the bottom of the bilge ! the ventilation holes are mounted on top the engine compartment, not the bottom .

the ventilation installation is for sure yard made and the blower attachment and direction of flow most probably also , especially when it gives no result to mix up polarity in a centrifugal blower so we can exclude the pre owner messed this up.

the blower is pretty strong in airflow , much stronger than e.g a hairdryer and with the hatch closed you can feel the air being exhausted on the opposite side via the inlet screens there when you hold your hand infront of it.

i start to believe the yard indeed designed it this way and the primary goal here is an effective engine room ventilation , not fumes removement !

i must say i never gave much attention to the compartment blower but will now take a close look on it and see if there is another system for fumes removing on my boat.

i will also look for this at the boat of my parents, a 2010 sea ray sundancer , how its designed there.

i keep you updated !

 

[Oshkosh1]

Re: engine room blower does not suck out but blows air in !

i start to believe the yard indeed designed it this way and the primary goal here is an effective engine room ventilation , not fumes removement !

The ONLY reason you need "engine room ventilation" is to VENTILATE possibly explosive fumes. Think of it as an exhaust hood over your stove/oven...it PULLS. You don't positively pressurize your kitchen to PUSH the smoke out...you directly remove it. As stated before...the fumes are heavier than air and will sit at the lowest point in the bilge. You MUST have the ability to draw them against gravity...up and out.

 

[UncleWillie]

Re: engine room blower does not suck out but blows air in !

... The blower blows into the engine compartment for VERY sure. but not really into the bottom of the bilge ! the ventilation holes are mounted on top the engine compartment, not the bottom ...

Not too many boats have the ventilation holes on their bottoms.
Those are usually used for scuttling. :facepalm:

The Blower need to draw from the bottom of the bilge with a vent hose that is within 3-4 inches of the keel.
The hose needs to be IN the fumes to draw out the fumes.
Drawing from the top will not do it.

 

[Willyclay]

Re: engine room blower does not suck out but blows air in !

i will also look for this at the boat of my parents, a 2010 sea ray sundancer , how its designed there.

It should have been built to the USCG requirements in Title 33 CFR Part 183.610. See the link below:

http://www.gpo.gov/fdsys/pkg/CFR-2004-title33-vol2/pdf/CFR-2004-title33-vol2.pdf

 

[MWG2600]

Re: engine room blower does not suck out but blows air in !

OP Post a pic of the setup, it will save many more pages!

 

[aerobat]

Re: engine room blower does not suck out but blows air in !

Not too many boats have the ventilation holes on their bottoms.
Those are usually used for scuttling. :facepalm:

hehe , correct !

seriously- the vent hoses do not end in the bottom vicinity but at the top of the compartment, close below the engine room hatch.

the sea ray has two hoses from each side which go to the bottom in the vicinity of the transom and suck air out. there are two blowers on this boat , one each side and beyond the blowers there is another intake screen each side. ( covered , barely visible on the sundancer)

i will make pictures, unfortunetly missed to do it today !

 

[Ned L]

Re: engine room blower does not suck out but blows air in !

It sounds like you may have to start from scratch & do it correctly, probably even with a new (explosion proof, USCG approved) blower. Uncle Willie (an those agreeing with him) have it correct. The bower needs to be connected to a 4" hose that leads to the lowest area of the bilge in which fumes may collect, so that you are drawing air from the lowest area and putting it overboard. The other vents (air inlet) do not need hoses on them. They only need to allow fresh air into the area.