[krazzz]

I am installing a new bilge blower because mine is so loud I can't tell if my motor is running without looking at the tach. I am going with one of the newer inline style blowers. While I am at it I would like to redo the tubing leading to the bilge. I was wondering if there is any reason one couldn't use rigid 3" PVC pipe? It would make for a much cleaner look and would last darn near forever. I just hate the look of the "dryer vent hose." I would use a rubber flex coupler from the tubing to the blower. Has anyone ever done this before? Pros/cons???

 

[CaptainForce]

I don't see why it would not work well, but back to the noise.... most often the noise from the in-line blowers comes from the vibration where the blower is mounted. I've found the rubber foot mounts insufficient and added sticky taped foam insulation around the body of my blower where it was touching in it's tight space.

 

[krazzz]

Thanks, I don't currently have an inline blower. Mine is the old school ultra heavy duty blower that might be original to the boat. It will be nice to be able to hear my stereo again while motoring.

 

[deniseO30]

The rubber couplings, are made to fit over the plastic pipe, about 3.5" dia so you would need a stub on the blower

 

[CaptainForce]

I've seen some of the "squirrel cage" blowers that are very quiet, but far more expensive yet more robust than the little $25-$30 dollar inline blowers.
These cheap inline blowers have been lasting me for about 5 to 7 years each and I run mine full time while motoring to keep my engine room cooler.

 

[deniseO30]

depending on the installation, squirrel-cage blowers push air well. propeller types pull better.

 

[ccriders]

depending on the installation, squirrel-cage blowers push air well. propeller types pull better.

That's interesting. How can that be? Isn't it simply a matter of blade surface area, pitch and speed?
John

 

[deniseO30]

Air handling 101 lol. I forgot most of it.

http://www.engineeringtoolbox.com/fan-types-d_142.html

 

[ccriders]

Well,I studied the graphs and can say with authority there is one more thing I know I don't know (with apologies to Mr. Rumsfeld).
So why are cage fans not used to exhaust the engine room? Save on the electrical run, puts the fan where there is access, pushes out more air per watt and is quieter. (Did I read the graphs correctly?)
Thanks,
John

 

[krazzz]

I have the cage style on mine right now and I am replacing it with an inline. My cage blower is incredibly loud and vibrates the whole boat. I will give it credit though, it does move a lot of air.

 

[deniseO30]

I have the cage style on mine right now and I am replacing it with an inline. My cage blower is incredibly loud and vibrates the whole boat. I will give it credit though, it does move a lot of air.

you should have a debris screen on the intake.. I could just bet something is inside the wheel throwing off the balance! (very common)

 

[krazzz]

I could just bet something is inside the wheel throwing off the balance! (very common)

Hmm... didn't think about that. I am really just looking for an excuse to do the rigid tubing but it might be worth a shot looking at it. I also think the mounting bolts could use a little tightening and maybe some rubber pads. I just want to be able to hear some music while I motor.

 

[Barquito]

I have a squirrel cage fan at the pulling end of the tube that seems to blow a lot of air, and is quiet. I would imagine that if the ID of the PVC is the same at the ridged hose, it will move more air b/c there is less friction. Now I am thinking of doing the same thing for my passive cowl engine vents. Would also make them more durable, as mine pass through a lazzerette, and get a little beat up from throwing stuff in the locker. Would look really koool too.

 

[krazzz]

Mine also passes through the lazarette and take quite the beating too. I want something that is durable and I don't have to worry about it being crushed flat and not moving any air. Also, it will look much better too.

 

[Barquito]

Here is another bit: PVC is probably more fire resistant than a thin-walled corrugated tube.

 

[deniseO30]

Ok thinkers.. Don't skewer me if I'm wrong.

Sq wheel fans draw less HP with restricted intake which = less discharge air.

Prop Fans will use more HP if the intake is restricted = less discharge

 

[Capt Len]

The sintered bronze (oilless )bearing don't last forever and a wee drop of oil can extend their life .

 

[Delta-T]

The difference in the between a prop fan and a centrifugal fan is huge. Prop fans have difficulty creating static pressure. Static pressure is need to push the air thru the tubing. The longer the tubing and bends in the the tubing, the more static pressure you need. Corrugated tubing creates a lot of static pressure, smooth PVC is much less.

You will commonly see prop fans in a window with no duct work. Centrifugal fans are used for almost every other application in HVAC.

And inline fan does not mean it is a prop fan. Most are Centrifugal fans.

As far as sound goes, hands down a Centrifugal is quieter. If a Centrifugal fan is noisy then it is out of balance from dirt or debris or the bearings are shot. Motors can be replaced.

 

[Delta-T]

FYI, a fan running and not moving air will over amp. Draw more power than when under proper load.

 

[deniseO30]

FYI, a fan running and not moving air will over amp. Draw more power than when under proper load.

A. Sqrl cage If, the INTAKE has high static, will draw less. At open, or 0 static, amps go up, this I I know from many years in HVAC.

Prop fans or high static types like dust control, I've Really Not played with .