Bilge Blower - "Intermittent Use Only"?

[Dave22q]

'Intermittent use' is not a characteristic of the boat but of the blower motor. Generally you see it on inexpensive motors that simply are not designed for continuous use, they might overheat and fail. You could look for higher quality units. However, you cannot avoid a manual switch if you want to be safe when refueling. Good practice is off when fueling, then run for a few minutes to clear the engine room, then start. Offhand I do not see an easy way to automate that.

[UNCIVILIZED]

Originally Posted by HopCar

Blue Sea Systems just came out with a timer that should do the job nicely.

https://www.bluesea.com/products/7615

Originally Posted by CarinaPDX

Yes, but at $135 MSRP that is a pretty spendy solution.

For the digerati, at $5, this would work for me: DC 12v 24v LED Display Cycle Delay Timing Timer Relay Switch Turn ON/OFF Module | eBay

For the analog crowd, for $10: Qianson DC 5V 12V 24V Infinite Cycle Delay Timing Timer Relay ON OFF Switch Loop

Greg

I'm definitely in the camp of wanting a continuous blower in the engine room, preferably one with a timer that runs the blower for a while after engine shutdown, in order to remove heat both from the engine compartment, as well as the boat in general.

As to running one continuously, the purpose is to keep both the engine, & the boat cooler. And with cooler air intake for the diesel, it runs more efficiently. Along with everything in the engine compartment living longer, since it doesn't get baked quite so much, thanks to the continuous flow of cool air.

Think about all the trouble drag racers, & race car teams go to to cool both their engines, as well as their fuel. The difference in HP output between being cold vs. room temp. is quite dramatic.

In an old issue of Professiona Boatbuilder magazine, they have the numbers for how much air per minute you should have moving through the space, based on the engine's HP rating. And the numbers are surprisingly large. Which, the article advocates both an air intake setup for the compartment, as well as one for cooling.

Keeping things cool really, really does make a difference. For example, Mazda quit producing the 3rd gen. RX-7 (with twin, sequental turbos) because the heat from them was frying major components in the engine. And the company was having to fix them under warranty, which cost them a LOT of money.

[GordMay]

Originally Posted by UNCIVILIZED

I'm definitely in the camp of wanting a continuous blower in the engine room ...
... In an old issue of Professiona Boatbuilder magazine, they have the numbers for how much air per minute you should have moving through the space, based on the engine's HP rating ...

I also.

The maximum temperature of the engine room should never exceed 60 degrees C (140 F) within 20mm (3/4") of any electrical equipment, and 45 C (113 F) at the air intake, or 46 C (115 F) anywhere in the engine compartment.

The approximate cooling ventilation (this is in addition to combustion air requirements) rate may be determined by the following formula:

CFM = (1000 x H.P.) ÷ T

where:
HP = maximum engine horsepower
T = allowable temperature rise, ‘F'. (often specified at 15 degrees)

[wingless]

Originally Posted by wingless

One of the modifications I made to my boat was the addition of a thermostatically controlled heat exhaust.

One of the nice things about this controller is that I now have a digital ambient engine room air temperature display, regardless of the heat exhaust blower being active or not. I placed my sensor near the engine ECU and the fuel rail. This provides a stable display of that, formerly unknown, temperature

[SeaSon]

Most of the 12v plastic housed blowers are recreational boat products intended for light duty intermittent use. In commercial and large private applications, continous duty blowers run 365 moving air through ship compartments, including the engine room. These *continous duty rated* blowers are 120v, squirrel cage type blowers.

Not likely what most of the people on this forum have space for.

[HopCar]

Originally Posted by SeaSon

Most of the 12v plastic housed blowers are recreational boat products intended for light duty intermittent use. In commercial and large private applications, continous duty blowers run 365 moving air through ship compartments, including the engine room. These *continous duty rated* blowers are 120v, squirrel cage type blowers.

Not likely what most of the people on this forum have space for.

Jabsco does make small plastic low voltage continuous duty blowers.
http://www.xylemflowcontrol.com/file...on_Blowers.pdf

[SeaSon]

Originally Posted by HopCar

Jabsco does make small plastic low voltage continuous duty blowers.
http://www.xylemflowcontrol.com/file...on_Blowers.pdf

You are correct. Also, note the high current draw for the units labeled heavy duty.

[a64pilot]

Originally Posted by HopCar

Jabsco does make small plastic low voltage continuous duty blowers.
http://www.xylemflowcontrol.com/file...on_Blowers.pdf

I believe one of these is what is on my generator to exhaust air from the sound enclosure,
From an amp draw perspective, that is because of the amount of air they move, they move a whole lot more than an inline bilge blower, and to some extent who cares what they draw, your alternator is on at this time

[wingless]

The 4" Jabsco blower moves 250 cfm and the 12V version needs a 15A fuse.

The 4" ShurFlo Yellowtail in-line 12V blower moves 220 cfm, draws 5A and requires a 7A fuse.

[CarinaPDX]

Originally Posted by wingless

The 4" Jabsco blower moves 250 cfm and the 12V version needs a 15A fuse.

The 4" ShurFlo Yellowtail in-line 12V blower moves 220 cfm, draws 5A and requires a 7A fuse.

And Lil' Champ Four Inch Ignition Protected DC Blower moves 350 cfm @ 8A (12v).

Of course these ratings are in free air - pushing air through a hose can reduce the flow rate substantially.

The Delta-T blower is a much higher quality unit than the mass market Jabsco and Shurflo - at a much higher price. It is the bottom of their line; most of their products are larger 120v units for power boats. I just got tired of dealing with mass market stuff.

Greg

[wingless]

Yes, all pumps and blowers are always specified at zero head and at free air.