Engine space blower fan

[osprey877]

The engine compartment on my 40’ sailboat with 4cyl diesel is equipped with a Perko centrifugal blower fan as shown in pic below. The blower exhausts into a 4 inch x 8’ length of flexible dryer vent style hose that goes to a vent in the cockpit, heating the cockpit enclosure when necessary.
My problem is that the Perko needs a new squirrel cage impeller and they are no longer available. I’ve checked with Perko and they stopped making these in the nineties and have no parts available. I cannot find a reasonably priced centrifugal fan that will fit the space available and would like to substitute a much cheaper radial fan as per the other photo below. Howeverr, I have read that radial fans, unlike centrifugal fans, don’t like any resistance downstream and thus are not used where you need to push air through ducting or the 8’ of dryer hose I have. I could put the fan at the exhaust end of the vent hose in the cockpit but I’m worried about the fan noise in the cockpit. So my question is does anybody have any experience using a radial style fan as a blower fan and does it work? Thanks and sorry for the length of my post.

[Tin Tin]

I have used both types the Johnson SPX continuous duty radial and the Shurflo in line continuous duty. The Shurflo makes a higher pitched sound and is more annoying, so I am about to replace it with the Johnson SPX which I had a on a previous boat and was no noisier than the Oscalati or Plastimo radials of the same size.


https://www.spxflow.com/johnson-pump...adial-blowers/


https://defender.com/en_us/shurflo-y...in-line-blower

[osprey877]

Originally Posted by Tin Tin

I have used both types the Johnson SPX continuous duty radial and the Shurflo in line continuous duty. The Shurflo makes a higher pitched sound and is more annoying, so I am about to replace it with the Johnson SPX which I had a on a previous boat and was no noisier than the Oscalati or Plastimo radials of the same size.


https://www.spxflow.com/johnson-pump...adial-blowers/


https://defender.com/en_us/shurflo-y...in-line-blower

Thanks. Was the Johnson SPX connected to venting, or did it exhaust the engine room air into an open space. I’m not too concerned about the noise, but more so about whether or not the radial fan can push air through a length of hose like a centrifugal fan will.

[jt11791]

The Shurflo inline fan pushes air just fine on my boat. It has to push through about 20 feet of dryer hose with multiple twists and turns. No complaints.

[Tin Tin]

Originally Posted by osprey877

Thanks. Was the Johnson SPX connected to venting, or did it exhaust the engine room air into an open space. I’m not too concerned about the noise, but more so about whether or not the radial fan can push air through a length of hose like a centrifugal fan will.

We were on a cat with a generator. We had three radials, the two on the engines were flange mounted to the exit port, the generator one was in line and had a flange to tail adapter I think, but was not long. The specific inline ones are are called "flex mount" the smallest one though is higher capacity than the smallest flange mount.

[GordMay]

Both Attwood and Shurflo axial [propeller] in-line bilge fans are designed as extractors, to be located as near as practicable, to the air supply exhaust outlet [at deck or transom], with flow arrow towards exhaust vent [“out”].
This doesn’t mean that they won’t “push” supply air, at all [arrow orientation “in”]. But, they were designed to suck/pull air out.

[zboss]

We have one of the those blowers in each hull and a centrifugal for the generator. They work just fine and find they last about two years. I keep a spare on board but this probably not necessary since they are pretty common at chandlery's where we cruise. I find that the centrifugals last much longer even though they are exposed to nastier conditions in the bow locker where our generator lives.

[osprey877]

Originally Posted by GordMay

Both Attwood and Shurflo axial [propeller] in-line bilge fans are designed as extractors, to be located as near as practicable, to the air supply exhaust outlet [at deck or transom], with flow arrow towards exhaust vent [“out”].
This doesn’t mean that they won’t “push” supply air, at all [arrow orientation “in”]. But, they were designed to suck/pull air out.

I am using it as an exhaust fan. I want to mount it in the engine compartment and have it push out the hot engine room air to my cockpit vent through 8’ of dryer hose.

[osprey877]

Originally Posted by jt11791

The Shurflo inline fan pushes air just fine on my boat. It has to push through about 20 feet of dryer hose with multiple twists and turns. No complaints.

Thanks. This is just the sort of feedback I was looking for.

[NorthCoastJoe]

While on this subject. Has anyone found a ( belt ) engine driven blower for engine room air exchange, in the 300-400 cfm range. My search so far has left me skunked.