Side exhaust fan to control tub temperature

[MuncyBob]

As had been suggested severeal times in the past, I recently installed a CFR brand exhaust fan(Amazon.com: CFR Performance 8" High Performance Electric Radiator Cooling Fan - Flat Blade: Automotive)
onto the PT 422's battery side of my tub cage. I am not satisfied with the air movement it is providing. I have tried all manner of configuration, reversed blade, changed polarity, etc. I would like to get as much air movement as the hydraulic cooler fan provides on the top of the cage. I called Tazewell thinking I would just get another of those fans but they want over $170 for it...yikes! What make/model fans have been installed that are doing a good job or has anybody found a more reasonable source for the top fan?

 

[ponytug]

The fan you bought seems pretty good, 1700 CFM rating. Have you checked the voltage at the fan, when it is running? Small voltage drops have a big impact. You may want to wire it with a relay to keep the wiring run for the high current (battery-fuse-relay-fan-ground) run short. Also, it is worth running heavy gauge wire for heavy loads like fans. No sense in wasting energy in the resistance of the wires!

What has an even bigger impact is that the fan is on the right way. Have you checked the arrow on the fan to ensure that fan is oriented correctly for the rotation (direction) that you have chosen?
Fans work better pushing air than pulling air. So if the fan is inside, have it push out; if it is outside, have it push in.
If you are sure about your location, you might want to consider removing the wire mesh tub grill. It will help airflow.

You can get fans fairly inexpensively by going to an auto junkyard, and pull one that you like. Of course, no bets on how long it lasts.

The PT OEM Spal fans are expensive- but they are well built and last, and last and... Mine has a couple of cracked finger guards, but that was due to a mischievous horse chewing on it. I'm considering replacing it with a bigger SPAL fan, and using it to push cool air into the tub, but it hasn't made it to the top of my do list.

All the best,

Peter

 

[SpringHollow]

I bought a couple of replacement fans on ebay when mine died. They were not very expensive - I bought a two pack. The replacement cost $32 delivered. I think that was per fan.

Ken

 

[MuncyBob]

I've seen some Spal fans on Ebay for $70 or less. Gonna have to check the part# of the stock PT fan to compare. The stock mounted fan pulls air up and out of the tub, doesn't this work against cooling the fluids as it is drawing the hot tub air up?

 

[ponytug]

I think the idea to add a second fan pushing cool air into the tub is a good one. It is relatively simple, low cost, and low power.

Some random thoughts, FWIW:

If you are buying SPAL fans, you probably want to make sure that you read the specifications for the model number that you buy. They make fans with very different performance in the same sizes.

Yes, the PT fan could be more efficient if it were mounted inside blowing out, or as you suggest blowing into the tub. My rationalization of the Tazewell thinking is that the current design lowers the center of gravity, and that it works well enough. The fan blowing in version heats the tub, which would make the heat issue of the green 4XX designs worse, and wouldn't help the 14XX/18XX red ones much either. You could make a duct to divert the heat, but it adds weight, and needs more fan power...

I haven't upgraded the fan (same size, higher performance) to see if it makes a difference, nor have I added an inline oil cooler for the motor circuits to cool them off.

Personally, I would trade the tractor being a little wider for having the original Deutz cooling path to re-enable a cool side to the engine and a warm side, so that one could have a booster fan that would help with the cold to hot gradient. It would also enable better cool air feed to the hydraulic cooler.

Too little time...

All the best,

Peter

I've seen some Spal fans on Ebay for $70 or less. Gonna have to check the part# of the stock PT fan to compare. The stock mounted fan pulls air up and out of the tub, doesn't this work against cooling the fluids as it is drawing the hot tub air up?

 

[MossRoad]

I've seen some Spal fans on Ebay for $70 or less. Gonna have to check the part# of the stock PT fan to compare. The stock mounted fan pulls air up and out of the tub, doesn't this work against cooling the fluids as it is drawing the hot tub air up?

I've often wondered about that....

On the one hand, pushing cool air through the cooler, heating the air and then directing it onto the top of the engine.

On the other hand, pulling hot engine air up through the cooler.

My guess is its not pulling that much hot air up as cool air is coming in from the sides VS how much hot air it would direct directly onto the engine if it was pushing air down.

I wonder why they didn't make an air channel under the cooler directly from each side completely blocking off the hot engine air. I wonder if it helps cool the engine too? Only extensive tests with a thermometer and reversing the airflow of the fan would tell.

 

[J_J]

I guess nobody goes to junk yards any more.

There are hundreds of radiator fan motors on old cars. $10 to $20.

I put a Mercedes fan motor on my PT hyd radiator, and it works great.

 

[Marks481]

On the other hand, pulling hot engine air up through the cooler.

If the air being forced through the engine is 150F, even that temperature air will provide cooling for 200F oil. Plus, like you said, mixing occurs with outside air.

The side exhaust fan is mandatory to keep temperatures down, IMHO.

I took the insulation wrap off my exhaust manifold, and built a better exhaust shield (two steel layers separated by 0/5", with reflective tape on the inside of each, and 1/4" insulation on the outermost shield). Results: not getting backfires after shutdown. Exhaust manifold is 600F, outside of outer shield is 130F, fuel tank isn't bubbling after mowing for an hour. I can live with that. I need to improve the shield (it is u-shaped, covering the bottom, from, and top) with a couple layers right where the manifold is close to the left rocker cover, since that is 300F, which is a bit too hot.

 

[Raw Dodge]

I guess nobody goes to junk yards any more. There are hundreds of radiator fan motors on old cars. $10 to $20. I put a Mercedes fan motor on my PT hyd radiator, and it works great.

I love your idea,unfortunately all the local salvage yards do not allow anyone inside,and parts are sold for year make and model,unless you know exactly what you need you might as well forget it,there used to be a few yards around you could spend hours in,and the owners didn't care,you could measure things,take them off and try them,and it was all good,the DEC has shut down most yards around here that aren't modern and high end,which means no customers in the yard ever. With the aftermarket parts availability better than ever and universal mounting setups,buying a used auto part doesn't make sense for most people...summit racing prices are so good you can get a good fan for not much more than a used automotive one....I know the OEM stuff is better in most cases..just not worth it around here.

 

[MossRoad]

This company has many yards around the country. You pay a few bucks, get your hand stamped and you can go in and out as many times as you want all day long. The yard here is neat, clean and not muddy. I've had great luck there.

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