Swampzilla..help me tame her down.

[fnieto]

Today I got her wired and plumbed. Fired up a Arocool IUP701 11,700 cfm swamp cooler. It's a two wet section commercial unit with 8" pads that should cool a 3200 sf shop. (40'X80') space. We calculated the ductwork and ordered up the spiral oval sections but still need to hang it. Today we erected the updraft ductwork but had a difficult time getting the amperage set right. The belt was very loose in order to get the amps set right. We ran 230 vac for this 2 hp motor which should pull 10.5-11.3 amp load when adjusted properly. The pulley is adjustable as well as the motor mounts, but when the belt is snug and not slipping at start up its pulling over 20 amps causing the circuit breaker to pop. We tried adjusting the pulley to bring down the amps but the temp on the pully itself got very high (around 250 degrees with temp gun) and belt tension was real loose. The pulley is turned out about five turns (from all the way in) to get the amps right but caused the pulley to get hot as well as belt to be very loose. What am I doing wrong?

 

[fnieto]

Swampzilla....please help.

 

[brewchief]

I would bet that you need the restriction of the rest of the ductwork, try blocking off a portion of the duct and see if it fixes it.

Sent from my SM-G900V using Tapatalk

 

[fnieto]

Thanks for the reply brewchief. We plan on installing the rest of the ductwork (inside) on Sunday.

 

[mitusa]

Not sure what your question is......it sounds like you may have a loose connection in your wiring...or your motor is bad?

 

[fnieto]

Not sure what your question is......it sounds like you may have a loose connection in your wiring...or your motor is bad?

Sorry, I posted original after a long day. Basically, to achieve the desired load amps the belt is real loose and slips at start up. The pulley in the motor is adjustable in 1/2 turn increments. I hope that makes sense.

 

[mitusa]

Your problem is prolly above my pay grade. I don't know much about the subject at hand and don't want to burden you with annoying questions......but, I would assume the variable speed pulley is just for setting the speed of the fan. Would it have anything to do with your amp spike ....tripping the breakers?

Don't worry about answering my post; I'll just wait and see if you get an explanation on what the problem might be. I'm just trying to learn.

Hope you get your problem resolved.

 

[ford63man]

sounds like you need to adjust the belt tension.
it should have a belt tension adjustment.

also you will have to re-adjust the fan speed after you install the ductwork.

 

[fnieto]

sounds like you need to adjust the belt tension.
it should have a belt tension adjustment.

also you will have to re-adjust the fan speed after you install the ductwork.

Yea, that's the problem. When I adjust the belt tension, the amps spike and trips the 20 amp breaker. That's where I'm at loss. When I active the desired amperage the belt is real loose.

 

[Jagmandave]

Wrong breaker? Not rated for the inrush?

is this 3 ph or 1 ph? I'm guessing 1 ph?

Is this a cap start motor? Is it the right HP for the load? Are you sure all your connections are good and tight?

Just spitballin here......

 

[fnieto]

Jagmandave,
20 amp double pull breaker about 80-90' feet away from cooler. #10 wire supplies the power to a single phase 208-230 vac 2 HP motor. This is the smallest motor I could use on this unit due to single phase power. All CFM calculations indicate a 2 HP would work at 650 RPM (squirrel cage) which can be don with the adjustable pulley on the motor.
If I snug the belt tension it pulls 21 amps and eventually trips the breaker (1-5 min).
It does have two capacitors and the motor can be wired 115 (low voltage) or 208-230 (high voltage).
I have wired it correctly according to the schematic on the data plate. The same plate indicates 10.5-11.3 amps in high voltage configuration. When I achieve the desired amps, the belt is way too loose. I should mention the unit has a double belt sheave but the smaller adjustable pulley on the motor is single sheave. I was told that the 5/8" shaft on the motor would not fair well with a double belt system. So I'm only running a single belt. I checked all the connections and they seem tight. The meter reads 239 vac at the motor.
I'm guessing one capacitor is a start and the second is a run capacitor.
I hope I explained the problem and not confused the issue further. I appreciate any and all help.

 

[98ssuck]

Sounds like you have a forward curve (overloading) fan blade in your unit and the ductwork is not sized properly.

 

[fnieto]

Sounds like you have a forward curve (overloading) fan blade in your unit and the ductwork is not sized properly.

Sorry to sure what you mean. Im not a HVAC guy. The unit is a commercial Aero Cool IUP 701. The only ductwork installed is from the unit to the building with no reduction in size. We have yet to install the interior ductwork (tomorrow). We calculated the system utilizing a .3" static factor. According to the charts, a 2 HP single phase 230 VAC would give us the CFM required to cool the space adequately . Could you please explain the"Forward curve fan blade" issue for me?
The photos show the ductwork we had made that will run down the center of the building. The largest spiral oval is 36" scheduled down to final section of 16" for a total length of 65' with a total of eight registers.
Thanks for your patience and explanation in advance.

 

[98ssuck]

Essentially the type of fan in your unit requires the restriction of the ductwork to give you back pressure on your fan blade. Without the back pressure the fan motor will draw higher than it's rated current and trip the overload. Look in the manual of the unit it will probably have a minium as well as maximum static pressure. Once you get the rest of your ductwork in place your problem should disappear.

 

[fnieto]

Thanks for the reply. We will hang the interior ductwork tomorrow after work. I never saw anything in the units manual. I will post the results when we finish. Thanks again for the replies.

 

[WVBrady]

Essentially the type of fan in your unit requires the restriction of the ductwork to give you back pressure on your fan blade. Without the back pressure the fan motor will draw higher than it's rated current and trip the overload. Look in the manual of the unit it will probably have a minium as well as maximum static pressure. Once you get the rest of your ductwork in place your problem should disappear.

If this seems counterintuitive, this seems to me like when you put your hand over the nozzle of a sweeper hose. You might think that the restriction would increase the load on the motor, but it will actually speed up.

 

[fnieto]

After installing the interior ductwork, We used a digital laser tachometer to determine the squirrel cage RPM. Using the CFM charts,motor HP etc. I realized the final RPM should be 282 at the squirrel cage. The main pulley is an 18" double belt set up. The motor sheave that was sold to me is a single belt 5" adjustable. I found out through some research that Aerocool sells three different sheaves for different RPM options. Turns out that the sheaves they sell are for double belt set ups. The size I need is a 6" adjustable twin belt which would allow me to get the final RPM to 282 +/- 3 RPM. The belt is still too loose withe the 5" sheave and the slowest RPM we could achieve was 308 RPM with a amp load of 15.3 (desired amp load for this motor is 10.5-11.3 amps) The final installation of the ductwork did in fact help with the previous issues we were having with amp loads. So come Tuesday, I will order the correct sheave, pick up 8-12"x24" registers and get this behind me.
we ended up using aircraft cables to suspend the ductwork in place as the suspension straps where not up to the task due to the weight of the system. On a funny side note, as each 10' section was hung, I was given the task to crawl into the hanging ductwork to tape and seal the joints. I could not do the last section as it was down to 16"x12". We sealed the last joint with clear silicone. My wife came into the shop when I was inside one of the sections when I poked my head out of a register and said "Peek-a-boo".Her reply was "your crazy" it was kind of funny.
Any way, I wanted to thank those of you who chimed in to help.

 

[justsam]

If it is already too fast with a 5 inch motor pulley, it will be even faster with 6 inch.

 

[fnieto]

If it is already too fast with a 5 inch motor pulley, it will be even faster with 6 inch.

Damn, you are right sir. 5" is the right size, but I still think I need to run a twin belt motor pulley. I should be able to open the pulley 2.5-3 turns. The single belt motor pulley get really hot even with the belt loose. I took a temp gun to it yesterday and it was hot at 250 degrees. Thanks for bringing this to my attention. It was a long day yesterday after a 24 hour shift then 10 ours installing the ductwork.

 

[2xs]

Yeah not have a restriction will overload a swap cooler motor in hurry. Also a 6 inch pulley will slow down the fan not speed it up bigger diameter longer it takes the pulley to rotate and spin the fan. If you were going to 4 inch in pulley it would speed up.

 

[Milton Shaw]

The pulley is getting hot from the belt slipping on it. Tighten the belt to eliminate the heat of slippage. 2xs is wrong the 6 inch on the drive motor will speed the fan up, stay with the 5 or go to a 4" to get it a lot slower. The ratio of small pulley divided by big pulley times the rpm of motor gives the fan blade rpm.

 

[danielzig]

Yeah not have a restriction will overload a swap cooler motor in hurry. Also a 6 inch pulley will slow down the fan not speed it up bigger diameter longer it takes the pulley to rotate and spin the fan. If you were going to 4 inch in pulley it would speed up.

When you increase the size of the drive pulley it will increase the speed. When you increase the size of the driven, it will slow it down.

 

[fnieto]

The pulley is getting hot from the belt slipping on it. Tighten the belt to eliminate the heat of slippage. 2xs is wrong the 6 inch on the drive motor will speed the fan up, stay with the 5 or go to a 4" to get it a lot slower. The ratio of small pulley divided by big pulley times the rpm of motor gives the fan blade rpm.

The belt is loose and still the amp draw is too high resulting in slippage (drive pulley getting hot) if I snug it up the amp draw is twice the recommended and will pop the breaker (20 amp). Would adding a second belt help with this issue?
Like I mentioned previously, the units squirrel shaft has a 18" pulley with two grooves and it even came with two belts. The supplier told me that a 2HP motor with a 5/8" shaft would only drive a single belt. After having these issues,I found that they do in fact make a double belt sheave for a 5/8" shaft. So before spending 100 bucks on a new sheave do you think I will be able to snug up the belt and achieve the desired amp load of 10.5-11.3 amps? At the moment the belt is loose (slipping and getting hot) and amp draw is 14.3 already too high.

Just to recap. Aerocool IUP 701 two wet sections 8" media, 2 HP motor wired 208-230 VAC #10 wire appox. 80-90 feet from panel. CFM factor of .3 scheduled ductwork about 67' long.

 

[larry_g]

...... I realized the final RPM should be 282 at the squirrel cage. .......... final RPM to 282 +/- 3 RPM. The belt is still too loose withe the 5" sheave and the slowest RPM we could achieve was 308 RPM
with a amp load of 15.3 (desired amp load for this motor is 10.5-11.3 amps)

A little quick math here

308/282= 1.092 , lets say 10% over speed

15.3/11 = 1.39 , lets say 40% over current

Make sure that reducing your speed 10% will drop your current 40%. I'm not sure if the load on a fan is linear with speed or some odd curve of speed to load. Gut feeling is that your going to have to drop the speed of the fan lower than 282 rpm to get your current draw under motor spec. Or your going to have to limit the amount of air (load) that is being moved by the fan.

What is the rated speed of your motor? Is it a 1200 or 1800 rpm? or something else? The best I can come up with is that your running a motor at 1050 rpm with no slip.

lg
no neat sig line

 

[justsam]

What is your incoming voltage? You stated motor is wired for 208-230. I suspect your line voltage is closer to 240 to 250.

I agree with Larry G, I too tried to back into what your motor speed must be and it looks like about 1050 RPM. What is the rated RPM?

What is the current draw with no load on the motor? Are you using a clamp on meter or?

Slipping belts are belts on their way to failure. Are you using the proper angle belts with mated sheaves?

 

[fnieto]

A little quick math here

308/282= 1.092 , lets say 10% over speed

15.3/11 = 1.39 , lets say 40% over current

Make sure that reducing your speed 10% will drop your current 40%. I'm not sure if the load on a fan is linear with speed or some odd curve of speed to load. Gut feeling is that your going to have to drop the speed of the fan lower than 282 rpm to get your current draw under motor spec. Or your going to have to limit the amount of air (load) that is being moved by the fan.

What is the rated speed of your motor? Is it a 1200 or 1800 rpm? or something else? The best I can come up with is that your running a motor at 1050 rpm with no slip.


lg
no neat sig line

What is your incoming voltage? You stated motor is wired for 208-230. I suspect your line voltage is closer to 240 to 250.

I agree with Larry G, I too tried to back into what your motor speed must be and it looks like about 1050 RPM. What is the rated RPM?

What is the current draw with no load on the motor? Are you using a clamp on meter or?

Slipping belts are belts on their way to failure. Are you using the proper angle belts with mated sheaves?

The rated motor RPM is 1725. The current coming into the motor is 239 VAC single phase. The belts (two) came with the unit but the motor pulley is a single belt type. I'm using a fluke clamp on ammeter. I did not check the amp load on the motor without a load (no belt). I will do that tomorrow as I'm on shift (24 hrs).
The receipt indicated the correct motor sheave for the belt, however I since found out they do make a double pulley sheave for a 5/8" shaft motor. The counter person where I purchased the unit and motor told me no such sheave existed for a 5/8" shaft (two belts). The only way I have been able to lower the loaded amp draw so far is to run the belt very loose resulting in heat due to slippage. I know this is wrong and leads to premature belt failure. How does one limit the air load mentioned?
I appreciate the help.

 

[RivennHewn]

Are your grill/defusers on yet?

Are they balanced?

Seems to me any adjustments made prior to the grills will need further adjustment once they are on.

 

[larry_g]

So more math

fan speed/motor speed x fanpulley = motorpulley

282/1725 x 18 = 2.94 or 3" motor pulley

5/3 = 1.66 or a 60% reduction in pulley size.
5/3.5 = 1.42 or a 40% reduction in pulley size. That is nearer the 40% over current calculated above. So I'm thinking you need to be nearer the 3" range for a motor pulley.

lg
no neat sig line

 

[fnieto]

Thanks larry_g,
The only pulley options for this motor are 5,6 and 8".
I'm hoping I could open the 5"pulley five turns open and get close. I still think I will need the double pulley to reduce the slippage when turning that big squirrel cage.
I will still take a amp reading on the motor without a load tomorrow.
Thanks for your time, I owe you one.

 

[larry_g]

http://www.tbwoods.com/PremiumBelts.asp

http://www.altraliterature.com/pdfs/P-1932-TBW.pdf

I don't know where your shopping for sheaves but look at the second link above and you can find most anything in the vbelt drive. If you can't access the second link directly go to the first one and the .PDF is at the bottom of the page. I realize these are not adjustable but available in small increments to allow you get close. Good Luck.

Can you post links to where you are getting your info and specs on this blower. Maybe someone can form some better answers from what they read from the source your using.

On edit, are you using this style pulley http://www.emersonindustrial.com/en...sheaves/fhp-variable-pitch/Pages/default.aspx

lg
no neat sig line

 

[fnieto]

So more math

fan speed/motor speed x fanpulley = motorpulley

282/1725 x 18 = 2.94 or 3" motor pulley

5/3 = 1.66 or a 60% reduction in pulley size.
5/3.5 = 1.42 or a 40% reduction in pulley size. That is nearer the 40% over current calculated above. So I'm thinking you need to be nearer the 3" range for a motor pulley.

lg
no neat sig line

Swampzilla is tamed and under control. Found a 4" twin belt adjustable sheave with 5/8" bore. Turned out (from closed) 3.5 turns adusted both belts to 1" slack. RPM at blower is 286 and running amp load is 9.3 (just under the lower range on data plate). No slip at start up/run.Temp gun on motor 108 f and sheave temp at 88 degrees. Thanks so much lg and all who chimed in I forgot to mention, I installed all the grill/defusers prior to final adjustments and readings.

 

[Dugan]

I think you might have to run another belt for the added friction at a less tense setting. We run dual to multiple belts at work on fan coolers. When running they seem loose, but the added friction from each belt is helping out.

Also your pulley dimensons might be off. Ive rarely seen where the motor pulley is larger than the fan pulley. But I guess it all depends on rated RPM.

Have you contacted the manufacturer? That would be the most logical thing to do as they might have OE on this.

 

[BillK]

Cant help you with the motor issue but I just have to ask ...... why would anyone want to use that type of cooler instead of an actual air conditioning system ? Are they that much less expensive to install and operate ? I would think that the humidity they introduce would play havoc with any type of tools or equipment.

Just trying to educate myself, you don't see them at all out in this part of the country. I have a 5 Ton AC unit on the roof of my 30x60 shop where my business is and it does great keeping us cool.

 

[fnieto]

Fellas, my last post was to tell the GJ community, we got the unit working properly with desired results. BillK, have you been to Arizona? It's HOT & DRY. I can get 30-32 degree pull down and not worry about opening a door. My home has two HVAC duel packs on the roof and they are awesome in both seasons. HVAC would not work out to good in my shop as I operate heavy welding machines, CNC plasma tables etc. As you know HVAC simply recalculates the air in a sealed (for the most part). I could not do this kind of work in a sealed room. As far as corrosion, never has been an issue for me, every once in a wile I will see surface rust (the kind that wipes off by hand) on one of the welding jig tables. This happens during monsoon season when the humidity level generally goes up and the swamp cooler doesn't work as well. Arizona really only has two seasons Hot *** Summer and mild winters. This system will work great for me. BllK I hope I answered your question. FWIW, I have 3K in the unit (not including ductwork) and operational cost should be decent at 220VAC pulling 9.4 amps. The water for the wet sections is minimal. I'm sure the media pads will cost a pretty penny when the time comes.

 

[BillK]

BllK I hope I answered your question.

Makes a lot of sense if it is real dry. Probably why we dont see them around here, typical summer days are 90 deg and 80% humidity

 

[larry_g]

Glad to hear it. So glad also that all the arithmetic we learned so many years ago has some use in reality.

lg
no neat sig line

 

[themiller]

Hey thanks for posting this up. I'll tuck this little bit o knowledge in the back of my head. Happy weekend all!

 

[Falcon67]

Makes a lot of sense if it is real dry. Probably why we dont see them around here, typical summer days are 90 deg and 80% humidity

In the desert southwest, a good swamp unit will freeze you out. Lots and lots in NM and AZ, etc. Not unusual for us here to run teen or single digit humidity either but it varies too much.