Bad Motor

[wayne100]

I bought a house a few months ago with an AGP it's 16x32. Last few weeks the filter motor has been making alot of noise and a couple of times it tripped the breaker. yesterday it just died. I need to get a new motor. I have a sand filter, looks like the previous owner already upsized it,the thing that holds the sand, old one is still back there. Anyway I can't find the motor online anywhere, don't know if he already replaced it or not, but it sure looks old. AO Smith Model# S48C51Z01 1 1/2HP 115V 60HZ 11 AMPS KW 1.12 SPD SF1 FR56Z
Anyone have any ideas?

 

[H2O_Keeper]

Perhaps someone else can help you with the specifics of your original motor specs but I can help you find a motor. All you need to do is match up three things with any motor manufacture:

1. HP --- 1.5HP
2. Voltage --- 110V (you need single phase)
3. Frame Size --- FR "56Z"

If there are any tractor suppply shops in your area they carry basic motors or you could goto mscdirect.com or grainger.com for a good starting point. Also I had my motor rebuilt by a local electrical motor shop, you may have some in your area. If it was noisy you may just have the bearings locked up, sometimes those can be swapped out and your windings/etc are okay.

I'm sure some pool supply stores will sell a comparable motor with the above specs but will run a lot more in cost.

 

[wayne100]

Thanks

 

[wayne100]

OK so I found my exact pump used on ebay for $50. Hooked it up and everything works better than before. The pressure gauge used to read about 10 or 12 and go up to about 20 before I backwashed. The new one reads about 38 and goes to about 41 before I backwash. All plumbed with 1 1/2 inch pvc. Today I noticed water in the pressure gauge and I don't recall seeing this before. Is this a problem?

 

[H2O_Keeper]

That much pressure seems unrealistic, others will have to chime in if its even possible with your setup to get that high. The only reason there would be a change that drastic and for it to be for real is due to a lot of slippage with your old setup or if you have/had an non-standard RPM rating on your before/after setup. I did not mention RPM on my spec because its rare you get those and they are usually very expensive.

A couple of side tips about gauges when you get a new one:

1. If you want a very long lasting one get a liquid filled version. They handle the shocks better as the PSI flutters while your system runs.
2. Get a manual shutoff going to the gauge and just open/close it as you want to read your pressure. This drastically increases gauge life. (Optional if you have a liquid filled version)
3. Get a maximum gauge range from 0-30psi. They also make 0-15psi. A smaller band makes it easer to see PSI changes. I had to order mine, the local pool stores only carried 0-60psi.

 

[wayne100]

Well the old pump was noisy from the day I moved in and it wasn't pumping anywhere near as much water as this one does. The eyeball is aimed up, the old one barely broke the surface and this one goes up about 2 inches above the water line.
I like your idea of a shutoff before the gauge.

 

[H2O_Keeper]

See this article in pool school, here.

Doing this in reverse

Pressure side head loss --> 38psi*2.31 = 88
Rough suction side loss --> 88*0.75 = 66
Overall Head Loss for your system would be: 154

You have to look for your manufacturer but for a general chart you cant have over 95 in head pressure for a 1.5hp motor or the system will stall out. This is why I said the gauge is probably not accurate but I cant say for sure. If you know the pressure is relative (ie a delta [change]) when its dirty than I wouldn't be that concerned about the true pressure. I have seen pressure gauges that dont go to zero and its all relative from that point to your reading. When the pump is not running does it go back to zero or stay around 30psi???

 

[wayne100]

Goes back to zero but like I said it's almost 1/2 way filled with water now so I'm guessing it probably bad so I guess I'll just replace it.

 

[cadillac]

could be that the old pump had been downsized to a smaller hp impeller. Assuming your gauge is correct, more pressure equals more water trying to go though the system. If you still have the old pump, look for numbers on the impeller and compare.

 

[budster]

could be that the old pump had been downsized to a smaller hp impeller. Assuming your gauge is correct, more pressure equals more water trying to go though the system. If you still have the old pump, look for numbers on the impeller and compare.

Possible, and it may be that the old motor was "uprated" with a lower service factor(S.F.), and the new replacement is "full rated", with a higher service factor. While this difference is not usually translated into higher head (pressure), it might have some influence.