View Full Version : Goulds Jet Pumps overheating.

07-04-2008, 05:35 PM
We have installed 3 Goulds 1/2 hp jet pumps this spring. J5 are the first letters in the model. All are used for psi booster pumps and installed in the utility rooms of the houses.

Vendor recommended pumps so should be proper ones used for these applications. Pumps are using 1" supply pipe and 1" outlet. 1 1/4" to 1" bushing used on the inlet side.

Two of three pumps get too hot to touch after running a few zones and start to make a lot of noise. These pumps are supposed to be wired for 120v from the factory, per our vendor.
We checked the first one and it was wired correctly. We changed it out and all is fine with that one.

We installed another two days ago and the owner called and said it is running hot and making a heck of a lot of noise. He said it sounded like it was sucking air or such.

I am sure this one is wired correctly also, although I won't be going out until Monday to check it.

Checking to see if anybody else is having trouble with these pumps or am I missing something?

John :usflag: :usflag:

07-04-2008, 06:13 PM
There's a chance the pumps are trying to pump more water than your supply can give it. You should know the pressures on both inlet and outlet, and the flows it operates at.

For a lot of weak supplies, with 5/8-inch meters in a basement fed by a 3/4-inch copper line, a 1/3 horsepower jet pump would be a better match. Not that you'll easily find one.

Goulds makes a high-head version of the J5, and it can't pull as much water as a standard J5

07-04-2008, 08:22 PM
Is it the pump end or the motor end that gets hot? The pump end won't get hot if there is water flowing through it. Even trying to draw more water than the line or meter can supply still won't get the pump end hot. Only a now flow condition will get the pump end hot.

So I assume it is the motor end that is getting hot. The motor is air cooled and also doesn't care if you are trying to draw more water than can be supplied. The motor will only get hot if you are letting out more water than the pump should produce, or if the air flow is impeded to the motor. It can also heat up the air in a small room so that it has no cool air left. Unless there is something wrong with the motor or pumps, your zones are too large for the pump or the air is not properly cooling the motor.

07-04-2008, 08:23 PM
Once again, I have failed to give all the info needed and also the wrong pump #.

The pump is a JRS5. The motor is overheating and not the pump itself.

The first failure was on a 1" input with 43 psi.. Municipal water supply. The flow was adequate for our usage as we had zoned for 14 gpm.. I personally ran the pump and after 10 minutes, it was getting too warm to keep your hand on it. So we shut it down.

The second install was across the street from the first and we have not heard anything at all from them so it must be functioning properly.

The third install/second failure was a replacement for an old pump. Input and output were already in place and I will have to check further as to the size of pipe incoming to the house.
I used the existing piping for the old pump.

Hi WB. I was under the impression that the motor is air cooled and not cooled by water in any way other than normal heat transfer, metal to metal.

When we started the last one, it sounded to me like it was sucking air at first and then it quieted down after filling zone with water. We left it at that and then the homeowner called and said it was damn loud and very hot.

07-04-2008, 08:25 PM
The meter on the first failure was a 1".

I will have to check on the latest but my guess it is a 3/4". Not much chance of a 5/8 in this area but I could be wrong.

Thanks for the help.


07-04-2008, 08:32 PM
The joys of guessing are replacing burned-up pumps on your dime. I bet a 'specialty valve' could keep the pumps happy, but I expect they cost more than the pumps do. Noisy pumps could indicate cavitation (sounds like gravel inside)

You know they have adequate power, and are not running at less than full voltage?

07-04-2008, 08:41 PM
On the first pump, the voltage was our first suspect but all was well. 124v and would drop to 117 when pump started .

The second one is a replacement for one that is probably 30 yrs. old. Zones worked fine with old pump until it started smoking last week and then ceased to run. As I said, I used the existing hookups, and homeowner said the old one was noisy also but it did not overheat.

WB, it did sound like it was cavitating when we first started it up but then it quieted down considerably. But from what the homeowner told me, it sounds like it is doing it all the time now. But the zone was operating fine. Homeowner says now it seems like there is more water coming out than before from his sprinklers.

If the zones work fine except for the noise and heat, wouldn't that signify that enough water is going through to allow the pump to run normally if it is mechanically and electrically sound.



07-04-2008, 09:29 PM
Cavitation noises must be immediately dealt with. "Oh, good, it went away." won't cut it.

07-05-2008, 12:22 AM
Ok. WB.

You stated the cavitation noises need to be dealt with. For a newbie like me, just what does that mean? Or entail?

Your patience is very much appreciated, and I am only trying to solve the problem.

Thank you for your help.


07-05-2008, 06:30 AM
It might be as simple as throttling down the outlet of the pump. That will reduce flow slightly, but can improve the operating conditions for the pump. You should really collect some pressure and flow data on these systems.

07-05-2008, 09:25 AM
I will have to plead ignorance all the way around.

Again, assuming stuff has probably bit me again. I assumed the pump would only put out what the zones were designed for. Apparently that thought process is not even close. Hence, the lack of flow testing. If I see a 1" POC and a 1" meter, and the pressure was in the 42 psi range, I thought I could just put in a jet pump and zone for 15-16 psi and all would be well.

So, WB, I may be able to ball valve the output and solve the problem? I understand now how that can keep the pump within the gpm of available water. And keep the pump from "sucking air" or cavitating.

Bear with me now. (Thinking out loud!) If the pump is cavitating and not moving constant water, the impeller is spinning much faster than it should and would cause the motor to overheat.

Thanks for the assist.


07-05-2008, 09:39 AM
I don't run pumps outside of their comfort zones, so I don't get to see what's happening with your kind of situation.

The last time I had cavitation when evaluating a well point install, I switched to a Goulds J5SH pump, which flows less than a J5S. I've never used the JR5 pumps, and probably never will.

07-05-2008, 09:51 AM
Thanks, Boots,

I am going to check the specs of the JRS5
and the J5SH and see where my thinking can be upgraded. And also the pump.

Thanks again for the help.


07-05-2008, 10:03 AM
I never loved booster pumps, and would prefer to never have one controlled by a pump relay, if I could just add a small pressure tank atop the pump, and let the pressure switch control operation.

For the same horsepower consumption, it looks like you can get more performance from a JS pump than a JRS. You'll spend more for them, probably.

07-07-2008, 11:16 PM
We went back to the house and installed a ball valve on the output pipe. We started the system and closed the output until the cavitation stopped. We ran all 5 zones and they all worked well. Total time was maybe 10 minutes. Motor was cool except for the rear housing which was warm.

Homeowner called 20 minutes later and said the rear end of the motor was hot and he could not hold his hand on it for more than 30 seconds. He said the front end of the motor was warm but not hot.

We have solved the cavitation part of the equation it would seem.

Pump runs quiet except for the rear end of the motor heating. No cavitation.

Is the rear end of the motor heating normal or was it damaged during the cavitation phase of this snafu?

We need to solve the problem, if there is one, regardless of who is responsible for the cost!

Thanks to all you insatiable pump gurus.

WB- I think that would include you.


07-08-2008, 10:44 AM
Those motors run hot anyway. If it is not tripping the thermal overload, it is OK.