16kw Generac Guardian generator will not run 1hp Grudfos well pump

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Jim Goodman

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I have a 16 kw Generac Guardian generator with an automatic transfer switch that is 2 years old. It's exercised every week. Today, for the first time since getting the generator, we lost power for about an hour. The high amperage loads in the house are a 2.5 ton heat pump, electric dryer, electric water heater, and 1 hp well pump. The dryer is obviously user activated, and the water heater has 50 gallons of storage, so those loads are easily eliminated, if we need to. The transfer switch contains a load shed module for the HVAC unit, and I am having that hooked up in a couple of weeks, but it currently is not connected. I am also having a Sure Start soft starter installed on the outdoor unit of the heat pump to reduce the starting amperage, but that is also not in place yet.

The generator has a running amperage capacity of 67 amps, and according to the specifications, a surge capacity of 130 amps (which seems high). Of the 3 high amperage loads (that I really don’t want to have to control manually and can come on automatically), the heat pump has a starting LRA rating of 47 amps and a running load of 11.7 amps. The well pump has a starting LRA rating of 48 amps and a running load of 8 amps, and the water heater uses 19 amps.

Today, when our power went out, I ran to the breaker panel and turned off the breakers for the heat pump, the water heater, and the well pump. With those items turned off, the total electric load that the generator was supplying was 21.3 amps. I wanted to make sure the well pump would run on the generator, so I went to the panel and turned on the well pump breaker. The lights went off and the generator stalled. At that point, the load was 21.3 amps (the stuff running in the house) + the starting locked rotor amps of the well pump of 48 amps = 69.3 amps, which is 3 amps over running capacity of the generator, but well below the supposed 130 amp surge capacity of the generator.

At this point, I flipped the breaker for the well pump off again and after about 15 seconds the generator started up and once again, was supplying power for the 21.3 amps of load that it had been supplying prior to my turning the well pump on.

Next, I flipped off all the breakers in the house….every single one…...so there was zero load on the generator. I once again flipped on the well pump breaker. At this point, the total load on the generator was only the current draw of the well pump at startup, which was 48 amps. The running capacity of the generator is 67 amps, so the well pump should have easily started, but it did not. Again, the generator stalled out. I flipped the well pump breaker off again, and this time, the generator did not start back up. I had to go out to the generator and reset the control panel, which had the error code E1902, “UNDERVOLTAGE OVERLOAD”.

If I were to do it again, I’d get a bigger generator, but this is what I have. It just doesn’t seem right that this 16kw generator will not start that well pump. I see people running well pumps off of portable generators with no problem. The well pump is on a 20 amp breaker in the house, and it never trips the breaker. And I have a Cycle Stop Valve and Cycle Sensor. The readout of the current draw when the well pump is running is 6-8 amps, once it’s running after startup. Hoping to get some opinions about this problem. I'm trying to eliminate possible reasons for this to try to get to the root cause. Do you think the well pump has anything to do with the problem or is it all related to the generator? Thanks.
 

Reach4

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I think you are saying that the pump starts sometimes, and sometimes does not.
Next, I flipped off all the breakers in the house….every single one…...so there was zero load on the generator. I once again flipped on the well pump breaker. At this point, the total load on the generator was only the current draw of the well pump at startup, which was 48 amps. The running capacity of the generator is 67 amps, so the well pump should have easily started, but it did not. Again, the generator stalled out. I flipped the well pump breaker off again, and this time, the generator did not start back up.
I don't know why the 20 amp breaker did not trip, but perhaps the control box (presuming you have one) for the pump is a problem. The starting capacitor may be weak, and should be replaced.
 

Drick

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I'll share a similar recent experience I had; We had a power failure due to a wind storm this summer and my 23 year old Generac Workforce 6500W (8125W surge) generator wouldn't start. I had a fridge and a freezer full of food so I borrowed a newer 8000W Gernerac from a friend. I connected it to the transfer switch and turned on all the lighting. No problem. Then I turned on my 3/4 HP well pump and the 8000W Generac barely pulled through. With my older 6500W Generac that would not have been a problem. At the time I was wondering if maybe there was old fuel in the generator, but after reading your comment it leaves me wondering if the newer models have an overstated surge capacity.

With that being said a 16KW generator should start a 1HP pump no problem when there is no other load. I would use an amp meter to confirm the pump isn't pulling more than its rated amps. If it wasn't I'd call someone out to look at the generator. It almost sounds like the generator is being shut down when it detects the voltage drop from the pump starting rather than pushing through and starting the pump. If that is the case maybe the low voltage shutdown is adjustable on your unit.
 

Drick

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I don't know why the 20 amp breaker did not trip, but perhaps the control box (presuming you have one) for the pump is a problem. The starting capacitor may be weak, and should be replaced.

A 20A breaker won't trip immediately with a 60A overload. It can take a couple seconds and by then the generator may have already shut down.
 

Jim Goodman

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Reach-4, thanks for your reply. It's a 2-wire pump, so it does not have a control box. It's a 1hp Grundfos pump and it's only 1 year old. The 20 amp breaker never trips on start-up......the pump works flawlessly with utility power. I've posted this question on a generator forum too.......just trying to rule out a problem with the pump before I call a generator repairman who will be willing to come out to fix it. I talked to one generator guy today, who won't come to fix it, who said that 90% of the time, a generator run-problem is fuel related. My generator runs on natural gas, and the guy I talked to suggested that not enough fuel is being delivered to the generator when it is suddenly called on to support a 48 starting load. Sort of like if you were driving a car and started to go up a steep hill and when you pressed on the gas pedal, the fuel injection system did not deliver more gas to increase the engine power to get you up the hill.

So, I'm pretty sure it is a generator problem, but I just wanted to make sure I wasn't missing something with the pump when it is starting up, that could be contributing to the problem. That new 1hp pump replaced my original 3/4 hp pump a year ago, and 12 gauge wire runs to the pump. I should have a 25 amp breaker on the pump, according to the manufacturer's specs, but the wire would need to be 10 gauge for that by code. I can't replace that wire....running under a slab. With 12 gauge wire, I'm not supposed to have a breaker larger than 20 amps, so that's what I went with. After talking with a couple of electricians, they said that would be fine, and indeed, I have had zero problems with the breaker tripping on startup, let alone when the pump is running. I just wanted to make sure that a 16kw generator should indeed be able to start that 1hp Grundfos pump. So, it looks like I need to get a generator guy out to solve the problem.
 

WorthFlorida

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When it comes to AC motors it is not just about the amp draw or KW's. You may need to call Generac on this or a Generac dealer to verify if the regulator board is good or not. These are excellent generators and well regulated. Under the right panel above the display sits the board. When things are running other than the well pump, what is the line voltage by using a meter? As each load is added, there may be a slight drop in voltage but it should immediately level out.

What type of well pump is it and how many wires? Voltage? Do you have a pump controller where the start cap is at the controller? With utility line power, get a motor start current reading by using a clamp meter.

I once tried to run my clothes washer with a 2.5 KW generator. Well I could get it to agitate but it never could do anything in the spin cycle.
 
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Valveman

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I am hearing from other installers that the 2 wire Grundfos motors are having problems. I believe high amperage is the problem they are having. I do know that a 3 wire motor with a start capacitor is much easier to start, but that big a gen set should easily start a 2 wire 1HP pump. I would check the starting amps of the pump before calling the generator people.
 

VAWellDriller

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I think you have a problem with the generator. You might be on to something with the gas line piping size....I know those NG and LP systems have super low supply head, and the correct size piping is crucial. There may be voltage regulator problem also. I've heard and had problems with Grundfos 2 wire motors, but it's not the problem if it works fine on the grid.
 

Water Guy

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comment related to someone suggesting it could be fuel related. I have a 15kw portable gasoline generac. one year it wouldn't run, so I did some research. I found out it has a mechanical fuel cut off mechanism to prevent backfire. removed The guts from that mechanism and it's been operating perfectly ever since. I'm not sure how safe it is however, so I do not advise it, just offering a suggestion as to what might be contributing to your problem. another option (if your not able to figure out the generator problem) is to get a larger 44 gal pressure tank that will give you 13 gallon reserve capacity, or even two 44 gallons tanks in series, giving you 26 gallons. keep in mind if you add tanks in series the pressure switch has to be on the last tank in series.
 
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Jim Goodman

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When it comes to AC motors it is not just about the amp draw or KW's. You may need to call Generac on this or a Generac dealer to verify if the regulator board is good or not. These are excellent generators and well regulated. Under the right panel above the display sits the board. When things are running other than the well pump, what is the line voltage by using a meter? As each load is added, there may be a slight drop in voltage but it should immediately level out.

What type of well pump is it and how many wires? Voltage? Do you have a pump controller where the start cap is at the controller? With utility line power, get a motor start current reading by using a clamp meter.

I once tried to run my clothes washer with a 2.5 KW generator. Well I could get it to agitate but it never could do anything in the spin cycle.

My Grundfos pump is a 2-wire pump, so I do not have a pump controller. The pump is 1 year old. It's 24o volts. Yesterday, I put a clamp meter on it and the inrush current was 44.7 amps, so that is actually slightly below the specified inrush current in the manual. I haven't checked the line voltage when other loads are running (minus the well pump) but I'll try to do that.
 

Jim Goodman

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I am hearing from other installers that the 2 wire Grundfos motors are having problems. I believe high amperage is the problem they are having. I do know that a 3 wire motor with a start capacitor is much easier to start, but that big a gen set should easily start a 2 wire 1HP pump. I would check the starting amps of the pump before calling the generator people.


Yesterday, I put a clamp meter on it and the inrush current was 44.7 amps, so that is actually slightly below the specified inrush current in the manual
 

Jim Goodman

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I think you have a problem with the generator. You might be on to something with the gas line piping size....I know those NG and LP systems have super low supply head, and the correct size piping is crucial. There may be voltage regulator problem also. I've heard and had problems with Grundfos 2 wire motors, but it's not the problem if it works fine on the grid.


I've been on a generator forum too, going back and forth with a couple of knowledgeable guys, and it's really sounding like it's a fuel problem. I've described in detail to them how the plumber set the fuel supply was set up, and it looks like there were some mistakes in how that was done. I'm going to get a gas guy out to work on it and put a manometer on it to address those issues first. If that doesn't solve the problem, then I'll get a generator tech out. Thanks to everyone for your help.
 

Jim Goodman

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comment related to someone suggesting it could be fuel related. I have a 15kw portable gasoline generac. one year it wouldn't run, so I did some research. I found out it has a mechanical fuel cut off mechanism to prevent backfire. removed The guts from that mechanism and it's been operating perfectly ever since. I'm not sure how safe it is however, so I do not advise it, just offering a suggestion as to what might be contributing to your problem. another option (if your not able to figure out the generator problem) is to get a larger 44 gal pressure tank that will give you 13 gallon reserve capacity, or even two 44 gallons tanks in series, giving you 26 gallons. keep in mind if you add tanks in series the pressure switch has to be on the last tank in series.

Thank you .
 

Craigpump

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Valveman is on the money. Grundfos 2 wire motors are junk! I’ve had brand new, out of the box motors not start and the ones that do pull excessive amps. They’re so bad that my supplier sent back their 4” Grundfos 2 wire pumps. Although I hate to promote anything made in china, the motors will start & run.
 

Jim Goodman

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Sorry, I missed your post....yes, here's the update. I just got it resolved a couple of weeks ago. It turns out, it was a fuel-related problem. In the long, sad story about this generator and its installation, I mentioned that the installation was not done by a Generac dealer but was done by a local electrician, who had been a certified Generac installer and the gas hookup was done by a local plumber. When the very first startup of the generator was attempted, the starter motor cranked, but it would not start. The plumber who did the gas work came out and checked his fuel pressure on the intake side of the fuel regulator in the generator. It checked out per the specs in the installation manual. At that point, I told him that he had done his job and it was my problem to get the thing running since he wasn't a Generac installer. At that point, I started going through the list of Generac servicing dealers in my city. I found a guy who was on the list on Generac's website and called him and he was very helpful. He helped me get it running over the phone. He told me that there was a connector under the control panel that controls the stepper motor that regulates the fuel butterfly, and sometimes that thing is not snapped in place properly during manufacturing. Sure enough, I reached under the panel and fiddled around with the connector, and indeed, it was not snapped in place properly. I snapped it into position and the generator started right up. I thought that was the end of my problems. From that point until we had that first power outage a couple of months ago, the generator started up for exercise each week, ran for 5 minutes or so, and shut down per the exercise sequence. BUT....note, that I never had a proper startup done on the system with a load test, and that chicken came home to roost with the first power outage. And note; at this point, the fuel pressure on the output side of the fuel regulator in the generator had never been tested.

So, as I mentioned in an earlier post, I was having my HVAC guy come out to connect my load-shed module and install a soft starter for my outdoor unit. Once I had those installations done, I was planning on trying to find a technician to figure out my current problem with the generator bogging down and stalling when the well-pump came on. The HVAC guy got the load-shed module hooked up, but my heat pump would not work with the soft stater, because of the way the control board worked, so the soft starter was not installed. Now we tested the generator. I had flipped off the water heater, well pump, and heat pump breakers. Once the generator was running, I flipped the well-pump breaker. The generator stalled out. Well, the HVAC tech was a multi-talented guy and he stuck his manometer on the gas regulator and found that the output was too low, and he turned it up so it met the Generac installation manual spec. Tried it again....turned on the well-pump.....it stalled. Then he noticed that a fuel hose feeding the carburetor had a bend in it and was kinked slightly at the bend. We repositioned the hose, removing the kink, and tried it again. This time the well-pump started right up and the generator ran, with no problem. Next, we tried the heat pump with the well-pump running, and the heat pump started right up. Next, with the heat pump running, we tried starting the well-pump, and the load shed module worked as intended and the well-pump started right up, with no problem. So, my HVAC guy solved the problem!
 
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Water Pro

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Sorry, I missed your post....yes, here's the update. I just got it resolved a couple of weeks ago. It turns out, it was a fuel-related problem. In the long, sad story about this generator and its installation, I mentioned that the installation was not done by a Generac dealer but was done by a local electrician, who had been a certified Generac installer and the gas hookup was done by a local plumber. When the very first startup of the generator was attempted, the starter motor cranked, but it would not start. The plumber who did the gas work came out and checked his fuel pressure on the intake side of the fuel regulator in the generator. It checked out per the specs in the installation manual. At that point, I told him that he had done his job and it was my problem to get the thing running since he wasn't a Generac installer. At that point, I started going through the list of Generac servicing dealers in my city. I found a guy who was on the list on Generac's website and called him and he was very helpful. He helped me get it running over the phone. He told me that there was a connector under the control panel that controls the stepper motor that regulates the fuel butterfly, and sometimes that thing is not snapped in place properly during manufacturing. Sure enough, I reached under the panel and fiddled around with the connector, and indeed, it was not snapped in place properly. I snapped it into position and the generator started right up. I thought that was the end of my problems. From that point until we had that first power outage a couple of months ago, the generator started up for exercise each week, ran for 5 minutes or so, and shut down per the exercise sequence. BUT....note, that I never had a proper startup done on the system with a load test, and that chicken came home to roost with the first power outage. And note; at this point, the fuel pressure on the output side of the fuel regulator in the generator had never been tested because

So, as I mentioned in an earlier post, I was having my HVAC guy come out to connect my load-shed module and install a soft starter for my outdoor unit. Once I had those installations done, I was planning on trying to find a technician to figure out my current problem with the generator bogging down and stalling when the well-pump came on. The HVAC guy got the load-shed module hooked up, but my heat pump would not work with the soft stater, because of the way the control board worked, so the soft starter was not installed. Now we tested the generator. I had flipped off the water heater, well pump, and heat pump breakers. Once the generator was running, I flipped the well-pump breaker. The generator stalled out. Well, the HVAC tech was a multi-talented guy and he stuck his manometer on the gas regulator and found that the output was too low, and he turned it up so it met the Generac installation manual spec. Tried it again....turned on the well-pump.....it stalled. Then he noticed that a fuel hose feeding the carburetor had a bend in it and was kinked slightly at the bend. We repositioned the hose, removing the kink, and tried it again. This time the well-pump started right up and the generator ran, with no problem. Next, we tried the heat pump with the well-pump running, and the heat pump started right up. Next, with the heat pump running, we tried starting the well-pump, and the load shed module worked as intended and the well-pump started right up, with no problem. So, my HVAC guy solved the problem!
congrats on getting it figured out. Your reply I'm sure will be a beneficial resource to those experiencing similar issues in the future. thanks for contributing. :thumbsup
 
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