DaveN
I just completed the install of my 16kw Guardian and I think something is not right. She started and ran fine with a light load but as the 3.5 ton ac kicked in (it bogged down bad but I will get a hyper soft start from this site) the engine surges a bit. Before the ac is on the voltage and hz are very tight and after it varies maybe 4-6 volts and the frequency about 3 Hz. I did notice that it is unbalanced 10-12 amps between the legs. I bought a nice manometer and on the service port of the regulator in the generator NG is 8.5 inches not running and 7.5 inches loaded, a very stable 7.5 inches.

Thoughts?

Gas meter was upgraded. 8 feet of 3/4" black iron from meter with full port valve. We run 2 pound NG here and I have the regulator (3/4" and rated at 350k btu for a single appliance or 650k btu total) a few pipe feet from the regulator in the generator. Electric is all #4 copper and only around 50 feet going to the 200 amp ATS.
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DaveN
Also it was connected to the wifi and started pulling an update. Came back after 30 min and it said it failed and now it will not connect to the wifi though it shows the right SSID and CAN ping. I guess I will retry setting it up otherwise I guess I need a service call the have the update down with via USB?
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Peddler
I would first check the capacitor/s in the AC unit to make sure they are in spec. It will bog down for a 30-50 microseconds maybe more but then should go back to 60Hz and stay there. What was the peak load you saw during the loaded run in amps (if you have an amp probe)? Also check the gas hoses between the demand regulator and the fuel pin to make sure they are not kinked.
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DaveN
When the ac was running I believe it was pulling 20 amps/30 amps. The ac us old so checking the capacitor is probably a good plan. Does the capacitor come into play once it is running? The voltage and hertz never settled down with the ac on.
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78buckshot
The most common ac condensing units have a dual run capacitor, half of it is wired to the compressor, the other half wired to the condenser fan motor. Some units will use a start capacitor with a start relay to drop out the start cap once the compressor is running along with the run caps. So as long as your condensing unit is single phase it needs the run capacitors hooked up and healthy.
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murphy
The last capacitor that I changed was rated at 45 microfarad and measured 0.7 microfarad. It definitely needs to be checked.. It is most likely that it is a run capacitor that stays in the circuit all of the time.
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78buckshot
3.5 tons is a hefty in-rush load for 16kw, I think the soft start is your best bet. Are you using the load shed module as intended?
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DaveN
I am getting the hyper engineering soft start. First I was concerned with the issues while it was running. I am hoping nothing is wrong with the genny. I was expecting the engine to run smooth and not surge. It is not a major surge but is noticeable and the voltage and hertz agree. I am an all gas house so I have nothing to shed. I will just swap the cap tomorrow. They are cheap and the unit is 20 years old. I did read and the rheem is a dual cap.

Thanks all!
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78buckshot
Do I understand correctly that while the A/C is running steady state the generator is hunting or surging? If that is the case try adjusting the fuel pin, the orange lever on the intake manifold that is used to change from natural gas to LP.
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DaveN
78buckshot;n58667 wrote:
Do I understand correctly that while the A/C is running steady state the generator is hunting or surging? If that is the case try adjusting the fuel pin, the orange lever on the intake manifold that is used to change from natural gas to LP.


Yes, ac is running and the genny is bunting or surging. The ac can have been on for a few minutes and it will still do it. The voltage and hertz also vary while it is doing still.

So if the lever/pin is all the way to NG just slightly twist to see if it helps?
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Brian Baughman
DaveN;n58654 wrote:
I just completed the install of my 16kw Guardian and I think something is not right. She started and ran fine with a light load but as the 3.5 ton ac kicked in (it bogged down bad but I will get a hyper soft start from this site) the engine surges a bit. Before the ac is on the voltage and hz are very tight and after it varies maybe 4-6 volts and the frequency about 3 Hz. I did notice that it is unbalanced 10-12 amps between the legs. I bought a nice manometer and on the service port of the regulator in the generator NG is 8.5 inches not running and 7.5 inches loaded, a very stable 7.5 inches.

Thoughts?

Gas meter was upgraded. 8 feet of 3/4" black iron from meter with full port valve. We run 2 pound NG here and I have the regulator (3/4" and rated at 350k btu for a single appliance or 650k btu total) a few pipe feet from the regulator in the generator. Electric is all #4 copper and only around 50 feet going to the 200 amp ATS.


Was the regulator designed for use on an engine?
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DaveN
I found another thread saying there was a design flaw on the 22kw air intake. I decided to test on mine and it too suffers from this issue. I switched over to the generator with the ac running and it was surging, you could see the throttle doing its thing. I then opened up the filter box and the surging instantly stopped. Close the filter box and it starts. I left the filter in too! I left the box cracked open for now and am calling Generac.

Generac says a bad batch of air filters is out there and they have too much flame retardant on them. They are sending a new one.

I verified that taking the filter out and closing the box also stopped the surging. I am leaving the filter in and the box cracked until the new one arrives.
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DaveN
Got the new filter. Same issue. They either have a large batch and cannot track the bad ones or there is an issue with the intake. Leaving the filter box cracked fixes it.
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78buckshot
Did you try adjusting the fuel pin?, indication is air/fuel mixture if the filter cover changes the hunting.
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MacL
Leaving the cover of the air box cracked is not advised as it can fall off and onto the exhaust pipes while it's running. Turn your gas pressure to the minimum at the final regulator. Screw the adjuster all the way out, leaving enough room to get the cap back on. That may be all you need.

The fuel pin is not adjustable. It is meant to be all the way one way or all the way the other way, depending on the fuel type. Pinching it off by leaving it in an "in between" position will seem to work, but you will be de-rating the generator to a lower KW basically, and could even cause a gas leak in the fuel pin bore to the outside. Practically, it will bog down and die when an ac comes on if you have the orifice smaller than designed.
State your problem, not your diagnosis.
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DaveN
MacL;n58722 wrote:
Leaving the cover of the air box cracked is not advised as it can fall off and onto the exhaust pipes while it's running. Turn your gas pressure to the minimum at the final regulator. Screw the adjuster all the way out, leaving enough room to get the cap back on. That may be all you need.

The fuel pin is not adjustable. It is meant to be all the way one way or all the way the other way, depending on the fuel type. Pinching it off by leaving it in an "in between" position will seem to work, but you will be de-rating the generator to a lower KW basically, and could even cause a gas leak in the fuel pin bore to the outside. Practically, it will bog down and die when an ac comes on if you have the orifice smaller than designed.


Thank you MacL. I did just as you said and she is happy now with the cover closed. I will put a manometer on it tomorrow just to see where that ended up leaving it.

I also got the Hyper E soft start on the A/C and now the lights don't dim anymore and the generator barely notices startup.
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MacL
The operating range for the evolution is 3.5"-7" wc.

Most off the shelf regulators say the spring range is 6-14", I'd guess actual minimum is 5 or maybe 4.5", either is okay for the evolution.

As a next step (if the problem returns), would be your choice of a) removing the baffle near the battery that covers the flywheel inlet, and/or b) enlarging the existing holes in the air cover and adding more, just as neatly of course.

I say "if it returns" because a warm engine tends not to do it, and a little dirt or oil on the air filter could put you back to the pulsing. It's not often getting the gas pressure down alone will do it, I hope so in your case. It is enough sometimes.
State your problem, not your diagnosis.
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DaveN
I honestly didn’t think the 8.5” at low load/ 7.5” at load would be an issue. Live and learn. The range is the range. I will keep your next steps in mind. The design issues are frustrating. Thank you again!
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