Powerhorse Generator with Electric Start — 27,000 Surge Watts, 18,000 Rated Watts

drmerdp said:

By load block I’m referring to the Garret KN demand regulator that’s mounted onto the side of the generator. Has that been adjusted since you first got the generator running on propane?

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drmerdp is referring to the adjustment on the demand regulator. It adjusts fuel/air ratio.

GenKnot said:

Sorry, didn't mean to insult. The thread is getting so long it is hard to follow everything that has been done.

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Oh, no insult taken. You've been very helpful. It's not you.

About 10 months or so ago, I started the conversion. The generator was new, and no kit existed. Texas T and I were able to get it working.

There were some issues. I installed and re-installed the snorkel several times but was unable to start. Changed orientation of snorkel, etc. I tried adjusting load block many times. Finally, Texas T discovered that the snorkel itself had a blockage. After a new snorkel was installed, still would not stay running but the hoses on snorkel were open. I discovered that the first stage regulator was bad and was sent another one. It leaked propane. Not wanting to wait for third one and desiring another brand, I went to a local shop and got one that immediately worked. It wasn't the tank size or needing to be purged as tech support originally guess. The generator fired up, 5 and a quarter turns and ran smoothly.

Now I am here several months later, load testing and discovered engine lugs on heaviest load on propane. U.S carbs is sending larger hoses, as this could be the issue as they don't really know what size hose this generator may need. The hoses that go from the demand regulator to the snorkel. I'll have to splice the larger hoses in. Once again, the tank is suspect, but I've tried another small older tank with same result, lugging under load, as the new tank.

Here's where I stand. I replaced the small tank regulator with the big Rego TR9 that I know is capable. I will attempt to adjust the second stage regulator to a higher pressure per U.S carbs. If that does not work, I may replace it. I'll install the larger hose when they arrive. Lastly, I'll make 100% sure I have a correctly sized and purged tank. Because that was not the issue last time, it still could be this time. U.S carbs believes it's the tank. It could be anything from the snorkel itself, hose size, or a bad regulator. I will again test the snorkel by blowing thru the hoses to make sure both sides are open. The kit that I was sent was created based upon a similar sized Generac generator. This generator has a large engine so it's being figured out with some experimentation.

The local propane shop does generator conversions. The guy there has a tank in bed of his pick-up truck and runs the truck off propane. I'm sure he'll be able to assist if I can't figure it out. He has gauges and can get a new regulator out of the shop if that's what it is.

Oh, I forgot, I was not able to test central air until I had a whole house manual transfer switch. With my set-up an interlock switch was not feasible That's why just now doing that Service Entrance Manual Transfer switch?? | Page 2 | Power Equipment Forum .

As far as loosing power with higher loads - it all comes down to fuel volume.

You have enough volume to supply the engine what it needs at no load up to light/medium load. But when you try to load heavy you don't have the volume.

What restricts volume (available at the demand) is the restriction in the fuel line. This is based on several criteria - diameter, bends, fittings, adapters, length, etc - on top of pressure. If you have light pressure then all of the previous mentioned factors will eventually cause the demand to starve of fuel once the demand gets too high - the restrictions tank the pressure too much as they are not able to deliver "enough fuel" (volume).

The kicker is you can't have "high pressure" going in to the engine. You need low pressure, high volume. Therefore, to compensate for the volume demand in to the engine you need high pressure until the demand reg so that the fuel in front of the demand reg is "there" to be drawn from.

If your down-stream (of the demand reg) plumbing can't give you enough "volume" then it doesn't matter what the pressure is ahead of the demand reg (as long as the reg can handle it).

If your down-stream (of the demand reg) plumbing CAN give you enough "volume" then your pressure up-stream of the demand reg matters.

If you had a way to measure pressures that would really help - especially upstream of the demand reg. If you could do this then it would tell you if the plumbing downstream (to snorkels) was up to the task or not. If it was then you would see the upstream pressure (upstream of the demand reg) go below a pressure that would allow the reg to work. If the downstream (to snorkels) plumbing was not up to the task then the pressure ahead of the demand reg would be adequate. Again - a pressure meter/manometer would tell you this.

The above is why I took my demand reg out of the circuit on the big gen on NG for the time being - with the plumbing I have there is too much restriction through it for the engine to even run with no load. The small 2600w unit I have will run on it. Interesting thought here - I have not tried the small generator without the demand reg, just load block, but I would be curious to do that to see what the difference is - I'm sure it is a lot. ~5hp engine on the small gen, ~23hp engine on the big gen.

FlyFisher said:

As far as loosing power with higher loads - it all comes down to fuel volume.

You have enough volume to supply the engine what it needs at no load up to light/medium load. But when you try to load heavy you don't have the volume.

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The engineer at U.S carbs believes that a fuel quality issue and not only volume is at play. That would cause the same result according to him. After discussing it with the lead tech further, there is no getting around the fact that my new tanks were not properly purged. The other tank I used to test is too small. I have to test with a properly purged at least 100-pound tank. I am following the steps the lead tech at U.S carbs and engineer are advising. The X factor here is that they have resolved these issues before. Really, I believe the advice to blow down the lines came from them. We were going in circles with the fixation on the load block adjustments. They knew their product. I don't believe we would have ever got generator started without their tech support.

I couldn't really take the demand regulator off with a propane generator. Really my goal is to be able to use at least two fuel sources. I am assuming the throttle adjustment was partly necessary because you don't have a demand regulator with your natural gas generator? You are optimized for that fuel. During hurricane Ida and Katrina many lost natural gas so I feel I need to be able to tap several fuel sources in my area and I only have a single generator.

As I increased pressure, I felt I no longer needed to be concerned with a throttle adjustment in my set-up for propane. I think the generator will maintain proper frequency with both fuels and no throttle adjustment. Because I increased pressure and the frequency stabilized at proper range for propane, U.S carbs is advising it's a fuel quality issue causing the lugging. The issue is too much air in fuel. They are also advising me how much to adjust the pressure on the second stage regulator to test that as well. Yeah, I know I can get gauges but based upon their experiences they are advising me to test these simple steps first which have solved these issues for others. It's quick easy and free. They are sending part, great company. I'm not that concerned. The generator is perfect on gasoline, and I'll use that as I sort this out. Thanks for the tips. I may need them later if the "quick" fixes don't work.

Bulldogger said:

I am assuming the throttle adjustment was partly necessary because you don't have a demand regulator with your natural gas generator? You are optimized for that fuel. During hurricane Ida and Katrina many lost natural gas so I feel I need to be able to tap several fuel sources in my area and I only have a single generator.

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To answer your assumption I'll make an assumption also. That said, this could really go down the toilet fast with all the assumptions

That assumption being - by "throttle adjustment" you mean the load block to throttle the fuel. In that case, yes. The load block is highly dependent on the energy in the fuel. In my case, the demand reg is is not used at the moment on NG but it is on Propane. To be 100% honest, I have not load tested the 2 rotary generators (2600w, 15kw) on propane, other than a small space heater. So I am not sure how the demand plays with the propane delivery like what you are trying to do - whole house power. I haven't been too concerned on propane.

Also countering my own assumption in an effort to be thorough - there was some discussion somewhere a while ago about the physical "throttle"/governor on a generator. This was the small 2600w on natural gas. The reason I even made that adjustment was that the generator seemingly shut down with too light of a load - I felt it should do more so I got in to what it would take to get a bit more out of it. That is where the oscilloscope and governor adjustment came in - on natural gas I loaded it with between 700-800w from a heater then got the screw adjustment up a bit to about 61hz on the AC frequency. I don't recall how low it was before. In any event, the adjustment appears to have made a difference.

Technically speaking, the governor adjustment should not be necessary. That is a mechanical adjustment and should be independent of fuel quality/energy content (NG, propane, gasoline).

As to the adjustment of the load block for natural gas or propane - if you are running through a demand regulator and have one load block this will have to be tuned with the switch as the setting is dependent on the fuel. I believe this is also why companies that have standby generators that can run on both fuels do not have a way to automate the switching of fuels. I have read that in other threads - where a homeowner doesn't want the hassle of tuning/adjusting/wrenching on their built-in generator to switch fuel, but is in the same fuel boat - they want the ability to use what ever fuel is available.

If you wanted to get "creative" - you could attempt to plumb with electronically controlled valves, or manual valves (more fail-safe with manual valves I would say) so you can "switch in" what fuel circuit you want - have one set on propane and one set on natural gas (if you have natural gas). That way if you have different components (demand regs, load blocks, hoses, what have you) and your tuning points are different for the different fuels, it might be just a matter of flipping a few valves on/off to switch fuels.

In my case, personally, I don't mind the "rigging up" of what I am running. That makes things portable for me. Yeah, it is a lot of work to, say, hook up the 15kw as I have to wheel it around to where it hooks up, then hook it up. No matter how I do it I have to work with the large fuel line and wrenches. I absolutely did not want any "quick connect" for the fuel hook up - I went with unions and to block off the union on the line at the hook up I have a threaded plug. The reason for "no quick connects" is leaks. The unions and threaded connections are more robust. So at that point - what is the big deal of tuning for the fuel type? Everyone's situation is different, though.

Bulldogger said:

As I increased pressure, I felt I no longer needed to be concerned with a throttle adjustment in my set-up for propane. I think the generator will maintain proper frequency with both fuels and no throttle adjustment. Because I increased pressure and the frequency stabilized at proper range for propane, U.S carbs is advising it's a fuel quality issue causing the lugging. The issue is too much air in fuel. They are also advising me how much to adjust the pressure on the second stage regulator to test that as well. Yeah, I know I can get gauges but based upon their experiences they are advising me to test these simple steps first which have solved these issues for others. It's quick easy and free. They are sending part, great company. I'm not that concerned. The generator is perfect on gasoline, and I'll use that as I sort this out. Thanks for the tips. I may need them later if the "quick" fixes don't work.

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The RPM/electrical frequency should stick - that is a mechanical adjustment. That should stick to the point of the fuel volume meeting the demand of the engine. If the fuel volume can't meet the demand then the RPM/frequency would drop down.

I'm in the same boat on a manometer - as of now I don't have one. I have been able to get around the issues I've had thus far. That having been said - it would have been really helpful to have one. I may go the route of making a water based one this season then see how things go.

On a bit of an off-topic - I wonder if the fuel volume through the demand reg on the small gen on ng (it uses it on both fuels) is why it cuts off with much load. That wouldn't surprise me at all - and if I had a manometer it would be pretty easy to determine that - the gas pressure ahead of the demand reg would drop too low.

drmerdp said:

Are you saying you’ve removed and are operating the generator without the Garret KN (or equivalent) regulator?

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Correct. The pressure reg at the meter is the only "regulator". From there the volume is adjusted at the gen with a load block. See above post. That is a temporary install, nothing is permanently installed. It is also why I have the electric ball valve - if the gen were to quit that would kill the power to the valve and close it.

Direct line is left of the reg. The "load block" is the yellow ball valve in that instance.

The hose to the manifold can switch between the direct line and the demand reg up top. When I was working on it this day I had taken the load block out, but there is a load block that can go downstream of the demand reg to tune propane.

There is a gas manifold that sits ahead of the carb, under the air cleaner box. I don't have the "snorkel" set up to shoot in to the two intakes, just one manifold that mixes the fuel with the intake air going to both cylinders.