# Natural gas conversion - upgraded gen supply, regulator, and more details on load testing 15kw



## FlyFisher (Jun 30, 2018)

All,

This is a continuation of my escapade on getting my 15kw up and running for home backup (its also used portable, so no way to do a hard install since it travels).

I got my gas feed upgrade for the generators yesterday. Its pretty simple - just a T, 1" valve, and a sediment trap is all it really amounts to. I have that stepped down to a 3/4" flex pipe.










It should be obvious what the upgrade was - all the new metal parts. I've since painted them over.

The good news:

Now I have enough gas to run the engine. I will discuss load testing further down - once again I am beyond shocked at what this will run(!!)

The bad news:

I still can't get the demand reg at the engine to work. The only way I can run the engine is to hold the primer button in - which was the issue in my earlier tests (on a smaller line that didn't have the capacity for the big gen's engine, it would run with no load but barely if I started on gasoline and switched to NG).

More detail on the set up:

A while back when I found I had issues on the small line (grill port out back) I thought about bypassing the reg entirely. As a safety device to do so I got an electronic valve. 12v+ to turn on, remove power to close. I have the electronic side worked to where the power from the generator holds the valve open then if power is removed it cuts power to the valve = valve closes (this is another subject entirely - but it is a cool set up!)

When I went to testing with the upgraded line I put the regulator (Century KN) back in line and opened the load block valve all the way. I primed with the primer button and cranked but I couldn't get the engine to fire. So I went to gasoline to start then transferred. On the 2nd attempt I went to the primer button to get more gas to flow (bypassing the reg) and found I was able to sustain the engine running - and it was running pretty good for a change.

So then I took the regulator out entirely and used the ball valve ahead of the electronic valve as a "load block". Running this way I am able to get the engine to run fine - and it needs to be closed down a bit to get the mix right so that tells me I have more gas available than I need.

If it means much - our gas service is 7in WC. That is 1/2 of the 14in WC max for the regulators (and is within range - the range for some appliances here is 6-14").

Here is a picture of the gas set up on the generator - with the yellow valve lever acting as the "load block" in the tuned position. The black cube down stream of the yellow valve is the electronic valve (motorized with capacitor return, not a solenoid).










I do not like the set up bypassing the demand regulator, however it does "work" fine. The fuel mix is tunable so the engine runs.

Here are a couple other closer up pictures of the plumbing from the reg/vertical pipe:











Below is the hose routing to the gas manifold that sits between the carb and air filter housing (up stream of the carb - not between the carb and engine intake manifold). There is some interference between the hose, shroud, and air filter housing - but it is not much. It doesn't really restrict the inside of the hose more than the oval shape it had when it was cut off the reel.









Question:

Is there any merit to the thought I have that the distribution from the output of the manifold to gas manifold on the engine might restrict the flow too much? If there is then the solution would be to increase the interior diameters of the parts (port on the manifold, barbed fittings, hose, load block, etc).

Is the 7in WC pressure really too low? (that is the service spec from the gas company, I have not physically measured with a meter). The next gas company upgrade is 2psi. That is a significant upgrade I don't think we're willing to do. The gas company did not mention there being a way to dial up the pressure of the current regulator - say, to go from 7" to 14" WC, however the plumber that did our upgrade said the regulator could have the pressure increased - just he couldn't touch it (the gas company would have to).

Load testing:

The engine runs a bit "weaker" on natural gas than it does on gasoline. What I mean by that is it will lag a bit with heavy loads, but I'm still surprised it holds on as strong as it does. The "bench mark", if you will, to that is my cheap 2600w rotary. If you hit it with a load that's too much it will definitely bog down - so much so that it will shut off entirely. This 15kw unit never even comes close to that - I can tell it lugs with the loads on NG, but it holds - big difference.

Now on to some more meat and potatoes.

Last time I load tested was on gasoline. The notable loads were central AC, portable/room AC, lights, fans (ceiling fans). There was so little lugging on the generator I had to go around to the central AC unit outside to see if it was, in fact, running - it was. What I did not do was fire up the microwave to see what would happen.

This time around, again - NG this time, not gasoline - I started with the same base loads - the 2x AC units and house circuits (lights/ceiling fans). All ran fine. So I thought I would really load it up and throw the electric clothes dryer on it. Fired up the clothes dryer and it lugged. I tweaked the load block and brought it back up in RPM. I figured since the last time I didn't run the microwave I would try that, also. I started the microwave up and it lugged a bit more, but it held it.

The kicker to the testing is I did not have a way to meter the loads so I am unable to tell you how many amps I was drawing or how many watts were being consumed - but the notable loads were 2x AC units*, microwave, electric clothes dryer (on reg heat, not low), and other regular house loads.

*The 2x AC loads were started first - so the compressors were already running when the other loads (dryer and microwave) were on so the start up loads of the AC's (neither has soft-start) were not at the same time the other heavy loads were running. I am positive the start up load, specifically of the central AC, will make a significant difference - perhaps enough to overload it.

The main breaker on the gen is a 50 amp and the feeder breaker on the panel is also 50 amp. No breakers blew. The only notable lack of "performance" was the lugging of the engine that was apparent this round running NG whereas it did not on gasoline.

In the testing I did I did not measure voltage and frequency. I was on a time crunch towards the end of the day. When I get to working with the unit and tweaking stuff again next, if I can load test, perhaps I can do some more data analysis on the numbers, waveforms, etc.

Also in relation to loads - in practice the last thing we would run if we were on generator power is the clothes dryer. Its only purpose in the test was just that - testing. I wanted to throw as much at it as I could just to see what happened. To that point - it held and I find that remarkable!


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## iowagold (Jan 22, 2020)

do you have a gauge for the NG?
you need to be able to check both the pressure and the suction from the system.
pm me for the details


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## ToolLover (Jan 13, 2020)

Seems to be missing a pre regulator on that supply line.
Without the pre regulator you have possiblly blown your generator mounted regulator.
The proper plumbing should be:
Pre regulator at the supply set for 5 to 7 inches of H2O,
cut off valve after the supply regulator,
hose to a cutoff at the generator mounted regulator,
out of generator mounted regulator then to the flow adjustable screw,
(This is where you set the frequency of the generator)
then to the connection to the carburator.
Add some quick connectors too.
add to that you need a transfer switch for the breakers you plan to energize while you are without utility power.


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## FlyFisher (Jun 30, 2018)

iowagold said:


> do you have a gauge for the NG?


I do not have one. 

The valve the plumber installed has a port for a gauge. Looks like the meter port is 1/8". I can detail the threads when I get that far. 





AY MCDONALD 560BC 1 FIP 175PSIG BLACK IRON FLAT HEAD LOCKWING GAS METER PLUG VALVE WITH 1/8 TEST PLUG ON INLET at http://rexpipelorain.com


AY MCDONALD 560BC 1 FIP 175PSIG BLACK IRON FLAT HEAD LOCKWING GAS METER PLUG VALVE WITH 1/8 TEST PLUG ON INLET at http://rexpipelorain.com




rexpipelorain.com


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## FlyFisher (Jun 30, 2018)

ToolLover said:


> Seems to be missing a pre regulator on that supply line.
> Without the pre regulator you have possiblly blown your generator mounted regulator.


There is a pressure reg for the whole house feed - that is what is at 7in WC per the utility company. The input pressure is up to 14in WC for the demand reg on the unit - so 7in WC is well under its rating. I don't see any reason why a "pre regulator" would be required? I suppose if we were at 2psi utility service then I would need a secondary step down reg to drop the 2psi down to 7-14in WC - but we're already there so whats the point? That just seems like unnecessary restriction.

Going back to the issue with the demand reg I have in-line - it appears to be too much restriction. If the regulator was blown I would think it wouldn't restrict as well. That having been said, again, when I push the primer button in on the demand reg I can get the engine to run fine. When I let off of the primer and let the regulator do its thing the engine is immediately starved of fuel. 

Maybe I am not getting enough draw/vacuum on the demand reg from the engine? This would be the opposite of there not being enough "pressure" - but both might be related to the size of the plumbing from the outlet of the demand reg to the fuel port on the gas manifold.



ToolLover said:


> The proper plumbing should be:
> Pre regulator at the supply set for 5 to 7 inches of H2O,
> cut off valve after the supply regulator,
> hose to a cutoff at the generator mounted regulator,
> ...


The electric valve, in the picture of how I had things set with the regulator bypassed, is the cut off valve - automatic (manual bypass to start). The yellow valve was the original "cut off" valve, but when I went to testing everything and decided to try bypassing the demand reg I needed a way to cut the gas off if the unit shut down = where the electric valve comes in.



ToolLover said:


> Add some quick connectors too.
> add to that you need a transfer switch for the breakers you plan to energize while you are without utility power.


Quick connectors - don't like them. The one on the grill leaks. I prefer threaded connections. 

As to transfer switch on select circuits - that complicates things too much and we have things that run on nearly every circuit anyway. So it would be pointless as we'd end up duplicating them. Running through the main panel works just fine.


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## ToolLover (Jan 13, 2020)

@ Flyfisher
You live and learn and sometimes you have to learn the hard way.
I got the Honda from a deceased friends wife and it was the one that I installed the regulator on it for a propane tank.
The propane feed had a preregulator for the tank.
The NG feed was set at 2 PSI.
So I decided to connect the Honda regulator to the 2 PSI that was fed from the meter so to have more gas flow to the regulator on the Honda.
All the time thinking that was the thing to do.
Well I got nothing but a failed regulator on the Honda.
Makes no sense to me, but for some reason the 2 PSI wiped out the Honda regulator.


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## iowagold (Jan 22, 2020)

FlyFisher said:


> There is a pressure reg for the whole house feed - that is what is at 7in WC per the utility company. The input pressure is up to 14in WC for the demand reg on the unit - so 7in WC is well under its rating. I don't see any reason why a "pre regulator" would be required? I suppose if we were at 2psi utility service then I would need a secondary step down reg to drop the 2psi down to 7-14in WC - but we're already there so whats the point? That just seems like unnecessary restriction.
> 
> Going back to the issue with the demand reg I have in-line - it appears to be too much restriction. If the regulator was blown I would think it wouldn't restrict as well. That having been said, again, when I push the primer button in on the demand reg I can get the engine to run fine. When I let off of the primer and let the regulator do its thing the engine is immediately starved of fuel.
> 
> ...


if the diaphragm is blown on the demand reg it will not open the NG demand valve flow.
or it could be off on the factory setting.
they set those with the BIG test bench not a field adjustable thing.

some where i have training diagrams on those demand regulators...
easy to rebuild them.

suction on the outlet trips the spring to flow.
so if you have the meter for suction you can check the suction signal on the conversion plate.

was this a home made plate?


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