Generac or Koehler whole house generator?

[ponytug]

Not sure if you’re responding to my post…. If you are, The two numbers I circled, where at least one of them must be wrong, are both labeled NG

I don't know if the numbers are right or not, but due to ignition issues, natural gas engines do not throttle back their fuel intake as much as propane or gas. It gets too dilute to ignite.

So I might believe that the numbers are in fact correct.

All the best,

Peter

 

[DarkBlack]

I don't know if the numbers are right or not, but due to ignition issues, natural gas engines do not throttle back their fuel intake as much as propane or gas. It gets too dilute to ignite.

So I might believe that the numbers are in fact correct.

All the best,

Peter

Those two numbers show a 100% increase output for only 25% more fuel (50% load vs 100%).

100% load is typical a bit more efficient than 50%, but not by that much. You can see it disagrees with the other 50 vs 100% load numbers, that are reasonable.
One of those numbers is definitely bogus

 

[ponytug]

Natural Gas seems like the best fuel because it shouldn't run out. I understand that something can happen to the pipeline, but there are more chances that you won't be able to get gas, diesel or propane then the Natural Gas Line not supplying it.

MY current generator is a 10,000 watt starting 8,000 watt running Champion generator that also used propane, but the rating decreases to 9,000 watt starting and 7,200 watt running rating. I have several propane bottle for it because it can be challenging getting gasoline here when we have a Hurricane/Tropical Storm, or even worse, an ice storm that closes the roads. When the power is out, most of the gas stations shut down because they do not have generators. The last outage, I had four 5 gallon gas cans filled up and I used 3 of them. A couple years ago, we lost power for a week because of an ice storm, and I used up all my gasoline and didn't have any propane, so I had to drive around to find an open gas station. I think I found gasoline somewhere around my 20th gas station.

For me, if I'm going to spend the money on a whole house system, I want it to run off of Natural Gas.

I've written it before, but I think it bears repeating for anyone thinking of natural gas powered generators, but especially for Texans.

Texas has had more than a few ice and snow storms that have frozen natural gas compressors. So, when the need natural gas is the greatest for heat and for backup, there is a likelihood that natural gas won't be available. From the reports that I have been reading, the gas suppliers are dragging their feet about the necessary upgrades.

Propane and diesel are relatively easy to stockpile, and as the "fuel overseer" you know what you have. I think that natural gas is a pig in a poke as far as being a backup energy source. You might have it, you might not.

All the best,

Peter

 

[ponytug]

Those two numbers show a 100% increase output for only 25% more fuel (50% load vs 100%).

100% load is typical a bit more efficient than 50%, but not by that much. You can see it disagrees with the other 50 vs 100% load numbers, that are reasonable.

Try thinking of it the other way around; dropping from a 100% to 50%, natural gas can't throttle back very much, or the engine stalls. So, 50% load is very inefficient (kWh/therm) for a natural gas engine, compared to kWh/therm at 100%.

Propane can throttle down better, gasoline even better, and diesel best of all. It is a question of the lower limit for combustion, and if the fuel gets too lean, it won't ignite and the engine dies.

Flammability limit - Wikipedia

en.wikipedia.org

Natural gas needs to be at a minimum of 5% to ignite, while propane is just over 2.1%, gasoline 1.4%.

Does that make more sense?

All the best,

Peter

 

[DarkBlack]

Try thinking of it the other way around; dropping from a 100% to 50%, natural gas can't throttle back very much, or the engine stalls. So, 50% load is very inefficient (kWh/therm) for a natural gas engine, compared to kWh/therm at 100%.

Propane can throttle down better, gasoline even better, and diesel best of all. It is a question of the lower limit for combustion, and if the fuel gets too lean, it won't ignite and the engine dies.

Flammability limit - Wikipedia

en.wikipedia.org

Natural gas needs to be at a minimum of 5% to ignite, while propane is just over 2.1%, gasoline 1.4%.

Does that make more sense?

All the best,

Peter

You’re just digging yourself in a deeper hole. Don’t try to reverse engineer a misprinted, or miss-written bogus number.

The 13 kw NG numbers I’ve now circled in blue look reasonable.
See the difference?
Now look again at the 10 kw numbers. You really think you can get double the power for only 25% more fuel…and at maximum load?
Of course not. ICE engines don’t work like that.

 

[D&D]

I've written it before, but I think it bears repeating for anyone thinking of natural gas powered generators, but especially for Texans.

Texas has had more than a few ice and snow storms that have frozen natural gas compressors. So, when the need natural gas is the greatest for heat and for backup, there is a likelihood that natural gas won't be available. From the reports that I have been reading, the gas suppliers are dragging their feet about the necessary upgrades.

Propane and diesel are relatively easy to stockpile, and as the "fuel overseer" you know what you have. I think that natural gas is a pig in a poke as far as being a backup energy source. You might have it, you might not.

All the best,

Peter

This is what’s left of a natural gas leak near Belair, Md Sunday morning.

 

[ning]

I've written it before, but I think it bears repeating for anyone thinking of natural gas powered generators, but especially for Texans.

Texas has had more than a few ice and snow storms that have frozen natural gas compressors. So, when the need natural gas is the greatest for heat and for backup, there is a likelihood that natural gas won't be available. From the reports that I have been reading, the gas suppliers are dragging their feet about the necessary upgrades.

Propane and diesel are relatively easy to stockpile, and as the "fuel overseer" you know what you have. I think that natural gas is a pig in a poke as far as being a backup energy source. You might have it, you might not.

All the best,

Peter

Are there dual-fuel NG/Propane generators which can use either, easily? If so, one could size the genset for NG, and use it if it's available, and switch to hoarded stockpiled propane if needed. Alternately, one could have a conversion kit handy as well.

 

[ponytug]

Are there dual-fuel NG/Propane generators which can use either, easily? If so, one could size the genset for NG, and use it if it's available, and switch to hoarded stockpiled propane if needed. Alternately, one could have a conversion kit handy as well.

I know that Generac has them, but I haven't seen many others, as generally the orifice needs to be switched to account for the different fuel contents of the gases. So for non-Generac units, doable, but you would need both orifices and the owner might need to tweak the regulator settings on the generator for the difference in fuel content. Generac uses the engine ECU to control a solenoid needle valve to meter fuel for the target oxygen level in the exhaust. (I think that it is a pretty clever use of some emissions information that was being collected anyway, but I'm easily amused.)

All the best,

Peter

 

[ning]

You’re just digging yourself in a deeper hole. Don’t try to reverse engineer a misprinted, or miss-written bogus number.

View attachment 898608

The 13 kw NG numbers I’ve now circled in blue look reasonable.
See the difference?
Now look again at the 10 kw numbers. You really think you can get double the power for only 25% more fuel…and at maximum load?
Of course not. ICE engines don’t work like that.

ICE engines don't... unless you have strict RPM requirements.
Here's another similar table straight out of a generator's spec sheet:

On this one, going from 50% load to 100% (ie, an increase of 100% load) takes 50% more fuel. Granted it's not as bad as the previous table, but look at the rest of the jumps.

"Exercise" is basically a no-load run, and it still takes 1/4 of the full load fuel requirement.
Basically like if I put my car in neutral and push the gas down until the engine's running at 3600RPM.

 

[newbury]

Are there dual-fuel NG/Propane generators which can use either, easily? If so, one could size the genset for NG, and use it if it's available, and switch to hoarded stockpiled propane if needed. Alternately, one could have a conversion kit handy as well.

They make tri-fuel kits (gasoline, propane, natural gas). Don't know of any that will use diesel and something else.