LP Powered Whole Home Generator

[jade97]

LP Powered Whole Home Generator

Is an LP engine affected by temperature and humidity like a gasoline engine? ie vapor lock, etc.

I have a Generac 38kw, with a water-cooled 4cyl turbo Mitsubishi engine.

We were w/o power this week for about 32 hours and occasionally it sounded like my generator would randomly "hiccup" and the lights would flicker.

I would assume, if I was overloading it, I would hear the engine sound like it was going under load, not popping or hiccup.

Again, this is a 38kw. I had some lights, heat pump (AC mode) and the refrigerators and freezer. It only seemed to exhibit this behavior between say ,,5pm and 9pm.

When it was installed, the vendor turned on everything in the house and it didn't slow down one bit.

Also, when we had power outages in the winter, is have the heat going, stove, oven, washer and dryer....no problem.

Weird.

 

[mike93lx]

Holy smokes. 38kw for just that stuff? Why?

 

[Chuckster in NJ]

Holy smokes. 38kw for just that stuff? Why?

Lottery winner?

 

[tarmy]

That is twice the size of my whole home…and I run TWO A/C units and all the rest of the normal stuff and mine works great. You got something else going on with a unit that big there should be no bogging based upon a home load (unless A/C, welder, pool pump, sewage pump and a marina suppling power to a houseboat….).

 

[bronc076]

Should be no problem with vapor lock as propane is delivered to the engine as a gas, not a liquid.

Does it have a dedicated LP tank? Properly sized regulator? Are there any other LP appliances kicking on and causing brief moments of fuel starvation?

 

[Shiftless]

Does it have a dedicated LP tank? Properly sized regulator? Are there any other LP appliances kicking on and causing brief moments of fuel starvation?

That’s all I could think of as well.
Even with all of your household stuff drawing power, you could still charge an EV or 2 and not exceed your 38 KW. rating.

 

[jade97]

My house is all electric, including the fireplace. Electric appliances, heat pump, well pump, septic, yada, yada, yada. Built with a 400 amp electrical service. We get outages frequently and if I am traveling for work, I didn't want my wife and kids to try to figure out load shedding, etc.

I have a 500 gallon dedicated LP tank for the generator.

I did have the regulator replaced last year because the original crapped out, allowing the pressure to exceed what the solenoid could handle to open when the generator would try to start. I will take a look at the brand & on of the replacement regulator.

Like I tried to mention, it didn't sound like it was bogging down, it would randomly "hiccup" or make a popping sound (like a miss). This wasn't happening through out the entire outage.

 

[AA/FC]

How many hours on the engine? Has it ever had an ignition system tune-up? Cap, rotor, wires, plugs, etc....

 

[Chuckster in NJ]

My house is all electric, including the fireplace. Electric appliances, heat pump, well pump, septic, yada, yada, yada. Built with a 400 amp electrical service. We get outages frequently and if I am traveling for work, I didn't want my wife and kids to try to figure out load shedding, etc.

I have a 500 gallon dedicated LP tank for the generator.

I did have the regulator replaced last year because the original crapped out, allowing the pressure to exceed what the solenoid could handle to open when the generator would try to start. I will take a look at the brand & on of the replacement regulator.

Like I tried to mention, it didn't sound like it was bogging down, it would randomly "hiccup" or make a popping sound (like a miss). This wasn't happening through out the entire outage.

Has ALL the piping been properly sized?
Do you have "full open bore" valves installed?
Have you checked the gas pressure while it has been running at full load?

 

[Metal-Marc]

Holy smokes. 38kw for just that stuff? Why?

OP has his own personal aluminum foundry.

 

[jade97]

I'll have to send pictures of the piping. Between the regulator and the generator, they installed a 2-3ft section of 2" pipe, which I believe is to have an extra volume of gas available for when the unit starts up. The only valves are shut off at the tank, before the regulator at the house and the solenoid valve in the generator.

This was installed in March 2018, we've had multiple outages and this was the first time I experienced this issue.

I have not checked the pressure since this occured.

One thing I just thought of but didn't check out...my tank is in ground and the storm had torrential down pours. Maybe the shroud around the fill port and tank regulator was filled with rain water and couldn't vent?

 

[bluedog225]

I’d also wonder about freezing with high flow.

 

[bronc076]

How many hours on the engine? Has it ever had an ignition system tune-up? Cap, rotor, wires, plugs, etc....

This was installed in March 2018, we've had multiple outages and this was the first time I experienced this issue.

I have not checked the pressure since this occured.

6 years old, you should probably get your generator guy out there to check it out. I assume you have regular maintenance performed on it. You might have a coil going south or something. I'd imagine it's computer controlled so it might have an error code of some sort, like what triggers the check engine light in a modern car. I've not worked on a modern generator so I'm not sure what method of engine control it has but it could be a failing component and not a fuel problem at all. Best get it looked at now.

 

[jade97]

Yes, I'm under a maintenance contract, so I'll have them look at it. What ***** is the warranty ran out at 5 years.

 

[walta]

LP Powered Whole Home Generator

Is an LP engine affected by temperature and humidity like a gasoline engine? ie vapor lock, etc.

Propane can have the opposite of a vapor lock. The propane is a liquid in the tank but you use the gas as the liquid boils and becomes a gas it absorbs heat and the tank gets cooler if you try to remove too much gas to quickly from too small of a tank in cold weather one can freeze the tank and or regulator.

If the problem was happening on a cold night in Maine with a small above ground tank, then maybe but the pro installers don’t make that type of mistake.

I have a Generac 38kw, with a water-cooled 4cyl turbo Mitsubishi engine.

We were w/o power this week for about 32 hours and occasionally it sounded like my generator would randomly "hiccup" and the lights would flicker.

I would assume, if I was overloading it, I would hear the engine sound like it was going under load, not popping or hiccup.

Again, this is a 38kw. I had some lights, heat pump (AC mode) and the refrigerators and freezer. It only seemed to exhibit this behavior between say ,,5pm and 9pm.

When it was installed, the vendor turned on everything in the house and it didn't slow down one bit.

Also, when we had power outages in the winter, is have the heat going, stove, oven, washer and dryer....no problem.

Weird.

Seems like you spent a pretty penny on this very nice gen set and the smart move is to describe the symptoms you were having to the pros that installed it and let them diagnose the fault. I find it insulting what part needs to be replaced.

Silly question, how sure are you the tank has enough fuel?

Yes, a regulator submerged in muddy water would be a problem.

 

[rmanrman]

500 gallon propane tank will not freeze up when used with a propane generator
I have a 1000 gallon tank and only once the shroud where the regulator lives was full of rainwater it flooded the regulator vent and it was starving for fuel. I’d replace the regulator

 

[mm08822]

Check the vents on both the hi and lo pressure regs. Water or nesting material in the vent will lockup the regulator.
If your unit has demand regulator check it too.

Make sure your tanks are full enough and note the current pressure. Ask your supplier what is the min tank pressure for the consumption rate of your gen.
How long total has it been running during this storm and when the hiccups start?

Get a 0-30" h20 gauge and check pressures while running and adding loads.

Does this unit require valve clearance adjustments like the air-cooled units?

 

[jade97]

Vents are clear. I'm not dismissing the possibility that the shroud filled with water, especially with the amount of rain that came down.

There is no cap & rotor to replace. This Mitsubishi uses a crank position sensor and coil pack.

The gas gauge is showing about 58% full.

 

[jade97]

 

[dave*99]

I see you have one of those seven ten caps.




Funny Story:
The other day I was in the local auto part store. A lady comes in and asks for a seven ten cap. We all looked at each other and said, "What's a seven ten cap?" She said "You know, it's right on the engine. Mine got lost some how and I need a new one." "What kind of a car is it on," they asked? I'm thinking maybe an old Datsun Seven Ten, but no, she said its a Buick. "OK lady, how big is it?" She makes a circle with her hands about 3-1/2 inches in diameter. What does it do?," we asked. She said, "I don't know, but it's always been there." One of us gave her a note pad and asked her if she could draw a picture of it. So she makes a circle about 3-1/2 inches in diameter and in the center she writes 710. The guys behind the counter are looking at it upside down as she writes it...and they just fall down behind
the counter laughing so hard in hysterics.


On a serious note - while that flexible line is short, it looks a bit small in diameter compared to the size of the pipe before it. Is your misfire related to load? Does it get worse with higher load?

 

[jade97]

The only thing that has changed since it was installed was the green regulator on the house, because the old one no longer regulated...

 

[Firebrick43]

The only thing that has changed since it was installed was the green regulator on the house, because the old one no longer regulated...

The kosan is an ok regulator, and it has a 1,400,000 btu capacity so it should be fine with capacity. And whomever did it used one with a Dielectric union so they have half a clue.

The 1st stage rego regulator at the tank has 1,500,000 btu capacity. The way either is installed your not going to have a water issue with them.

They installed the recommended 5' of black iron pipe between the regulator and generator, and even over sized it.

A buried tank like you have will never have issues with withdraw rates unless you live in international falls in feb.

If your maintaining 10.5" of WC at the test port of the second stage regulator your problem should be in the generators fuel system or ignition.

 

[PCustoms]

That entire length of galvanized pipe after the 2nd stage regulator looks wrong to me.

• Debatable if galvanized should be used in place of black iron
• Drip leg is in the wrong spot
• Random black iron thrown in the middle and painted?
• Flex line looks small

I'd call for a service and possibly change the pipe layout to keep **** out of the generator. Could be having some issues based on gunk in the line or need some adjustments due to age.

 

[Firebrick43]

That entire length of galvanized pipe after the 2nd stage regulator looks wrong to me.

• Debatable if galvanized should be used in place of black iron
• Drip leg is in the wrong spot
• Random black iron thrown in the middle and painted?
• Flex line looks small

I'd call for a service and possibly change the pipe layout to keep **** out of the generator. Could be having some issues based on gunk in the line or need some adjustments due to age.

Galvanized is perfectly fine for propane, by code, as long as it meets A53/A53M specs. NG is the one that attacks galvanized pipe. NFPA 58


Flex line is usually provided by the generator manufacture. It looks small because they oversized the iron pipe.

The paint looks like cold galvanizing to me.

 

[PCustoms]

Galvanized is perfectly fine for propane, by code, as long as it meets A53/A53M specs. NG is the one that attacks galvanized pipe. NFPA 58

Sure. But the pipe looks odd to me, almost like it's RMC...

Flex line is usually provided by the generator manufacture. It looks small because they oversized the iron pipe.

Really? All the installs around here are hard piped. It looks small to me, but that's based on the size I had to use on my on demand water heater to hit the BTU/hr rate.

The paint looks like cold galvanizing to me.

Sure..but why randomly add black pipe fittings into a galvanized run?

And what's with the drip leg?

 

[Firebrick43]

Sure. But the pipe looks odd to me, almost like it's RMC...

It looks like its electrogalvanized. Without looking at the stampings the pic really doesn't confirm if its RMC or A53 to me

Really? All the installs around here are hard piped. It looks small to me, but that's based on the size I had to use on my on demand water heater to hit the BTU/hr rate.

Every generac and kohler I have installed recently have had a flexible fuel line with the generator and require 5' of hard line beyond that according to the manufactures instructions. If they are not installing them they are not following the manufactures instructions.

Sure..but why randomly add black pipe fittings into a galvanized run?

I don't know, technically not a code violation. One county here requires all gas pipe outdoors to be painted grey. Why gray we have not been able to get out of them. But yellow, the standard color is not acceptable to them and they will fail it if not grey.

The installer really should have painted it all one color for craftsmanship reasons alone.

And what's with the drip leg?

That is what is known as a drip Tee. It is properly sized in diameter and placed correctly. Its only for moisture as opposed to a sediment trap that most call a drip leg.

LP generators don't actually require a sediment trap as they have one installed inside the onboard regulator (B)

 

[mike93lx]

The installer really should have painted it all one color for craftsmanship reasons alone.

The paint won't really stick to the gslv:d section, though, right?

 

[Firebrick43]

The paint won't really stick to the gslv:d section, though, right?

scuff it up or use ospho it will

 

[jade97]

If I remember correctly, they used some kind of galvanized type spray paint on the pipe threads that they cut. I do not believe they used black pipe fittings.

 

[brewchief]

Does the hiccup happen right as the AC kicks on? That would be a big load that quickly lessens so the generator would get loaded down then have to quickly throttle back.

 

[jade97]

No, the AC was running for probably 2-3 hours at that point.

 

[PCustoms]

Delete

 

[Firebrick43]

No, the AC was running for probably 2-3 hours at that point.

A compressor capacitor starting to go bad certainly could cause higher than normal amp draw? They will act up more when they are good and hot before they completely give up. Such as when the hot evening sun starts shining on the outside unit?

 

[jade97]

A compressor capacitor starting to go bad certainly could cause higher than normal amp draw? They will act up more when they are good and hot before they completely give up. Such as when the hot evening sun starts shining on the outside unit?

Ill have to take a look at that. Never crossed my mind.

 

[My Old Tools]

I have the same genny about 15 years older. I hear mine give a little hiccup every once in awhile. Mine is piped with 20 feet of 5/8 copper from the tank and only one reg at the tank. It works fine. The only issue I have had with mine was a couple of years ago when we went to minus 12 degrees for 3 days. The PVC valve froze and pumped all the oil out the dipstick. The oil pressure switch shut it down. That little Mitsubishi motor is the same they used for years in their small trucks, except they added a turbo to the big gennys. It's pretty bullet proof.

 

[bronc076]

Jade97

In one of your pictures it looks like a harness from what I believe is the ecu is touching the radiator, it's hard to tell but you might check for chafing. Give it all a good physical inspection, might be something simple like a rubbed wire intermittently grounding out. That unit looks pretty clean and it sounds like you have a solid propane install from the posts above.

 

[jade97]

I'll double check it again, but it appeared that the loom is protecting the wires.

 

[u3b3rg33k]

Should be no problem with vapor lock as propane is delivered to the engine as a gas, not a liquid.

Does it have a dedicated LP tank? Properly sized regulator? Are there any other LP appliances kicking on and causing brief moments of fuel starvation?

right but it has to boil off SOMEWHERE (in the tank) for that to happen. you could live somewhere cold enough where you can stand outside and hold a cup of LP (-44F, I believe).

Doubt that's the issue here.

as for sizing, 38kW = 158 Amps 240V. MIGHT be big enough you don't need load shedding by code/mfg recommendation for a 200A whole house transfer switch.

 

[jade97]

right but it has to boil off SOMEWHERE (in the tank) for that to happen. you could live somewhere cold enough where you can stand outside and hold a cup of LP (-44F, I believe).

Doubt that's the issue here.

as for sizing, 38kW = 158 Amps 240V. MIGHT be big enough you don't need load shedding by code/mfg recommendation for a 200A whole house transfer switch.

I have a 400A transfer switch. The builder installed a 400A service on the house.

 

[u3b3rg33k]

I have a 400A transfer switch. The builder installed a 400A service on the house.

my point is more that most generator contractors won't install a generator that can't run your calculated loads unless you have a way to load-shed (or upsize until you don't need to).

e.g. the generator needs to be able to start both ACs with your oven and dryer running, or something has to mange the loads so the generator doesn't trip out/stall/undervolt.

400A is nice!