Can I revisit wet stacking?

[Summerpaws]

First, before I get to my question, let me tell you a bit about myself. I am a retired mechanic/stationary engineer. I retired from a large manufacturing company (1 million square feet). The company was founded and owned by a gentleman who was an officer on a carrier in the Navy. His dream was to build a company that was isolated from any utilities. That meant it had a power plant, wells, LNG and propane and diesel storage. When I started there in 1982, the power came from 4 Caterpillar 399 750kw co-gen generators and 2 398 500kw co-gens. Shortly after that we added a 2mw Fairbanks Morse OP gas/diesel co-gen unit. In 2000 we got rid of the FM and added the first 5mw Solar gas turbine (also co-gen) with plans to add a 2nd in 10 years.
Our goal was to keep each generator at 100% load. Obviously they were most efficient there as well as providing the most heat for the low pressure steam boilers that the exhaust ran. Obviously that wasn't as critical when we got the gas turbine but we still wanted at least 50% load on it. My job was to operate the plant in the most efficient manner by adding or dropping generators and in some cases, load shedding.
I knew about wet stacking of course, but I never saw it.
Now, my situation. I have a MEP 802a. It is wired into the house with the use of an interlock. I have done a lot of testing to see what my house draws for power. I chose the 5kw 802 because it would be much easier to load it appropriately even though I could easily overload it if the power demands were not controlled.
On a normal day, the house draws roughly 750w. That is my 120 volt load. I have sump pumps and in the summer, a/c, but that only adds maybe 1000 to 1200 watts. The sump pumps cycle maybe 5 times an hour for less than a minute each time.
My wife does a load of laundry once a day. Our dryer uses close to 3000 watts. I have an electric water heater (4500 watts). Stove and oven are the only other high loads. Obviously I manage the load and usually leave the 230 volt breakers off with the exception of the stove/oven.
Let's say we have a small 4 hour outage. No load on the genny higher than 1750 to 2000 watts. That is my usual outage. How many of these small outages do I have to have before it's necessary to load up the genset and clean it out? I have read through over 200 pages of this forum and it seems that most folk do a run with a load bank every 3 months or so. I want to set up a schedule to run at 100% for a couple of hours but I am not sure how often I should do it.
I usually lose power 4 or 5 times a year, usually for the afore mentioned 3 or 4 hours. I live next to a swamp in a 200 year old farmhouse and I cannot go without power for more than an hour due to the amount of water that pours into my dirt floor basement. Right now, with all the rain we have had (and 3 sump pumps running), more like 1/2 hour.
How long does it take to start wet stacking? I know it's cumulative, but how many hours with a light load until there is performance limiting carbon buildup?

 

[Guyfang]

Well, thats hard to say. But if I ran a gen set for a week or two at low loads, I would maybe think about hooking up a load bank or some type of load and run it for a few hours at as close to 100% load as I could. But its not all that critical. You are not going to kill your gen set. But I see it from another side that most folks here have never seen. We ran 24/7, 365 days a year. Turning something off was often not an option. Adding load was also not an option. Some of our equipment did not draw a lot of load, unless someone was trying to kill you. THEN it would over load, and shut down. So we accepted some wet stacking, and when we could swap a gen set, we did a service and pumped up the load for 6-8 hours to 100%. That took care of wet stacking. Your few times a year, and the few hours you run it, really is no big deal. If thats all the the accrued time, I would suggest one time a year to load it up and clean things up.

I know there will be people that want to burn a cross on my lawn now. But its a long swim here!

 

[Summerpaws]

Well, thats hard to say. But if I ran a gen set for a week or two at low loads, I would maybe think about hooking up a load bank or some type of load and run it for a few hours at as close to 100% load as I could. But its not all that critical. You are not going to kill your gen set. But I see it from another side that most folks here have never seen. We ran 24/7, 365 days a year. Turning something off was often not an option. Adding load was also not an option. Some of our equipment did not draw a lot of load, unless someone was trying to kill you. THEN it would over load, and shut down. So we accepted some wet stacking, and when we could swap a gen set, we did a service and pumped up the load for 6-8 hours to 100%. That took care of wet stacking. Your few times a year, and the few hours you run it, really is no big deal. If thats all the the accrued time, I would suggest one time a year to load it up and clean things up.

I know there will be people that want to burn a cross on my lawn now. But its a long swim here!

Thanks Guy. That's basically what I was wondering. How quickly these things build carbon deposits. Before the 802, I ran my house from the generator in my motorhome. 5500 watt gasoline Onan. 120 volt only. I kept records of run time. Last year it ran 17 hours. Mostly because I went to bed and it ran until I woke up. That poor Onan has saved my butt over the years. I've had it since 2002. It's ran 10 days straight for an ice storm and multiple nor'easters. It has 1700 hours on it and I really don't think I can rely on it like I can for the MEP. Plus the motorhome is going up for sale shortly.

 

[2Pbfeet]

Thanks Guy. That's basically what I was wondering. How quickly these things build carbon deposits. Before the 802, I ran my house from the generator in my motorhome. 5500 watt gasoline Onan. 120 volt only. I kept records of run time. Last year it ran 17 hours. Mostly because I went to bed and it ran until I woke up. That poor Onan has saved my butt over the years. I've had it since 2002. It's ran 10 days straight for an ice storm and multiple nor'easters. It has 1700 hours on it and I really don't think I can rely on it like I can for the MEP. Plus the motorhome is going up for sale shortly.

FWIW: a while back, I bought a used Onan 5500 with close to 5000 hours on it. It didn't run that well and smoked a bit. I serviced the fluids, add carb cleaner to the fuel tank, changed the filters and spark plug, started it up (smoking), then gradually loaded it up to full load and ran it for a couple of hours at full load, and it hasn't smoked since. I suspect that the prior owners ran it at a low load for a long period of time.

I think that there is a huge difference in the build quality of those air cooled gasoline Onans and the military 80X generators. I tend to believe that quality diesel and SeaFoam or other lubricity enhancers are your friends, as these gensets weren't designed for modern ULSD.

All the best,

2Pbfeet

 

[Summerpaws]

FWIW: a while back, I bought a used Onan 5500 with close to 5000 hours on it. It didn't run that well and smoked a bit. I serviced the fluids, add carb cleaner to the fuel tank, changed the filters and spark plug, started it up (smoking), then gradually loaded it up to full load and ran it for a couple of hours at full load, and it hasn't smoked since. I suspect that the prior owners ran it at a low load for a long period of time.

I think that there is a huge difference in the build quality of those air cooled gasoline Onans and the military 80X generators. I tend to believe that quality diesel and SeaFoam or other lubricity enhancers are your friends, as these gensets weren't designed for modern ULSD.

All the best,

2Pbfeet

I am religious on maintenance. I haven't had any issues with mine with the exception of the drive belt between the engine and the generator head. Around 300 hours it shut down and the fault code wasn't helpful. I ended up pulling the set from the motorhome and found the drive belt shredded. Looking at the pulleys I saw that the belt had been installed incorrectly from the factory. Half off the pulleys. I replaced the belt and the idler and it's been fine since. It's weird generator. It has 2 separate windings in the generator. One set is 3000 watts, the other 2500. I use the 3000 watt set to run the house. Never strained it but when a sump pump kicks on you know. It's also not real clean power. You can hear it on any electric motor.

 

[MatthewWBailey]

First, before I get to my question, let me tell you a bit about myself. I am a retired mechanic/stationary engineer. I retired from a large manufacturing company (1 million square feet). The company was founded and owned by a gentleman who was an officer on a carrier in the Navy. His dream was to build a company that was isolated from any utilities. That meant it had a power plant, wells, LNG and propane and diesel storage. When I started there in 1982, the power came from 4 Caterpillar 399 750kw co-gen generators and 2 398 500kw co-gens. Shortly after that we added a 2mw Fairbanks Morse OP gas/diesel co-gen unit. In 2000 we got rid of the FM and added the first 5mw Solar gas turbine (also co-gen) with plans to add a 2nd in 10 years.
Our goal was to keep each generator at 100% load. Obviously they were most efficient there as well as providing the most heat for the low pressure steam boilers that the exhaust ran. Obviously that wasn't as critical when we got the gas turbine but we still wanted at least 50% load on it. My job was to operate the plant in the most efficient manner by adding or dropping generators and in some cases, load shedding.
I knew about wet stacking of course, but I never saw it.
Now, my situation. I have a MEP 802a. It is wired into the house with the use of an interlock. I have done a lot of testing to see what my house draws for power. I chose the 5kw 802 because it would be much easier to load it appropriately even though I could easily overload it if the power demands were not controlled.
On a normal day, the house draws roughly 750w. That is my 120 volt load. I have sump pumps and in the summer, a/c, but that only adds maybe 1000 to 1200 watts. The sump pumps cycle maybe 5 times an hour for less than a minute each time.
My wife does a load of laundry once a day. Our dryer uses close to 3000 watts. I have an electric water heater (4500 watts). Stove and oven are the only other high loads. Obviously I manage the load and usually leave the 230 volt breakers off with the exception of the stove/oven.
Let's say we have a small 4 hour outage. No load on the genny higher than 1750 to 2000 watts. That is my usual outage. How many of these small outages do I have to have before it's necessary to load up the genset and clean it out? I have read through over 200 pages of this forum and it seems that most folk do a run with a load bank every 3 months or so. I want to set up a schedule to run at 100% for a couple of hours but I am not sure how often I should do it.
I usually lose power 4 or 5 times a year, usually for the afore mentioned 3 or 4 hours. I live next to a swamp in a 200 year old farmhouse and I cannot go without power for more than an hour due to the amount of water that pours into my dirt floor basement. Right now, with all the rain we have had (and 3 sump pumps running), more like 1/2 hour.
How long does it take to start wet stacking? I know it's cumulative, but how many hours with a light load until there is performance limiting carbon buildup?

For what it's worth, we used to perform 100% load testing on pump station backup gens and the spec was every 5 years. The EPA required (then and now) that sewage pump station backup gens ran 8hrs a month for "exercising", but not required to be loaded. So 8*12=96 hrs a year of non loaded exercising. x5 = 480hrs. So every 500hrs of lite operation would be my lowest number for gen load bank testing.

 

[Summerpaws]

For what it's worth, we used to perform 100% load testing on pump station backup gens and the spec was every 5 years. The EPA required (then and now) that sewage pump station backup gens ran 8hrs a month for "exercising", but not required to be loaded. So 8*12=96 hrs a year of non loaded exercising. x5 = 480hrs. So every 500hrs of lite operation would be my lowest number for gen load bank testing.

Good to know. I think it's safe to say that if I load bank this thing hard once a year I should be good to go. If I do get a prolonged power failure, it will run at near 100% within 24 hours because I'll switch on the breaker for the water heater and my wife will have done a load of laundry.
I had 2 fire pump stations for the plant and every Sunday they were run for a 1/2 hour. Both were old Cummins non turbos. One was a 1968 and the other a 1980. Both were serviced once a year and still looked brand new. Never even thought about wet stacking on them

 

[MatthewWBailey]

Well if you run it like that, you've essentially "load tested" it. 100% is 100%.

 

[Summerpaws]

Well if you run it like that, you've essentially "load tested" it. 100% is 100%.

Absolutely. Haven't had a long outage in a couple of years but I find myself kinda wanting one!

 

[loosegravel]

I retired from the local transit company here 2 years ago. The first time that I saw "wet stacking" was at work. We have a crew of people whose glorious job is to clean the inside of these buses. I'm here to say that their job is the toughest in all. Most of them work the graveyard shift when the buses are in the yards. In the summertime, the inside of these buses can be very warm. Conversely, in the wintertime they can be very cold. They will run the buses on fast idles while they're working on them to maintain a decent climate control inside of the buses. Their job takes about 4 - 5 hours per bus when done correctly. At mileage intervals, the buses are brought in for their preventative maintenance inspections. If a bus is brought in for a PM right after an inside wash, the inspector will usually always write them up for a bad turbo charger, because the exhaust will be dripping with oil. I wish that I had 1/2 of the money that has been spent on replacing good turbo chargers over the years. I would be rich! The truth is, the buses just needed to be put back into service under a good load, and the oil would simply burn off. Try to explain that to a parts changer though!

It seems that the naturally aspirated gensets tend to wet stack more so than the turbo charged ones do. At least that's been my experience with them so far. But none the less as has been suggested above, the best thing to do is simply run your genset as you need and don't worry about a light load. When your mainline power comes back on, simply run the genset for a while with an artificial load of some sort to burn out the excess oil if there is any. I've become a fan of using a brine tank to load test my generators. It's simple, it's cheap and it's effective. Google it and check it out. I can bring my generators to their knees without a bunch of expensive equipment, and it's also very accurate and precise. The only thing is, as the brine mixture temperature goes up, so does the resistance and thus the amperage. So, I have to stay with it for a few minutes to make sure that I don't go over-current.

 

[FarmingSmallKubota]

I retired from the local transit company here 2 years ago. The first time that I saw "wet stacking" was at work. We have a crew of people whose glorious job is to clean the inside of these buses. I'm here to say that their job is the toughest in all. Most of them work the graveyard shift when the buses are in the yards. In the summertime, the inside of these buses can be very warm. Conversely, in the wintertime they can be very cold. They will run the buses on fast idles while they're working on them to maintain a decent climate control inside of the buses. Their job takes about 4 - 5 hours per bus when done correctly. At mileage intervals, the buses are brought in for their preventative maintenance inspections. If a bus is brought in for a PM right after an inside wash, the inspector will usually always write them up for a bad turbo charger, because the exhaust will be dripping with oil. I wish that I had 1/2 of the money that has been spent on replacing good turbo chargers over the years. I would be rich! The truth is, the buses just needed to be put back into service under a good load, and the oil would simply burn off. Try to explain that to a parts changer though!

It seems that the naturally aspirated gensets tend to wet stack more so than the turbo charged ones do. At least that's been my experience with them so far. But none the less as has been suggested above, the best thing to do is simply run your genset as you need and don't worry about a light load. When your mainline power comes back on, simply run the genset for a while with an artificial load of some sort to burn out the excess oil if there is any. I've become a fan of using a brine tank to load test my generators. It's simple, it's cheap and it's effective. Google it and check it out. I can bring my generators to their knees without a bunch of expensive equipment, and it's also very accurate and precise. The only thing is, as the brine mixture temperature goes up, so does the resistance and thus the amperage. So, I have to stay with it for a few minutes to make sure that I don't go over-current.

I think i will stick with using my load bank or resistance heaters. Thats quite a death trap you have there.

 

[Summerpaws]

I retired from the local transit company here 2 years ago. The first time that I saw "wet stacking" was at work. We have a crew of people whose glorious job is to clean the inside of these buses. I'm here to say that their job is the toughest in all. Most of them work the graveyard shift when the buses are in the yards. In the summertime, the inside of these buses can be very warm. Conversely, in the wintertime they can be very cold. They will run the buses on fast idles while they're working on them to maintain a decent climate control inside of the buses. Their job takes about 4 - 5 hours per bus when done correctly. At mileage intervals, the buses are brought in for their preventative maintenance inspections. If a bus is brought in for a PM right after an inside wash, the inspector will usually always write them up for a bad turbo charger, because the exhaust will be dripping with oil. I wish that I had 1/2 of the money that has been spent on replacing good turbo chargers over the years. I would be rich! The truth is, the buses just needed to be put back into service under a good load, and the oil would simply burn off. Try to explain that to a parts changer though!

It seems that the naturally aspirated gensets tend to wet stack more so than the turbo charged ones do. At least that's been my experience with them so far. But none the less as has been suggested above, the best thing to do is simply run your genset as you need and don't worry about a light load. When your mainline power comes back on, simply run the genset for a while with an artificial load of some sort to burn out the excess oil if there is any. I've become a fan of using a brine tank to load test my generators. It's simple, it's cheap and it's effective. Google it and check it out. I can bring my generators to their knees without a bunch of expensive equipment, and it's also very accurate and precise. The only thing is, as the brine mixture temperature goes up, so does the resistance and thus the amperage. So, I have to stay with it for a few minutes to make sure that I don't go over-current.

That's one job I would not care for. I can imagine all the wonderful stuff that needed to be cleaned. I have done my fair share of nasty jobs. My department was called Plant Services. We gave the plant power, low and high pressure steam, chilled water, hot oil for production and compressed air. We were also tasked with maintaining and repairing the utilities in the building. That included the waste systems. With close to 500 people in the building, things could and did get out of wack. We had three pumping stations and that was where most of the problems arose. Tyvec suits, gloves and boots sealed with duct tape and a respirator were common. We all wore pagers tied to the alarm system in the power plant. Murphy would frequently visit us as we got a 911 on our pagers while deep in a pumping station and covered in...well..you know what.
I will look up your brine system. Looks pretty cool. I have an old Dayton 5000 watt shop heater that I will use but I'm not sure how well it will work in the summer. Thanks!

 

[MatthewWBailey]

I retired from the local transit company here 2 years ago. The first time that I saw "wet stacking" was at work. We have a crew of people whose glorious job is to clean the inside of these buses. I'm here to say that their job is the toughest in all. Most of them work the graveyard shift when the buses are in the yards. In the summertime, the inside of these buses can be very warm. Conversely, in the wintertime they can be very cold. They will run the buses on fast idles while they're working on them to maintain a decent climate control inside of the buses. Their job takes about 4 - 5 hours per bus when done correctly. At mileage intervals, the buses are brought in for their preventative maintenance inspections. If a bus is brought in for a PM right after an inside wash, the inspector will usually always write them up for a bad turbo charger, because the exhaust will be dripping with oil. I wish that I had 1/2 of the money that has been spent on replacing good turbo chargers over the years. I would be rich! The truth is, the buses just needed to be put back into service under a good load, and the oil would simply burn off. Try to explain that to a parts changer though!

It seems that the naturally aspirated gensets tend to wet stack more so than the turbo charged ones do. At least that's been my experience with them so far. But none the less as has been suggested above, the best thing to do is simply run your genset as you need and don't worry about a light load. When your mainline power comes back on, simply run the genset for a while with an artificial load of some sort to burn out the excess oil if there is any. I've become a fan of using a brine tank to load test my generators. It's simple, it's cheap and it's effective. Google it and check it out. I can bring my generators to their knees without a bunch of expensive equipment, and it's also very accurate and precise. The only thing is, as the brine mixture temperature goes up, so does the resistance and thus the amperage. So, I have to stay with it for a few minutes to make sure that I don't go over-current.

Pretty cool. Just be careful. I've seen this done on a larger scale. Works with the proper babysitting. Only change I'd do is to double-wall the brine container bc the liquid is energized.

 

[2Pbfeet]

That's one job I would not care for. I can imagine all the wonderful stuff that needed to be cleaned. I have done my fair share of nasty jobs. My department was called Plant Services. We gave the plant power, low and high pressure steam, chilled water, hot oil for production and compressed air. We were also tasked with maintaining and repairing the utilities in the building. That included the waste systems. With close to 500 people in the building, things could and did get out of wack. We had three pumping stations and that was where most of the problems arose. Tyvec suits, gloves and boots sealed with duct tape and a respirator were common. We all wore pagers tied to the alarm system in the power plant. Murphy would frequently visit us as we got a 911 on our pagers while deep in a pumping station and covered in...well..you know what.
I will look up your brine system. Looks pretty cool. I have an old Dayton 5000 watt shop heater that I will use but I'm not sure how well it will work in the summer. Thanks!

Great stories. I can only imagine trying to clean/disinfect a pager that had been deep in...

I'm curious what did the plant make?

All the best,

2Pbfeet

 

[Summerpaws]

Great stories. I can only imagine trying to clean/disinfect a pager that had been deep in...

I'm curious what did the plant make?

All the best,

2Pbfeet

It is a non woven textile manufacturer. It takes polypropylene and polyester resin pellets and extrudes them into fibers. Then it's baled and carded into fabrics. Then they are usually coated and sold to companies to be used in everything from clothes to carpet. When I started there our normal load for the power plant was 2.5 mw to 3mw. Now it's between 5mw to 8mw.
Yes, there was a lot of disinfecting to be done from time to time.

 

[Ray70]

I suppose I'll add my worth of useless opinion, but if you're going to perform a periodic 100% load test / carbon clean-up, why waste the fuel and energy trying to boil water or dump heat outdoors?
Why not use your existing load ( house ) and capitalize on the energy you're creating during your test rather than throw it away?
Plan things ahead so you do several loads of laundry back to back that day, or turn off the hot water heater for a day, use up the hot water then turn it back on for an extended length 4500 watt load?
Hell, plan a load test for Thanksgiving Day, and use the turkey for a heavy load!

 

[Summerpaws]

I suppose I'll add my worth of useless opinion, but if you're going to perform a periodic 100% load test / carbon clean-up, why waste the fuel and energy trying to boil water or dump heat outdoors?
Why not use your existing load ( house ) and capitalize on the energy you're creating during your test rather than throw it away?
Plan things ahead so you do several loads of laundry back to back that day, or turn off the hot water heater for a day, use up the hot water then turn it back on for an extended length 4500 watt load?
Hell, plan a load test for Thanksgiving Day, and use the turkey for a heavy load!

Ray, I read your answer and said to myself, "Duh". I could actually go over 100% for a short time. I like the idea of shutting off the water heater so it's cold. Maybe it would be a good time to flush it so it's really cold. Like Matt said, 100% load is 100% load.

 

[2Pbfeet]

I suppose I'll add my worth of useless opinion, but if you're going to perform a periodic 100% load test / carbon clean-up, why waste the fuel and energy trying to boil water or dump heat outdoors?
Why not use your existing load ( house ) and capitalize on the energy you're creating during your test rather than throw it away?
Plan things ahead so you do several loads of laundry back to back that day, or turn off the hot water heater for a day, use up the hot water then turn it back on for an extended length 4500 watt load?
Hell, plan a load test for Thanksgiving Day, and use the turkey for a heavy load!

I agree. I wired up a spider box to be able parallel the house, and be able to run additional heater loads from the spider, as well as the house loads (generator to spider, spider with two high amp outlets, one to the house, one to a 1.5-10kW heater). Kills two birds with one stone, so to speak. It also adds an extra inline breaker.

But for initial debugging and burn in, I prefer not to have the house involved, but that's me.

All the best,

2Pbfeet

 

[87cr250r]

I run John Deere 4045AFM85 engines as generator sets in my fleet. They spend 99% of their life at 10% load with monetary peaks to 75% load. We certainly do get carbon buildup in the stacks but have never actually experienced wet stacking or a stack fire. These engines average 2500-3000 hours per year of runtime.

Our exhaust piping is fully insulated. Perhaps this helps, thought it melts and makes a mess during a stack fire.

 

[Guyfang]

I have never seen any fires due to wet stacking. But have seen 45-60 KW gen sets not be about to pull 15-20% load, without dying in their tracks. We ran a lot more then 3000 hours a year on many sets. And the mess that runs out of the engines is most foul. We several times STARTED a fire, cleaning up the sets. Progressively stepping up the loads till we hit 100% rated load, and then let er rip for 6 hours. The sludge turns to carbon and it spews out the exhaust. After the first time, we had someone near by with several fire extinguishers. My shop was in the middle of the woods, and dry pine needles burn well.