The Generator Thread

[Bomber 1,091]

18 hours ago, Scorpio64 said:

ftfy.

A three month outage, that's getting into prepper territory.  Might not even have NG if that happens.

People in Puerto Rico were out over three months and running gen sets on gasoline,  sucks but it can be done. (Cold weather operation would be more challenging for sure).

One guy had well over 1000 hrs on his Briggs Storm Resp. Gen set. 

 

[Scorpio64 5,147]

4 hours ago, Bomber said:

(Cold weather operation would be more challenging for sure).

Especially for those with propane gennys.  I don't have any personal experience, but I've read that below 20deg F, propane does not always want to come out and play.  Something about tank size, pressure and condensation and stuff.  Maybe Hank Hill knows.

Diesel can also be a bummer when it's very cold.  That's why they bury tanks.

[fishnut 2,358]

28 minutes ago, Scorpio64 said:

Especially for those with propane gennys.  I don't have any personal experience, but I've read that below 20deg F, propane does not always want to come out and play.  Something about tank size, pressure and condensation and stuff.  Maybe Hank Hill knows.

Diesel can also be a bummer when it's very cold.  That's why they bury tanks.

I have twin 120 gallon above ground propane tanks and have had no issues running my furnace down to -15°F. The lowest temp I've run my propane fired generator was -8°F. Took a few trys to get it going but once it was running I had no issues. 

Now that I heat with a wood stove the 240 gallons of propane is really just for the generator and the furnace if I get lazy in the middle of the night and don't put more wood in the stove. 

[Malsua 1,422]

47 minutes ago, Scorpio64 said:

Especially for those with propane gennys.  I don't have any personal experience, but I've read that below 20deg F, propane does not always want to come out and play.  Something about tank size, pressure and condensation and stuff.  Maybe Hank Hill knows.

Diesel can also be a bummer when it's very cold.  That's why they bury tanks.

The BTU available starts to drop precipitously below 20 degrees.    Just google "propane tank vaporization rate".

Determine what your generator uses and make your decision.   Most of these propane grill tanks probably cannot produce enough BTU at 0 degrees for any generator over about 4000 watt.  Here's a link.  There are tons of them https://motorsnorkel.com/propane-consumption-rate/

I will only say that bad storms do not tend to occur when it is super cold.   It's usually ice storms and hurricanes which knock out power. Hurricanes are in the fall when it rarely drops under 50, ice storms tend to be right at 32.    Heavy wet snow storms also occur in the early fall, right around freezing temp.  In over 18 years of having generators, I've never needed one any colder than 25 degrees.

 

[Scorpio64 5,147]

Just now, fishnut said:

I have twin 120 gallon above ground propane tanks and have had no issues running my furnace down to -15°F.

The issue with propane is not strictly ambient temp, it has something to do with the size of the tank, how full it is and the amount of LPG that can create pressure.  Too much trouble to read all the details, because I don't use LPG, but I've seen it mentioned on other genny and RV sites.  Sometimes the solution is as simple as using a 40# tank instead of a 20# tank, but I can't swear by that.

No one fuel is magical, they all have at least a few drawbacks, varying in degree, which can usually be managed.

[Scorpio64 5,147]

16 minutes ago, Malsua said:

The BTU available starts to drop precipitously below 20 degrees. 

Thank you Mr Hill.  I think motorsnorkle was one of the sites that I came across that info.  Since I don't use the stuff, I didn't invest much time in it.  But though it may be something that propane and propane accessory users may want to know about.

[Malsua 1,422]

36 minutes ago, Scorpio64 said:

Thank you Mr Hill.  I think motorsnorkle was one of the sites that I came across that info.  Since I don't use the stuff, I didn't invest much time in it.  But though it may be something that propane and propane accessory users may want to know about.

The only reason I have any idea about it was when I was adding a furnace, previously having just burned firewood, I thought a 350 gallon tank would be enough.   The salesman from Eastern Propane said "Your generator needs more surface area to boil off propane than a 350 gallon tank can provide when the tank gets low or it's cold".   It led me down a path to figuring out what that actually meant since it never occurred to me that it made any difference.  Propane is propane, right?  Yeah, sorta.  It just behaves different when it's cold and low.

As an addendum, when I took chem 1 and 2 in college, I KNEW all this stuff.  I'm not sure why my brain turned off when it came to applying it in real life.  Temp made sense, I just didn't realize that surface area IN the tank was important.

 

 

[Sota 1,191]

I remember reading about people insulating their propane tanks, and/or installing heating elements on the outside of the tank.  usually some like either those heater wires for gutters, or a flat stick on heater pad or blanket.  They'd run the heaters when the temp got low enough, to keep vapor pressure up.  Obviously if you do that, you'll want your heating element(s) to be also powered by the generator when the time comes.

 

[Sota 1,191]

https://www.engineeringtoolbox.com/propane-vapor-pressure-d_1020.html

You can see from that that 1bar is about -40C, and at about 0C it's 3bar.  The question becomes what's the flow rate at that pressure, taking into account all the losses from everything between the bottle and the inlet to the generator's carburetor.

 

[Sniper 6,372]

3 hours ago, Malsua said:

I will only say that bad storms do not tend to occur when it is super cold.   It's usually ice storms and hurricanes which knock out power. Hurricanes are in the fall when it rarely drops under 50, ice storms tend to be right at 32.    Heavy wet snow storms also occur in the early fall, right around freezing temp.  In over 18 years of having generators, I've never needed one any colder than 25 degrees.

When I saw the conversation switch to the below freezing temps, that's exactly what I was thinking. I don't ever remember a power outage when the temps were below 20 degrees. It usually happens with ice storms  or wet snow, right around the freezing point, or hurricanes.

[Sota 1,191]

Right, but can you say with 100% certainty that after wet storm you won't have a brutal cold snap press in?

[Sniper 6,372]

Just now, Sota said:

Right, but can you say with 100% certainty that after wet storm you won't have a brutal cold snap press in?

Is it possible? Sure. Just haven't seen it in all my decades on this rock.

[Sota 1,191]

7 minutes ago, Sniper said:

Is it possible? Sure. Just haven't seen it in all my decades on this rock.

2020: hold my beer...

[Sniper 6,372]

8 minutes ago, Sota said:

2020: hold my beer...

Ha... Yeah, based on the way this year has been going, I guess nothing would be a surprise... 

[Malsua 1,422]

3 hours ago, Sniper said:

Ha... Yeah, based on the way this year has been going, I guess nothing would be a surprise... 

 

[Sota 1,191]

We really need someone who can answer my question in my post a couple up, regarding minimum pressures and flow rates.

[Malsua 1,422]

1 hour ago, Sota said:

We really need someone who can answer my question in my post a couple up, regarding minimum pressures and flow rates.

The bottom line is that ALL those factors would have to accounted for or you just go to a bigger tank where if even every value is at a minimum there is _STILL_ sufficient available gas for your genset while running at maximum.

This is why I posted some posts back that I wished I had insisted on a 1000 gallon propane tank instead of the 500 sitting there now.   I know that if my tank is at or below 17% of total capacity AND the temperature is below 20F(actual value about 14F) then my generator cannot run at maximum load.    At 0 degrees, it will start starving at 50% load.  

One final thing of note.

When I boil maple sap in the spring time I use a 60,000 BTU burner, all the way at maximum.   I exhaust the BBQ grill gas tanks in about 9 hours.   If it's cold outside, and it usually is in late Feb and March, the burner will start burning less energetically when the tank gets low.  My solution to this problem is to pour boiling water on the propane tank.   This will last about 15 minutes and it will be iced over again and running low.   Usually about 3 or 4 times doing this and the tank is exhausted.

 

 

 

 

[M4BGRINGO 139]

On 8/20/2020 at 9:34 AM, RUTGERS95 said:

1 propane is equivalent to 5gallons of gas.  I've used propane on my former genny throughout Sandy and was the easiest, most efficient, care free way to operate.  Long lines for gas, I just stroll up to exchange propane tanks.  5 minutes vs 2hours in the line

Not if you went shooting at Lehigh Valley Sporting Clays and stopped in PA with 6 5 gallon jugs and filled them up like we did!

[SmittyMHS 603]

Maybe it's just me but I'd rather have 6 20lb cans of propane. For many reasons. The least of which is the weight of lugging the gas around.

[10X 3,296]

13 minutes ago, SmittyMHS said:

Maybe it's just me but I'd rather have 6 20lb cans of propane. For many reasons. The least of which is the weight of lugging the gas around.

The weight issue is almost a wash, but may slightly favors gas.  Tare weight on a 20 lb BBQ tank of propane is usually about 17 lbs, so a full tank is 37 lbs, a Blue Rhino refill is 32 lbs, since they only fill 15 lbs in a tank.

5 gallons of gas weighs 30 lbs, or maybe 32 lbs in a plastic gas can.

Further up the thread, it was posted that a propane tank is equivalent to 4 gallons or 5 gallons of gas (the difference between the posts I suspect is due to fill amount in the propane tank).

Each has advantages and disadvantages, but I went with gas to avoid buying a bunch of $35 propane tanks that have to be re-tested or scrapped every 10 years if you have them filled yourself.  Blue Rhino will exchange the outdated tanks, so you can avoid the retest cost, but not the purchase cost or the 15 lb fill limitation.

At present, gas locally costs a little more than half what an equivalent amount of propane costs

[Zeke 5,504]

On 8/22/2020 at 11:18 AM, Sota said:

We really need someone who can answer my question in my post a couple up, regarding minimum pressures and flow rates.

I have 1 client with a propane standby. It’s hooked to 3 200# above ground tanks. The reason being sooo the don’t freeze up. It was recommended by the gas supplier. Sooo there’s that. Most of my clients have ng. This one is an oddball 

[Sniper 6,372]

2 hours ago, 10X said:

The weight issue is almost a wash, but may slightly favors gas.  Tare weight on a 20 lb BBQ tank of propane is usually about 17 lbs, so a full tank is 37 lbs, a Blue Rhino refill is 32 lbs, since they only fill 15 lbs in a tank.

I think his point was that 6 - 20lb tanks are easier to move around as needed then one- 100 lb tank.

2 hours ago, 10X said:

Each has advantages and disadvantages, but I went with gas to avoid buying a bunch of $35 propane tanks that have to be re-tested or scrapped every 10 years if you have them filled yourself.  Blue Rhino will exchange the outdated tanks, so you can avoid the retest cost, but not the purchase cost or the 15 lb fill limitation.

So what I do, when the tank is outdated, is to exchange with a new Blue Rhino that one time. Yeah, I bite the bullet and eat one gallon of propane. But every other time after that, I get them manually refilled to the full amount.

[10X 3,296]

5 minutes ago, Sniper said:

I think his point was that 6 - 20lb tanks are easier to move around as needed then one- 100 lb tank.

Ah.  If that was the comparison, then yes, much easier to move, though not as good in very cold temperatures.

[Sniper 6,372]

13 minutes ago, 10X said:

Ah.  If that was the comparison, then yes, much easier to move, though not as good in very cold temperatures.

As we've said above, I don't remember having a power outage when temps were really low, the lowest was around the freezing mark, so I've never experienced it. I've seen the tank struggle when running my big shop heater (80K btu) in really cold temps.

But as I've also mentioned, the 20 lb tanks get used for other uses too, besides the genny. The grill, portable heaters, firepits, camp stoves, lanterns, turkey fryer, etc. So, the smaller, portable tanks work better in those situations too, which are way more common then using them for the genny..

[Sota 1,191]

one of the aspects I need to decide, is which one is better: 60' run of gas pipe to the generator, or 60' run of electrical wire back to the panel/transfer switch.  thinking the latter.

[SmittyMHS 603]

27 minutes ago, Sota said:

one of the aspects I need to decide, is which one is better: 60' run of gas pipe to the generator, or 60' run of electrical wire back to the panel/transfer switch.  thinking the latter.

Pipe is cheaper then wire.

just sayin...

[Sota 1,191]

8 hours ago, SmittyMHS said:

Pipe is cheaper then wire.

just sayin...

yea but pressure losses depend on run length, pipe diameter, and number of turns.  It's possible that to run a bigger generator (10kW+) I'd need to get my meter replaced.  Then questions get asked.  I'm already at the far end of the run for the whole house.

unless you're suggesting I run a full sized pipe directly from the meter, around the outside of the house.

[SmittyMHS 603]

3 hours ago, Sota said:

yea but pressure losses depend on run length, pipe diameter, and number of turns.  It's possible that to run a bigger generator (10kW+) I'd need to get my meter replaced.  Then questions get asked.  I'm already at the far end of the run for the whole house.

unless you're suggesting I run a full sized pipe directly from the meter, around the outside of the house.

You're gonna need a minimum of a 1" pipe to feed the beast. Do you have that near where you intend to put the genset? Is it before or after your furnace/water heater? I think a plumber would size the piping for the BTU use total on the line. Which wouldn't be the case if the power is out. Best of course is to have it on its own supply direct from the meter. Not always necessary in an emergency. If you want to heat the house, cook diner, take 3 showers, and run the generator all at the same time, you may have a problem. If you want a whole house power supply for everything and not worry about it. Get a supply line sized to the max load.

[Malsua 1,422]

27 minutes ago, SmittyMHS said:

You're gonna need a minimum of a 1" pipe to feed the beast. Do you have that near where you intend to put the genset? Is it before or after your furnace/water heater? I think a plumber would size the piping for the BTU use total on the line. Which wouldn't be the case if the power is out. Best of course is to have it on its own supply direct from the meter. Not always necessary in an emergency. If you want to heat the house, cook diner, take 3 showers, and run the generator all at the same time, you may have a problem. If you want a whole house power supply for everything and not worry about it. Get a supply line sized to the max load.

I can only tell you what I have at my place, but I have a high pressure propane line from the Propane tank to the regulator that goes into the house and the same high pressure line has a T that then goes to my standby Generator which also has its own regulator.

On a Nat Gas, you're probably low pressure from the main regulator so you'd need a big pipe and bigger than standard regulator.

[siderman 1,137]

When I ran a ng pipe to my portable gen I used a proprietary chart that was on the website for US Carb. Wasn't concerned about propane as that is a direct connect tank.