Carburetor heater on standby generators?

[gspren]

  Today I got my Kohler 20K propane fired standby genny up and running and the "start-up" dude said I should get a carb heater installed at a hundred something, although they are back ordered like everything else. He claimed in cold climates like here the cold carb can form condensation which will run down and contaminate the oil, does this sound correct? I said if they need it why didn't Kohler put it on and his reply is "half the country doesn't need it". I can easily afford it but is it a gimmick or a good idea when they actually get them in stock? I'm not familiar with propane fired engines.

[btulloh]

Probably a real good idea. Propane doesn't like to convert as well at low temperatures. No doubt there's some good info out there from a non-salesman source. 

[TroyC]

Sure enuf, Azon got them. Never heard of one but in Florida don't guess I need one. Azon says help with cold weather starting. I can't imagine getting enough condensate to blow by the rings to contaminate the oil. Within a minute or so of startup the cylinder walls would be hot enough to vaporize the moisture. Water injection systems didn't contaminate the oil that I can recall. However, if your carb leaks gas from the needle and seat, the gas will leak past the rings and cause you to have more oil than you need in the crankcase.

[sawguy21]

Unless his is dual fuel he won't have a needle and seat. The big problem with propane in the cold is mixer icing, Kohler does offer a duct kit to direct exhaust heat around it but some light tin and creative snip work will accomplish the same thing. 

[stavebuyer]

I know I have one of the "Big Buddy" portable propane heaters. It will freeze up and shut down if run on the "high" setting when it is cold enough to need it. The fine print from manufacturer confirms as much so I'd want the heated carb for sure.

[gspren]

I guess I'll get it when they are available through the genny dealer, who knows when that will be. It's 7 deg F here this morning and they are calling for snow turning to freezing rain later, I hope I don't need the genny but it's a nice feeling that if the power goes off I don't need to go out and mess with a portable genny like I've done for years.

[snowstorm]

i had a genset installed 2 yrs ago. i asked about the heater as he put it i have never sold one. mine comes on for 10 min once a week its never failed to start even at minus 15

[hamish]

Alot of it has to do with your specific region.  Here our winters are cold and humid, even with the carb heater when running propane the engine still creates condensate through the crankcase breather and causes issues.  The best it when the "off grid folks" have to run there generator to power the carb heater, and finally realize the true cost of propane up here.  One customers house, new build, new solar install in 2015, the generator has 29436hrs( yes I just looked at the picture of the hour meter I took).

The further north you fo its all Diesel and fuel oils for everything.

[YellowHammer]

I get the feeling think he is mixing up two different problems, but yes, a carb heater would solve some of it.  So he may be right, may be wrong, but here is what I experience with propane and LP generators that may help.  

Yes, propane, especially from the gas side of a smaller tank, will ice up both the tank, the regulator, and the lines, as the continued expansion of the gas from the tank causes the temperature of the gas to drop and will cause ice up.  So on smaller tanks, especially if drawing from the last quarter tank, it's important to keep everything warm and that is one reason most standby generators are fully enclosed, to keep everything warm.  If using a smaller remote tank, place it where the exhaust from the generator will be pointed at the tank and keep the tank and tank regulator warm enough to not freeze.  I have to do that with my standby generator or it will die about 45 minutes into a run, with completely frosted fuel lines.  So the freeze up will occur after many minutes of running, not during start up.

Any hydrocarbon, and propane is famous for it, will generate water in the exhaust as a combustion by product.  Propane produces so much water vapor from combustion that on a forklift where the exhaust is obvious, water will be seen dripping or spitting from the exhaust for about 5 or 10 minutes after the engine is started, winter or summer.  Some people may have noticed water dripping from their car exhaust occasionally.  So the worst thing that can be done with a propane fired engine is to run it for only a few minutes and turn it off regularly, before it's been warmed up. At that point, there is water vapor everywhere, even in the combustion chamber, and it will just sit there and corrode and rust things up, or slowly seep by the rings into the crankcase, or go anywhere else it can go.  I just had to change out the rusted spark plugs in my 65Kw generator last weekend.  The same with the plugs on my propane forklift, I've had to change them and they come out corroded and white, not to mention they may strip the threads removing them.  

The solution to this is to run the engine long enough to get it hot where the water will be evaporated and come out as a gas vapor and not a mostly liquid condensate.  With my big generator, I will not shut it down until I see that the steam vapor coming out of the stack is cleared and coming out invisible.  This normally isn't a problem with cars, trucks, tractors, etc as they will "smoke" badly when they cold start and warm up, but most times they are operated for extended times and the water is cleared from the combustion chamber.  With generators, they normally are only started and stopped as part of the maintenance cycle, and sometimes that is not long enough to clear the water vapor, which is never good inside an engine.

As a point of interest, forklift and big generator have a small radiator fed hot water hose running to the carburetor "called a vaporizer" to provide constant heat to the system to keep the fuel system warm for continued operation, and also to pre heat and liquify the propane before it goes into the combustion chamber.  

[gspren]

@YellowHammer , I have a feeling that we won't have as many long outages here as what we had on the farm but I was tired of portable gennys so I had this 20K Kohler installed, I had a 500 gallon tank installed under ground and the line is also buried up to about 3' from the genny which will start once a week for a few minutes, I don't remember how many. Other than the carb heater what else could be done, I don't really hear of people having problems in this area where single didgets and below are possible but rare, mostly lows are teens and twentys.

[YellowHammer]

I'm thinking the the propane tank you have is buried so when the vapor expands from the tank, the underground burial should? help heat it so its not ice cold when it gets to the carb, I would guess?

My forklift with cold propane will barely crank when it's under 30F so we keep it inside.  Same with our big generator.  It doesn't like to start with cold propane at all.

It makes me wonder with the house standby generators like yours if they have something in the circuit to help it cold start?  id be interested to know.  Maybe it has a higher compression ratio?   

Definitely let it run long enough to stop getting the steam cloud from the exhaust stacks.