1. Welcome Hearth.com Guests and Visitors - Please enjoy our forums!
    Hearth.com GOLD Sponsors who help bring the site content to you:
    Hearthstone Soapstone and Cast-Iron stoves( Wood, Gas or Pellet Stoves and Inserts)
    Caluwe - Passion for Fire and Water ( Pellet and Wood Hydronic and Space Heating)

Conversion of gas generator to multi fuel

Post in 'DIY and General non-hearth advice' started by Ossy, Aug 1, 2008.

Thread Status:
Not open for further replies.
  1. Ossy

    Ossy New Member

    Joined:
    Jul 13, 2008
    Messages:
    46
    Loc:
    Central Maine
    Anyone ever use one of the conversion kits to convert a gas gen to run on other fuels such propane?....results and feed back appreciated...

    Regards
    Ossy

    Helpful Sponsor Ads!





  2. Redox

    Redox Minister of Fire

    Joined:
    Feb 23, 2008
    Messages:
    1,099
    Loc:
    Burbs of B'more, MD, Hon!
    Glacialhills made mention of a place on this thread:

    http://www.hearth.com/econtent/index.php/forums/viewthread/20419/P45/

    Gaseous fuels are great for an internal combustion engine. Propane stores indefinitely and NG comes to your house without a delivery truck. They are both cheaper to run than gasoline right now. The only drawback is the price of the kit and installation. You will get over that after the next big ice storm...

    Chris
  3. Gooserider

    Gooserider Mod Emeritus

    Joined:
    Nov 20, 2006
    Messages:
    6,737
    Loc:
    Northeastern MA (near Lowell)
    The question I'd have is how feasible is it to do an NG / gasoline "dual fuel" setup, w/ a disconnect - I have a medium size portable generator - inherited from my father... It runs on gas presently and I wouldn't want to loose that ability, but I'm wondering if it would be possible to also run off our piped in NG supply as well - presumably using one of those quick disconnects like they have for gas grills...

    Gooserider
  4. Redox

    Redox Minister of Fire

    Joined:
    Feb 23, 2008
    Messages:
    1,099
    Loc:
    Burbs of B'more, MD, Hon!
    Shouldn't be a big deal on a generator. Just insert the vapor carburetor on the intake of the gasoline carburetor and valve off the liquid fuel when you want to run vapor. This is how early CNG conversions were done.

    The quick connect is liable to be an issue. NG is such low pressure that you need a lot of volume and might hit a pressure drop on a small connector. My 8.5 needs every bit of a 3/4 line to it to make capacity.

    Chris
  5. Gooserider

    Gooserider Mod Emeritus

    Joined:
    Nov 20, 2006
    Messages:
    6,737
    Loc:
    Northeastern MA (near Lowell)
    Thanks, sounds like I'll need to do a bit more research...

    Gooserider
  6. Highbeam

    Highbeam Minister of Fire

    Joined:
    Dec 28, 2006
    Messages:
    8,480
    Loc:
    base of Mt. Rainier on the wet side, WA
    I have been reading up on the tri-fuel conversion to my 6.5 HP gas engined genset. Up to 12 HP it is a simple deal to bolt on the LPG/NG "carburetor" and then you use the proper QD like for a BBQ to hook up to either LPG or NG. The runtime on a single 20 lb BBQ tank of LPG is reported to be about 24 hours on my engine. If you run out of propane then use the gasoline. The gasoline system remains completely intact.

    The kit is less than 200$ and allows a non-destructive conversion to whichever fuel is cheapest or available at the time. Read up at the US carb site about how to do it with photos and then there is a guy at the RV.net site that documented his conversion to an LP only setup and he is very happy. The RV guys always have propane so a conversion makes more sense.
  7. Gooserider

    Gooserider Mod Emeritus

    Joined:
    Nov 20, 2006
    Messages:
    6,737
    Loc:
    Northeastern MA (near Lowell)
    I agree, LP looks easy, but while I have a couple of LP tanks, what I would like to do is run off our Natural Gas connection... The existing gas line runs around the house, and has a connection into the garage for the garage heater, but I'm not sure if it is a big enough line to feed the generator, or how hard it would be to put a QD connector at the meter and get an extra long hose to feed the generator instead...

    Here in New England, I'd say our two biggest concerns are either winter storms or the tail ends of hurricanes (and we are WAY past due for a big one...) - neither is likely to disrupt the NG supply, so there are definite advantages to having a fuel supply that is always available and on... I'd like to still be able to burn gasoline on the off chance that we might want to take the generator someplace else... Looking at the place that offers the kits, I'd say it is definitely doable, the big question is how best to do it...

    As I said, it is something I need to do more research on, but it's not my highest priority project...

    Gooserider
  8. Highbeam

    Highbeam Minister of Fire

    Joined:
    Dec 28, 2006
    Messages:
    8,480
    Loc:
    base of Mt. Rainier on the wet side, WA
    Your typical 10 HP engine by definition equals 25,444 btu/hour which is a pretty small consumer. Turns out though that some references through experiments identify the same 10HP as consuming 108,000 BTU/HR. A typical home boiler is 100,000 btu/hr.

    So if your garage heater is more like 100,000 btu/hr then the NG line feeding it may be large enough to pass the amount of energy that your 10HP engine wants. I personally would have a plumber extend the NG line, verify capacity, and add a QD for the genset.

    I wish I had NG available.
  9. Gooserider

    Gooserider Mod Emeritus

    Joined:
    Nov 20, 2006
    Messages:
    6,737
    Loc:
    Northeastern MA (near Lowell)
    Well, it is hard to say for sure, as I can't see most of my gas piping, however I'm assuming from where the meter and other appliances are at, and what I CAN measure, that I come into the house w/ a 1" pipe, which "T's" to a 3/4" line that feeds the hot water heater and furnace in one direction, and a presumably 1/2" line for the stove, dryer and garage heater, in that order... (I MIGHT have 3/4" as far as the stove branch, but the line is only 1/2" at the point where it splits to feed the dryer and garage heater.) Ballpark measuring gives me about 40-45' to the garage heater, and I would need to add about another 20-25' to get to the point that makes the most sense for the QD fitting.

    This gives me a 1/2" run of about 65' in total. According to the US Carb website, that size line can deliver 61 to 66 CFH at normal gas pressure.

    My generator is a 5500 Watt Wheel House / Generac model 01646, which according to the US Carb site, uses a 10hp New style Briggs and Stratton, OHV, Gentek engine - the generator doesn't say what size the engine is, but it's consistent otherwise....

    The pipe sizing page on US Carb says that you should assume an engine will require approximately 10 CFH per HP, or 100 CFH - thus the existing line appears unable to deliver the required fuel volume...

    This means it looks like I have two choices - either to re-plumb the entire line, which would likely be messy and expensive, or to try putting the QD fitting in the line running from the meter into the house, and get an extra long hose (70' max 3/4" would be about $250) This would be a bit of a pain to hook up when needed, but probably would be cheaper to get.

    I also tried calling US Carb, and essentially they said the same thing... The new B&S;engine may be more fuel efficient than the older engines, but it still has the same requirements for line sizes.

    Gooserider
  10. Highbeam

    Highbeam Minister of Fire

    Joined:
    Dec 28, 2006
    Messages:
    8,480
    Loc:
    base of Mt. Rainier on the wet side, WA
    I just read their publication and I too concluded that the 1/2" line is insufficient after a short ways. The 1" line can go 150' and a 3/4 is 20-50' They run NG at super low pressures. 1/4 of a psi.

    I wonder what a plumber would charge you to run a whole long run of 3/4 or 1" to a new QD from the meter?
  11. Redox

    Redox Minister of Fire

    Joined:
    Feb 23, 2008
    Messages:
    1,099
    Loc:
    Burbs of B'more, MD, Hon!
    My Kohler mechanic says that this is one of the most frequent problems with home generator installs-low gas pressure due to pressure drop. I ended up running a 3/4" piece of gastite flex back to the meter just to make sure it wouldn't be a problem.

    Chris
  12. Gooserider

    Gooserider Mod Emeritus

    Joined:
    Nov 20, 2006
    Messages:
    6,737
    Loc:
    Northeastern MA (near Lowell)
    Well, the chart they show, 3/4" pipe would have been fine for me - as I need 100 CFH, and according to the chart, I can get that out to 100 feet, and could maybe push it to 125... But I only have 1/2", and I suspect it would cost a LOT to increase the size of the run... I'm not allowed to DIY on gas piping, and our usual plumber costs close to $100 just to pull into the driveway... It would probably be about the same to put in a new line as it would be to replace the old one - as the old line pretty much goes exactly where any new line would need to be. It would also take a pretty good bit of demo to open up the walls and ceiling to access the pipes.

    OTOH the second approach that they suggested would probably be less - cut into the line coming out of the gas meter, before it enters the house, and put a QD fitting there. This would be pretty simple from a plumbing standpoint as there's a foot or two of exposed line that could be replaced with a pair of shorter nipples and a "T" fitting with minimal headaches. Then do a custom long rubber connection line, which I could do up to 70' with 3/4" line. It would cost a couple hundred bucks, depending on the exact length I decided on - with the possibility of a tradeoff between the length / location of the electrical line and the hose length depending on just where on the driveway I wanted to put the generator... Aside from it being a bit of an extra pain to hook up the gas line (maybe have to wade through deep snow to get to the QD fitting) it would probably work just as well, and avoid the cost / mess of tearing things apart to put in a bigger gas pipe.

    Gooserider
Thread Status:
Not open for further replies.

Share This Page