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Trading No kaboom for BIG KABOOM!!! Converting stove from CNG to LPG.

TomY

Alden Forum Moderator
Jun 22, 2004
2,299
Alden 38' Challenger yawl Rockport Harbor
The New England supplier for the CNG exchange, Corp Bros out of Mass, was sold. The new owner won't be continuing this service. So those of us with CNG are out of luck, it appears. No plans to do it this season but I expect to before next season. I have nothing against LPG and use it at home. The only good thing about CNG was the lighter than air nature. But I won't miss the cost, nearly $100 a tank.

Doing some research, a 5 pound LPG tank holds more BTU's than the typical "20 hour" CNG bottle. Plus it fill for between 5 and 10 bucks.

In the event nothing materializes, I'm asking for any experience converting marine stoves like our Tasco 3 burner with oven to LPG. I've had household stoves converted with new orifices, but haven't found much on marine type stoves.

Anyone done this?
 
Oct 26, 2010
1,062
Hunter 40.5 Beaufort, SC
Waiting with anticipation for the responses - I may be faced with the same thing.
 
Sep 22, 2018
1,342
Hunter 216 Kingston
You likely already know this, I was thinking the manufacturer might offer a conversion “kit” but it appears that’s not likely an option as it looks like they stopped support in 2015.


I know propane is just as safe as any other fuel when handled properly but using it in an enclosed space is kinda scary imho.

I’m also amazed at the cost of CNG! Natural Gas certainly isn’t rare. Is this just a packaging-distribution issue in that demand is dropping so fewer vendors???
 
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Oct 26, 2010
1,062
Hunter 40.5 Beaufort, SC
The just opened an ENMARK station in Savannah Georgia with CNG pumps. The problem is that the pumps are 3600 psig supply pressure and the tanks that we use on boats are not rated at that high a pressure. I've got a CNG fill adapter that will fit the pumps and connect to my tank but I'm hesitant to try to fill a tank rated for 2000 psig at pump that delivers at 3600 psig. Has anyone tried this or knows of a source of tanks rated at 3600 psig?
 
Oct 26, 2010
1,062
Hunter 40.5 Beaufort, SC
I’m also amazed at the cost of CNG! Natural Gas certainly isn’t rare. Is this just a packaging-distribution issue in that demand is dropping so fewer vendors???
CNG gas itself is really cheap - probably less than a $1 or $2 for a full tank the size we use on boats. The problem with exchange services is that they have to make sure the tanks are withing their use dates (recert by hydro every 5 years I believe) and then there is the "supply and demand" part of the equation. We have them, you want them, we get to set the price.
 
  • Helpful
Likes: Hunter216
Sep 22, 2018
1,342
Hunter 216 Kingston
The just opened an ENMARK station in Savannah Georgia with CNG pumps. The problem is that the pumps are 3600 psig supply pressure and the tanks that we use on boats are not rated at that high a pressure. I've got a CNG fill adapter that will fit the pumps and connect to my tank but I'm hesitant to try to fill a tank rated for 2000 psig at pump that delivers at 3600 psig. Has anyone tried this or knows of a source of tanks rated at 3600 psig?
Kind of out of my depth here but I went Googling and found this.

 
Nov 22, 2011
801
Ericson 26-2 San Pedro, CA
Kind of out of my depth here but I went Googling and found this.

All for only $1853! :yikes:
 
Sep 22, 2018
1,342
Hunter 216 Kingston
All for only $1853! :yikes:
I just pasted the tab of the website I was on, here is a different one for a lot less. Like I said out of my depth as I don’t even know what size of tank would fit on a boat.
Just trying to help.

 
Oct 26, 2010
1,062
Hunter 40.5 Beaufort, SC
I just pasted the tab of the website I was on, here is a different one for a lot less. Like I said out of my depth as I don’t even know what size of tank would fit on a boat.
Just trying to help.

Probably a lot cheaper than converting and I still get to keep the CNG. Since we have a CNG station nearby I might just spring for it. It says its good for 20 years too!!!
 
Sep 22, 2018
1,342
Hunter 216 Kingston
Might want to check at filling station to see if they allow filling your “portable” tank first.
 
Feb 11, 2017
30
Wow, the tank weighs 98 pounds! That is substantially more weight than current tank. There could be other issues introduced using one of these new tanks at 3600 psi in that the rest of your system (hoses and stove/oven ) may not be able to handle that higher pressure
 
Jan 11, 2014
5,606
Sabre 362 113 Fair Haven, NY
The New England supplier for the CNG exchange, Corp Bros out of Mass, was sold. The new owner won't be continuing this service. So those of us with CNG are out of luck, it appears. No plans to do it this season but I expect to before next season. I have nothing against LPG and use it at home. The only good thing about CNG was the lighter than air nature. But I won't miss the cost, nearly $100 a tank.

Doing some research, a 5 pound LPG tank holds more BTU's than the typical "20 hour" CNG bottle. Plus it fill for between 5 and 10 bucks.

In the event nothing materializes, I'm asking for any experience converting marine stoves like our Tasco 3 burner with oven to LPG. I've had household stoves converted with new orifices, but haven't found much on marine type stoves.

Anyone done this?
Well, the folks over on the Sabre group have been dealing with this for a number of years. Generally, there are not many good options. LPG is cheaper, more readily available, and has more BTUs in the tank. On household devices, stoves, HW tanks, grills, etc. changing the orifices works. However, these conversion kits appear to be no longer be available for marine stoves.

The easiest and cheapest option used to be an Origo non-pressurized alcohol stove. But these are no longer being made.

Another obstacle is the propane locker. LPG tanks do not easily fit into CNG lockers and CNG lockers are not properly vented for LPG. One option is to hang a tank on the pushpit.

If you go the LPG route all the gas plumbing has to be replaced, solenoid, regulator, and gas sensors.

It is rumored that on eBay CNG couplings can be bought to allow the refilling of CNG at CNG vehicle fueling stations. The safety and legality of doing this is up for debate. The concern is the high pressure required for the CNG tank, if I recall correctly somewhere between 2K and 3K PSI. The CNG tanks are basically scuba tanks.
 
Oct 26, 2010
1,062
Hunter 40.5 Beaufort, SC
Might want to check at filling station to see if they allow filling your “portable” tank first.
Agreed - was planning on stopping by there and asking about filling a "new" portable tank rated at the pump pressure.
 
Oct 26, 2010
1,062
Hunter 40.5 Beaufort, SC
Wow, the tank weighs 98 pounds! That is substantially more weight than current tank. There could be other issues introduced using one of these new tanks at 3600 psi in that the rest of your system (hoses and stove/oven ) may not be able to handle that higher pressure
The weight is a little of a concern but not too much. The gas itself doesn't weigh that much in addition to the tank weight. The hoses and stove/oven don't see the tank pressure. The regulator reduces the pressure at the regulator to only a few psi. The question though is whether the regulator is rated for that pressure and can reduce it to the proper pressure. I'll have to check on that. All those technical issues will need to be resolved.

I have also found an industrial gas supplier that can provide " compressed methane" at 96% pure which is the same as CNG. Not sure what a filled tank cost though
 

CarlN

.
Jan 4, 2009
442
Ketch 55 Bristol, RI
If you have a genset, how about converting to an induction range top and a small microwave/convection oven. The induction ranges are incredibly efficient. I got one of the $70 one burner Induction units off Amazon and use it more than my propane stove. I can finally boil a big pot of water for pasta without noticeably aging! Easy to run off an inverter if you have a good size battery bank. I’ve got propane but considering switching myself to be finally done with the damn tanks.
 
Last edited:
Oct 26, 2010
1,062
Hunter 40.5 Beaufort, SC
It is rumored that on eBay CNG couplings can be bought to allow the refilling of CNG at CNG vehicle fueling stations. The safety and legality of doing this is up for debate. The concern is the high pressure required for the CNG tank, if I recall correctly somewhere between 2K and 3K PSI. The CNG tanks are basically scuba tanks.
I don't know if I'd trust a CNG coupling to refill a CNG tank bought on ebay. I might be leary of its components when using at 3600 psig. However, you can assemble one yourself from properly rated components for the pressures and the gas service from places like McMaster Carr. That is what I did. All parts are rated for gas application and the pressures at which it will be operating. The new tank shown above for $685 is rated for 3600 psig so that takes out of the equation trying to fill a 2000 psig tank from a 3600 psig fill station. Now the question is whether the station will allow filling a portable tank from their equipment. I figure the cost to convert, including a new stove/oven, all the hoses and safety equipment, a new propane locker, and installation is well in excess fo $3000 if not more. If they will allow it to be filled, $685 is a bargin since it only costs about $2 to fill a tank from the station plus you get the added "safety" of using a gas that is lighter than air and not likely to sink to a void (like the bilge) if you get a leak. If the regulator can't handle the 3600 psig, I guess one could fill it and then bleed off pressure until it is within the specs for the regulator. The gas itself is super cheap.

:wow3:- I think I might just have talked myself into the new tank. First a check on if the regulator can reduce it from 3600 to the required operating pressure and then a quick trip to the ENMARLK station in Savannah to see if they will let me fill it there. Anybody out there an expert on regulators?
 
Oct 26, 2010
1,062
Hunter 40.5 Beaufort, SC
If you have a genset, how about converting to an induction range top and a small microwave/convection oven. The induction ranges are incredibly efficient. I got one of the $70 one burner Induction units off Amazon and use it more than my propane stove. I can finally boil a big pot of water for pasta without noticeably aging! Easy to run off an inverter if you have a good size battery bank. I’ve got propane but considering switching myself to be finally done with the damn tanks.
Great thinking outside of the box! I do have a 5.5kW generator so that is also a possibility. I've only used the oven a few times so might just be able to get buy with a regular microwave oven. I love this forum!!
 
Jun 11, 2004
965
Oday 31 Redondo Beach
.... First a check on if the regulator can reduce it from 3600 to the required operating pressure and then a quick trip to the ENMARLK station in Savannah to see if they will let me fill it there.
If the regulator can't take 3600 you could just fill the tank to whatever your regulator will take. Yes you will be getting less than capacity but the price for the gas is very low.

I fill my tanks to settle around 2000 after cooling off. They are rated to 2250.

p.s. FWIW I have never seen an attendant at a CNG station. Only self serve.
 
Feb 11, 2017
30
Richard- do you use an adapter similar to the ones sold on ebay with 2 gauges (one measuring your tank pressure and one measuring the input pressure?
Smokey - if you end up buying a new tank rated for 3600, does that mean you don't need to measure how full the tank is with a gauge when refilling,since the input pressure is the same? How would you purge the air out before using first time (like when buying a new propane tank they charge you for that service). Also, shipping a 100 pound tank from California would be another expense to consider.
I would very much like to continue to use cng if st all possible so am very interested in hearing how everyone solves their problem.
 
Sep 22, 2018
1,342
Hunter 216 Kingston
The new tank shown above for $685 is rated for 3600 psig
I would point out that there are numerous companies that sell tanks. The one I posted was simply the first one I came upon. Apparently there are at least 5 “types” of cng tanks based on construction, weight and cost.