CNG to Propane Stove Conversion

[SV THIRD DAY]

Long story short, my daughter has bought her first boat (a Newport 33) to move onto and live aboard and the boat came with a CNG stove/oven in perfect condition. Well perfect for a CNG stove anyway that needs to be converted to Propane. So the question is do we set the CNG stove at the dumpster and let someone else mess with it OR can it be converted to propane. From my research I can see that I need to change the orifice to a smaller size and I've already identified and removed the cap style orifices. BUT....now I'm trying to find new ones for propane. I've found this site:
Cap Orifice (CO) Archives - Anderson & Forrester
Which I think has what I need, BUT not wanting any liability they don't help you...they just sell parts.

So has anyone out there converted a CNG Gas Systems Oven/Stove to Propane that would be willing to offer up some advice?

[Bill Seal]

It would seem to me, once the CNG (compressed natural gas) gets past the regulator, it becomes plain old fashioned home type natural gas, so your best bet would be to go to an RV place, or home propane supplier, and get the conversion kit.

[twinboat]

Propane is heavier than air and stoves that use it have safety thermocouples on them.

If the flame blows out, the gas flow stops.

CNG is a light gas, so no buildup in the bilge.

I would send it to the dumpster.

[Island Time O25]

Years ago when we got our current boat we were faced with the same question/dilemma. But after an initial successful season of CNG use decided that the extra cost of CNG refills is worth the safety margin CNG provides. Why expose your boat to any more danger than it's already exposed to? Unless you're out in the boonies w/o any CNG sellers nearby I say leave the well enough alone.

[Mo Surprises]

It's not hard to convert to propane from CNG. Get the proper orifices from the manufacturer if possible and install a proper propane solenoid shutoff at the tanks and a control panel in the salon/galley. It would be a good idea to run new propane lines too. No big deal. I did this 20 years ago and it still works fine. Save your money for cool gadgets instead.

[svHyLyte]

Originally Posted by SV THIRD DAY

Long story short, my daughter has bought her first boat (a Newport 33) to move onto and live aboard and the boat came with a CNG stove/oven in perfect condition. Well perfect for a CNG stove anyway that needs to be converted to Propane. So the question is do we set the CNG stove at the dumpster and let someone else mess with it OR can it be converted to propane. From my research I can see that I need to change the orifice to a smaller size and I've already identified and removed the cap style orifices. BUT....now I'm trying to find new ones for propane. I've found this site:
Cap Orifice (CO) Archives - Anderson & Forrester
Which I think has what I need, BUT not wanting any liability they don't help you...they just sell parts.

So has anyone out there converted a CNG Gas Systems Oven/Stove to Propane that would be willing to offer up some advice?

Rich--

If she's in California, and plans to remain, there is no difficulty obtaining CNG cylinders or having her own refilled. Otherwise, converting to Propane is merely a question of changing the orifaces to the burners. The larger question is whether her existing stove is fitted with the thermocouple shut off valves although most stoves designed for shipboard use have been since the 1980's. The other addition, mentioned above, is the addition of a gas solenoid valve at the tank coupled with sniffers to detect leakages, one under the stove itself and another in the bilge, to close off the gas flow in the event of a leak. Overall, however, the change isn't that difficult.

FWIW...

[capt jgw]

It depends on how the original installation was done. Propane, being heavier than air, has more restrictive rules than cng. If it was production installation with the option of either gas type, than the rest of the system is probably good. If purpose built for cng, then the tank locker, valves, and piping might not be up to standard. And as mentioned above, if the stove has the thermocouples like a propane unit then changing the orifices will fix it. But it probably doesn't.

[S/V Alchemy]

CNG is a superior fuel in terms of safety. Stay with it if it's possible and the stove is otherwise OK.

[Suijin]

Originally Posted by Mo Surprises

It's not hard to convert to propane from CNG. Get the proper orifices from the manufacturer if possible and install a proper propane solenoid shutoff at the tanks and a control panel in the salon/galley. It would be a good idea to run new propane lines too. No big deal. I did this 20 years ago and it still works fine. Save your money for cool gadgets instead.

If the stove does not have thermocouples on the burners then this is A Really Bad Idea.

All it takes is forgetting the stove is on and the flame blowing out and you'll turn your boat into a bomb. The solenoid and panel won't help you at all in that situation.

[Stu Jackson]

Rich, take your subject title to Google and find the answer. Yes, it can be done. CNG is getting harder to find even in California. I have CNG and moved to Vancouver Island in September. CNG does NOT exist here. You need to change the burners/orifices, install a solenoid (electric) inside next to the stove [forget the thermocouple chicken little warnings], and install a safe to standards box for the tank(s) or install them out on the pushpit.

This question has been asked and answered on every single boating forum since Al Gore invented the internet.

Good luck, it's an easy fix. Don't trash the old stove.

And forget the propane vs CNG heavier than air crap, too. Thousands of boats have propane, more than CNG.

[Rorzech]

Switching your stove should be easy. You can braze the old orface and redrill it to proper size.(Google the size) and usually you can unscrew the cap in the regulator and reverse the spring to give it the proper push, or use a regulator off a BBQ . CNG 7" pressure Propane 11" pressure. Or just buy a new propane stove. The electric solenoid that stu mentioned is a good plan too. Soap test "everything" real good when pumped up with air (30 lbs for 30 minutes).Propane is safe if respected.

[newhaul]

Rich shoot me a pm I have three words for you. Granger, Johnstone supply.

[hamburking]

My Hunter Legend 35.5 came with a CNG stove. And CNG is not available where I live. And US CNG tanks are not legal in Canada. I spent a small fortune to get my 2 CNG tanks upgraded to canadian standards, and filled. I live in Kingston, and had to travel to Toronto to get the work and fill done. No place else would even touch them. It was nuts. It was expensive. I wasted a ton of time.

And here I was with a beautiful boat, and I couldn't heat up a cup of water to make a coffee.

I WISH I had just taken the CNG stove to the dumpster, and let it be someone elses problem. Some things are just not worth the trouble.

Personally, I like the Origo (aka cookmate) alcohol stoves...I've owned a few and they are awesome. But if you are living aboard, cooking a lot, then I can see how propane might be better for you.

So save yourself the grief, dumpt the CNG stove (and tanks)...maybe you can sell them cheap? And get yourself the stove you really want.

[puffcard]

Guys this isn't a gas grill on the patio, don't tell him the make new orifices or switch the spring in a regulator. It's his daughter's boat and it's a very explosive gas that needs a ton of respect. We lost 25 boats to a propane explosion and fire. If you do propane you do it right and if it's your daughter's boat you make certain to double check and check her out.

If CNG is available use it, safest marine cooking fuel.

[SV THIRD DAY]

Well I think I can do it with some emails and PMs I've gotten from the group...so THANKS for that.

So here's my end game thinking after first being cheap, then being practical, then being cheap again, then being an anti-conventional wisdom type of guy, followed lastly by being a dad helping my 19yr old daughter set up her new boat as a comfortable and reliable liveaboard boat/college dorm.

The oven burner on this circa 1983 Gas Systems stove has a thermal couple, and I have found (thanks for the email and link Ed) a propane replacement cap orifice.
But the three burners on stove don't. So if the oven somehow went out, propane wouldn't fill the bilge and explode. But if the Pasta pot was to boil over and the water extinguishes the flame while she is in the shower....hmmm...there could be a KA Boom problem. Sure the propane alarm/solenoid shut off "could and should" prevent a boom, but do I want to trust it?

After getting all the data, yes, I guess the conversion could be done but I'm just not comfortable having it on my daughter's first boat with all the other learning curves to deal with. So today I placed the order and then sent a text message (the safest way to go) to my wife with the news that she is getting a brand new Force 10 3-burner oven for Christmas. The "old" one bought new in 2007 (and working great) prior to casting off cruising is going to be installed on our daughter's boat!

New tanks, Hoses, Solenoid, Alarm, and all the other damn high dollar fixings are on the way. I wish water makers had the margins that all these things have in them...sheesh. It turns out that freeing up the aft cabin on our boat is gonna cost me...but daughters always do...ha ha ha

On a side note: I have a good Gas Systems 1984 CNG Stove for sale!