[C38] CNG propane conversion. lines?
Charles Finn
charles at finn.ws
Tue Dec 22 18:39:48 EST 2009
CNG lines cannot be used for propane. Besides not being rated for
propane, the existing lines are not long enough to mount the tank and
codes won't allow joints in propane lines within the boat.
Regarding explosions: In the fire service, we know whether a house has
blown up from propane or natural gas by figuring whether the walls are
blown out at the bottom or the top of the house (bottom means propane,
top means natural gas). Please note they both blow up houses!
I also changed out my thermostatic gas valve when I made the conversion.
As Tom was explaining, CNG is a relatively high volume gas per BTU
compared to propane. This means the thermostatic valve for CNG will
allow greater flow to the jets than a propane valve allows. I would note
that when I have converted stoves in homes, I have not replaced the
valve. However, the Seaward folks were pretty adamant about that part of
the retrofit and when it comes to something that might blow up my
boat... I went with the experts.
Regarding the tank location: I went with an aluminum tank and hung it
off the stern rail. Aluminum because the steel one began rusting almost
immediately. Stern rail because propane lockers are very expensive and I
really could not give up the space in the port locker! Don't forget you
will need a remote propane shut off solenoid!
A bonus for removing the CNG high pressure setup from the port locker is
being able to saw out the floor of the locker, which really does make it
easier to access the engine and drive train. I also have plumbed my
grill to the big tank, which is much more convenient and safer than
having a bunch of lightweight propane bottles knocking around the boat.
Charles Finn
Mighty Quinn #114
Great Lakes
D. R. Strong wrote:
> Tom: Thanks for the informative post. We have grey plastic lines that
> carry the CNG from the tank to the stove. Is not a different kind of
> line needed for propane?
> regards, Don
>
>
> Tom T. wrote:
>> Hello gentlemen,
>> I can't imagine a problem converting from CNG to propane. I've done
>> several natural gas to propane conversions on home heating units and
>> with them, the only thing you do is reduce the jet size to make a
>> more oxidizing (lean) flame, otherwise you will have a reducing
>> (rich) flame if you don't reduce the jet size. I do heating and air
>> work on the side and have done several home conversions from natural
>> gas to propane and vise versa on heaters and hot water heaters.
>> I have never bought jets for a natural gas to propane conversion. I
>> use a small hand held collet chuck drill bit holder with a set of
>> small drill bits. I start by finding a drill bit that fits the old
>> jet exactly and make a note of it. I then solder up the old jet and
>> drill through the solder with a smaller drill bit.
>> If there is any yellow in the flame, I repeat the above procedure
>> going to a smaller drill bit and check the color of the flame again.
>> I repeat the above procedure until the flame is totally blue with no
>> yellow showing. A blue flame indicates complete combustion with
>> absolutely minimal O2.
>> Some stoves, hot water heaters, and HVAC central home units offer
>> their products with conversion jets to make the conversion from
>> propane to natural gas or visa versa but sometimes there are small
>> other differences between the two product lines other than just the
>> jet. Whatever the differences are, they must be minimal because from
>> comparing two seemingly identical space heaters for different gasses,
>> I could not see any differences other than the jet sizes but the
>> manufacturer listed totally different part numbers for the two units
>> so there must be some small difference.
>> As simple as a boat range is, I doubt there would be any problem
>> changing the jet size and trying it. If the procedure wasn't
>> satisfactory, just drill out the solder and return the range back to
>> stock.
>> I would be highly surprised if changing the jets to a smaller size
>> wouldn't produce a perfect conversion but since the conversion is so
>> simple and cheap, why not try it if your range and oven is in good
>> shape otherwise?
>> Not only is propane cheaper and easier to find than CNG, it also
>> provides more BTU's for more efficient tank efficiency.
>> One property of CNG that was highly praised in the 70's when it first
>> became popular for boats was that CNG is lighter than air and would
>> not concentrate in bilges making shipboard use safer. In actual
>> practice, some boats have been blown up with CNG from overhead cabin
>> lights making little or no difference in actual safety experiences
>> between the two gasses in enclosed vessels like ours reducing the
>> popularity of CNG.
>> Anyway, that's my two cents. As I type this, I'm sitting here keeping
>> warm near a non-vented gas space heater converted from propane to
>> natural gas. Propane to natural gas is an easier conversion than visa
>> versa because all I needed to do was enlarge the jet instead of
>> making it smaller making soldering the jet orifice unnecessary.
>> Tom Troncalli
>> Renata #95
>>
>> ----- Original Message -----
>> *From:* David Epstein <mailto:davidepstein at seicontrol.com>
>> *To: *Catalina 38 Listserve <mailto:listserve at catalina38.org>
>> *Sent:* 12/22/2009 1:23:11 AM
>> *Subject:* Re: [C38] New Owner w/ CNG question
>>
>> Hi Jay,
>>
>> Congratulations on your "new" boat, and welcome to the C38
>> family. I know Broad Reach very well. We used to race against
>> them, and I even raced on it a couple of times.
>>
>> I have never had any problems finding CNG. You can get it a gas
>> dock that is not too far from San Diego Yacht Club (SDYC) in
>> Shelter Island in the SD harbor. I think it might be called
>> Pearsons Marine Fuels. You don't have to get your tank filled,
>> you just remove yours, exchange it for a full one, and you are on
>> your way. In fact, I always try to get a tank when we are in SD
>> as they seem to put a bit more gas in the tanks than they do in
>> Marina del Rey. As I recall, you get as much as 2300 lbs, and we
>> are lucky to get 1900-2000 lbs in MdR.
>>
>> Personally I would not consider changing to Propane, unless you
>> are planning to spend a lot of time in Mexico or other areas
>> outside So Cal. CNG is lighter than air, making it much safer
>> than Propane, which will settle in the bottom of the boat.
>>
>> Let me know if I can be of any help to you, and again, welcome.
>>
>> David Epstein
>> C38 #122, SuperStar
>> Marina del Rey, CA
>>
>> At 01:17 PM 12/21/2009, you wrote:
>>
>>> Greetings All. We recently purchased C-38 Hull # 311 “Broad
>>> Reach” with the original CNG system. The boat is going to be a
>>> San Diego boat and I was wonder what other So Cal owners have
>>> done to fill their tank. Is there an exchange site around, do
>>> you use an adaptor and fill at the auto stations, or has
>>> everyone given up and converted to propane? Love the boat
>>> overall, but this CNG issue may be a hassle for weekend
>>> cruising. Would also like to hear from other C-38 owners in the
>>> area to exchange ideas and information. We can be contacted off
>>> list at jsorensen at novarx.com <mailto:jsorensen at novarx.com>
>>>
>>> Thanks!
>>>
>>> Jay & Dorothy Sorensen
>>> C-38 #311 “Broad Reach”
>>> San Diego, CA
>>> _______________________________________________
>>> Listserve mailing list
>>> Listserve at catalina38.org
>>> http://catalina38.org/mailman/listinfo/listserve_catalina38.org
>>
>> David Epstein
>> President, Sound Solutions
>> Chairman, CEA TechHome Division
>> Member of the CEA Board of Industry Leaders
>> Member, CEA Division Executive Board
>> Tel 310.398.0032
>> Fax 310.398.0036
>> www.soundsolutions.com
>> <http://www.soundsolutions.com/>www.ce.org
>>
>> <http://www.ce.org/>
>>
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>
> --
> Donald R. Strong
> Professor
> Section of Evolution and Ecology
> University of California Davis
> 95616
> 530 752 7886
>
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