Seaward Stove Conversion

Seaward Stove Conversion

I converted my Seaward to propane last year. The conversion kit is available from Seward (about $120), which includes new jets, thermostat, oven burner control, etc. You will find the model number of your stove on the back and it helps when talking to Seward. I had to get back with them as my kit did not have the correct oven jet. Please note that changing from CNG to propane IS NOT the same as going from propane to CNG! You will need the correct oven burner control as the CNG control allows too much gas to enter the system. Some things to consider:

1. You must run a propane line directly from your propane tank (or locker if you have one) to the stove. Common sense and all the regulations say it is a very bad idea to have joints in your supply line as each joint is a hidden location that can fail and put propane in your bilge. I mounted an aluminum tank on be rail ($140) and ran a 30 foot line to the stove. I also have a propane heater mounted on the bulkhead and have another 40 foot line running to that unit (lines run about $70).
2. When installing propane you must have an external shutoff switch that can be operated from within the cabin. I wired mine to the masserator switch as I removed that unit some time ago (These begin at about $70 as I recall).
3. You will remove all of your CNG gear, which will allow for better access to you engine compartment if your is mounted like mine was in the port lazzerette. Once this gear was gone, I cut a much larger opening to the engine compartment and this modification was one of the best things I have done to my boat! I found the gas fitting from the CNG hose to my stove to be extremely tight and I had to use a pipe extension on my cresent wrench to free it.
4. Re-plumbing the stove essentially requires that you completely remove the stove as you will find it much easier to do the job if you remove the stainless cover on the right side of the stove to get to piping for the gas and thermostats. While doing this, I also removed the teak panel from behind the stove to snake the propane hose in. I discovered a good sized cubby that someday I will figure out something to do with. It appears a previous owner used it to store some emergency sustanance (beer).
5. You should also install a propane detector. I purchased one from an RV seller for about $50 and installed it at the bottom, starboard side of the cabin steps. The unit I bought malfunctioned last fall after only four months of use. Don’t know whether it was too exposed to weather in the location I chose or what. I wired the unit so it would come on when I switched on the propane.

As usual, the cost and complexity of this conversion is significantly higher that it would seem on its face (a generalizable truth regarding sailboat projects). The project itself is not rocket science, but does require some time and care. For example, I checked every one of my connections with soapy water to ensure against leaks. This required I hook the stove up to propane and testing it while the right panel was still off and unit was sitting on the fridge. It also requires you run lines up, around and through from your propane tank to the stove, which is no fun if you don’t cut out the false floor in the port lazzarette. Would I do it again? Absolutely! as propane is so much easier to obtain and use in my area. I cannot imagine running my heater with CNG as the cost would be astronomical!

Charles Finn
Mighty Quinn #114

3 Responses to “Seaward Stove Conversion”

  1. sgallagher says:

    The above isn’t dated, but after contacting the manufacturer they referred me to a local dealer… below is a copy of the email he sent me on how to do the stove conversion as of 10/2011:

    Sean Gallagher

    The CNG kits, Seaward carried, are long out of production, I have been stocking CNG Conversion Parts, for many years…

    Top Burners are converted from CNG to LPG, with new brass orifices. These are the brass pcs. that “meter” the LP Gas, into each Top Burner.

    Here is a picture of a longer orifice and a Top Burner similar to yours, that I use in another application. The orifices you need are shorter, but otherwise the same:

    Your stoves Oven Thermostat, can be converted, from CNG to LPG. The process can be as simple as turning a slotted stem, with a screw driver and changing 2 orifices, for the oven burner. It depends on the particular oven thermostat you have.

    There were two types used by Seaward, who manufactured your stove. CNG stoves were sold by a company named Gas Systems, which you see on the front of the stove.

    From the top view, if you hinge up the stove top, the Thermostats both look identical. The difference is only seen from the front of the thermostat. In order to do this you will need to remove the thermostat, to have a closer look…

    Below is a picture, of the model that “converts” the thermostat by turning a slotted stem, 180 degrees from “NAT” to “LPG”.

    If you are lucky enough to have one of these models, you are half way there:

    (sorry the link to this pic wont copy over)

    If yours says, NAT and OFF, you will need to buy a rebuilt LP, thermostat. They haven’t made these thermostats for many, many years… I keep a small supply on hand for CNG customers like yourself and others with LP systems, that may need replacement oven thermostats. They are remanufactured with new parts.

    Of course your thermostat needs to “work” with CNG, to be convertible to LPG, otherwise you may have to replace other parts, to make it work…

    Your cost for parts, if you have the “convertible” thermostat, pictured above, would be $75 and includes, some instructions and phone support from me, if you should need it.

    If you need a rebuilt LP Thermostat, your cost, for parts, would be $195 and of course includes phone support.

    If you need the $195 option, you will need to send me your thermostat, so I can recycle it, with my supplier, it doesn’t matter if it works or not they can re-build it, with LP Parts.

    There are some additional plumbing changes, needed, that I can supply: LP Hose, LP Regulator, and 3/8” flare inlet fittings, on the stove and to connect all together. (Your CNG stove has compression fittings, which we don’t use with LPG).

    Shipping and 6% sales tax (if shipped to Florida address) will be added to above prices…

  2. mlewis says:

    I have picked up this trail for converting “GAS Systems” CNG to LP. Seaward; maker of GAS Systems, who bought parts from RobertShaw (who no longer offers oven thermostats on their web site) says: We no longer stock parts or conversion kits and recommend replacement. Seaward referred me to Ronnie 626-443-8825, for tech support. Ronnie confirms that conversion is not mainstream (ie. you are on your own to find obscure kits/parts). He also feels the newer units have improved safety features that make selecting new easier. We discussed just converting the burners (three orifices at $10 or less a piece), and capping the oven side and removing the parts (I rarely bake and wouldn’t need to on the boat). He still felt spending a few hundred on a gimballed cooktop with newer features (auto ignition and gas leak preventers) was a better investment. (It’s more like $400-$500 for Seaward stove tops.)

    My thermostat doesn’t have any markings for Nat, LP, or Off that I can see. Cannot find this part or it’s equivalent anywhere. I am leaning towards burner conversion only, and removing the oven shell and putting my microwave there. It just fits at 19″. Suggestions/comments?

    Bluewater #6

  3. Charles Finn says:

    I think we need to get a bit further outside the box as our original parts get harder and harder to find. The truth is that just about any small stove controller will work. This means we can obtain parts for the newer stoves in our conversions. The only thing to match is burner-controller relationship.
    Essentially, what we have is a nice stainless steel insulated box! Putting new “guts” into it from any small RV type stove will work!
    By the way, one good reason to keep the oven is it is THE place to store your electronics during thunder storms! It is pretty much a perfect Faraday Cage.

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