Propane to Natural Gas?

[H.Callahan]

Are most things that use propane as fuel usable with natural gas instead?

Here is what I am thinking. The garage that I do most of my smelting in (currently with a plumber's lead furnace sitting on a 20lb propane tank) is piped for natural gas. It runs the unit heater that is in there to warm the garage in the winter. While I can still get the propane tank that runs it filled, I have to take it to a propane refilling company that is on the other side of town to get it done. I can't do the exchange thing because the valve is different than what is used for the BBQ propane tanks. I was wondering if I could tap into the existing natural gas connection and run the furnace off of that. Alternatively, could something like a propane turkey fryer work? It would be an endless supply of gas (as long as I pay the bill!) and I wouldn't have to try to find a time to get the propane tank over to the propane refiller (their hours of business coincide with my working hours almost to a T).

Can something like this be done?

[deepwater]

I used "gas" forges in my architectural blacksmithing businesses for 30 years. Homemade and commercial furnaces. They were usually designed for natural gas. To run them on propane in my rural setting, the orifice was changed out to a slightly larger hole because propane has less BTU s than natural gas. Sometimes I purchase a new orifice, sometimes I just drilled a larger hole. On one forge I installed a ball valve and was able to continually adjust the amount of gas at will (separate from the total air/fuel volume). As the forge heated up I could turn back the amount of propane for a neutral flame.

In your situation, I would believe that a slightly smaller orifice would be the way to go.
You need to reduce the fuel to air ratio. Depending on the burner, this may be done with a sheet metal rotating cover over vee shaped holes or an outright restricting orifice. In the later case, a spot of weld or braze and redrill to a smaller hole size. Increase hole diameter until a neutral blue flame appears.

[turmech]

I do heating and air conditioning and deal with converting furnaces to propane from natural a lot. An appliance will not run correctly off of the incorrect fuel.

that being said I would try it just don't use the regulator on the hose that connects to the lead melter to you portable LP tank. This regulator changes tank pressure to 11 inches of WC. The natural gas supply at the shop heater should already be lower at 3.5 inches WC. You will lose some Btu's and I would not leave unattended not that anyone would leave melting lead unattended.

[skeettx]

I have seen many folks using an old water heater burner as it is set for Natural Gas

[dragon813gt]

The natural gas supply at the unit heater should be above 5". Now the manifold side of the gas valve should be between and 3.5"-3.7"(it depends on the particular unit). That's also based for at sea level. There is a bunch of math involved in converting from natural to propane as far as orfice size goes. It's easier to go from propane to natural because you can drill out the orfice with the correct size bit. Going the other way is going to require a new orfice.

Also the regulators used on propane tanks are PSI based. Not inches of water column based. There are about 27" of water per one psi but this is specific gravity based. Like I said, a bunch of math.

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[turmech]

dragon is correct I was wrong and thinking of manifold pressures not supply line pressure. I would try it and if it melts the lead at the lower btu's and does not soot it should be fine for what little it is probably used.

[Gee_Wizz01]

I am with Skeettx, find an old natural gas water heater and take the burner out and it will make an outstanding lead smelter. The best part, is you can normally get one FREE! The last one I got, I found the old heater sitting on curb for trash pickup. If you know any plumbers, you can probably get one for free, or very little cash.

G

[BoolitSchuuter]

Natural gas is regulated to 4 - 5 inches of water column, propane is regulated to 10 - 15 inches of water column. to put this in perspective, 1 PSI = 27.7 inches of water column. Orifice size will be determined by the BTU output you want. Like Dragon said, whole lot of math involved. Lots of charts available on the web so its really not that difficult. Just ask the right question. Or go to your local heating and cooling guy.

[H.Callahan]

Wow. I had no idea that this was going to get this complicated! I was kinda hoping that it was going to be as simple as running a flexible connection from the T stub that is already in the line and figuring out the right connectors to fit everything up without leaking. Kinda like a Bunsen burner only with a lot more flame/heat.

I may try locating an old water heater. Dad was a plumber (that's where the lead furnace came from), but I think all his buddies are either retired or dead. Maybe one of the live ones can point me in the direction.

Also, what about those "table top" gas stoves? Would they put out enough heat to do the job?

[mtnman31]

Go with the old water heater burner. I have one that I use when I smelt. I have not tried to set it up to control the flame - it is just on or off. The price was right (free) and I only smelt every so often so I didn't need anything fancy or complicated. The fittings cost me a couple bucks but it was definitely worth it in the long run since propane can get expensive when you add up camping trips, grilling and tailgates. The natural gas cost was easier to stomach, especially when I used to rent and utilities were included.

[Adk Mike]

I've been in the propane business for 28 years. Keep it simple a turkey and a 20 lber works good. In cold weather I hook two together. If your values out of date you can't legally fill the tank. I like the cooker with the red regulator (high Pressure). When your done just keep the tank out side. Mike

[dragon813gt]

I was wondering how he was getting the tank filled. I remember having to buy new tanks new years ago.


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[H.Callahan]

I think the laws vary state to state. I am getting mine filled at the local welding gas supplier. Actually they supply propane for most of the places in town. At any rate, they have told me that (here, at least) there is an exemption for propane used for commercial, welding or smelting purposes (ie, anything that is not attached to a grill or consumer level products). Even though I am a consumer, since it is attached to a plumber's furnace (and would have to be given the type of valve it has), I am good to go with refills.

[H.Callahan]

Are there flexible hoses for natural gas? Another thing I have been reading is that flexible connections with natural gas are hard to seal (?) and need to have a plumber/steamfitter to do them properly (again, ?)

What I am trying to get to is a semi-portable burner that I can place inside the garage on the floor, then run a hose (or equivalent) to a NG connection with a valve along the wall. Then when done smelting, move the burner and hose to a storage location. Since there are hoses for propane to grill, fryer, whatever, I just assume that the same kind of setup would be possible with NG? No?

[dragon813gt]

They sell short flexible hoses for hooking up ranges at Lowes/Home Depot. If you're talking a long length then you're into CSST and most wholesalers will not sell to you unless you've gone to the training class. It's really easy to use but the training is for liability reasons.


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[Fugowii]

Also, what about those "table top" gas stoves? Would they put out enough heat to do the job?

Absolutely! I melt lead on a Coleman propane stove sometimes. Not too much as the grating doesn't like the weight.

[turmech]

The metal flexible connectors for hooking up appliances come in lengths at least up to 48". I think they can legally be 72" by code but I don't remember seeing them larger than 48 for sale.

If I was going to hook it up only when smelting I would adapt to use the current hose. Or copper tubing. Although neither of the above meet code so I would not leave it unattended and I would have a valve before the connection to turn if off.

Also make sure you cap the tap after the valve when not in use to prevent someone from turning it on.

[Gee_Wizz01]

I recently bought a Natural Gas conversion kit for my propane grill. The kit came with a flexible hose about 6' long and quick disconnect that screwed on to my gas valve. The quick disconnect is similar to the type used on air hoses. You should be able to use one of those hoses for a gas smelting setup.

G

[moptop]

To run them on propane in my rural setting, the orifice was changed out to a slightly larger hole because propane has less BTU s than natural gas.

It is the other way around. Propane produces more BTU's than Natural gas because it has more carbon atoms per molecule. The orfice should have been reduced in size not increased.

Sorry, occupational hazzard of being in appliance repair business.

[Wayne Smith]

Something else to consider. I have a gas furnace and added a gas water heater. I was talking to the contractor and he told me that I was using all the gas available with my current setup. If I wanted to add a gas kitchen range I would have to either go to a larger inlet or to a pressurized system. I know nothing more than this one experience.

[Mal Paso]

It is the other way around. Propane produces more BTU's than Natural gas because it has more carbon atoms per molecule. The orfice should have been reduced in size not increased.

Sorry, occupational hazzard of being in appliance repair business.

I saw that too. Propane is heavier and needs to run at higher pressure so a smaller orifice is used for the same BTUs as Natural Gas. Conversion charts are available. I got one with my Orifice Drill Set which is basically Numbered Drills 40 through 80 plus a pilot reamer. Use the drills as gauges to find the current size and BTU on the chart and it will give you the Natural Gas size. Might need adjustment of Air Shutters etc. A good appliance guy can do this.

[warf73]

Something else to consider. I have a gas furnace and added a gas water heater. I was talking to the contractor and he told me that I was using all the gas available with my current setup. If I wanted to add a gas kitchen range I would have to either go to a larger inlet or to a pressurized system. I know nothing more than this one experience.

Not sure how the gas is piped in Virginia but when I bought my house it had a gas furnace and gas water heater like you. I added a gas stove and gas drier to the house before we moved in. The only thing I done was add the pipe were it was needed to make them 2 extra items work. That was 1998 and nothing else has ever been needed to make it all work. I am talking about Natural Gas not propane, I would chat with someone else about your gas needs other than the contractor sounds like he is after more money that might not need to be spent.

[dragon813gt]

Gas piping size is determine by the BTU load of the appliances hooked up to it and the total length. Most residential homes get by just fine with a 3/4" main. Instant water heaters are where you have to start upsizing the main. Or I tend to manifold it right inside the house and run a dedicated line for it.

Either way it sounds like the contractor did not know what he was talking about. The pressurized system makes me think this. It's already pressurized and you are not going to have a residential house converted over the a PSI based commercial pressure.


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