We just bought another house out in the country where there is no natural gas lines. The central HVAC's gas furnace label says natural gas however, it looks like it was connected to a line that leads to where a LPG tank used to sit.

Is there a way to look at the burner to determine if it has been converted to LPG?

I was thinking that most HVAC furnaces were fuel specific and couldn't be converted but it's been a few years since I messed with that.`But, that said, whoever converted it to LP should have installed LP rating stickers on the unit and the burner valve but that sometimes gets overlooked when non-professionals do a conversion.

IMHO, the foolproof way would be to call a local propane provider and have a tech come out and look it over. That said, the burner orifice would be pretty small for LP but that's relative if you don't have the original NG orifice to compare it to. Also, if the burner assembly has an air shutter, it would be closed down pretty far.

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Never a dull moment at Berry Hill Farm.

It's not possible to look at a furnace and determine if the orifices are sized for natural gas or LP unless you're very experienced in that field. The difference is very small and the absolute size is dependent on the specific machine.

Only the manufacturer or a suitable tech rep will know that info.

If they are like grills, all you need to do is change the orifice if you change gas. Its mainly due to the pressure difference. I ran a propane gas grill on natural gas with no mods, it just makes the flames look weak. You need a bigger orifice for the natural gas. A drill can handle that chore. Going the other way might be more exciting if you put high pressure propane in a larger natural gas orifice.

You are not dealing with propane though, but LPG is also a liquid in the tank, like propane is.

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MB-less

Have a qualified tech check the orifice in the gas valve, most furnaces are ng and lp.

Whoops, do what Leo said.

Get it checked out by a pro. There are other things like mixture and flame impingement that need to be checked. A little CO can ruin your day.

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1985 380SE Blue/Blue - 230,000 miles
2012 Subaru Forester 5-speed
2005 Toyota Sienna
2004 Chrysler Sebring convertible
1999 Toyota Tacoma

Whats the difference between LPG and propane. LPG just means it's liquified doesnt it? Also what pressure does natural gas come out of the wall at I never thought about that before.

I'll take a closer look and see if I can locate a sticker somewhere. Looking at the install I'd say they were "non-professionals". It was a foreclosure I picked up cheap enough that I can afford to redo if needed.

Now, I gotta locate some day labor for 55 tons of stone going on the exterior.

LPG is a mixture of hydrocarbon gases, primarily propane and butane. The mixture can change depending on the season. Natural gas out of the ground is made up of various components, such as methane, butane, propane, ethane, pentane, heptanes+ and various impurities. The difference in each of these is the number of carbon and hydrogen atoms in each molecule.

My guess is a propane tank is around 100 psi, it is measured by weight rather than pressure. A natural gas line at your house is around 3-4psi. That is why it takes so long for a home CNG compressor to fill your car-the system is so low pressure and volume, it just doesn't give up enough to fill it fast.

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MB-less

If you have 3-4 psi coming into you house you should call the gas company. Its to much. We measure it in inches of water column and the typical coming into a home here in NY is between 7"-10" wc. Thats less than 1/2 of a psi. I was a HVAC Tech for the last 10 yrs until my back went out

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'83 300D 198,000mi Howard
'03 Saturn Vue CVT 75,000mi(wifeys)

I have seen service line pressures from 2-5 psi. Much lower than that and the regulators and meters won't work properly. Gas meters by nature are extremely inaccurate unless you are flowing at a stabilized rate/pressure.

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MB-less

The problem is, household appliances(furnaces, water heaters etc) cant handle 3-4 psi coming into them. The gas valves could be damaged, leading to the unit overfiring wich could cause damage to a furnaces heat exchanger and it producing excessive amounts of carbon monoxide. Here is the tag on my hot water heater. 14" w.c. = .5psi

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'83 300D 198,000mi Howard
'03 Saturn Vue CVT 75,000mi(wifeys)

Somewhat on topic about why you don't mess with gas. This happened a few miles from my house.

http://www.wilx.com/home/headlines/30521299.html

http://www.freep.com/apps/pbcs.dll/article?AID=/20081006/NEWS06/81006082/1008/NEWS

Don't trust the gas company, they did this to us:
http://www.cincymagazine.com/ME2/dirmod.asp?sid=2CE771F28E0D4281817E2E034A9C57C6&nm=Archive&type=Publishing&mod=Publications%3A%3AArticle&mid=61465020993F438B9FCD60C66CC58CDC&tier=4&id=3BAE467FCFD34854B93DFC82D1E6218E

To this day I don't understand why automatic shut off valves are not code.