Furnace – What’s the Right Size Pipe to Buy for Gas Supply for Furnace?

I'm not sure exactly where this pipe is, or how far back the pipe runs. Though most codes now call for a shutoff valve be installed for each appliance, in the same room and within 6' of the appliance. I'm going to assume that the piece of pipe you're looking to replace, runs from the shutoff valve to the appliance (this might be a terrible assumption, but you didn't supply much detail about your situation). If this is the case, you could use a piece of flexible copper pipe exactly the same size as the one you're replacing. Or you could use a corrugated stainless steel tubing (CSST).

As you've seen, flexible copper is prone to kinking, especially if you're moving the stove often. The CSST is more resilient to movement, and is typically easier for DIYers and homeowners to work with. If you do switch to CSST, you might find that you need an adapter to connect it to the valve. You should be able to find CSST fittings in various lengths, at your local hardware store.

If you choose to replace the pipe with flexible copper, you should shut off the gas and take the pipe with you to the store. With the pipe in hand, it should be no problem finding replacement pipe. You might also find that the end(s) of your copper pipe are flared. If they are, you'll also need to flare the ends of the new pipe. Some stores can do this for you. If they can't, you'll need a special tool to do it.

Without actually seeing the installation, it's difficult to provide any more specific information.

First, check to see if there are any tax breaks on the LP system for your area.

My rule of thumb on energy savings savings is, it must pay off in less than 10 years or half of it's usable life (which ever is shorter). Since you have to replace the unit, see if the difference in cost - expected savings in energy over 10 years justifies going LP. A lot of times, the energy efficient items don't pay off unless they have a tax break or you have to replace an entire system anyways.

Edit: I was curious about the results and looked up the values. Assuming you are using 800 gallons of oil each year at a rate of $4.21 a gallon = $3368 year. You would need 1060 gallons of propane to match the 800 gallons (taking into account different efficiency) at a rate of $3.80 a gallon = $4028 a year.

Cost data came from here: http://www.eia.gov/dnav/pet/pet_pri_wfr_a_EPLLPA_PRS_dpgal_w.htm BTUs of propane: 91,500 per gallon BTUs of heating oil: 135,000 per gallon Conversion from oil to propane used: oil gallons * oil BTUs * oil efficiency = 92,880,000 effective BTUs used each yet. 92,880,000 / propane efficiency / propane BTUs = 1057.38 gallons of propane used.