I have an oil boiler in my house (boiler and burner about 27 years old) and, as part of a renovation project, I may upgrade to something more efficient. I thought I would have to stay with oil because I have no natural gas available on my street.
I was surprised when a recommended heating guy suggested replacing my oil system with one based on liquid propane. When I do the numbers, the price per gallon for oil and LP are about the same in my area (Massachusetts) but LP has fewer BTUs so the price per BTU is cheaper with oil.
The guy said that the gas boiler (Viessmann) can get up to 96% efficiency where the best oil boilers can only get up to about 86%. While those numbers are true based on what I've read, my simple calculations show that that difference is not enough to make up for the higher cost of LP.
He claims that those numbers don't tell the whole story because the entire LP system would be more efficient: modulating, condensing, etc. But I thought modern oil boilers have those features too? He was saying that those simple numbers don't tell the whole story.
I'm willing to believe LP can be better but I haven't seen good arguments. Is this guy simply wrong or is he right but not able to express his information well?
Best Answer
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.