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propane vs oil fired boiler

jroy's picture

My hvac contractor is recommending a new hi eff propane boiler versus an oil fired version. I realize that the propane version will be more efficient...but is propane worth the higher fuel cost associated with propane (vs oil) as well as the lower btu output? It seems that when oil prices rise so too does propane. I dont have a natural gas line to tap into so my choice is limited to either oil or lpg.

You can compare the relative (post #184846, reply #1 of 8)

You can compare the relative costs, but you need the fuel costs and the efficiencies of the units. If one costs less to operate, but costs more to buy, you can estimate "payback" with HDD (heating degree days) for your area.

What reason does the contractor give for his recommendation? There are some very nice, very efficient oil boilers out there (i.e. Viessman). What type of system do you have, hot water or steam? With a steam system, the process limits the efficiency no matter the fuel.

Personally, I prefer LPG. Not really affected by temperature, not as messy, tank is outside. thousands of NG products that can be easily converted to LPG.

There is no number at which (post #184846, reply #2 of 8)

There is no number at which propane works out. '

a gas furnace should be cheaper up front, but will cost more in the long run.


I just installed a 92 percent Buderus oil, so I have done the math.


I too wish I had gas in the street....


>>There is no number at which (post #184846, reply #3 of 8)

>>There is no number at which propane works out. '

It depends on where you are - for the OP, SE Mass is likely stay oil=centric for a long time to come.  In many parts of the country, I believe residential oil is no longer cost competitive

>>a gas furnace should be cheaper up front, but will cost mre in the long run.

Including maintenance?

E.g., One never has to replace jets on a gas combustion device


Including life expectancy?

Including producing hot water?


IS there a reason far more parts of the country use gas rather than oil?

I don't know the answers to these questions, but think they are worth considering.

======================================== "Man's capacity for justice makes democracy possible, but man's inclination to injustice makes democracy necessary." Reinhold Niebuhr: 'The Children of Light and the Children of Darkness' ========================================

Gas yes, propane (post #184846, reply #4 of 8)

Gas yes, propane no



just do the math

Oil fired!  They make oil (post #184846, reply #5 of 8)

Oil fired! 

They make oil fired burners that can burn various oils from Kerosene to used motor oil, and they burn clean. This is just a sample link so you can see what I mean.

If you could get an oil change place to give you their waste oil, you may not even have a heating bill, well not the bill for fuel anyway. Waste vegtable oil works too.

I'm trying to build one from scratch, (Not recommended), it has a learning curve to it. :-)


Hi, You can calculate which (post #184846, reply #6 of 8)


You can calculate which is cheaper easily using this calculator:

We use propane -- the price around here for propane is very volatile.  It was 80 cents a gallon when we started 10 years ago and is not about $2.20. 

Spend your money on more insulation :)



Hi Jroy,   up here in (post #184846, reply #7 of 8)

Hi Jroy,


up here in maine, oil and propane are close to the same cost per gallon.  oil has about 160kBTUs/gallon and propane has about 90kBTUs/gallon.

propane will easily run 20% more efficiently, real world, in a sealed combustion/modulating unit than any oil unit on the market in america will.    that's easily:  the AFUE may not show that, but with modulating operation and sealed combustion operation, we've seen it time and again.

I know there is a "92%" efficient oil boiler out there and hey, maybe I'm wrong, but I think it's still a high mass cast iron unit and unless they have very radically changed the design and control of the beast in more than just the nozzle design I'd have to be pretty skeptical you're ever going to see that out of oil.  for now I'll ignore that boiler at any rate.

but even 20% more efficiently isn't so great.  If you assume 95% vs 75%, for example, that's still 86kBTUs vs 123kBTUs... oil still delivers the same heat in 2 gallons that propane will in 3. 

so propane will probably never close that gap.

that said, it also does not require a chimney, fires quieter and cleaner too.  those count for something.  how much?  depends on you.  In my case I had a powervent on oil that stunk up my screen porch on domestic calls.  it was worth a lot to get rid of that.


Rockport Mechanical

HVAC Design and Installation in beautiful Rockport Maine

Thanks for all the thoughts (post #184846, reply #8 of 8)

Thanks for all the thoughts on this subject as Ive decided to stick to oil for heating.  My hvac guy has suggested using a Biasi B10-5 w/Superstore s.s indirect water tank for a replacement heater.  I like the Buderus BE125, but the price is too steep.

The reason Im looking to switch (from a furnace) is two fold...I cant run ductwork into parts of my new addition & my furnace is over 25yrs old, oil fired water heater 12yrs old.  I have a air handler in the attic which runs off the water heater to provide heat to the bedrooms and Ive never liked having it run off the water heater.  So changing to a boiler will allow me to use the air handler for the bedrooms, run hydro air in the ductwork I have (along w a/c)and run baseboard to the areas of the addition where duct work isnt practicle.

I would appreciate your thoughts on a good quality, efficient boiler that is reasonably priced.