Propane or pellets, breakeven analysis matrix

[Frank Nuhfer]

Has a breakeven analysis ever been done to determine which is cheaper to heat your house? I have my Austroflamm Integra II stove set to 5% out of 100% and one bag lasts almost one day. I currently pay $5.49 for one bag of pellets, so I use about 33 bags a month or $183 a month in pellet fuel. I have not included any electric costs in burning the pellet fuel.

I also have two propane forced air heaters, one for the bedrooms end of the house and one for the main house. Propane here costs about $3.51 gallon and I just filled the tank which cost me $615. I run the pellet stove 24/7 and it does a good job in the room where the stove is located. It's cooler at the far ends of the house but not cold. We like a cooler bedroom area, so keep the door closed going to the bedrooms. The propane heater basically heats the bedrooms. My house is a little more than 3000 sq ft single floor, so it is all on one floor.

I just wonder sometimes if I would be better off just running propane or should I shut off the stove at night and start it in the morning again. Anyone have any data on converting bags of pellets into the equivalent gallons of propane??

 

[mikkeeh]

Propane is about 90K btus /gal. Wood pellets are approx. 8K btus/lb.. So roughly 11lbs of pellets = 1 gal propane.

 

[jfunk138]

Based on raw BTU, 1 bag pellets = 3.5 gallons propane = 2.5 gallons heating oil = 3.2 therms NG.

Assuming equal efficiencies, you would have burned 115 gallons of propane to provide the same heat as your 33 bags. At the price you quoted that is $403. Sounds like you came out $220 ahead with pellets. (or looking at it another way, you paid yourself $220 for all the pellet hauling and stove cleaning you did for a month)

 

[moey]

Something to think about if your heating just your bedrooms with a propane boiler or furnace you are doing it pretty inefficiently. Your system is sized for your entire house not just the bedrooms. That usually is where short cycling starts. I used to run a space heater on the furthest parts of my house otherwise the boiler would fire every 20 minutes to heat one room very inefficient.

 

[AndrewChurchill]

I use a spreadsheet to calculate how much I am saving by using wood pellets over oil or propane.

My December daily average of pellet usage is 116 pounds or 1009200 btus per day based on 8700 btus per pound.

Cost of pellets is $262.5 p/ton or .13 p/lb.

Daily average cost to heat my house, apartment, and DHW is $15.08

Oil based on $3.75 p/gallon would be (1009200/138000) * 3.75 or $27.42

Propane based on $2.62 p/gallon (1009200/91500) * 2.62 or $28.90

 

[SuperGenius]

https://www.hearth.com/econtent/index.php/articles/fuel_cost_comparison_calculator/

The key is to enter accurate efficiency figures.

 

[chken]

Given your pellet cost and your propane cost, almost certainly, it is cheaper to heat with pellets. However, because of where your stove is located, it probably makes sense to heat with pellets, but to supplement the bedroom area with propane for comfort.

 

[moey]

I dont know where you live in Maryland but at $3.51 a gallon theres a good chance electric is cheaper. Assuming a 90% efficiency for your propane units that would be equivalent to about .14 kw/hr electric rate. I also doubt your pulling that high of efficiency because the unit is probably short cycling because your stove is running.

 

[GeHmTS]

Has a breakeven analysis ever been done to determine which is cheaper to heat your house?

Sounds like you have all the data. Create a linear equation with cost vs pellets; create another linear equation with cost vs propane. The intersection is your break even point.

 

[Indiana]

I use a very simple calculation. While heating with propane and setting the thermostat at 64 I use 1600 gal per 12 months at 3.55 a gal. With pellet heat, I use 400 gal every 18 months for dryer, water heater and cook top. I normally by my 5 ton of pellets for $180 a ton in October and maintain 70+ degrees all winter long. By my calculations I'm not spending over $4500 on heat. That is well worth my efforts in hauling, stacking, and cleaning my Englander CPM.

 

[IHATEPROPANE]

Pellets cost me about 1/3 of what propane would cost.......

 

[moey]

Its hard to compare a space heater to a central heating system. The best way in my opinion is to look at past years on the number of gallons burned and compare that to the number of pellets burned. As a few have mentioned.

 

[Frank Nuhfer]

Something to think about if your heating just your bedrooms with a propane boiler or furnace you are doing it pretty inefficiently. Your system is sized for your entire house not just the bedrooms. That usually is where short cycling starts. I used to run a space heater on the furthest parts of my house otherwise the boiler would fire every 20 minutes to heat one room very inefficient.

I have two propane forced air furnaces, one just for the bedrooms, and one for the rest of the house. The main house thermostat is around a corner from the pellet stove so the pellet stove heat creeps around the corner and causes it to not kick in as often as it would w/o the pellets stove running. Since I burn a little more than a bag a day, and the propane furnace kicks in off/on all day also, I just wondered whether I was wasting money by running both.

 

[moey]

I have two propane forced air furnaces, one just for the bedrooms, and one for the rest of the house. The main house thermostat is around a corner from the pellet stove so the pellet stove heat creeps around the corner and causes it to not kick in as often as it would w/o the pellets stove running. Since I burn a little more than a bag a day, and the propane furnace kicks in off/on all day also, I just wondered whether I was wasting money by running both.

Sounds like your probably saving some money if thats the case. I never liked our boiler running because one zone would call for heat and it would cycle a 75k boiler to make heat for a 10*10 room. Lots of waste on startup to get up to temp.

 

[SuperGenius]

I have two propane forced air furnaces, one just for the bedrooms, and one for the rest of the house. The main house thermostat is around a corner from the pellet stove so the pellet stove heat creeps around the corner and causes it to not kick in as often as it would w/o the pellets stove running. Since I burn a little more than a bag a day, and the propane furnace kicks in off/on all day also, I just wondered whether I was wasting money by running both.

You're not wasting money, Frank. Your pellet stove is pumping BTUs into the house, and that's heat your main living area furnace doesn't have to produce, so it will run less often and use less propane. The trick is maintaining comfortable/even temperatures over the entire area heated by that furnace, which might take some damper tweaking and additional fans, etc.

 

[Frank Nuhfer]

https://www.hearth.com/econtent/index.php/articles/fuel_cost_comparison_calculator/

The key is to enter accurate efficiency figures.

Wow is all I can say. My electric rate is .154611 per kwh and I used 1388kwh in December. My pellets cost $275 ton with a fairly new stove, 2007 or 2008 IIRC, so I used their efficiency numbers. I don't heat with electric, I just use electricity to run my fans to burn pellets or to run the fan on my furnaces along with propane. According to the table,
$22.73 per Million BTU of Heat delivered to home $2,159.35 per year for normal home for Pellets
$49.95 per Million BTU of Heat delivered to home $4,745.25 per year for normal home for LP (Propane) Gas

Based on the above two methods of heating, I am paying over 220% more if I use LP gas, not counting the electric needed to make both work.

 

[SuperGenius]

Keep in mind that calculator assumes a "normal" home uses 95 MBTUs worth of heat annually. You can determine yours by multiplying your annual propane gallons by 91,500 (which is the appoximate BTU/gallon for propane), then multiply that figure by the combustion efficiency of your furnace(s). Do the same for the pellets, using the appropriate numbers.

In my case, I average 400 gallons of heating oil @140,000BTU/gallon to heat my house and hot water, so: 400*140000= 56,000,000 BTU. My boiler is 87% efficient, so: .87*56,000,000= 48,720,000 BTU total heat energy.

Also, your furnace fans are much higher wattage than your stove fan, so it should be much cheaper, electrically, to run the stove.

 

[PassionForFire&Water]

[quote=". My boiler is 87% efficient, so: .87*56,000,000= 48,720,000 BTU total heat energy.[/quote]

Do you mind sharing the brand and model of your oil boiler?
87% seems quite high

 

[SuperGenius]

Do you mind sharing the brand and model of your oil boiler?
87% seems quite high

Actually, 87% is pretty common these days, some are a few points higher. Mine is an Energy Kinetics System 2000 boiler with a SuperStor Ultra indirect water heater, installed Sept 2008. My oil consumption went from about 650 gallons/yr to about 400 with zero supplemental heat. Interestingly, my previous boiler was 83% efficient, so it's obvious that AFUE ratings don't tell the whole story. Quite a few "heating professionals" told me not to bother replacing my 1994 New Yorker for the 4% savings, yet the S2k has almost paid for itself already. Unfortunately, this makes it harder to justify a fireplace insert, but I'm slowly convincing the wife...