Heating fuel cost comparision

[Bigrhamr]

Okay it's time for me to pick a boiler for my radiant floor. Natural gas is not available so it's propane or electric.

Without going into BTU per gallon and BTU per KW calculations and just using the calculator here:

http://www.builditsolar.com/References/Calculators/Fuels/FuelCompare.htm

which does the math for you I get these figures.

My current propane cost is $2.15 a gallon giving me a cost per 100K BTU of $2.75 assuming 85% efficiency. Electric is .0636 per KWH giving me a cost per 100K BTU of $1.86 assuming 100% efficiency.

Does that math look right to everybody? And what what other points would you consider in picking the fuel type? I've got a 400 amp service so the juice to run it is not a problem, I just want to keep the costs as low as possible. FYI it's a 4800 sq foot building with high ceilings, well insulated (or it will be anyway) and I put 4,800' of 1/2" pex in the slab.

 

[tdkkart]

If you're stuck with no natural gas then electric is the best choice IMO. Electric is typically closely regulated so the price remains fairly constant, propane can be all over the map. Propane costs have been known to double virtually overnight at the whim of speculators.
I can only dream of getting electric for $.06/KW. The thieves we buy from are at $.134/KW delivered on our last billing.

I like the safety aspect of electric, no sparks, no open flames, the heat is all contained inside the system.
I also like the fact that electric requires no venting. I don't like holes in my building, every hole is/will be, a maintenance headache at some point.

 

[Charles (in GA)]

I can only dream of getting electric for $.06/KW. The thieves we buy from are at $.134/KW delivered on our last billing.

Same here, six cents a kwh is way cheap. Here I take the bill total and divide by the kwh and usually get .13 or so per.

Charles

 

[porcupine73]

Not considering the cost, one thing I like about propane is that you are less impacted by short term supply chain issues. What I mean is say a storm comes through and knocks out the power for a week. At least with on-site propane you have your own supply right there.

 

[tdkkart]

Not considering the cost, one thing I like about propane is that you are less impacted by short term supply chain issues. What I mean is say a storm comes through and knocks out the power for a week. At least with on-site propane you have your own supply right there.

True, but some people just can't seem to grasp the concept, every time there's a big ice or snow storm somebody calls in needing a snow plow to get the propane truck out to their place cuz they ran out of gas.

It gets really interesting when the propane company then calls in and says they're not delivering till the customer pays their last 2 bills........

 

[rlitman]

I can only dream of getting electric for $.06/KW. The thieves we buy from are at $.134/KW delivered on our last billing.

I can only dream about 13c/kWh. Around here, it's 19 or so for residential, and depending on demand billing, runs around 21 for commercial.

 

[HoosierBuddy]

I'd suggest the OP go through the calculation (as others have suggested) of looking at their electric bill and making the calculation to verify 6 cents/KWH is the appropriate figure.

However it is possible that the figure is correct. Many power companies are going to a straight-fixed variable rate design where they enbed all of their fixed costs into the customer charge so that their commodity charge only has to cover the incremental costs of the power itself.

How this typically plays out is your customer charge may jump from say, $15/month to $40/month. Meanwhile your cost per KWH should go down.

The net effect of this change is it makes propane or other bulk fuels less cost effective, because you have to have power and you're going to get hit with the big customer charge regardless of the amount of power you use.

A cynical person might think that's why the power companies have gone to SVR rate design. To eliminate the competition.

Phil

 

[Jackfre]

I'm a gasser, but if you do go electric I would suggest that you be certain of how rates are calc'd. The reason I say that is if you have a significant kwh boiler you want it to bring itself to capacity in stages. That way you aren't browning out the neighbors and you avoid any shenanigans by the power company basing your rate on what is called "demand shadow". I do not know if such billing exists, but I'd check to make sure prior to going elec. With utilities and in so many other things, it is the questions you didn't ask...

As well, it being radiant, I would put a good outdoor reset controller on the boiler (Tekmar and I think Taco make them). That will help your system. The better modcon lp boilers will have that built in.

Also, I didn't run the numbers to confirm your calcs, but NG is 100kbtu/therm. LP is 92,000btu/gal

Good luck!

 

[tdkkart]

I'm a gasser, but if you do go electric I would suggest that you be certain of how rates are calc'd.

Mine's easy, this is included in a box at the bottom of my bill each month:

"AVERAGE UNIT COST"
"(EXCLUDING SALES TAX)"
"Elec $ .134"

 

[adorf]

I am a plumbing/radiant heat contractor and I often recommend electric boilers. Take a look at Electro Industries. They have models that have built in outdoor reset.

 

[Bigrhamr]

Thanks for the replys. That figure of .0636 is correct, it has it right on the bill and if you divide the usage portion of the bill by the KWH it comes out right. That is the commercial rate and we don't have any adjustments for peak/off peak usage etc..
The power co here is a member owned co-op, so at least if we get screwed it's by our friends and neighbors. When I built the shop I paid dearly to get 3 phase put in and have 75 KVA transformers that only serve me so dimming the neighbors lights is not an issue.

I've got a propane furnace and hot water heater in the house and as mentioned prices wildly fluctuate so I'd rather not get in any deeper with those guys.

I have a diesel generator for backup if the power goes out but when that happens I'll more than likely just lock up the shop and give myself a vacation day.

Here's the one I'm considering, a Slant Fin Monitron II.

http://www.slantfin.com/images/stories/Product-Literature/catalogsheet_monitrondeluxe_eh_m2m3_10.pdf

It has outdoor reset built in, and starts just one element at a time with a delay in between. You can also manually shut off elements for moderate weather conditions.

Still looking at other options but I'm leaning towards that one pretty hard.

 

[Dragster Racer]

I ran the numbers, and got an electric heater. I paid the first two bills, and ran out and bought a propane heater. I don't know why the calculations and reality don't add up, but I am not the only one who has been down that road.

 

[SeanM]

Xcel energy here in St. Paul MN
Cost per Therm is .1301
Cost per kW/h is .1355

This was a no brainer for me.

 

[SeanM]

Maybe I mention that 1 Therm is 29kW/h or 100kW/h

 

[siduramaxde]

Any thought given to geo thermal? It would be electric. It only costs me about $1 per day to heat and cool my 2000sqf house on a yearly average. And I don't skimp on the thermostat. I pretty much set it on auto (heat on at 69 cool on at 72). This is in the St. Louis area.

I will install geo thermal in my next shop. A/c in the shop would be awesome in the summer.

 

[HoosierBuddy]

Xcel energy here in St. Paul MN
Cost per Therm is .1301
Cost per kW/h is .1355

This was a no brainer for me.

That gas price seemed impossible to me, so I checked:

http://www.xcelenergy.com/staticfiles/xe/Regulatory/MN_PGA.pdf

Gas price is currently $.742977 per therm (1 therm = 100,000 BTU).

That equates to $.02535 per KWH if you are a residential customer with them.

Phil

 

[danski0224]

I'd do a heat load and figure out the btu requirements first.

If you do a condensing boiler, you can approach 98% efficiency with low temperature radiant.

 

[SeanM]

That gas price seemed impossible to me, so I checked:

http://www.xcelenergy.com/staticfiles/xe/Regulatory/MN_PGA.pdf

Gas price is currently $.742977 per therm (1 therm = 100,000 BTU).

That equates to $.02535 per KWH if you are a residential customer with them.

Phil

Yea, I screwed up on typing that (this is what happens when I try to do real work on my tablet)

The "winter" rate is 0.62931, my average price per therm with associated local fees, taxes, and this thing they add to pay for local income customers (I note this because it pisses me off) is 0.83634

Anyways, my point being. With the addition of a efficiency coefficient gas is still 3.5x cheaper in comparison to electric to run.

 

[BadgerBoilerMN]

I am a plumbing and radiant floor heating contractor and I design hydronic heating systems for living here in Minneapolis. I too use and even own an Electro boiler but using electricity is rarely cheaper in the long run.

Now compared to Geo, electric boilers are a bargain by any standard. Geo is hard to justify if you calculate your return on investment for most residential applications.

The question of cost-per-therm is erudite, but ROI is the end game.

So, how much did it cost to a dollar per day electric bill?

 

[Bigrhamr]

I am a plumbing and radiant floor heating contractor and I design hydronic heating systems for living here in Minneapolis. I too use and even own an Electro boiler but using electricity is rarely cheaper in the long run.

QUOTE]

BadgerBoiler,
can you elaborate on why electric might not be cheaper in the long run given the pricing I posted above? That's what I'm looking at is if there is something I'm missing here. I mean isn't a BTU a BTU, and a dollar a dollar, and more BTU's for less dollars = lower operating cost?