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Electric versus propane and oil. (27 Posts)
Electric versus propane and oil.I'm trying to get some insight on the pro's and con's of electric boilers. Have any of you any experience with them? The current LP price is $2.25 per gal. Electric is 8.75 cents per kw. If I did the math correctly electric is coming out ahead of even a 95% efficient mod con gas boiler. As long as I can remember any kind of direct resistance electric heat has been considered totally out of question. Are we just going through a unique time period or is electric becoming a more viable option?
Not in my areaElectric is 11.5 cents a KW 4 times the cost of NG at .82 a therm for the same btus. You would need a pretty inefficient heat source to come out ahead with electric.
IS the .0875 cents after all end user fees?
GordyThis post was edited by an admin on January 3, 2012 10:09 PM.
There is a $25 dollar access feebut everyone has to pay that already anyway. Other than that 8.75 cents covers generation charges, distribution charges and everybody. I live in a rural district so most of us don't have access to natural gas. I'm with you as far as electric boilers going totally against the grain. It just don't seem right. But unless I made a grevious error in my math It looks as though for my area, it would be cheaper.
I wouldn'tMost electric production involves the use of fossil fuels, and that's not likely to change.
Also heating with electric takes a lot of electricity.
1 gallon propane= 91800 btu = $2.25
91,800 btu = 27 kw = $2.36 (not including other fees)
27 kw at 240 volts = 112 amps
Unless your house is already set up for electric, the initial investment would likely require a minimum 200 amp service and breaker panel to the house, plus the boiler.
And copper is not cheap!
If electric were the only option, I'd look into heat pumps.
You are right. I should probably scrap the idea.Although the energy gap costs are getting very close to the same in my area. There are a lot of other factors to consider. The Electric boiler requires a min flow rate and flow switch to keep from burning out the elements. Also it would require annuall serviceing of the eletrical connections, since it's a heavy load. And there is a certain wisdom to staying on the beaten path. I like going on an occasional walkabout though. It is a good reminder of why we do things the way we do.
flow switch?you need a different electric boiler.NRT.Rob
you missed somethingyour 91800 BTU did not take out for efficiency. even if you get a real-world 95% on the propane consistently (yeah... right) then you're at the same operating cost for propane vs electricity for the original poster. If *anything* happens to drop that efficiency further, then electricity is ahead on operating cost... right now... for him.
1. install cost on the electric should easily be 30% of the propane boiler install cost or less
2. Nearly no maintenance on the electric boiler.
3. Flow rate requirements on electric boiler are typically very low and pressure drops are usually low too... could drop a pump and its running costs.
4. No question about the electric boiler efficiency... it's 99-100% utilization of the energy you are paying for.
5. Fossil fuels historically appreciate in price about 5%/year. Electricity, only 2%. Smart money says propane and oil will be dead ends very soon. Heck, I can run heat pump numbers right now that show than no one here in maine should be running propane, right now, unless they buy in extreme bulk.
6. You can offset electricity with onsite generation, now, or in the future as prices drop. You will never do that with oil/propane.
However, depending on where you are your electricity may be coal which is the dirtiest possible thing in the world. Here in maine it's not as bad (natural gas/hydro, mostly). Your point on the amperage is very worthwhile to consider as well, but 4-5 amps per 3500 BTUs should be doable for most people.
I am seeing more and more applications for electric boilers every day. And many more for heat pumps as well.NRT.Rob
think heat pumpif you are considering electricity as your fuel source. What sort of supply temperatures do you require?
Electric depends a loton where you are. Like a LOT. In most areas it is true that most electric is fossil fuel -- even in southern New England where everybody assumes it is (but actually nuclear is almost 40%).
That said, there are at least a few areas -- the most notable being Quebec-- where electric is almost entirely either nuclear or hydroelectric, and where electric rates are low enough that electric heating -- either direct or with electric boilers -- is definitely competitive.
There are not hard and fast rules; broad generalities yes.Jamie
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
Cost per BTUNever hurts to look at all options. If we look at strictly cost, not where does electric come from, future costs of fossil fuel generation, carbon footprint, electric service upgrade, initial costs of new boiler and venting versus no venting etc etc. What is the true costs of LP after all taxes, delivery charges, hazmat fees? Is it still $2.25? What about a KWH of electric, is it still $0.0875? LP at 91800 BTUs a gal is before efficiency is factored in. Assume electric at 100%. If those costs are the final prices then it a wash at a 95% efficient LP boiler. You have to determine the pros and cons on all the other factors. Mike
another advantage of electricI read alot (and righfully so) on this board about CO dangers. It seems to me one advantage of electric is no more worries in this regard, and having no combustion take place in the home seems maybe like a big advantage generally that might be worth paying some extra money.
AdvantagesNo chimney, No blower fan, no gas valves / lines / oil filters / tanks / makeup air / combustion testing. Sort of like living on unemployment.
Can;t wait for cheap reliable personal nuclear reactors.
Wow... cheap...Im up to $0.25/KwH here on Long Island... You guys are lucky...
with a COP 3 heat pumpyou too are equivalent to 0.08/kwh ;)NRT.Rob
comparisionsTake a boiler with an input of 210000 btuh it runs on average 4 hours a day its NG fired a t .82 cents a therm (100000 btus)..
210000 btus inputx4 hrs run time=840000 btus used. 840000/100000=8.4 therms
8.4 therms x.82=6.88 dollars
To do the same with electric at .115 KWH
840000/3412 btus per KWH=246.19 KWH 246.19KWH x .115=28.31 dollars
Lets just say that the behemoth boiler is 80% so knock 20% off of the 28.31=22.65 dollars
So for the OP if boiler runs say 3 hours a day and its 100000 btu input on LP.
300000 / 91800 = 3.27 gal propane so 7.35 dollars a day.
electric 300000/3412= 87.92 KWH 87.92 x .0875 = 7.69 a day Take 10% off for high eff boiler = 6.92 you come out ahead on electric in your area.
Even though electric boilers, and water heaters are 100% energy to the medium there is just something about electric using more energy to heat that medium then a gas appliance even though 10 or 20 % goes out the flue. Or is it just elements are always undersized to really compare say water heater electric to gas recovery sucks in electric.
As far as heat pumps need to know what the ops emitters are if higher temp then heatpump may not cut it.
The reason electric recovery seems to suckis that most elements are undersized. An element works off of resistance. The hotter it gets the more resistance, the more resistance the hotter it gets. A flame, on the other hand, burns hot from the get go. I know an air to water heatpump uses far less energy. I did training for the Alltherma, and they were showing effieciencies comparable to geothemo systems. Unfortunatly they cost more than most of my customers prefer to spend. The electric boiler that I'm looking at is a Slantfin. It is a fully modulating boiler with an outdoor reset. The outdoor reset determines how many elements it will turn on. It also modulates between elements so as to keep the usage equal between all 4 elements. It basically has all the goodies we have come to expect in our modern boilers.
It irritates me when I hear about NG at .82 a therm. I live in PA and have a ton of wells practiclly in my back yard but can't access it. From what I hear, most of it is going to Texas. I guess thats the way our global trade works.
I suppose I'll probably get a boiler in, hang a KW meter on it and run it through the mill.
electric boilerI put in way more electric boilers in my area than propane, probably 10X more. We also pay about .076 KW/Hr, it definitely comes out cheaper than propane around here. I have a nat gas mod-con in my own place and I pay about 1/2 of what most of my electric customers pay for heat.
LEED is the answer!The ground source heat pump system at my sister's house (at 5500 feet in Utah) gives energy performance 25% of US average domestic energy consumption! LEED Platinum, second in Utah!
so many things to go wrong with groundthat's why we got into air source. real world COPs are pretty comparable too.NRT.Rob
I agree with you.I never jumped on the ground source heat pump and I never will. I think it will be gone before it was here. Around here we have well drillers putting in complete geo systems. I asked one, so how deep are you drilling to match the btu load. His short answer was X number of feet per ton. I said what about soil conductivity tests. He squinted his eyes a little bit and replied they aren't necessary in this area. I left it at that and went my ways. Now I hear though that these chaps are doing pump and dump. They claim with these varible speed pumps that this is the way to go. It is just an easy way out for them cause they don't know how to do the math.
The homeowners are blissfully happy with thier high tech systems. They just know that since the system cost a small fortune it has to be incredibly efficient. I don't tell them different cause I love happy people.
GSHP mathA GSHP system requires a significant amount of CapEx and can be quite complex, but IF the seasonal loads are relatively equal and IF the annual load is big enough and IF the hydrogeology is right, and IF the system is properly engineered, installed, and maintained, they are truly awesome...
Reliability of the electric source?Living up here in New England, I would be worried about the electrical distribution system. We lose power four or five times a year. Buying a generator big enough to power an electric furnace is some bucks. Assuming 100 A at 240 V is a 24 KW unit just for the furnace. Now add fridge, freezer, microwave, well pump, sump pump, plus lighting, you are looking at a 30 KW generator. Not a hardware store special for sure.
Not to mention the size of the connection set up to provide temporary power to the furnace. This is not a 12 gauge extension cord you can splice into the furnace power feed.
running on gensetReciprocating engines only deliver ~30% of the available energy in fuel to the crankshaft and some of that will be lost in the alternator. The other ~70% comes out as jacket (radiator) heat and in the exhaust.
Assuming this is a hydronic system with an electric boiler, you could install a heat exchanger ahead of the radiator and recover a good portion of the jacket heat.
You could go further and put one on the exhaust (which can get you to ~75% net efficiency) but that will be far more complex due to the high temperature of the exhaust (have to protect the fluid from boiling and the HX from thermal shock.)
If you want to pull heat off of a gen setyou don't need to put a HX in front of the radiator. The engine block is water cooled so you can tap directly into that. It has been done plenty of times already.
The electricity in my area has never been off for more then 24 hrs at a time. Since the boiler has multible elements, you could always run it on just a few and stay relativly warm unless the outside temp was at design temp.
HX required?Depends on what you run in the genset cooling system, which is often dictated by the engine manufacturer's requirements.
We did one Diesel with Evans waterless coolant - expensive but IMO worth it -- increases efficiency of the mover a bit (by raising the jacket temp.)
Cogen is cool -- one of the few low hanging fruits left.
lots of ways to keep a place warmwithout the primary heat source.
I have seen cheap secondary sources used or more commonly, a woodstove or space heater in those cases.
Pretty bad idea to commit to decades of higher energy costs in the name of a few days or so a year of downtime, max, in my mind.NRT.Rob
Horses for CourseIC engines used as 'micro-CHP' power sources can be remarkably efficient.
Danish company I'm familiar with has a system with Toyota-origin gas-engine (runs on methane or LPG) and delivers about 35kW of heat (via the cooling system) and 14kW of electricity.
To make best use of such a machine, you need a bottomless 'heat-dump' for the heat output. Then, the Run/Not Run decision is based on the price you can get for the electrical output, assuming you're going to sell it back to your grid supplier, or whether it will be cheaper to use the CHP electricity than grid-supply. There are of course more complex calculations based on the total cost of running the machine versus the combined value of the heat and electricity produced, versus the cost of electricity and heat from other sources. The controller on the machine does these calcs in real-time and starts and stops it automatically.
Note also a well-designed CHP machine can run for 100000+ hours between major services (!!)This post was edited by an admin on January 7, 2012 2:29 PM.