Propane vs Electric Costs fro garage heating?

[jessrice]

Okay,

I am getting ready to figure out the best way to heat my overly large shop (gloat, in case you didn't get it). My two choices so far are propane wall heaters, or electric wall heaters, both with blowers. I actually have 3 separate areas that will or could be different temps, at any one time, so a central system is out.
I have already calculated the btu requirements of each using the calculator at www.heatershop.com. I have also figured the cost of the heaters, and installations, which i can do either myself.

So really i am down to the actual energy costs and wanted some of you good with numbers to check my math if you wouldn't mind.

To keep it simple. lets say I need 91000 btus of heat, because that's what a gallon of propane will produce. ( if I heated all three area, I am really looking at well over 160,000 btu's) If i used electric it would take 27000 watts, or 27 KW's to produce 91000 btu's.

My electric rate is .0786 cents kwh, and propane is 2.39 gallon (delivered). So I figure to get the same amount of heat, it will cost $2.13 for electricity and 2.39 for propane. Electric being .26 cents cheaper per hour.

To top it all off, we are getting a 5% electricity decrease in January, and the propane man tells me to expect a .20 cents per gallon increase, resulting in electric costing 2.01 and propane 2.59, for a difference of .58 cents per hour,


So do all those numbers look right? Electricity is about 30% cheaper, btu for btu than propane?

I know there are other variables, and have figured out much of that, but didnt want to fill the thread. But for reference for those that are interested, the install rate for piping and valves is about equal to wire and breakers. For the heaters i am comparing I would need about twice as many electric heaters as propane, resulting in twice the cost.. The electric service base fee is $12.00, and the tank rental is 10.00, but i need the electric anyway.

With propane, I would have heat when the electricity was out, but would also need to worry about explosive vapors. In the bonus room section the wife could have a propane fireplace. With the wall mount electric heaters with plug (cadet garage 4000) i can move those around if needed.

Anyway, i have calculated most of the variables, and if my numbers are correct, it will cost me at the most 750.00 more to install electric heaters, than propane, but i am more efficient and comfortable installing electric. I can also try to find some eletrci that cost less per btus to buy.

At .58 cents an hour it will take me 1200 hours at 91000 btus of electric heating to break even and start saving.

So can any of your engineers or mathematicians tell me if i am right so far?

thanks

Jesse

[maxparot]

1 thing I'd consider is the posibility of calling on other propane companies in your area. Since it is a delivered service I would think there would be some competition and a chance to get a lower price. And you may be able to contract a years rate to avoid increases. With the electric you are completely at the mercy of the utility company. Utility companies adjust there rates according to seasonal demand and fuel costs as allowed by law. So even though you are computing a proper base rate the final actual figure could be different.

The next thing I would consider is the fact that there are different heaters available and some are more efficient than others. An investment in a more efficient heater may have a higher initial investment but a reasonable return in monthly savings.
Also consider a dual system. A propane system of minimal capacity backed up by portable electric units such as oil filled electric heaters.
The propane system would have advantages in quicky changing the temperature in the area where the oil filled electric is very good at maintaining a stable temperature and it is less fire hazzard than most other type portable. Also portables have the advantage of being able to placed so to create a comfort zone.

[LCHIEN]

your math looks good assuming the given numbers are correct (checked the BTU to KWH conversion no.- its OK)

Looks like you answered the question yourself. My comments:
.078 per KWH - very low, and it's going lower? Where do you live?
It's running almost twice that here in TX.

Someone mentioned contracting the propane supplier for a fixed rate,
you can also contract wit the utility compnay here in TX for a fixed rate for a year, too.

Have you calculated the cost benefit of extra insulation vs.heating costs? In you case, since you have three areas, the heat loss in the other two areas not being heated are being fought all the time even when you try and heat only one area. You'll lose heat much faster even from the heated area if the unheated areas are poorly insulated. Insulation works full time w/o add'l energy costs if you see what I'm getting at. The local area will still get heated but the gradient and hence the heat loss will be lower.

I'd feel safer with electric (no leaks!)

[Russianwolf]

ever look at old victorian houses? small rooms right. Reason being is a small room takes much less to heat than large rooms with unused space. If you can separate the three areas you are talking about, and insulate well throughout and between, you will cut that cost by a two thirds I bet.

My other opinion is go propane. Doesn't need electric to work, so if you have an outage you'll stay warm (especially if your house is on electric heat.)

[jessrice]

LCHIEN,

i live in Pasco, WA, which is in Franklin county. http://www.franklinpud.com/html/resi..._schedule.html
is the link.

Since I am here in the northwest, we are getting mostly all hydro power, with some new wind farms, and selling extra to CA. It is also a public owned utility district vs private power, so the rates only change yearly if at all.

I want to say about 4 years ago, before the big DAMS vs SALMON, it was about .056 per kwh. The increase is from spilling extra water during migration.

I am super insulating everything, and have 6" walls, so I am doing r-21 in then, and r-30 of spray in in the attic. I also bought r-16 garage doors, 3 of them, to the tune of 5600.00. I have built everything myself, caulked any gaps, and even foamed the spaces between the eves and top plates of the walls, so only then vents are passing air. I am also insulating the walls and ceiling in between each area with r21 batts. Other than double garage door seals, i think i am will be as insulated as possible

We do have 2 propane dealers, and they do seem flexible in install costs and tank rentals, but not on actual fuel pricing.

I really like the propane idea, and was sure it was going to be cheaper (all the commercials say so), which is why i asked for the extra checking from you guys when electricity came out cheaper.

The ventless propane heaters are 99.9% efficient, and i know that i can get them 50% off at lowes every spring, but right now we have a home depot relocating and the have their electrics on clearance at the same price.

The propane could also be attached to the BBQ grill, smoker and if the wifey gets her way, out door kitchen (think like 5 years), but then again, i can go get my 5 gallon propane tanks filled for 1.69 gallon at the farm store, so its convenience vs cost.

The other challenge i have is in the largest area, it is 32x36 with 17' ceiling, so i am going to have to install ceiling fans to get the heat back down to my area.

The other two areas are above/below each other, 17x36 with 8' ceilings. The lower we are attempting to license for a winery (max 600 sq-ft for home run winery) and the upper is a "bonus room" for the wife. Which is why all three will be heated at diff temps and amounts of time.

I wish the natural gas line was closer, but it is about 1000 feet away, and they wanted almost 10,000.oo to run it, so that calculation isnt worth it.

I may also figure out what it would cost to install small electrics in the smaller areas to prevent the pipes from freezing and then install mini split heatpump/AC's in those areas when they are actually being used. And just worry about heating the large "shop" area. But that is more calculations!

Anyway, thanks for checking out my calculations. I appreaciate it!!!

Jesse

[TheRic]

I was also surprised to see propane higher than electric. Did some looking, found propane prices have about doubled in the last 5 years. Must be all those BBQ grills out there. Sounds like you are doing a decent job of insulating everything. Also sounds like you have thought out a lot of things.

Not sure what temperatures wine needs to be at, but I'm betting it doesn't want to freeze. If you lose electric for several days / week. What will happen to the wine??!!

You mentioned using ceiling fans to help with the heat in the shop. I would think they would also move the dust more. Make sure you have a decent air filter!!

[Jeffrey Schronce]

Why is propane for your 5 gallon tank $1.69 and delivered volume $2.39? I just took delivery of 424 gallons of LP at $1.489. How big of a tank are you filling for that $2.39? Are you getting price break for volume? This doesn't make a lot of sense.

TheRic makes a point on the air filter. A large air fliter is going to move a lot of air to a point it may reduce the need for ceiling fans.

[jessrice]

i am not sure why the pricing for 250 gallon tank is 2.39, and i can go to the farm store and get it for 1.70, but thats the way it is.

My mother just filled 2 of her 100 gallon tanks at the rental center fo 1.79 a gallon. I called another propane distrubutor and they gave me 2.36 gallon delivered.

Both of them offer a 1.99 per gallon first time fill, but after that its market rate. Petroleum poducts are just more expensive here. Our diesel and gas are the same way, about 30 cents more per gallon, than the cities (Yakima) just 45 minutes away.

With the potential volume of propane i could pull at one time, lets say 160,000 btu plus, two 100 gallon tanks would freeze up due to lack of surface area, so that really isnt a convient option, although the chances of ever needing to run all heaters at once is probably slim.

If i have just one 30,000 btu fire place like my mom, i would consider that route.

The other option i have for the big bay is to just keep using the 170,000 btu diesel torpoedo heater i have been using during construction. i havent calculated the cost to run it, but i am guessing it does burn at least a gallon anf half an hour. Heck it has a bigger thank than my wifes buick, 13 gallons. It does a good job, and normally i get it warm, and then shut it off, leaving a space under the door for ventilation. But it doea stink a little when you shut it off, and sounds like a jet engine when its running.

As far as wine goes, yes it like to keep at a stable temp, about 64 is what i like, i mean the wine. That room will be insulated to the equivilent of r-39 and with liquid mass, it tends to hold temps longer. I do have a small honda generator that i could put a heater to maitain it in an emergency. or we could start drinking the wine to stay warm!!

My biggest problem, is that the bay I "get" doesnt need to be heated unless i am out there, and that might be a few hours through the week, and 10 hours on a weekend. If it was a working shop, i would have sprung for radiant heat in the slab, but didnt want to have to maintain warm temps for such little use.

One thing is for sure, I hate the cold breeze that the bt3000 blows on my hands when i am using it, so i am gonna get heat of some sort! It was 23 degrees in there today. I locked the door behind me, and started figuring out this heat thing!

thanks for all the input so far, and other than the cost, i am still wanting propane!

Jesse