Propane Dryer gas usage

brn3aMarch 19, 2008

So we bought a propane clothes dryer 8 years ago when propane was reasonably priced. Now propane in our area is almost $3/gallon. I'm trying to get a handle on what percentage of our propane go towards running the dryer and whether it is worth it to buy a whole new electric dryer.

So, how much propane does a propane dryer use to dry a "typical" load and is there a way to figure out which is cheaper to run (propane or elect.)? Propane is $3/g and elect ~10c/kwh

Anyone have any idea on either the 1st or 2nd question?


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- The cost of drying a typical load of laundry in an electric dryer is 30 to 40 cents compared to 15 to 20 cents in a gas dryer

- Most gas dryers use only 110 electric current to run the drum to circulate the clothes, rather than the 220 electric
current that electric clothes dryers use


The U.S. Department of Energy states it costs half as much to run a gas/propane dryer than electric.

I'd put in a call your electric and propane companies and see if they have any up-to-date information or statistics.

The front page of our newspaper said we're going to get a price hike (electricity). Glad I rarely use the dryer - the lines in the basement and the one outside are pretty cost effective.


    Bookmark   March 19, 2008 at 7:15PM
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This is a good example of looking at opinions rather than looking at facts. Gas advocates like to sling vague terms and unsubstantiated claims and I'm troubled by it. Also, propane provides less heating BTUs than natural gas and this confuses people too.

I think what you're looking to find out is something a little more unbiased that you can actually compare. Just assuming that the philosophy gas is always cheaper... won't always fit.

Here's some things to consider:

A) Both dryers will have a motor turning the drum, therefore consume electricity. Contrary to the biased opinions on gas, gas dryers use electricity! This is seldom factored in. Without knowing the motor sizes in each dryer we can't calculate the actual costs, however considering that the motor use is far less than the heat cost, it's reasonable to go, as I am, for the purposes of comparison, with the assumption that they're using comparable motors using comparable electricity, and most sources consider this to be under 10/load, usually closer to 5¢-7¢ depending on electric rates.

2) 1 kwh of electricity produces 3,412 BTUs of heat.

3) 1 gallon of propane produces 91,200 BTUs of heat.

4) 91,200/3412=26.72919109027 so it takes 26.729 KWH to get the equivalent heat of one gallon of propane.

5) 26.729 KWH @ 10¢/KWH=$2.67 & 1 gallon of propane at your rate is $3.00. Therefore, $2.67 (to $2.74*) worth of electricity will give you equivalent drying BTUs that $3.00 worth of propane will give.

*My disclaimer: I used generally accepted rates of the BTUs for this comparison. Different sources give propane ratings from 90,600 to 91,600 BTUs per gallon of propane and electric rates from 3340 to the DOE universal value of 3,412 Btu/kWh. Too many different combinations to calculate here but even using the lowest electric vs the highest propane, the rate would be $2.74 compared to $3.00, so I won't argue with the gas folks. And yes, I have an electric dryer!

So, this shows that in your case, with the figures you provided, electricity is roughly 9% cheaper than gas! Boy is this going to irritate some people! LOL

I can't find a source offhand to give an idea how many BTUs are needed to dry a load of clothes and since that will vary with how much water is spun out, how heavy the clothes are, the relative humidity, etc, and propane consumption can vary with temperature, volume in tank, etc, so I can't go much further on cost comparison in an unbiased way.

However, I will say that factoring in the cost of a new dryer at $200 to what, $1,200 (or more?) and potential costs of running a power line to the laundry area if needed, I doubt if it would pay to replace a working dryer with a new one simply for the cost savings unless you do an awful lot of drying! If you have to replace it, you may give it a consideration, since you could also factor in that usually a gas dryer costs more to buy than electric. I did some computations a while back to figure out whether it would pay for me to replace my dryer with gas. Without including the cost of running the gas line, plumber's fees, etc, it would take me 8-10 years at the rates in effect at the time to break even. Then throw in a percent or two interest per year on the money, well no, it wasn't worth it for my situation. Of course, as always, YMMV.

"The U.S. Department of Energy states it costs half as much to run a gas/propane dryer than electric." No facts or rates are offered to support this and I certainly won't call the DOE liars, but I remember being told by the Feds there were weapons of mass destruction in Iraq too. LOL

Let's put it this way: I don't believe everything I hear or read and I dislike blanket statements. I like to see some substantiation since these wild and usually self-serving claims are dangerous and are all-too-often misused, misunderstood and/or confused.

Oh, and interestingly, the Amerigas link does make the disclaimer that AmeriGas propane can save you money! Yet they give NO facts or rates to substantiate these claims.

Another thought, is your electricity regulated? How much variation is there in pricing? We all know that propane rates vary a lot and IMO, rates can be expected to continue to fluctuate. Can we expect to see $4/gal for propane? Wouldn't seem unreasonable. Do the math on the difference in cost at $4 if your electric rate is the same.

Which brings up another thought, some areas will give discounts at different times or if you install energy saver switches or the like so that can have an impact and of course electric rates can go up too.

But I want to emphasise again, these prices will vary for each person, each locale and with time. Don't accept blanket statments on what is cheaper since that will vary literally daily.

Whew! Hope this helps. Happy drying!

    Bookmark   March 20, 2008 at 12:28AM
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Wow. Cynic thanks for all the GREAT information. Makes me lean more towards electric. I overestimated the current electricity costs (closer to 6-7c/kwh) to account for changes in season and usage and the current cost of propane in my area is 2.96/g. Lots to chew on here.

    Bookmark   March 20, 2008 at 8:33AM
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I imagine that with the new, high efficiently washers that spin out more water, the cost-of-use difference between gas/propane/electric dryers are less significant now than they were in the past.

If your washer is an older traditional Top Load model, and you use propane to heat your water, switching to a HE FL washer which uses much less hot water, and removes more moisture, may be a possible cost saver in the long run. You will use less propane to heat water, and less to dry the clothes since they will need less time in the dryer.

Just thought I would throw that out there.


    Bookmark   March 20, 2008 at 12:10PM
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We use a HE FL washer and it does spin our clothes pretty dry. Not dry enough to wear, but pretty dry!

    Bookmark   March 20, 2008 at 2:29PM
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Well i think the calc's look good for you, but out where i'm at in calif, i'm on pg&e and 11 cents is the baseline, and it goes up from there on a tiered arrangement.. peak use 300% is .52 cents per kWh in the summer. that said and looking at your electric baseline then you can account for your cost. i know there are areas that have straight price per kWh.. (sounds like you do) nice, but i'm on a tiered setting.. so although i did wire for 220 and propane i'm using propane right now.

I'm have a family of four and we seem to wash at least once a day, and i use 1 gallon of propane per day on the dryer, cooktop and water heater, so that's about 30 gals per month, propane out here is in the 3.25 range last i checked.

    Bookmark   April 4, 2008 at 2:20AM
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One more thing to note is that propane, and natural gas, both contain a certain percentage of moisture... Therefore although they are used to dry your clothes, they are also injecting moisture at the same time resulting in a longer dry time. You can see this moisture in highly efficient furnaces which have to drain off the moisture to a discharge line.

    Bookmark   April 4, 2008 at 9:39AM
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I disagree that gas dryers are slower than electric.

It has been my understanding that the gas and propane burners in a dryer have the potential to generate more heat than the heating element in a dryer. Comparing the gas and electric dryers I have used, it seems gas dryers heat up to the set temperature more quickly and dry a little faster. I have also read that they are gentler on the clothing, for the very reason that there is moisture in the air.

If I have a load that has been sitting in the dryer and I run the touch up cycle on my gas dryer, I see the moisture condense on the window at the very beginning, but then it quickly dissipates, and the wrinkles are reduced in a few minutes. When I use an electric dryer, I usually have to add some moisture, like a wet washcloth or mist the clothing for the wrinkles to come out.


    Bookmark   April 4, 2008 at 2:20PM
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About "Cynic" calculations. it appears that in 2014 his price per kWh of electricity is outdated. I just moved to Mid Hudson Valley in NY. The total (all the categories and fees in the bill added) price per kWh of electricity for the last quarter fluctuated from $.17 to $.24/kWh. While price per gallon of propane I just obtained a quote for is $3.36 (based on consumption for cooking and water heating).

So, using calculation of "Cynic", par. 5, average ($.20/kWh) cost of 26.729 kWh would be $5.35 vs. $3.36 per gallon of propane, to produce the same amount of heat. Per information in the attached link, let's say you consume 1 gal of propane per week in your dryer. Your saving per year would be at least $100.

    Bookmark   December 27, 2014 at 4:01PM
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I think all are right to a point. It would be a very challenging justification to add gas lines or high voltage electric lines and justify a cost savings if both were not already in place.

The only real truth is that blanket statements don't apply to everyone because of substantial variations in utility cost across the country, differences in water temperature, and differences in the spin capability of different washers mated to the dryers.

At one time I did a calculation of the change in entropy at about 42% efficient for the change in state of liquid water at 60F to evaporated at 120F. I doubt it has changed much through the years. Electric dryers are indeed a bit more efficient and can in fact dry a bit faster because they produce a dry heat. As others have stated, one of the byproducts of combustion is the creation of water, and that water passes through the load on its way out the vent.

Where I live, upper Midwest, electricity is relatively cheap, but natural gas is even cheaper, and natural gas has crashed 40% in most areas over the last 2-3 years due to gluts of gas availability. For the average homeowner in our area, natural gas is still the best option. But, this is for natural gas, LP is potentially a different story because of higher average costs. Some recent winters have had shortages in LP, which caused sudden, violent spikes in price. Meanwhile electricity cost, while still cheap, is rising quickly with some significant rate hikes on the horizon.

And yes, a gas dryer uses electricity to turn the basket, but those are typically equipped with 1/4 hp motors or at most 1/3 hp, which draw about 200-300 watts of electricity, so only about 5-10% of BTU equivalent of a gas dryer running. For those not living watts and horsepower as parts of their career, about 746 watts = 1 hp, and induction motors are anywhere form 50-80% efficient in converting electrical energy into mechanical energy, the rest lost as heat. For comparison sake, I think most small electric dryers use 4800-5400 watt heating elements, so 300 watts to turn the drum and run the controls is next to nothing compared to the elements.


    Bookmark   December 28, 2014 at 12:13PM
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