energy cost comparisons

Brad White_19

to make people move to Cleveland? :)

Seriously- I have enjoyed my work there at MetroHealth, CWRU and The Clinic. Cleveland is an under-rated city and with cheap juice to boot! Can you send some our way?

Dorsey Davis

energy cost comparisons

I'm a plumber who just recently came out from the crawlspace, dusted off the cobwebs to start playing where its dry and well lit. In other words I'm getting into hydronics. I have customers already, believe it or not, and they're asking difficult questions like...
"What's the difference in energy cost between a propane boiler and an electric boiler?"
So I looked it up and found that 1kWh = 3,412BTU and 1 gallon of propane = 91,547BTU. So that leads me to conclude that a small heat demand requiring a 50,000 BTU per hour boiler for an infloor system would convert to 14.65 kW per hr for electric and .55 gallons per hr for propane. 1kWh out here in Washington state costs 6.75 cents. 1 gallon of propane costs about $2.00 So 50K BTU costs about 99 cents of electricity and $1.10 of propane. Is it this straight forward of a conversion?

Dorsey Davis

energy cost comparisons

I'm a plumber who just recently came out from the crawlspace, dusted off the cobwebs to start playing where its dry and well lit. In other words I'm getting into hydronics. I have customers already, believe it or not, and they're asking difficult questions like...
"What's the difference in energy cost between a propane boiler and an electric boiler?"
So I looked it up and found that 1kWh = 3,412BTU and 1 gallon of propane = 91,547BTU. So that leads me to conclude that a small heat demand requiring a 50,000 BTU per hour boiler for an infloor system would convert to 14.65 kW per hr for electric and .55 gallons per hr for propane. 1kWh out here in Washington state costs 6.75 cents. 1 gallon of propane costs about $2.00 So 50K BTU costs about 99 cents of electricity and $1.10 of propane. Is it this straight forward of a conversion?

Jane Simms

And....

don't forget. Electric is the only fuel that requires no venting and is 100% efficient. I am in Northeast Ohio (the snowbelt LOL) and we do get a lot of snow but have VERY cheap electric rates. I have done gas or propane change outs for people with electric boilers and saved them anywhere from $25-$150/month.

Wayco Wayne_2

The math is right

but did you remember to factor in the efficiency of the propane boiler. 50,000 worth of propane into a 90% high eff boiler such as a munchkin only puts out 45,000 btu output. This makes the propane even less desireable at your energy costs for electricity and propane. Here in MD, nat gas and oil prices have risen to the point that I am recommending heat pumps for any forced air system with fossel fuel back up. The technical term is dual fuel, but I have started telling the customers it's a hybrid system like the cars since it uses both electricity and gas at different but appropriate times. For hydronic systems ground source heat pumps are the only option availible to get the heat pump cost benefits but they are only applicable for radiant floors, since they can only generate 120 degrees. Glad you came out of the crawlspace. Who knows what other critters were down there with you. WW

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Brad White_19

Congratulations, Dorsey

on branching out, guarding the nations health and now comfort. As soon as you stop squinting and adjust to the light, I have some reading for you

Excellent question and you got the first part correct, the cost of the fuel itself. (Electricity we will call a fuel for these purposes because, well, it is, even if you do not "burn" it.) For our discussion, all of the fuel units you cited are called "Gross Input" values.

The other part of the equation is "efficiency", the ratio of how much heat is delivered to the heated space compared to the gross input of fuel you started with. Efficiencies are usually expressed as a decimal, with 1.00 being 100 percent efficient and 0.80 being 80 percent efficient. This is because it is a multiplier (or divisor) in various equations.

For example, typical efficiencies of various systems might be:

Electrical Resistance: 1.00 (may be a tad less but this is short-hand for what your clients are asking)

Electricity in a Heat Pump (varies 1.5 to 3.0 due to heat of compression. Such a deal.)

Natural Gas: 0.80 in conventional systems, 0.92 to 0.96 in the best condensing systems.

Propane: Similar to natural gas, some variation.

#2 Fuel Oil: 0.80 to 0.86 with modern equipment. Some (very few) can achieve in the 0.90+ range.

Glaze-Over Alert!:
Bear in mind that all of these efficiencies are averages. You will see terms such as "AFUE", an annualized value promulgated by the Department of Energy. This takes into account a full season in all weather and is really a way to rate boilers 'apples to apples'. It is limited but at least consistent for efficiency purposes, for it presumes the boiler has been running for 20 minutes, is done in a lab and is based on an average climate which in reality does not exist. The other part is "combustion efficiency" which is a manufacturer's "personal best", highest output, usually done by standardized if not independent testing. This is always higher than your average annualized efficiency. Lots of factors figure into efficiency as postings on The Wall make clear, but let's keep this simple for your question.


So, using your figures, let's say you want to deliver that 50,000 BTU's (per hour understood throughout) to your client's house:

Electricity, straight resistance:
50,000/3413/1.0 = 14.65 kWH x $0.0675= $0.99

Propane, conventional, 80% AFUE:
50,000/91,547/0.80 = 0.683 gallons x $2.00 = $1.37


If I may recommend a very useful tool to you: John (Siggy) Siegenthaler, a contributor to this site -and the industry- has a software package called "Hydronics Design Studio". I think 1.13 is the current release, the one I have is anyway.

www.hydronicpros.com

This suite has a number of modules covering baseboard sizing, hydronic circuits, expansion tanks, various fluids (glycols), injection pumping, pipe insulation, etc. etc. and guess what? A very handy calculator to give you answers to your cost of energy questions! Change a variable, whether cost, efficiency or geographic location anywhere in the US and Canada and you get an adjusted annualized cost. Could have saved myself some typing but what fun is that?

I have been in the HVAC design side for over 28 years now and have taught at the undergraduate and graduate levels (love it). Even with that experience, I find this suite well suited for any number of levels. I recommend that you buy it and play with it a bit. There are a number of books, one a companion package you will also enjoy on that site and on this site you will find as many if not more excellent reading resources. Check out the "Shop for Books and More" link and ask around.

Best of Luck!

Brad

STEVEN MARKS

rates

Don't forget to look at past history and the future when making recomendations to change fuel source. In CT the electric rates have gone up 17% as of Jan. 1st and another 10% as of April 1st this is after what I believe was about a 20% increase last year. Alot of electric power plants still depend on fossil fuels to produce electricity and when those fuels increase in price so does your electric rates.

Steven

Brad White_19

Point

well taken, Steven!

Unless projecting future costs, all fuel comparisons should be considered as "applicable to today's rates only".

And if projecting future costs, your guess is as good as mine. You will not find me at Foxwoods

Blackoakbob

comparision chart.....

There is a nice chart available at www.electromn.com you can copy. It compares the cost of 1,000,000 btus thru various types of heating appliances rated by efficiency. That's just 10 hours of run time for a 100,000 btuh heating appliance. Check it out!
Did someone say Foxwoods? We had a great time there a couple years ago. You east-coast guys are real characters to watch and talk to. Best Regards.

Brad White_19

We east coast guys do

talk kinda funny, yup.

Thanks for the tip- I will check it out. My only mention of Foxwoods is that I am not a gambler, especially on utility rates, but you knew that!

Best,
Brad

Jane Simms

Well...

Cleveland is considered one of the countries "most livable" cities. I don't know about that but...been here all my life. They say it is for our cheap living, arts and entertainment, etc. I guess some people like the snow! LOL We have really have a very mild winter though lately. Let's hope it stays that way. Our electric company has prided itself on keeping rates low anyway possible for All Electric customers. Historically, in our area, in the last 50 years, electric has only NOT been the best choice for 6 years....that's good.

Wayco Wayne_2

In MD

we get most of our electricity from coal, and we got lots of coal, so fossel fuel prices dont affect our elec. rates as much as other areas might. It just costs us some of our mountains to strip mining. Yeesh! Is the money you save worth the price that you pay? I sure don't know. Don't get me started. I find myself caught between the conservative short sightedness and the liberal whine. I sure enjoy my warm house and hot showers you betcha. I know in CA they built some new power plants real quick after the problems they had even getting electricity with the prices going through the roof a few years back. Problem is they are run on nat gas, a finite resource with the price increasing every year. Can you say "nuclear??? Heat pumps are the best bang for saving money but are not the most comfortable since they are easier to use with forced air systems. WW

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Jason_15

Nuclear electricity

Nuclear is the only way to go for generating electricity IMHO! why waste any fossil fuels for that purpose? we need those for heat! Last time we had a thread on this subject it got over 200 posts. Lots of opinions!!

jp_2

Hmmm, you never hear of wind or water power?

Wayco Wayne_2

A possible trend

in the future is localized water power for small municipalitys next to a river. Wind is getting better technology every day. There's no avoiding nuclear though. Fed gov just initiated several new neclear plants I've heard. WW

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Jason_15

Yes

Sure I have. The problem is that there is no way you can get enough baseload power from these sources. They are great supplements, unfortunately that's all they are! By the way, did you know that coal plants release far more radioactivity into the environment than a nuclear reactor. FACT!