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Author Topic: How are propane boilers supposedly so efficient?  (Read 4478 times)
Sean
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« Reply #15 on: January 04, 2010, 06:57:37 AM »

Regardless of how many BTUs are in a pound or gallon of diesel or propane, Clifford has indicated he is using a lot less total BTUs of fuel to heat his bus with a propane boiler versus a diesel boiler.

Are diesel boilers terribly inefficient compared to a propane boiler?  I know propane seems to burn with a nice blume flame compared to diesel.  There has to be some reason a propane boiler can heat with fewer BTUs of fuel.


Please re-read my post -- I already answered this.

With all respect to my friend Clifford, he can only be extracting at most 4-5% more of each BTU with LPG than with diesel.  Boiler systems for both fuels fall into the ~85% efficiency range, plus or minus a few percent.

FWIW, my Webasto burns with a blue flame, too.  So do jet engines, which operate on even denser fuel oil.  Appearances are deceiving; because LP is a gas at room temperature, it can easily be burned with a simple air-mixing nozzle; heavier fuels like diesel, jet fuel, bunker oil, etc. need to be heated and atomized first, then fed more air under higher pressure.  This is why the Webasto has a high-volume blower, atomizing nozzle, and fuel pre-heater.  Once all these things are done, nearly as much energy can be extracted from the fuel as from simpler fuels like methane, butane, propane, pentane, etc.

-Sean
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Jerry32
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« Reply #16 on: January 04, 2010, 07:04:26 AM »

All I know is I heat my 40 foot bus with diesel hot air and it has more windows than the 32 foot allegro MH I used to have but takes less gallons of diesel than the other did of propane. Jerry
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« Reply #17 on: January 04, 2010, 07:20:04 AM »

Yep Jerry and your Allegro had a forced air RV furnace also they do burn propane. 
Sean does have a clean burning unit a lot better than most I parked beside him at the last Caverns rally but it still had a smell with smoke and the train sound when it fired that cold morning .
I filled with propane a month ago 40 gal tank for a 1.85 per gal it is 2.15 today it always goes up in the winter here for the snowbirds.
I have owned both the Webasto and Aqua Hot my Primus unit will burn about 1 gal per day and I love it but it is different strokes for different folks



good luck
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Sean
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« Reply #18 on: January 04, 2010, 07:53:51 AM »

I filled with propane a month ago 40 gal tank for a 1.85 per gal it is 2.15 today it always goes up in the winter here for the snowbirds.


Clifford, where do you get your LP? I want to put it on my list... most of the places we've filled, they're charging way above market.

As far as comparing systems across widely different types of rigs with different heating methodologies, it's really not possible to draw far-reaching conclusions.  As I wrote in an earlier post, you have to consider the totality of the system -- good insulation and window coverings will go a lot further to reduce fuel consumption than a few percentage points on burner efficiency.  And, as with anything, there are crappy diesel furnaces just as there are crappy LP ones.  Lastly, maintenance is a factor -- the diesel systems, in particular, require careful attention to nozzles and airways; LP is more forgiving in this regard (although a single mud dauber can screw up either system in a flash).

-Sean
http://OurOdyssey.BlogSpot.com

p.s. With regard to noise, you are absolutely correct.  One of the significant drawbacks of a Webasto, Espar, or any other good diesel unit is that the blower-burner combination has that, umm, jet-engine sound to it, which can be quite loud.  Exhaust mufflers can be added to help with this a little, but, of course, at the expense of efficiency.  We opted to do without, so my apologies to anyone parked directly behind us when it's running.  (It doesn't bother us inside the bus; we hear it, but it is just low-level white noise.)
« Last Edit: January 04, 2010, 07:57:43 AM by Sean » Logged

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« Reply #19 on: January 04, 2010, 08:24:11 AM »

Propane here in Yuma is $1.99 if you go to the plant but delivered it runs around $3. Jerry
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« Reply #20 on: January 04, 2010, 08:40:30 AM »

As pointed out by Sean, propane price gouging is quite common.  If you go to Walmart to exchange a BBQ tank, they will charge around $20. last time I checked.  If you go to the Amerigas depot, it's just a low per gallon price.  They are actually filling those bottles for Walmart.  Obviously one must watch where they buy diesel also, but the price variation is not quite so outrageous.
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« Reply #21 on: January 04, 2010, 10:16:48 AM »

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« Last Edit: July 16, 2010, 11:08:06 AM by Now Just Dallas » Logged

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« Reply #22 on: January 04, 2010, 11:06:05 AM »

I get about the same deal as Dallas, and my LP is delivered on a bobtail by the local distributor.

I get my gas for around $2 per gallon, but have to be home when the truck shows up to get that deal.

If I run out, it's better for me to drive over to the LP shop for the good pricing...they don't like making deliverie$ when it'$ not $cheduled.

Jay
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« Reply #23 on: January 04, 2010, 11:31:57 AM »

N.J. Dallas,

I did not mean that every place that charges more than the bulk dealer is gouging.  As you point out, there can be other costs involved.  You charge by gallon which includes the cost of product, fees, and services.  I would not expect a restaurant to charge merely the price of the groceries.  However, places that charge a $20. flat fee per 20# tank and generally only put about 4 gallons in them are certainly doing well on the convenience factor.   I have also seen fill stations within a mile or 2 of each other with a $2./ gallon difference in price.  I use the term "gouging" to classify the extreme.  I apologize for any misunderstanding.
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« Reply #24 on: January 04, 2010, 11:53:10 AM »

Dallas,

Great post!  Great arguments and detail.  You left out the loaded labor charges and that has to be the least resented of them all.  There is a data element called the "Break Even Point" and I think all can intuit that definition.  What is your Break Even Point in terms of "gallons sold" and how many gallons do you typically sell in a month(on average)?  Some parks sell Propane as a service to it's customers and I know of one that said it actually cost him a few bucks a month to do that.  Hope he is rare in that regard.  BEP, profit margins and cost analysis are all closely guarded secrets in industry and business....no question about that.  Yours is not a competitive cost structure cause your overhead seems to be regulatory fees and associated charges.  All of those are documented and in the public domain and can't be a secret.  Your having already compiled those numbers I wonder that you might want to share them?  I know that different agencies appear to have redundant charges, such as a fee charged for the same service by a Local, state and Fed agency.  You mentioned those in one breath and I assume you are referring to those repeat charges.  Tell me what those type charges are called and I will research it, superficially, on my end as those type charges seem to be the same all over the country.

Interesting topic Dallas and thanks for your contributions,

John Smiley Smiley Smiley
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« Reply #25 on: January 04, 2010, 11:56:19 AM »

Nick....Nick??....NICK!!

You awake yet?  LOL.  Wheres the beef, Nick?LOL  Weigh in on this, will ya?

John Grin Grin Grin
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« Reply #26 on: January 04, 2010, 12:10:02 PM »

Lin,

I don't see where you owe any apology to any here.  Dallas was referring to charges his employer, as the owner, uses to compile costs that he uses to set sale price.  Gouging has two aspects that clear it up....UNWARRANTED and UNEARNED or OPPORTUNISTIC.  Please don't start walking on eggs , Lin, as your questions and info are of interest to many and support the policy of this place(our place).

Thanks for all your contributions,

John

Dallas too, understand

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« Reply #27 on: January 04, 2010, 01:28:26 PM »

Thanks John,

It is my feeling that, since misunderstandings are so possible in this media, I wish to make sure to clarify anything I write that might have offended someone unintentionally.  Apologies are free but can be of amazing value.  In the Off Topic section, on the other hand, being provocative is just part of the fun.  The kitchen is supposed to be hot; other places may require climate control (I guess this is Nick's territory both literally and metaphorically).
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« Reply #28 on: January 04, 2010, 01:55:58 PM »

The $20 at wal mart is for tank exchange. Buried in that price is the cost of new cylinders when someone swaps in a dud that is past it's prime. Don't forget the repair costs they incur for the duds people exchanged because that was cheaper than fixing what they had. . . .
There is also the cost for the propane that leaked out past a faulty valve.

Then there in the convenience of not having to go out of the way to get 'em filled. . . .

So, it ain't exactly apples to apples . . . .


As for propane being more efficient than Diesel -
Propane has a theoretical flame temp of 3660F
Diesel is above 3860F

The temp difference isn't enough to make much difference. Especially when the state of tune can cause the flame temp to change.

As has already been said - the design of the heater has more bearing on efficiency than the fuel used. What works well for one may not do so well for someone else especially when the situation isn't exactly the same.

Not all heaters are the same, so before buying one, one needs to do some homework to determine which fits their needs best.

If you find you already own one - doing a little homework will enable you to make the best use of what is available - sometimes that means using it at diminished performance, sometimes it means selling it & buying something else. . . .

YMMV
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« Reply #29 on: January 04, 2010, 03:26:34 PM »

Bitte, Lin.
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