An actual analysis of the cost difference between heating with Propane vs Diesel fuels

[PeterPiper]

Hello,
I've seen a lot of comments here and there regarding the cost to heat with diesel fuel vs the cost to heat with propane.
I kinda wanted to know empirically.
I "think" I've done a fair analysis so let me share it here......(for those who give a hoot)

Diesel Fuel
BTU's in a gallon of diesel fuel = 137,381 Btu
Cost of 1 gallon of diesel fuel today $3.70 (average)
4.6 gallons of diesel fuel BTU = 631,952


Propane
A standard sized 20-pound propane cylinder holds approximately 430,000 BTUs of liquid propane
20 pound propane tanks are often referred to as grill cylinders and hold 4.6 gallons of propane when full.
Cost of 20lb propane tank fill (January 4th, 2021) $18.00
Cost per gallon of propane $18.00 / 4.6 = $3.91

Diesel Fuel and Propane both have the same HCE (Heat Conversion Efficiency) which is important

Summary
As you can see, a 20lb tank of Propane costs $18.00 and yields 430,000 BTU's of heat energy. ( I use a 20lb tank for the cost analysis because we are talking about amounts that can be utilized in RV's and mobile vehicles).
Propane "may" cost a bit less when purchased by the 100gallon or more, but again, you can't carry that on an RV.
4.6 gallons of Diesel fuel yields 631,952 BTU's

The cost for a gallon of Diesel Fuel is nearly equivalent to the cost of a gallon of Propane, with propane costing slightly more. With that factored in.......
It costs 35% more to heat with propane today than with diesel fuel

Then there this from another member.....which if true could raise the cost of propane even further...maybe to 70% more expensive than diesel.

I don't know the exact numbers but I think typical propane furnaces (in RVs) are in the neighborhood of about 50-70% efficient.
A lot of the heat is blown right out the exhaust port. But for a typical diesel bunk heater the efficiency is higher, I think around 90%. The waste heat is just a small trickle coming out the exhaust port, and yet the heated space is nice and toasty.

An one last thing.....
Diesel fuel can be bought almost anywhere and you can directly fill your Diesel tank readily at almost every gas station.
Propane requires a heavy metal tank that must be exchanged at certain locations or refilled at Propane retailers. A bit more cumbersome.
Personally, for me, that would raise the cost of propane to 50% more than Diesel fuel, but that's just an opinion.

Of course, if you are repulsed by the smell of diesel or just can't stand "dirty" fuels, then you may be a "Propane Person" , and that's just fine too.
Sometimes there are factors other than cost alone.

I welcome your correction as I am only doing a rough estimate here and I have been known on occasion to make really big booboo's in my analysis.

Hope this helps.

Best Regards

 

[user 423]

^
The smell factor for diesel would be big for me. Since they are vented to the outside, I'm wondering why would there be much odor in the living space? Or are you referring to it being smelly when you refill?

I have a small LP generator that I use with a small 11 lb. tank for charging batteries. I use a butane stove and don't have a heater of any kind since I don't spend winters in the van.

Propane can be used for more than just heating. If I installed a 20 lb. or larger propane tank, I could supply multiple appliances. The generator, a heater and a stove. I may go full-time in the future and may go that route.

 

[ahh_me2]

I'll disagree on two points, not to imply that I am correct and that you're not, but moreso to illustrate a different perspective.

Currently where I am in Canada, price of diesel is approximately $1.30/litre, 3.7854 x1.30= $4.92/gallon.
Multiply by 4.6 to get the equivalent of a #20 tank of propane, and we have $22.63 equivalent cost.
Propane, for a common #20 tank is anywhere from $12(Costco) to $25(others and exchange a tank service)

This to me indicates that at the lower price of $12 for a propane fill, it is still cheaper than diesel
considering the different btu values.

2nd point is that I would disagree with tx2sturgis regarding the efficiency of the 2 types of heaters.
I can believe the old style rv furnaces, which were gravity type units, would have the efficiency he claims,
but I wouldn't agree whatsoever that these modern furnaces have such a low efficiency.

I have installed a standard chinese diesel heater in a conversion I was doing for someone else and
I found a huge amount of heat escaping out of the exhaust, to the point the exhaust almost glows red in a dim light environment.

Having 2 rv furnaces in 2 different structures, both Suburban series with standard 2 hole vertical intake/exhaust plate,
I have yet to see any red glow in the exhaust tube, and the exhaust that is escaping is not anywhere near the temp of the diesel one.

I therefore believe that there is less heat waste from the rv furnace.

Something else to consider, is that both types of heaters operate on a similar principle, that of a sealed combustion chamber, and a separate forced air(fan driven) system which in turn blows ambient air over the combustion chamber zone, effectively performing a heat exchange in the process, which is how we get clean dry hot air to heat the environment it's in.

Is one heat exchanger more efficient than the other? I don't know...but I seriously doubt there is a huge difference in either case.

Diesel Fuel
BTU's in a gallon of diesel fuel = 137,381 Btu
Cost of 1 gallon of diesel fuel today $3.70 (average)
4.6 gallons of diesel fuel BTU = 631,952

My cost per gallon:$4.92

Propane
A standard sized 20-pound propane cylinder holds approximately 430,000 BTUs of liquid propane
20 pound propane tanks are often referred to as grill cylinders and hold 4.6 gallons of propane when full.
Cost of 20lb propane tank fill (January 4th, 2021) $18.00
Cost per gallon of propane $18.00 / 4.6 = $3.91

My cost per gallon:$3.20 based on a $15 fill of #20 tank
So my cost ratio propane/diesel would be 4.92/3.20= 1.54

btu ratio:
4.6 gallons of diesel fuel BTU = 631,952/A standard sized 20-pound propane cylinder holds approximately 430,000 BTUs
Those are the figures you supplied, so: 631,952/430,000 gives a ratio of 1.47

Basic summation would be as follows: price of diesel over propane is 1.54 times higher
and as far as btu ratio we have: btu's of diesel over propane is 1.47 times higher

All other things being equal, I get a better bang for my buck on propane!
So now the all important geography comes into play...where you are determines how much you pay,
and this affects the outcome of your analysis.

I think it's important to address this issue of geographical location as there are members on here from all over the place, and as such if they don't sit down and work out the math themselves
can easily be mislead by a cost analysis based on information that is technically incorrect for
their geographical location.

So as to my opening statement:
"I'll disagree on two points, not to imply that I am correct and that you're not, but more so to illustrate a different perspective."

I believe I have therefore demonstrated an alternate answer to your cost analysis based on the very important perspective of geographical/economic location.

Now, with all that being said, I've omitted references to the stink of diesel,the fear of propane, the cost of the respective heaters, their lifespan and lifetime operating costs, power consumption etc,
as the title of the thread is :
"An actual analysis of the cost difference between heating with Propane vs Diesel fuels"
although I did touch upon the question of efficiency to a certain extent.

Bottom line? Numbers need to be addressed in a proper context!

Otherwise, I think it's an interesting discussion!

 

[PlethoraOfGuns]

Changing tanks out or finding special fill stations was a no go for me. My van engine is diesel so it was a no brainer for me when I decided to get a diesel heater. But most RV's come stock with everything propane. Great, use the propane. You'll probably never see a price difference if you rip it all out and install diesel heater. Yes, I believe the diesel is more efficient and cost effective, but don't worry about it, run what you got.

The smell from diesel only comes from filling and spilling it. Don't spill it as it won't evaporate like gasoline will. But one thing nobody mentions is the fact that diesel is way safer than propane. A propane tank is basically a bomb you're carrying around. Gas leaks out into your living space? Bigger bomb. Diesel doesn't behave in a volatile manner like that. Be careful out there...

 

[PeterPiper]

^
The smell factor for diesel would be big for me. Since they are vented to the outside, I'm wondering why would there be much odor in the living space? Or are you referring to it being smelly when you refill?

I have a small LP generator that I use with a small 11 lb. tank for charging batteries. I use a butane stove and don't have a heater of any kind since I don't spend winters in the van.

Propane can be used for more than just heating. If I installed a 20 lb. or larger propane tank, I could supply multiple appliances. The generator, a heater and a stove. I may go full-time in the future and may go that route.

I never smell any diesel odors while running the units.
The only time I smell a little diesel is when filling the tanks or transferring the fuel.
It never really bothered me but some are repulsed by it. I would imagine none of them are truck drivers

 

[PeterPiper]

I'll disagree on two points, not to imply that I am correct and that you're not, but moreso to illustrate a different perspective.

Currently where I am in Canada, price of diesel is approximately $1.30/litre, 3.7854 x1.30= $4.92/gallon.
Multiply by 4.6 to get the equivalent of a #20 tank of propane, and we have $22.63 equivalent cost.
Propane, for a common #20 tank is anywhere from $12(Costco) to $25(others and exchange a tank service)

This to me indicates that at the lower price of $12 for a propane fill, it is still cheaper than diesel
considering the different btu values.

And there is the fly in the ointment.
You are viewing the issue from a Canadian perspective while mine is from that of a US citizen.
I was not able to find ANY 20lb propane tank fills at $12.
$18.00 was the lowest I could find.

Also, as you correctly point out......local fuel prices will totally dictate which is more economical.
In my case, I am in the USA where all fuels are generally less expensive (for the time being) than in Canada.

So in Canada, the argument that diesel heating is more expensive could be true......
while in the USA the opposite could be true.

Then there is this.....

Skyrocketing propane prices could mean trouble for some Canadians this winter​

https://www.ctvnews.ca/canada/skyro...uble-for-some-canadians-this-winter-1.5633607
Unless one is significantly and consistently higher than the other I'd suggest going with which ever you personally prefer for whatever reason.

I'm not offended by a little smell of diesel while refilling and I'm not as comfortable with the explosive nature of propane or carrying around the heavy tanks nor the lower availability of propane. So diesel was a natural choice for me. YMMV.

Long term thinking......
Diesel fuel for heavy trucking and delivery will remain in the foreseeable future. Electric is not yet at a state where it is viable for heavy transport.
That means for me at least, diesel will remain readily available and relatively cheap.

 

[Oneleggedcowboy]

Stirring the pot here. As a lifelong farmer and petroleum business manager in my previous life.
Here a a few points...

1.Diesel fuel gels in cold weather so be sure to get it as winterized formula. This is a blend of kerosene and diesel. How does the diesel heater run off this blend?

2. Sludge will form in the tank. How often are you supposed to clean the tank.

3. Bacteria will grow and accumulate in a diesel tank. While sludge develops in the bottom of the tank bacteria can grow anywhere. So is there a filter between the tank and heater?

 

[PeterPiper]

Stirring the pot here. As a lifelong farmer and petroleum business manager in my previous life.
Here a a few points...

1.Diesel fuel gels in cold weather so be sure to get it as winterized formula. This is a blend of kerosene and diesel. How does the diesel heater run off this blend?

2. Sludge will form in the tank. How often are you supposed to clean the tank.

3. Bacteria will grow and accumulate in a diesel tank. While sludge develops in the bottom of the tank bacteria can grow anywhere. So is there a filter between the tank and heater?

Good points and certainly worth mentioning.
The fuel pumps in these heaters use the oil in the diesel fuel for lubrication.
Diluting it with, or using too thin a fuel will have an adverse effect on the life of the pump.
Every rose has it's thorns they say.

I solve most of those problems with this (see image below)......just a few drops per gallon. This bottle treats up to 256 gallons.
In all fairness and for full disclosure...it does add .07 cents to the cost of each gallon of diesel fuel.
As far as diesel fuel gelling, the fuel is in the heater which is kept in the vehicle so it never gets below 45F.

If you use your heater often, most of the problems are not an issue. However, if you do not use it for months at a time you will need to treat the fuel to stabilize it or remove the fuel and clean the system at least once a year.
Again, those darn thorns. Some may find these thorns too much. I have no problem with these measures as I'm a "Fix anything", "Ultimate Do It Myself" guy.

 

[66788]

Hello,
I've seen a lot of comments here and there regarding the cost to heat with diesel fuel vs the cost to heat with propane.
I kinda wanted to know empirically.
I "think" I've done a fair analysis so let me share it here......(for those who give a hoot)

Diesel Fuel
BTU's in a gallon of diesel fuel = 137,381 Btu
Cost of 1 gallon of diesel fuel today $3.70 (average)
4.6 gallons of diesel fuel BTU = 631,952


Propane
A standard sized 20-pound propane cylinder holds approximately 430,000 BTUs of liquid propane
20 pound propane tanks are often referred to as grill cylinders and hold 4.6 gallons of propane when full.
Cost of 20lb propane tank fill (January 4th, 2021) $18.00
Cost per gallon of propane $18.00 / 4.6 = $3.91

Diesel Fuel and Propane both have the same HCE (Heat Conversion Efficiency) which is important

Summary
As you can see, a 20lb tank of Propane costs $18.00 and yields 430,000 BTU's of heat energy. ( I use a 20lb tank for the cost analysis because we are talking about amounts that can be utilized in RV's and mobile vehicles).
Propane "may" cost a bit less when purchased by the 100gallon or more, but again, you can't carry that on an RV.
4.6 gallons of Diesel fuel yields 631,952 BTU's

The cost for a gallon of Diesel Fuel is nearly equivalent to the cost of a gallon of Propane, with propane costing slightly more. With that factored in.......
It costs 35% more to heat with propane today than with diesel fuel

Then there this from another member.....which if true could raise the cost of propane even further...maybe to 70% more expensive than diesel.




An one last thing.....
Diesel fuel can be bought almost anywhere and you can directly fill your Diesel tank readily at almost every gas station.
Propane requires a heavy metal tank that must be exchanged at certain locations or refilled at Propane retailers. A bit more cumbersome.
Personally, for me, that would raise the cost of propane to 50% more than Diesel fuel, but that's just an opinion.

Of course, if you are repulsed by the smell of diesel or just can't stand "dirty" fuels, then you may be a "Propane Person" , and that's just fine too.
Sometimes there are factors other than cost alone.

I welcome your correction as I am only doing a rough estimate here and I have been known on occasion to make really big booboo's in my analysis.

Hope this helps.

Best Regards

Here in Southern Oregon propane sells for $2.52 per gallon, so it's more economical than diesel.

I heat my step van with 120v shore power because electricity here is 8 cents per kilowatt. On the road my vented propex HS2800 has served me well for more than three years with no maintenance and 100% reliability.

 

[PeterPiper]

Here in Southern Oregon propane sells for $2.52 per gallon, so it's more economical than diesel.

I heat my step van with 120v shore power because electricity here is 8 cents per kilowatt. On the road my vented propex HS2800 has served me well for more than three years with no maintenance and 100% reliability.

Interesting.
The price of diesel fuel according to Gas Buddy is rather high in that area.
I am somewhat surprised in the spread between diesel fuel and propane.
In that area that would make propane a much better choice cost wise.
In fact, I could see people running from diesel to propane at that spread.

Thanks for sharing that info.

 

[DannyB1954]

A diesel heater needs to be vented, this causes a loss of efficiency, Figure a 15% loss as most liquid fuel heaters are maybe 85% efficient. Most all of them also require electricity. If you have plenty of solar, fine. If you run a generator to charge the batteries, there is a cost there for fuel and maintenance. It takes a while to fully charge a battery. If you are handy, the cost to install is the same. if you are not handy, you will need to pay to install a diesel heater.
If a propane heater fails, any hardware or Walmart will have a replacement. Parts for your diesel heater will either need to be stocked by you, or ordered. Then again, are you handy to fix it yourself?
Diesel heaters are also not silent. You and everyone else will know that you are using them. Everything has advantages and disadvantages, so pick the one that has the disadvantages that you can live with.

 

[Camper]

I'm not concerned at all about the cost to run my vented propane heater. It's worth what I have to pay to be real warm every day and night.

 

[hugemoth]

Here in Bend Oregon there isn't a big difference in cost per BTU between propane and diesel.
Diesel 137381 Btu per gallon at $3.80 per gallon = 36153 Btu per $
Propane 91452 Btu per gallon at $2.80 per gallon = 32661 Btu per $
Propane costs a little more per BTU but all those BTUs stay inside on an unvented heater (not on a vented heater). Diesel is a bit cheaper per BTU but some heat is lost out the exhaust. Cost wise it's pretty much a draw.

As previously discussed there are differences in electricity requirements, moisture and condensation, containers, hassle involved in filling containers at the gas station, simplicity and reliability of the heaters, installation cost, smell, noise, fire hazard, etc..

 

[rruff]

Propane costs a little more per BTU but all those BTUs stay inside on an unvented heater (not on a vented heater). Diesel is a bit cheaper per BTU but some heat is lost out the exhaust. Cost wise it's pretty much a draw.

I guess you are referring to catalytic propane heaters? If your heater itself is unvented, then you need to vent the space you are in... or vent it more than you normally would.

 

[PlethoraOfGuns]

Any heat type that burns a combustable needs to be vented in some way. Burning propane, diesel, gasoline, or even wood requires ventilation. Don't think that you're capturing more Btu's with your Mr. Buddy heater because it doesn't "vent" hot air/gas to the exterior. Also, both vented propane and diesel heaters use fans to blow air, so they are both loud. It appears the cost difference between the two fuels varies greatly depending on location. Electricity is probably the best of all heat but that's not always readily available to us in a mobile environment.

 

[tx2sturgis]

For Peter Piper:

I believe you took my quote somewhat out of context. I think that was from a more complete explanation of generally how higher quality bunk heaters work, but if I recall correctly, I was probably NOT talking favorably about chinese 'diesel heaters'....can you state for me the date and thread that quote came from? I have no idea what the efficiency of a chinese 'diesel heater' would be, but I DO know that the top brand bunk heaters have efficiencies that are very high.

Also, I do stand by the fact that RV furnaces are very low efficiency. Raw efficiency of an RV furnace is about 70-75% based on published input BTU vs output BTU, but then we add in the energy to run the blower on and off, and the lost heat in the ductwork when the blower stops, and below floor losses, and efficiency typically drops to 50-60%

Anyone who has gone thru two 20# tanks of LP in a week trying to keep a modest sized RV warm in cold weather below 32f probably knows this. There is nearly as much heat blasting out the outdoor exhaust port as there is entering the RV cabin thru the barely adequate duct system...and some RVs have holding tanks that are warmed by the furnace also...further increasing LP use.

 

[PeterPiper]

No worries.
The OP was based off of my attempt to do a fair and informed analysis. Things don't al;ways go exactly as planned.
It seems the best thing for everyone to do is just go with what they are comfortable with.

I don't have room in my little Dodge Caravan to carry even 20lb propane tanks so I use diesel.
But I can see the benefits of a vented propane furnace. I don't like all the moisture from unvented propane systems but some might.

I didn't keep track of where the quote came from but if you do a search on the quote I'm sure you'll find it.
Things change. No worries.

 

[frodo2222]

Good points and certainly worth mentioning.
The fuel pumps in these heaters use the oil in the diesel fuel for lubrication.
Diluting it with, or using too thin a fuel will have an adverse effect on the life of the pump.
Every rose has it's thorns they say.

I solve most of those problems with this (see image below)......just a few drops per gallon. This bottle treats up to 256 gallons.
In all fairness and for full disclosure...it does add .07 cents to the cost of each gallon of diesel fuel.
As far as diesel fuel gelling, the fuel is in the heater which is kept in the vehicle so it never gets below 45F.

If you use your heater often, most of the problems are not an issue. However, if you do not use it for months at a time you will need to treat the fuel to stabilize it or remove the fuel and clean the system at least once a year.
Again, those darn thorns. Some may find these thorns too much. I have no problem with these measures as I'm a "Fix anything", "Ultimate Do It Myself" guy.

I have a 1993 Dodge D250 with a 50 gallon auxiliary tank which I treat with a lubricity fuel additive..I use a diesel heater which I fill from the truck tank whenever I need it so...I NEVER run out of fuel and after running 2 years straight took out the screen and glow plug and looked like new, no soot at all, heat my 30 foot 5er with 9 foot ceilings and 2 slides just fine...it does struggle some in below 25 degrees but I could put another if really needed it. Due to having a club card for diesel current I am paying $3.18 a gallon which is about 65 cents below market..I've had big and small buddys, furnaces and I love the Chinese heater way better..remote to warm up from bed, low power draw (live off grid) and dry heat! was in weed in pic got stuck in 50 MPH wind storm and then had 6 inches of snow..was great and even had 2 other campers I saved that did not have heat or batteries

 

[PlethoraOfGuns]

Oh boy, I'm not the best at math, it hurts my brain. But I sat down and did some, which is nice because it gave me some context to my own diesel setup. I wanted real world data, so I didn't compare fuels, but the actual units that burn the fuel. This is a direct comparison between two heater units. Yes, different units will vary in efficiency. These are the two I choose, deal with it. Not happy? Do your own comparison and share. The dollar amount per gallon I took a national US average. If you're driving cross country, this price will average out. Yes, I realize some people it would vary, but seriously, we have to use averages here, don't get your panties in a wad. Diesel is $3.57/gallon and propane is $3.25/gallon as of yesterday.

Eberspacher S3 Diesel Heater
17050 btu
Fuel consumption-0.155 gallons/hr
110000 btu/gallon
30812 btu/dollar

Propex HS2800 Propane Heater
9500 btu
Fuel consumption-0.1 gallons/hr
95000 btu/gallon
29230 btu/dollar

These be the numbers I gots. When you add the dollar amount, the two heater units are very similar. 30812 btu/dollar vs 29230 btu/dollar. The diesel is slightly more efficient in this comparison, but I'm calling it dead even. I'm pretty sure I got the math right, take it with a grain of salt. I'd say it's a draw between the two fuels price wise. Talking tank sizes, diesel will always hold more btu's in a smaller volume of space, so there's that. Funny we mention volume. Lets see what happens when talking fuel storage efficiency. We'll compare storage of the two fuels, same btu amount, just looking at the volume of storage space and weight differences.

20lb Propane Tank
37lbs total weight when full
430270 btu capacity
18"x12.5" tank dimensions=9.5 gallons of physical displacement

9.5 Gallon Diesel Tank
67lbs fuel weight + 2lbs tank weight?=69lbs total weight
1305120 btu

Wow gallon per gallon of physical storage space you can store 203% more energy with diesel fuel! But what about weight? That amount of diesel weighs a whole lot more than a propane tank. Let's match the weights with 4.9 gallons of diesel.

37lbs propane=430270 btu
35lbs diesel+2lbs tank=677230 btu

Diesel has 57% increase in btu/pound.

Ok, I had my fun. Do what you want with this data. I need to stop looking at the computer screen...

 

[unaccompaniedsenior]

I guess you are referring to catalytic propane heaters? If your heater itself is unvented, then you need to vent the space you are in... or vent it more than you normally would.

Since when do catalytic heaters burn fuel?