Oil vs natural gas

ben_18

I have heard people say that oil burns hotter than natural gas. They say therefore you need a bigger natural gas boiler than an oil burner. Why would that be? If the natural gas is putting in 1 million BTU and the oil is also, and they are both burning at 80% aren't they putting out the same amount of steam?

Steve Nichols

BTU's are BTU's

When I had an oil burner I constantly heard my tech say that phrase.   If you look at the BTU's of each fuel source (140,000 per gallon for heating oil and 100,000BTU of natural gas per therm, about 100 cubic feet),  I think it's a case of comparing two different measurements  (a gallon of liquid and one a volume of gas) and getting confused. 

In the end, it comes down to properly sizing the boiler to match the EDR or square feet of heatin area of all your radiators.  For oil or natural gas, you need to hit certain target BTU values to keep everything heated.  It's more critical that you get the EDR correct and match the connected radiative load to the "square feet of steam" produced by the boiler; the BTU's will fall in line with respect to that.

To add another thing to the mix, some installers here have had great success with wet base boilers with gas burners that can get upwards of 87% (or higher?) Thermal Efficiency.  Atmospheric Natural gas boilers hover at around 82% but you are probably more around 80% when all is said and done. 

So...the only wrinkle here is if you choose a specific fuel source/boiler configuration, the thermal efficiencies will vary and that affects the operating cost each season

Sorry if I went off on a tangent.  I really dig this stuff!

Gordy

Yes

Oil, and Propane both have more btu content than natural gas. But in the end it comes down to cost, and efficiencies. NG is cheaper per 100,000 btus than oil, lp, and electricity in most areas. you have to break it down to apples vs apples. in other words how much does 100000 btus cost in oil, and propane, and electricity.



Plus the oil burners are not as efficient as lp or natural gas when talking modulating condensing boilers.

CMadatMe

I Think

To many worry about the energy being created in the boiler. Like others have said, a btu is a btu is a btu. The true efficiency should be the efficiency of the system not just the heating plant. Who cares and what good is the efficiency of the btu/hr being created if that energy isn't being deployed efficiently.



As an example, I could take a 83% cast iron hw gas boiler and make the system more efficient then some of the modulating condensing gas boiler installations I see out there being installed everyday. I've replaced existing condensing boilers with another condensing boiler and have provided some serious savings of up 20-25%. Was it just the boiler change? No, it was proper system design. From doing the heat loss, to calculating the correct heating curve and sizing the right pumps.

JStar

Fuel

The only people who tell you these myths are the ones who work strictly with oil (or any other product, and have something to lose if you convet). Steam only works with oil. Always oversize your boiler. Who cares about venting. Oil doesn't produce CO. So on and so forth.



You can get the sense of how easy it is for people to belive these lies when it is "common knowledge" passed on from old timers that apparently always have to be trusted. When only 10% of the industry actually understands steam, combustion, and efficiency, I wouldn't know who to trust either.



But, you are absolutely right. A BTUH is an unchangeable measurement. It does not matter how you achieve that BTUH, it will always produce the same result. The only part that does matter, is how much you pay to get that BTUH. Both from an initial cost, and an ongoing maintenance/service cost.

SWEI

Ten percent?

I can only wish that we had that kind of education level around here

Gordy

Link to heating fuel cost comparisons

https://www.google.com/url?sa=t&rct=j&q=heating%20fuel%20cost%20comparison&source=web&cd=1&ved=0CDUQFjAA&url=http%3A%2F%2Fwww.eia.gov%2Fneic%2Fexperts%2Fheatcalc.xls&ei=v83-UbD4EcnkyQHV24HADg&usg=AFQjCNEI3O4-27x7XDhiFFJKOpjvhEZHsA&bvm=bv.50165853,d.aWc

heatpro02920

the winner of this Vs. is getting answered everyday,

when I price 6 oil to gas conversions a week all summer long, and the grids wait for service connections goes from 4 weeks to 8...



Its a tough stone to roll, rite now NG is cheaper, but what happens if "they" make it harder to get, like outlawing or making it more expensive to set up these fracking sites...



I like most of us don't know the future, and I try to help my customers make an educated decision when deciding whether or not to change from oil to gas. I have invested hours upon hours making graphs and charts that show the benefits at our current prices... I am currently working on a set that incorporates the equipment I sell and a time scale of how long their current equipment will last, so they can decide if it makes sense to change oil equipment that still has life left in it to a new gas system...



I hate to say it but rite now I am booked to the end of September with A/C installs and gas conversions, I used to install 3 oil boilers a week, now I pull 5 a week out and maybe 1 goes back in...



I prefer propane to oil in my own house (I have both) and I have done a lot of oil to lp swap-outs as well...

ben_18

Oil vs ng

Thank you guys for clarifying this. Like chris said a btu is a btu is a btu!

But is it possible that 1 million BTU of ng doesnt burn as hot as 1 million BTU of oil in terms of the temperature of the fire. (I'm trying to make some sense of what I heard from a seviceman who works for an oil company who said oil burns hotter so you need a bigger NG burner than an oil burner.)

Rich_49

Ben

A BTU is a BTU is a BTU is correct .  The definition of a BTU is as follows and I'll leave it at that for you to make your own case .. BTU =  the amount of energy required to raise the temperature of 1 pound of water 1 degree F in 1 Hour .  This is where the 500 (499.8) in the hydronics formula comes from  8.33 lbs in a gallon x 60 minutes in an hour equals 499.8 .    So a gallon of fuel oil is roughly 139,000 BTuh

 NG is 100,00 per therm , propane 91,800 / gallon , electric 3412 /KWh ,  Hardwood 14,000,000 cord . You get the idea

Gordy

Ben

If you had 2 identically sized boilers for your heatloss. one burns oil, and one burns NG. Both being same efficiency. It would be way cheaper to heat with NG.

Burner size is bigger but thats not the point, and service guy is probably trying to keep you from converting to NG.



Go to the link i provided above. the table shows how much 1,000,000 btus cost for each fuel type.So if your home needs a million btus to heat for two days it does not matter what burner is bigger or smaller.

JStar

Fuel

Think about it this way...



You have a car that runs on oil and a car that runs on natural gas. They both go up to 65 MPH. The only difference is that you fill up the natual gas car 1.25 times for every 1 time the oil car fills up. But, it costs you 1/2 the price each time with natural gas. They both get you to your destination at exactly the same time.



YES, oil burns hotter. Is this better? NO. A higher flame temperature, means more themal stress due to higher temperauture difference. Steam likes to be gradual, and smooth. Oil techs will tell you that oil heats the water faster. How could that be possible, given that a BTUH cannot be changed? A BTUH is defined both by energy AND time. I'll tell you how... they oversize their burners! Sometimes, I think that most oil companies are allergic to small nozzles. It's bad for oil sales. Anybody who understands what a BTUH really is, and how a steam system operates (low pressure), will be able to explain this without being biased.



We install both oil and gas boilers. Both work. Never had a customer "run out" of steam.

Jean-David Beyer

BTU = the amount of energy required to raise the temperature of 1 pound of water 1 degree F in 1 Hour .

It seems to me that a BTU is the amount of heat required to raise 1 pound of water 1 degree F. Nothing to do with how long it takes. A BTU is like a kilowatt-hour. (not 1:1, though; 4000 BTU is about one KWH). If you deliver one BTU to a pound of water in one minute, it will raise its temperature 1F. If you deliver it in one second, it will raise its temperature 1F, etc.

JStar

BTU / BTUH

Correct. But all boilers are rated in BTUH's, not BTU. They define the time for you.

billtwocase

let's not

throw all us oil guys under 1 bus

Spence

How Much Does 100,000 BTUH Cost?

NG: $0.00 per 1,000 ft3 divided by 10, unless your utility prices it in therms. A therm is 100,000 BTUH, so there would be no division.

LP: $0.00 per gallon times a factor of 1.087

Oil: $0.00 per gallon times a factor of .72

Electricity: $0.00 per kiloWatt times a factor of 29.3



Since we are talking about the same amount of heat (100,000 BTUH), this makes fuel cost comparisons easy to understand and appreciate for both technician and customer.

SWEI

Fuel Math

Gordy posted this above, but the link was really complex http://www.eia.gov/neic/experts/heatcalc.xls



It should be in everyone's toolbox -- really.

Gordy

Thank SWEI

Don't know what happened to the link I posted.

JStar

Oil

I try to remain unbiased and civil. Here in NJ, that is a very hard thing to do when talking about oil companies. My apologies. I try to use the words "most" and "generally". I'm so used to being disgusted by the state of our local oil guys, that it's hard to break the verbal habits.