Bought Propane this week… Did some math

 
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BlackBetty06
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Post by BlackBetty06 » Sat. Dec. 10, 2022 2:04 pm

Filled up on propane this week at 1.50 a gallon. This got me wondering about costs per BTU between propane, heat pump, and coal. Here’s what I came up with doing my tests….

PROPANE: The figure I used was 91,600 btu/gal.
I combustion tested my furnace with a testo analyzer at 96.1%. Efficient. That means for every gallon (1.50) I burn in propane I recover 88,027.6 BTU as heat into the house. Calculating blower and combustion blower electrical usage into this equation 11.19 cents per hour to run the blower and 7 cents per hour for the furnace inducer motor. (Amps X volts = Watts. My kw/hr delivered price is 14.612 cents. The furnace is 60,000 btu/hr. Basically 1.5 hours of burn time per gallon. So i took 1.5. Times the electricity used and added it to the price of the fuel to come up with $1.77 per 90 minutes of furnace run time

HEAT PUMP: It is typically very warm in my part of SE PA so a heat pump does very well due to the high ambient temps and damp conditions (latent heat). Here is my heat pump COP at 46.6 DB 40.6 WB outdoor conditions. With the heat pump running steady state (15 minutes of run time to stabilize) here are the results. I again used 88,027.6 BTU to keep it equal to the propane. The total wattage draw of the condensing unit outside and the blower in the furnace was 2,800 watts even. This equates to 40.91 cents per hour the heat pump runs. My 2.5 ton heat pump was returning 35,214.48 BTU/HR (temp rise X cfm X 1.08) 2,800 watts equals 9,556.4 BTU/ hr in electrical power input. (1 watt = 3.413 BTU). 35,214.48/9556.4= 3.685 COP. In other words. For every dollar of electric i spend I was receiving 3.685 dollars of heat out. Theoretically the heat pump was running at 368.5% efficiency. This number of course goes down the colder it gets outside. Hasn’t been below 32 to test. This makes 88,027.6 BTU/HR out of the heat pump come in at $1.02

Coal: I run a hitzer 50-93. I was very generous in giving the hitzer an estimated efficiency rating of 70%. Here’s how coal compares at $341 per ton delivered. Blower off. I also used a generous 13,000 btu per pound of coal figure. Again 88,027.6 btu was the target number. $341/2000 lbs= 17.05 cents per pound. 9.674 lbs of coal equals 125,760 btu at an estimated 13,000 btu/lb. At 70% efficiency = 88,032 btu at the cost of $1.65.

So i save an estimated 12 cents using coal for every gallon of propane I burn. The propane is consistent and will give me the same results over and over. The coal can vary a bit each way. At these prices I figure coal is a wash to propane. I suspect propane is cheaper in reality because I’d be floored if my coal stove was actually 70% efficient.

The 15 SEER fixed speed heat pump blows both propane and coal out of the water (keep in mind the warm and damp outdoor conditions 46.6 dry bulb 40.6 wet bulb) saving 63 cents over coal and 75 cents over propane for the said 88,027.6 btu.

Hope this was interesting reading for you. My coal stove remains on ice at this time. Saving it for when its no longer available or the price goes even higher next year.


 
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Sunny Boy
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Post by Sunny Boy » Sat. Dec. 10, 2022 2:27 pm

I wish we were that cheap for pro-pain. We're more than twice that per gallon. And the price took a jump shortly after our former idiot governor caved in to some tree-huggers and banned all gas exploration and fracking in NYS.

https://www.nyserda.ny.gov/Researchers-and-Policy ... ane-Prices

Paul

 
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BlackBetty06
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Post by BlackBetty06 » Sat. Dec. 10, 2022 2:33 pm

Sunny Boy wrote:
Sat. Dec. 10, 2022 2:27 pm
I wish we were that cheap for pro-pain. We're more than twice that per gallon. And the price took a jump shortly after our former idiot governor caved in to some tree-huggers and banned all gas exploration and fracking in NYS.

https://www.nyserda.ny.gov/Researchers-and-Policy ... ane-Prices

Paul
Yes i am very fortunate with our propane prices here. I know you guys up there in California East are paying a lot for it and even more for coal. Idiot governors are a pre qualification for the states on the east coast from virginia on up.

 
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Post by franpipeman » Sun. Dec. 11, 2022 9:47 am

I did my own calc on this issue as well though not as detailed as Blackbettys. In addition to your generous 70 percent efficiency for coal , I gave it 65%. i think a human labor value should be included for coal burden such as ash removal and disposal and handling the unburnt coal which varies in very installation. That should have a price also.
In my sons case almost all of his electric supply is from his photovoltaic system. His back up sources other than heat pumps are a wood burning boiler located 300 ft from house and propane hydronic radian heat. That being said the heat pump does use up his Banked solar produced KWH to the point that its empty in another month . He also powering his plug in hybrid from his solar panels .
Also a factor should also be included when you keep the coal burning when it turns into a warm day and the propane boiler can be shut down what the control panel calls "Warm weather shut down" That is when it gets 53 degrees outside my 91 percent boiler will shut down until the temperature drops to 46 degrees. That is saving also

 
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Post by fig » Sun. Dec. 11, 2022 12:19 pm

I saw that propane price and had to check the date this was posted. 😆 haven’t seen it that low in years. Kind of makes me wish I didn’t get rid of my propane furnace.

 
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Post by warminmn » Sun. Dec. 11, 2022 1:13 pm

There can be some expensive repairs in modern furnaces too. Older ones some of us can cobble repairs. But then older ones arent very efficient. Money wise its pretty much a wash meaning using what you prefer to use.

 
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BlackBetty06
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Post by BlackBetty06 » Sun. Dec. 11, 2022 3:04 pm

warminmn wrote:
Sun. Dec. 11, 2022 1:13 pm
There can be some expensive repairs in modern furnaces too. Older ones some of us can cobble repairs. But then older ones arent very efficient. Money wise its pretty much a wash meaning using what you prefer to use.
Yes, fully modulating gas furnaces with ECM blower motors and ECM inducer motors and communicating control boards can have some pretty expensive repairs. These furnaces are pushing 98% efficient and are fully modulating so they will only burn with the fuel needed to satisfy the heating demand. For example if its a 60,000 btu furnace like mine but is 35 degrees outside, it may only run at 41,000 btu or whatever the need would be. For me the extra 2% in efficiency loses out to the simplicity of a single stage furnace that I can rig up with jumper wires and relays and buy replacement motors at any motor shop. My furnace is a Payne 96% AFUE single stage condensing gas furnace. It uses a standard multi tap 120 volt blower motor The inducer motor is a little single speed 120 volt motor. Nothing fancy there. The control board is just a plain Jane little 24 volt control board with relays on it. Little hot surface igniter. One pressure switch. Single stage gas valve. Really, the only thing expensive on the furnace is the heat exchanger, and at that point if it fails, ill scrap it and buy a new one.The whole furnace cost me 760 bucks in 2018. I believe closer to 1000 today but would have to double check. I do this for a living so I put it in myself. I’m missing the steady heat of the coal but as Fran said, days when its warm outside, the stove is still burning and consuming fuel. Guys talk about just opening windows but with coal prices thats not realistic to me anyway. The furnace or heat pump just shuts off and sits there until called upon. Hopefully this country turns around and energy goes back to where it was, but I dont see that happening unfortunately.


 
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Post by warminmn » Sun. Dec. 11, 2022 4:21 pm

Freight has to drop before I burn coal again, other than the half ton I have left. 1000 miles from the mines to my house. Once in a while some are for sale on facebook so who knows. Wood until then for me.

My Dads Trane furnace's motor had to be replaced this fall. It was 9 years old so still under warranty. It's the quiet model so I bet that wouldnt have been cheap.

But if I have to choose between propane and coal I'll take the coal if the cost is the same or close. I dont have a furnace, just a 72% efficient space heater. I like a stove to sit by and be warm.

 
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Post by Hoytman » Mon. Dec. 12, 2022 10:06 pm

I know very little about furnaces and even less about “modulating” ones and less yet about heat pumps.

I’m interested in this, but that first post made my head hurt with all those figures. :lol: Having slept on the couch two nights straight while the wife recovers from the flu, might have something to do with my head spinning.

I have an oil furnace, 1999 Thermopride, I think they call it a down draft model. Sits in the closet on a slab and the hot air is blown down through the concrete floor and into and through a crawl space under main part of the house. That crawl space is uninsulated and so is the duct work under the main floor, all floors.

Still scratching my head trying to decide if grandpa did that (uninsulated duct work) on purpose in order to try and keep some heat under there to keep pipes from freezing or not. Has worked so far to -27F when we was using the furnace. Now that the coal stove is being used as the main heat source not sure if the crawl space needs any heat or not, or if the pipes would freeze using only the coal stove.

Would love the closet space the furnace is occupying. Would love a cheaper furnace or other means of cheap heat. That said, we love the radiant warmth of the coal stove versus furnace at the same temps. No comparison in the warmth of the coal at the same temperature as the furnace…even burning the coal lower temp it is still a warmer type of heat. Floors, walls, and objects are warm instead of being cold at the same air temperature.

If oil remains high then a propane furnace might become “popular” in a hurry, or some type of heat pump as a back up heat source for the wife.

First year we moved in fuel oil bill for the season was north of $2500+ and oil was $2.67/gal then. Now it’s nearly $6 I think.

 
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Post by waytomany?s » Tue. Dec. 13, 2022 6:36 am

My mother told me that her friends at church keep their thermostat set at 58. Another lady hasn't set at 62. She uses fuel oil. Don't know about the other couple. Mom uses wood, bout 77 at her place.

 
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Post by fig » Fri. Dec. 16, 2022 5:59 am

Seems kind of weird that propane isn’t following fuel prices. It did back in 2008-2009.

 
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Post by lincolnmania » Fri. Dec. 16, 2022 6:20 am

I paid over $4 a gallon to have my 20 pound tanks filled. Propane not cheap if you don't own your own large tank.

 
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Post by waytomany?s » Fri. Dec. 16, 2022 6:25 am

lincolnmania wrote:
Fri. Dec. 16, 2022 6:20 am
I paid over $4 a gallon to have my 20 pound tanks filled. Propane not cheap if you don't own your own large tank.
TSC here will charge that much. If you can a supplier and fill at.their location it can be more reasonable.

 
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Post by lincolnmania » Fri. Dec. 16, 2022 6:34 am

waytomany?s wrote:
Fri. Dec. 16, 2022 6:25 am
TSC here will charge that much. If you can a supplier and fill at.their location it can be more reasonable.
Went to a propane gas supplier for that price. The local hardware store is getting $18.50 for a refill.

 
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Post by waytomany?s » Fri. Dec. 16, 2022 7:11 am

A 20# max holds 4.5 gal. That's 18$.


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