Sunday, December 16, 2007

How much fuel do I use?

When I first began using a pellet stove to heat my home there was a sharp learning curve. Not just in lighting the stove (as self-igniting systems were not common), or cleaning the stove, but in learning about the fuel to heat ratio. How much fuel does it take to heat my home, and how differently will I heat my home with this fuel?
I grew up with natural gas heat in my home. I could not have told you what natural gas looked like, how much space it took up, or how much volume of gas it took to heat my home in a day/week/year. It was piped directly into my home, and was supplied as my demand required. I'd get a bill each month for what I used. I would set my thermostat at 73 and be done with it. Pay the piper later.
I once lived in an apartment that had electric heat. So the same concept applied but I was able to tune each room to my desired temperature. Absolutely no concept of how much or what type of fuel was used to create the energy to heat my space with this fuel source.
When I moved to New England, I found that oil was the predominant heat source. With oil heat you pre-buy fuel in the spring using their guidelines and past usage history to determine how much fuel to buy for the year. For example, an early buy of 1,500 gallons is common for an average three bedroom home. But how much fuel is used each day? What kind of space does that much fuel take up? How much will I use in January? I really never focused on that because the oil company comes to fill a large storage container which then feeds directly into my furnace/boiler. So on a day to day basis, I had no quantification for, or need to quantify, how much fuel it takes to heat my home. I would set the thermostat on about 70, then as winter wore on if I had a lot of fuel I would turn it up, or if it was getting down to the wire I would turn the thermostat down and put on a sweater. How warm it was became a factor of how much I had left, not how warm I wanted my home.
Then we got the pellet stove. "How many bags will I use each day?" was my first question. Never mind how subjective and virtually impossible it is for someone to speculate how warm it will be outside, how warm I want it inside, what my rate of heat loss is, and what the winter's weather will bring. To me it seemed a fair question. Our friend struggled to explain some averages, show some examples, but would not give me a concrete answer. I was frustrated at this. How could someone not know? I pushed a little further, and was told the minimum and maximum fuel intake of my stove based on how many btu's I would need. This was starting to sound complicated. What happened to just setting the thermostat? I like being green, and using an alternative energy source to heat my home, but now I have to think?!? We bought three tons based on what the previous owner told us they used and off we went. Wow, those bags are heavy. We loaded all three tons, one bag at a time, into the garage. Then came the tradition of loading the stove each day. We thought it would be once a day, but that only kept my house at about 60 degrees. I like it warmer than that! So a bag and a half or two bags a day became the norm. In the coldest months we would turn on the electric heat to supplement. The stove was running on high (almost three bags a day) and the house was still not as warm as I was accustomed to. Wow, that's a lot of pellets! It seemed like so much! Why is my stove eating so much fuel? It must be eating it, because that is a lot of fuel and my house is just warm, right?
Then I started thinking about it. Is it so much? Do I have enough knowledge and experience to determine this? How much fuel did my furnace used to eat? I had no idea. No. I don't have anything to relate it to. Is it possible that my stove "eat" fuel without equivalent heat output? The flame looked fine, the heat was blowing off, so no, not likely that it is merely eating the fuel. I realized that I just never knew how much fuel it takes to keep me and my home comfortable. How much fuel I burn isn't really a function of the stove at all, other than a stove can produce up to a maximum heat (amount of btu's per hour).
How much fuel I burn is relative to how warm I want it to be in my home, how big my home is, how well my house holds heat, and how much it takes to heat it as related to how cold it is outside.
What a learning curve, though. The bag a day that many people touted was not true for me. Sure, they were using their stove as a supplementary system in addition to their oil furnace, but why would my situation be that different? Actually if you do the math burning a bag a day in your pellet stove (only) is like using a little electric box heater to heat your house. Would that work for your home? Certainly not mine. I want it comfortable!
So, I try to remember that when I am putting two to three bags of pellet fuel in my stove each day, I am actually saving five to seven and a half gallons of oil. That is a lot of oil. Imagine how heavy and messy that would be if you had to pour it in to your furnace/boiler each day! Yuck! What if you spilled a little? At least the pellets are easy to pour and if I spill a little a dust pan and broom are all that are needed to scoop them back up and I can put them right into the hopper.
After using my stove for years, I had a wood pellet boiler with a bulk bin installed. I find that I am slipping back into the pattern of just setting the thermostat, since I don't have daily contact or concept of fuel used. I do appreciate that I was able to learn how much fuel it does take to heat my space. It gives me an appreciation for how many resources I use, and makes me appreciate even more that I use a renewable, local, alternative energy source like wood pellets.


fuels4heat said...

Thank you for your reporting about the European trade show and mentioning some of the brand names.
Having been to their show and seen all the European boilers; did you purchase a brand made here or the brand made in Denmark, that is available here?
Does the boiler uses less fuel, to heat your house to the same temperature; that the pellet stove did?

WoodPelletGuru said...

I heat with a US made Harman boiler. I look forward to the day when more European manufacturers export their products to the US. The Tarm is a good system. I know of a few commercial sites that have them installed. I believe New England Wood Pellet has some info on their web site about them as they have them and provide fuel for a few of the installations around them.
I will do a future post about central heat versus single point heating (stove). Central heat systems in general tend to use more fuel. I am no exception...

Genuinosity said...

Thanks for this information. I have just installed a Harmon PF100 Pellet Furnace. I have an old, 2 story, 2500 sq. ft. brick home (plaster walls -- no insulation in walls). I live in rural southwest Ohio (Its windy and moderately cold here). I was told I would probably use about 5-6 tons per year but I am using 4 bags ($20) a day! I set the temp down (60 deg) and the feed rate down to the lowest setting but it still uses 3 bags a day. That's about twice as much as I thought I'd use. And it has been warm (40+ deg. F). The stove puts out lots of heat but appears not be as cost-effective as I had hoped. I'm still learning, maybe I am doing something wrong. BTW, I have lots of woods on my farm, maybe I should look into making the pellets myself!

WoodPelletGuru said...

I would have to start by saying that your biggest bang for the buck would probably be investing in some insulation. Wind doesn't help that situation much... Not sure about your area but we have had a much colder than winter than last year, too. Do you know how much fuel per day you were using with your 'old' fuel? Especially with the installation/replacement of a whole house system (as opposed to a stove-single point system) your fuel consumption/btu output is likely to stay near the same. If you are keeping it warmer your usage will go up. You want to be sure to set the Feed Adjuster (little knob with numbers and test) to around 4 and LEAVE it. This is a trim pot only! Use the large dial with temperatures on outside and numbers on inside to control your unit. Room Temp (L to H) and the temperature on large dial help keep your room at a set temp. Stove Temp (L to H) and inside numbers help you determine feed rate and fan setting manually. Note that the the number do not correspond directly to pounds per hour, rather how many times unit pulses per control board setting. Hope this helps!