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Posted By Curve,
Jan 17, 2013 at 8:17 PM
i have a VistaFlame VF-55. This is a clone of the Enviro M55.
green team $269
north american $209
more heat but more ash.we buy pellets for heat so i think you found yourself a winner there curve.
since you say they burn a tad hotter than the GTs , i may try another couple bags to give them another shot.what settings are you burning on.are you measuring your temps or just doing the fanny test.
Ash is the first thing they see(really the only thing). So many complain. Heat is what I keep the closest eye on then how long they last. Usage can be deciphered. Just takes a bit of math. I put an hour meter on my stove, But you can just note the time you put it in the hopper. see how long it lasts. If your Harman truly gives the same temp no mater the pellet. Time will tell which is the best deal. Trouble starts when you try to figure in the dollar factor. Easy if the brands your sorting through cost the same.
Once you figure the pounds per hour. Multiply that by the dollar amount per pound. You should be able to get what your stove cost per hour to burn for each brand of fuel.....
Just for giggles, Heres an Example: MWP($209/ton) vs Vermonts($285/ton)
79.85 lbs. MWP lasted 27.8 hours= 2.87 pounds per hour @ $0.1045 per pound = $0.30 per hour
81.44 lbs. Vermonts lasted 27.62 hours= 2.94 pounds perhour @ $0.1425 per pound = $0.42 per hr.
My testing was done with the same feed rate. Vermonts were a bit hotter so I could reduce the feed rate a tick. They would use less per hour if I evened out the temp as close as possible..
This post got me thinking. This morning I shutdown the beast and scooped out the Northeast pellets. Refilled with Vermonts after weighing the bag. Started the stove and tweaked the feed and trim settings to get the Vermonts to burn close to 245 and ran it for a few hours. Shutdown and scooped out the remaining pellets and figured out how much it used per hour. Turns out it only used 2.72 lbs/hr to get about the same temp as the MWP.
2.72 pounds per hour @ $0.1425 per pound = $0.39 per hour.
What did it prove? IDK, But for a few hours I wasn't bored!
I think you just proved that even though Vermonts contain 5% more heat (2.72 vs 2.87), the MWPs are about 25% cheaper (30 vs 39 cents per hour at your prices) to get equal heat out of your stove.
This is assuming your 245F was the convection air, and the convection air intake temp and blower rates were the same on the two runs. You set up the stove/pellet for equal heat rates (the temperature increase thru the heat exchanger). By measuring time, you got a direct comparison of the 2 pellet brands' heat content.
Yes, convection temp is what I am going by. Air intake temps were not measured(using an OAK with cold winter air for both tests). Combustion blower speed was the same and so was the damper(set with a magnehelic gauge). Convection blower speed was also the same. I used the feed trim to adjust the amount of fuel to equal the temp reading. Tried to keep things as close as possible. But definitely not a lab test by any means! Shear boredom tis all!
I had some 2 years ago, ash was heavy and I remember a stinking while burning. Heat was reasonable
Except for the question of the OAK intake and convection intake (room) temperatures, that was about as good a test as we're going to see short of a dedicated lab environment. Nice job!
Convection intake was close for each maybe 66 to 68 For the MWP and this morning it was 64 for the Vermonts ..... I'd say out side temps were about 20 to 30 for both. Humidity was probably very close as well. The MWP might have had a very slight edge?
I have to add that the real brain for my stove is the thermostat. I went back to my normal burn settings(feed rate) to get more heat rise per hour. I let the stove burn hotter and the stat controls the house temps. Stove will run shorter with a hotter pellet, And less waiting for the house to warm up. So if I had some MWP I would need to do the opposite side and raise their feedrate to get the house warmer quicker. If I had some MWP I would do the a test on what their consumption was at a higher feed rate to equal the Vermonts.
To me the stat is the equalizer. What ever the BTU of the pellet it just runs the stove longenough to warm the shack. I'd need to do some other things to figure if the stat is evening up the actual score. One of these days I'll get a data logger. It would allow the 2 bag runs to be graphed and timed. Insted of the actual stove burning time. I could also see just how long they actually last in total hours(hard to explain). Just seems I'm missing something.
I guess what I am asking is would either pellet have an advantage in heat days? Example: Stove maybe running for 27 hrs, But is it lasting 3 days while doing that?
When you set the stove for equal temperatures like you did, you're getting the same amount of heat output per auger rotation. So I think the stove performance would be identical, whether it runs continuously or through ten cycles of the thermostat. All else being equal, the two pellets should even give the same on-off times from the t-stat. (I'm not sure how well this holds for a hi-lo stove.)
Using your MWP vs Vermont measured feed rates (2.87 vs 2.72 lbs/hr), I would expect to see the Vermonts have the same 5%-lower usage at other temperature-equalized feed rates (say 260F instead of 245F). This should hold even when using the t-stat... so a 40-lb bag of Vermonts should last 5% longer than a bag of MWP. Over 3 days, the Vermonts might go an extra 3.5 hours. Is this what you were trying to get at?
Another twist: that's by weight. Your first example had the Vermonts feeding 2% faster (2.94 vs 2.87). Does this imply the hopper will hold 2% more pounds of Vermonts? I don't know. If so, a hopper of Vermonts might last around 7% longer than MWP. So in a hypothetical 3-day thermostat-controlled run, a hopper of Vermonts might go an extra 5 hours.
Looks like you got plenty of feedback.