magnum 7500 new stove need help.

[wes]

Spray, one thing you are not taking into your calculations; Cornman would have to give us the specs on the cfm output of the draft blower, but I am sure it is waaay smaller than the 1260 cfm output of the room blower. To test the efficiency by measuring exhaust output temp versus blower temp, you would need to have the cfm output identical. If one blows more air than the other, the temp will be hotter. Case in point, the St Croix stoves. They put out very hot air into the room, but you can not feel it very far away due to lower volume.
I do not know the entire process, but I do know that Magnum stoves and furnaces are tested by an independent testing lab to determine their efficiency rating.
My question to you would be regarding your venting configuration. Please describe your stovepipe. I am a dealer for these products, and visited a home that had a similar situation; high temperature on the pipe, stirrers burning out, etc. The culprit turned out to be his venting. he had terminated 4" pipe directly into his chimney. The chimney was pulling a tremendous natural draft through the furnace; so much so that even when the damper was completely closed there was too much air. When I opened the ash pan it sounded like a tornado! This was pulling a huge amount of heat through the chimney and the high volume of draft was combining with the fire to act like a torch on the stirrer. Often in this situation you will see the stirrer burn through on the left side.
From your description, I suspect a similar problem in your case. High exhaust temps, premature stirrer failure, and the fire going out unless the level is high are all classic symptoms of too much draft.
I may be prejudiced, but I do not think there is a design flaw in these furnaces. They are basically the same design as the 3500, which has given me many years of service!
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3500P clinker pot in house. 3500P stirrer pot and baby countryside with cast iron pot in shop.


If we forget that we are one nation under GOD, we will be a nation gone under.-Ronald Reagan

[Cornman1]

well you won't get as much % eff. burning pellets. Think about it, the average size of pellets vs the size of corn augering through the system. You will have more air space with pellets than corn. Thus less fuel and less heat output than corn.

[spray]

alaska aviator, are you interested in a furnace?? i am not joking if you like yours so well and "i will never get it" than please send me a check and i will sell you this thing anything over scrap price will be a plus. thank you
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magnum 7500 since 04

[spray]

wes , i have burned this furnace off and on for six years. lets get one thing straight right now. the 7500 magnum furnace is a totally different animal than your 3500 period. they may look allot alike but they are totally different. i can go through way too many configurations than you would care to here on how i have set this thing up. i don't have too much draft i have a system that is set to aes installation guidelines to a tee. and it still does whatever it wants too. i am waiting on a clinker pot from sign2024 . please don't compare a countryside 3500 to a magnum7500. i like the 3500 and think of it as a pretty darn good stove but these are like comparing apples and oranges. thanks for the info wes.
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magnum 7500 since 04

[AlaskaAviator]

Probably cost prohibitive to send it to alaska. The 7500s that we have around here work very well but we don't have corn, all we have is wood pellets. May be you should try burning some pellets, I think they are a lot more forgiving than any kind of grain.
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AES 3500P & 7500 furnace

[spray]

wes , efficiency= the amount of btu input vs. btu of output in heat to your space .if you put 10,000 btus in and you are 100% efficient than you get 10,000 btus output this means no flue or exhaust you capture 100% of all btus into heat in your home like electric element. my unit pushes as much heat out the flue as i am sure most of yours do as well. as it does room air that to me equals about a 50% efficiency rating. look at my previous numbers i think that you will agree. thank you
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magnum 7500 since 04

[spray]

magnum 7500. good warm heat while running=very much so
renewable energy biomass better than propane= yes
magnum 7500 87% efficient= no way
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magnum 7500 since 04

[spray]

alaska, i have burned lots of pellets. i live in ohio in the corn belt. so the corn grows in the field behind me . i dont have to have pellets shipped in for more cost. my nearest pellet mill is quite aways away.and i am sorry to here that you dont burn corn. i know what science says is that corn and wood pellets have about the same btus but i have to disagree. corn will give you more fuel on any given setting being feed through an auger. but in my opinion with all things being equall. corn still burns hotter that even the most premium wood pellets that money can buy.
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magnum 7500 since 04

[AlaskaAviator]

May be but I bet I have to ship corn further then you have to ship pellets. Funny thing though last year we bought pellets from Sams Club for $244 a ton and they came from Georgia and now we have a pellet mill down the road about 140 miles and they get $250 a ton, go figure.
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AES 3500P & 7500 furnace

[wes]

Spray, I agree with your assessment of corn vs pellets. I do not agree with your calculations of efficiency. You may be getting the exact same temperatures at your exhaust as you are at the plenum of your furnace. Let's throw out a few figures.
If your room air blower runs at 1260 cfm at a temp of 135, your heating value is 170,100.
If your draft fan runs at 200 cfm at a temp of 135, your heating value is 27,000. (again, someone will have to verify cfm of the exhaust blower)
Add 170,100 and 27,000 and you get a total output value of 203,850.
14% of 203,850 is 28,539, which means you would be getting between 85 and 87% efficiency.
As I stated before, the 7500 was tested for output and efficiency at a private lab. The company did not just grab a figure out of the air. The efficiency varies greatly with the amount of draft, moisture and quality of fuel, etc. That is why it is listed as "up to" a certain figure in both efficiency and btu output.
I was told by a person at the factory that there were tests done on one of the stoves. If I recall correctly, there was a gain of 30% efficiency by closing the damper to 1/3 of the way open versus fully open.
I did not mean to upset you by asking about your venting configuration; I was simply trying to help.
I have been a dealer for these units for years, and it is my experience that if you are sending the same amount of heat out the chimney as you are putting into your house you have too much draft. Period.
Sorry if that upsets you, but that has been my experience. I welcome other's comments if they agree or disagree with me.
Good luck!
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3500P clinker pot in house. 3500P stirrer pot and baby countryside with cast iron pot in shop.


If we forget that we are one nation under GOD, we will be a nation gone under.-Ronald Reagan

[spray]

wes i have not checked my exhaust temps lately. and i run the intake dampener barely open . i will be able to tell you tomorrow on if i have too much draft as my clinker pot will be here but i don't believe that i do i will tell you why i have ran the unit with outside air hooked up since day one but i have unhooked the o\s air and burned it for a few hours this way and have observed no changes in burn i have ran the draft dampener plate full closed and everywhere in between .i usually run the o\s air just cracked open a little bit and it seems to work real well what i have found to be a perfect flame for this stove.thanks for the info wes
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magnum 7500 since 04

[wes]

Good Luck! Let us know what you think of the clinker pot.
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3500P clinker pot in house. 3500P stirrer pot and baby countryside with cast iron pot in shop.


If we forget that we are one nation under GOD, we will be a nation gone under.-Ronald Reagan