Kuuma VF 100 burn time

[woodey]

Well, not much of a winter so far, save a couple days...getting a little tired of running in "shoulder season" mode.
So it appears that the splits in your picture are at least partially charred...the pic was taken a bit after loading?

Yes, after 5-7 minutes

 

[yooperdave]

Similar to my first post on this thread. Going on year 7 with the Kuuma and I have only filled it to the max a couple of times. Last night at 10:40 I filled it fully with five 19” splits and two 16” on the top, and set the computer slightly above the low setting. Temperature at 22 with gusty winds.

This morning at 7 a lot of large coals, blower on and 70 in the house. Blower ran constantly until around 11 (26 outside)
at which time I pulled the coals forward, adjusted the BD to increase the draft to the furnace and didn’t need to reload until 12:20 PM. The old house holding steady at 69. As stated in my original post “ very impressive for what I’m heating “!!"View attachment 308584

Hole cripes @woodey ! I have never filled mine that full yet......even when we had a couple days of below zero temps earlier this season.

Typically, I'll only fire up with 3 pieces during the day and 4 at bedtime. The longest I've gone without reloading is a touch over 10 hours. And then there were enough coals where I did not have to re-light a fire.

There is some -0 temps on tap for this weekend but I don't think it'll even get to -20. So, there has been no true life real world test of this unit for me yet!

I'm looking forward to warm weather to take a peek as to what I have (or don't have) in the chimney.

 

[JRHAWK9]

Hole cripes @woodey ! I have never filled mine that full yet......even when we had a couple days of below zero temps earlier this season.

Typically, I'll only fire up with 3 pieces during the day and 4 at bedtime. The longest I've gone without reloading is a touch over 10 hours. And then there were enough coals where I did not have to re-light a fire.

There is some -0 temps on tap for this weekend but I don't think it'll even get to -20. So, there has been no true life real world test of this unit for me yet!

I'm looking forward to warm weather to take a peek as to what I have (or don't have) in the chimney.

All depends on heat load. You must have a -VERY- light heat load if you are able to heat your place 10 hours with such a small amount of fuel (wood) when it's zero outside. That is great, however, some of us aren't so lucky. When it gets below zero, I have to let 'er eat.

 

[yooperdave]

All depends on heat load. You must have a -VERY- light heat load if you are able to heat your place 10 hours with such a small amount of fuel (wood) when it's zero outside. That is great, however, some of us aren't so lucky. When it gets below zero, I have to let 'er eat.

Not when it is zero.....that won't happen. Fired up last night at about 10:30 and then again this morning at 6:00. The blower had already stopped blowing but there were enough coals to rake forward and leave the bottom door open for 15 minutes ish to let them burn down before the re-load. Indoor temps dropped from 69 to 67 overnight.

The 10 hour burn was during the crazy shoulder season that we just got through; that was also with the blower motor shutting off long before the coals died down and indoor temps dropping a couple. Outside temps in the upper 20's/low 30's and overnights in low 20's. We even had a couple nights where the temps never got below freezing...in January!! Thats probably when I didn't reload until 10 hours.

I am still learning this furnace. I wish we had a normal winter so I could compare the wood usage to what I had before. That being said, there is less usage due to longer times between re-loads so far.

Last night it got to 5 outside; I loaded up the firebox pretty much to the smoke curtain-but not higher.

 

[lampmfg]

Not when it is zero.....that won't happen. Fired up last night at about 10:30 and then again this morning at 6:00. The blower had already stopped blowing but there were enough coals to rake forward and leave the bottom door open for 15 minutes ish to let them burn down before the re-load. Indoor temps dropped from 69 to 67 overnight.

The 10 hour burn was during the crazy shoulder season that we just got through; that was also with the blower motor shutting off long before the coals died down and indoor temps dropping a couple. Outside temps in the upper 20's/low 30's and overnights in low 20's. We even had a couple nights where the temps never got below freezing...in January!! Thats probably when I didn't reload until 10 hours.

I am still learning this furnace. I wish we had a normal winter so I could compare the wood usage to what I had before. That being said, there is less usage due to longer times between re-loads so far.

Last night it got to 5 outside; I loaded up the firebox pretty much to the smoke curtain-but not higher.

What size is your house, and how well insulated? How much wood were you burning before? Thanks

 

[yooperdave]

What size is your house, and how well insulated? How much wood were you burning before? Thanks

Burning less wood than before, but......given the extended warm spell for a month or so there, everyone has been burning less wood.

House is near 3400 sq ft

I am still in the learning curve phase of the vapor fire but am close to getting it dialed in. (Or maybe it's dialing me in !)

The hardwood I am using has been CSS for years and is without a doubt way too dry for the optimum performance of the Kuuma.

Attic insulation is being upgraded to R-50 as we speak as well as air sealing of ex fans and scuttles. There was probably 26-30 R value up there before today.

 

[yooperdave]

I sure do like the burn times I'm getting from this Kuuma with highs in the 20's-30's and lows in the singles to teens.

A very well designed stove IMO.

Also, I have found that hardwood that has been seasoned 2 years is about the perfect fit for it. Go figure! The same wood would not perform anywhere near as well in an epa wood stove.

 

[JRHAWK9]

Also, I have found that hardwood that has been seasoned 2 years is about the perfect fit for it. Go figure! The same wood would not perform anywhere near as well in an epa wood stove.

I've burned oak that ranged from 2 years to 7 years old so far over the 8 years I have had my Kuuma. The longer I have it, the older the wood I am burning. The furnace was able to burn it all just fine though. However, I still prefer my 15-17% stuff over the 25%ish I was burning very early on. I don't notice any reduction in burn times and common sense would dictate I am boiling off less water, therefore I'm getting more useable BTU's out of the drier wood.

 

[yooperdave]

I've burned oak that ranged from 2 years to 7 years old so far over the 8 years I have had my Kuuma. The longer I have it, the older the wood I am burning. The furnace was able to burn it all just fine though. However, I still prefer my 15-17% stuff over the 25%ish I was burning very early on. I don't notice any reduction in burn times and common sense would dictate I am boiling off less water, therefore I'm getting more useable BTU's out of the drier wood.

I agree completely. But, some hardwood that has been ready to burn for over 5 years would set off the high temp alarm. I would throw in a piece or two of stuff that was 1 or 2 year seasoned and that would eliminate the overtemp alarm. While burning the "fresher" stuff, I would actually notice a slightly longer burn time. The ash left on the inside of the furnace door was always a fine white powder. Not like the inside of the energy king door that would always be a sooty black. With the energy king (last winter) I would make sure to burn only the 5 year and longer seasoned hardwood and cleaned the chimney twice that season. I did choke down the combustion air draft to nothing which accounted for the chimney buildup.

Anyway, this kuuma seems to be burning a lot better, seems to be burning much cleaner (judging from the inside of the door), and even given the mild winter I'm having.....burning a lot less wood.

I look forward to warm weather to inspect the chimney for cleaning and will report on that as compared to what I got from the energy king.

I do have a moisture meter, two actually, but have not felt the need to take any measurements on the firewood. Maybe I'll do that today just so I have something else to post!

 

[JRHAWK9]

I agree completely. But, some hardwood that has been ready to burn for over 5 years would set off the high temp alarm. I would throw in a piece or two of stuff that was 1 or 2 year seasoned and that would eliminate the overtemp alarm. While burning the "fresher" stuff, I would actually notice a slightly longer burn time. The ash left on the inside of the furnace door was always a fine white powder. Not like the inside of the energy king door that would always be a sooty black. With the energy king (last winter) I would make sure to burn only the 5 year and longer seasoned hardwood and cleaned the chimney twice that season. I did choke down the combustion air draft to nothing which accounted for the chimney buildup.

Anyway, this kuuma seems to be burning a lot better, seems to be burning much cleaner (judging from the inside of the door), and even given the mild winter I'm having.....burning a lot less wood.

I look forward to warm weather to inspect the chimney for cleaning and will report on that as compared to what I got from the energy king.

I do have a moisture meter, two actually, but have not felt the need to take any measurements on the firewood. Maybe I'll do that today just so I have something else to post!

The inside of the Kuuma firebox/door should always be white flyash. Inside the heat exchanger will be the same way. When you go and clean the heat exchanger, you will also not find any creosote, just flyash. The only place where you may see some black flaky stuff is on the rear wall near the corners and possibly the inside of the ashpan door. The inside of my ashpan door will be flaky black during the shoulder seasons and white when it gets colder out when I can do more back to back to back loadings on coals.

I'd try lowering your draft down to -0.04" or so when burning the dry stuff. I run mine at that or maybe even a bit less...until it gets cold for extended time periods and then I will bump it back up to -0.05" to -0.06" or so. If you don't have a manometer, GET ONE! Without one it's like driving your car with no speedometer being blindfolded.

 

[Macandmall]

I'm getting used to my new vapor fire. At first, I was filling it up almost every time, and getting house temps from 73-75. That was a little too warm, especially at night. 2 loads a day. The last few weeks I've been filling about 1/3-2/3 full. The outside temps are warming, so I thought I'd cut back the size of loads. I'm still usually able to fire it without a match twice a day. It may have something to do with all the am elm I'm burning. Lots of ash, the coals lay in the ash and are easy to got red hot with an open ash door. warmer days I may not fill in the morning, then I need a match in the evening. 1600 sq ft ranch, 20 yrs old. Furnace is in insulated basement. Inside temp is around 70 now. I am surprised at how little wood I burned. I expected to burn 4-5 cord like Dale had said, but it's going to be 3-4, very similar to my previous cast iron and soapstone stoves used. They did not heat my house without assistance from the lp furnace. I'm near Wisconsin dells

 

[JRHAWK9]

I expected to burn 4-5 cord like Dale had said, but it's going to be 3-4, very similar to my previous cast iron and soapstone stoves used. They did not heat my house without assistance from the lp furnace. I'm near Wisconsin dells

I've burned just over 3 cord of oak so far this winter.

 

[brenndatomu]

I'm getting used to my new vapor fire. At first, I was filling it up almost every time, and getting house temps from 73-75. That was a little too warm, especially at night. 2 loads a day. The last few weeks I've been filling about 1/3-2/3 full. The outside temps are warming, so I thought I'd cut back the size of loads. I'm still usually able to fire it without a match twice a day. It may have something to do with all the am elm I'm burning. Lots of ash, the coals lay in the ash and are easy to got red hot with an open ash door. warmer days I may not fill in the morning, then I need a match in the evening. 1600 sq ft ranch, 20 yrs old. Furnace is in insulated basement. Inside temp is around 70 now. I am surprised at how little wood I burned. I expected to burn 4-5 cord like Dale had said, but it's going to be 3-4, very similar to my previous cast iron and soapstone stoves used. They did not heat my house without assistance from the lp furnace. I'm near Wisconsin dells

Sounds like you are experiencing similar to me, on a lesser scale though, since you guys still seem to get winter...here in the tropics of NEO I spend a lot of time figuring out how to not have to do cold starts all the time, and not overheat the house. I'd say the VF100 is too big for our house, but then when we do get some cold weather, it is about perfect...super cold weather (rare) I might even have to start to push it a lil bit (hush up JRHawk )

 

[woodey]

At first, I was filling it up almost every time, and getting house temps from 73-75. That was a little too warm, especially at night. 2 loads a day.

If the temps in your house are warmer than you want you can dial your lower limit switch up to 110-115 which will allow the blower to kick in less often, then dial back when the house is cooler.

 

[JRHAWK9]

I might even have to start to push it a lil bit (hush up JRHawk )

yeah, you run the furnace like you do your wood splitter.

If the temps in your house are warmer than you want you can dial your lower limit switch up to 110-115 which will allow the blower to kick in less often, then dial back when the house is cooler.

Doing that is just decreasing your delivered efficiency. It'll work, but it wastes a little bit of BTU's. If you load according to heat demand you will use less wood over the long haul.

 

[woodey]

It'll work, but it wastes a little bit of BTU's.

No doubt, but a easy short term solution until you become more familiar with the furnace

 

[brenndatomu]

I'm getting used to my new vapor fire. At first, I was filling it up almost every time, and getting house temps from 73-75. That was a little too warm, especially at night. 2 loads a day. The last few weeks I've been filling about 1/3-2/3 full. The outside temps are warming, so I thought I'd cut back the size of loads. I'm still usually able to fire it without a match twice a day. It may have something to do with all the am elm I'm burning. Lots of ash, the coals lay in the ash and are easy to got red hot with an open ash door. warmer days I may not fill in the morning, then I need a match in the evening. 1600 sq ft ranch, 20 yrs old. Furnace is in insulated basement. Inside temp is around 70 now. I am surprised at how little wood I burned. I expected to burn 4-5 cord like Dale had said, but it's going to be 3-4, very similar to my previous cast iron and soapstone stoves used. They did not heat my house without assistance from the lp furnace. I'm near Wisconsin dells

I have found that low BTU wood is a pretty good solution...pine, soft maple, boxelder (I get quite a bit of that) poplar, even sometimes cherry and ash, especially if the ash is EAB killed that is a bit past its prime. Burning these species allow you to load enough wood (volume wise) to make the furnace burn correctly, without enough weight (the true measure of BTU's loaded...as long as its sub 20% MC wood) to burn too long and overheat the house.
Also helps save the "good stuff" for when you really need it, which can be nice for a new burner that may not have a proper 2-3 year wood supply CSS'd (cut/split/stacked)

 

[JRHAWK9]

Also helps save the "good stuff" for when you really need it, which can be nice for a new burner that may not have a proper 2-3 year wood supply CSS'd (cut/split/stacked)

I happen to know a guy who has some good and dry stuff about 15 minutes away.

 

[yooperdave]

I'm getting used to my new vapor fire. At first, I was filling it up almost every time, and getting house temps from 73-75. That was a little too warm, especially at night. 2 loads a day. The last few weeks I've been filling about 1/3-2/3 full. The outside temps are warming, so I thought I'd cut back the size of loads. I'm still usually able to fire it without a match twice a day. It may have something to do with all the am elm I'm burning. Lots of ash, the coals lay in the ash and are easy to got red hot with an open ash door. warmer days I may not fill in the morning, then I need a match in the evening. 1600 sq ft ranch, 20 yrs old. Furnace is in insulated basement. Inside temp is around 70 now. I am surprised at how little wood I burned. I expected to burn 4-5 cord like Dale had said, but it's going to be 3-4, very similar to my previous cast iron and soapstone stoves used. They did not heat my house without assistance from the lp furnace. I'm near Wisconsin dells

I loaded it full two times I think and that was enough of that! First winter with one here and it is yooper approved! Even though the temps this winter have been more mild, I believe it uses substantially less wood and burns cleaner....based on the white ash on the inside of the firebox door. Looking forward to inspecting the chimney this spring. Last winter, with the energy king, I had been on the roof 3 times!

3400 sq ft counting full basement.

Guys across the lake have one and speak highly of it also.

 

[lampmfg]

I loaded it full two times I think and that was enough of that! First winter with one here and it is yooper approved! Even though the temps this winter have been more mild, I believe it uses substantially less wood and burns cleaner....based on the white ash on the inside of the firebox door. Looking forward to inspecting the chimney this spring. Last winter, with the energy king, I had been on the roof 3 times!

3400 sq ft counting full basement.

Guys across the lake have one and speak highly of iI might steal this "Yooper Approved"

Fantastic - I might steal this "Yooper Approved"

 

[Macandmall]

I have found that low BTU wood is a pretty good solution...pine, soft maple, boxelder (I get quite a bit of that) poplar, even sometimes cherry and ash, especially if the ash is EAB killed that is a bit past its prime. Burning these species allow you to load enough wood (volume wise) to make the furnace burn correctly, without enough weight (the true measure of BTU's loaded...as long as its sub 20% MC wood) to burn too long and overheat the house.
Also helps save the "good stuff" for when you really need it, which can be nice for a new burner that may not have a proper 2-3 year wood supply CSS'd (cut/split/stacked)

Yes I save the good stuff for the cold days and the punky elm for warmer days. My wood for next winter is a mix of oak and silver maple. I think that combination will work great

 

[brenndatomu]

I think that combination will work great

I bet you are right