New Kuuma VF100 Install

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Ncguy427

Member
Oct 23, 2021
40
Greensboro, Nc
Hey Guys, Finally got my VF100 is installed and up and running. Got the first fire going in it this morning. Had a new stainless steel 30ft liner put in and raised my thimble up from 3ft for my old stove to 6ft for the VF. The draft is strong, but the barometric damper is keeping it in check. We ran some 8x24 rectangular ducts from the VF to my central units plenum. House is 4000sqft, average insulation at best,

I can’t believe how well it works. House was pretty cold this morning, around 65. Fired up the VF and turned it to high and it was 74 in here in no time. That’s when I decided I needed to turn it down to low lol. I’ve been going around the house and feeling the registers and the air is very hot. The VF in the basement and there’s two floors above it and the blower seems to really distribute the air well, even to the rooms furthest away.

The way this thing controls the burn is crazy. I filled it up about 3/4 full with red oak 6 hours ago, and I stlll have full logs left, though they are coaled. With my old stove by now at best I’d have a pile of hot coals, but no distinct log shapes left. At this rate idk if Its going to be ready for the overnight load in 2-3 hours. It seems like I could probably get away with 2x a day loading, but will see as I use it more,

It also keeps the basement warm. I wasn’t sure if it was going to be able to due to the layout. The VF is in 1 of 5 rooms down here and 4 of them are comfortable. The 5th, my workshop has never been warm since it’s so far away.

Only thing I’m going to probably change is the location of the low limit switch. The blower is going on and off. But I’m not even sure if that’s a bad thing, since it helps not overheat the house. If I Move the low limit up the plenum will the blower constantly run?

All in all I’m really happy so far. We’re supposed to be getting some cold weather this week, so I’m excited to put it to the test. My only complaint is having to cut my wood down from 24-26 inches to 20. But since it’s so late in the season I only have about 2.5 cord left instead of 7. I appreciate you guys suggesting getting the Vf now and skipping the used old school furnace.

96267E7E-ACBE-4107-BC2A-33585E366C09.jpeg F9851F09-1590-41D6-8048-3308DB15E830.jpeg 5E1807C6-35D8-4232-9473-488308568A3C.jpeg
 

brenndatomu

Minister of Fire
Aug 21, 2013
7,123
NE Ohio
could probably get away with 2x a day loading
Very likely, yes...I do 2x most of the year...even 1 x when it get a lil warmer. Only go to 3x when it gets really cold (but they are smaller loads though too) We had a day a few weeks ago that the local airport weather station shows the average temp for that day was 3.5*F...my records show just shy of 106 lbs of wood that day, which provided 100% of our heat, and kept the house in the low 70's. I never did take the computer off low for that. Don't be afraid to try leaving it on low, see how it goes for you...I bet it stays there most of the time.
If I Move the low limit up the plenum will the blower constantly run?
It should, yes.
My only complaint is having to cut my wood down from 24-26 inches to 20
You might consider just cutting some of that in half...you probably get a decent amount of mild winter weather down there, so having some shorter wood will allow you to load smaller loads (by weight, which is what really matters) but still be able to stack the load a little higher in the front of the firebox, which makes the VF really purr IME...kinda extends your wood supply then too since you can use it all as normal loads instead of some firewood, and a bunch of lil chunks...which you then have to kinda mix in as you can.
Congrats on the inaugural burn...by the way, that is one crazy cool lookin supply plenum! ;lol
 

Ncguy427

Member
Oct 23, 2021
40
Greensboro, Nc
In definitely going to have to dial In my loading times. Usually I load around 11pm for the night. 11pm last night was 8hrs into the burn and It wasn’t even close to needing a reload. It was going to be cold last night (for Nc, 20s) so I stayed up until 1 and loaded it then, 10hrs in and the blower was still cycling. This morning 8hrs later I Still have a massive probably 1ft tall bed of coals, so I’ll be waiting another few hours to load it up. Daytime I burn poplar, so I’m excited to see how long a load of that lasts today.

This thing is so easy. There’s no more frantically running downstairs because I forgot to close the air lol. Or the back and forth up and down the stairs trying to dial the air in before going to bed. And definitely no more 4am wakeups to add more wood on the cold nights.

So far it seems to be running really well well. I haven’t gotten any high temp alarms or anything. The barometric damper seems to be doing it’s job. When it’s flapping I can see into the stove pipe and it looks like nothings coming out. I don’t see any smoke, let alone sparks or anything. And nothing really ever comes out the top of my chimney.
 

Ncguy427

Member
Oct 23, 2021
40
Greensboro, Nc
Very likely, yes...I do 2x most of the year...even 1 x when it get a lil warmer. Only go to 3x when it gets really cold (but they are smaller loads though too) We had a day a few weeks ago that the local airport weather station shows the average temp for that day was 3.5*F...my records show just shy of 106 lbs of wood that day, which provided 100% of our heat, and kept the house in the low 70's. I never did take the computer off low for that. Don't be afraid to try leaving it on low, see how it goes for you...I bet it stays there most of the time.

It should, yes.

You might consider just cutting some of that in half...you probably get a decent amount of mild winter weather down there, so having some shorter wood will allow you to load smaller loads (by weight, which is what really matters) but still be able to stack the load a little higher in the front of the firebox, which makes the VF really purr IME...kinda extends your wood supply then too since you can use it all as normal loads instead of some firewood, and a bunch of lil chunks...which you then have to kinda mix in as you can.
Congrats on the inaugural burn...by the way, that is one crazy cool lookin supply plenum! ;lol
Cutting them in half is a good idea. I’m into my red oak supply and most of the pieces are ever so slightly too long. 21.5-22 inches. So I’d hate to cut 1.5-2 inches off. Last night I threw all the end cuts on the very top.

I see now you really do need 15-16 inch pieces for the very top row. When I’m bucking up logs I’ll have to remember to cut 1 at 16 for every 3 I cut at 20.

And ya the plenum is pretty big. The original plan was for a 18 inch plenum. Then my father in law shows up with this thing. It’s 38 inches tall, which gets us to the height we needed to run the main supply duct over to my central system. It seems to be working so I can’t complain.
 

brenndatomu

Minister of Fire
Aug 21, 2013
7,123
NE Ohio
Daytime I burn poplar, so I’m excited to see how long a load of that lasts today
I run low BTU wood (Box Elder) most of the year the last few years. Didn't switch over this year until the real cold weather moved in 2-3 weeks ago...and even then I didn't use that much of the real heavy hitter wood...used quite a bit of Ash...going back to the "junk" this week.
Yup, just load some of that poplar on the pile of coals and I bet that's all that you will need for the day.
One thing that's kinda hard to wrap your mind around, especially when coming from an old school burner...when it gets real cold out you can technically get more heat from pine, poplar, stuff like that, (as long as someone is there to load more often) because it makes a lot of heat fast, and you don't get the huge coal piles that you have to figure out how to burn down...
 

Ncguy427

Member
Oct 23, 2021
40
Greensboro, Nc
I run low BTU wood (Box Elder) most of the year the last few years. Didn't switch over this year until the real cold weather moved in 2-3 weeks ago...and even then I didn't use that much of the real heavy hitter wood...used quite a bit of Ash...going back to the "junk" this week.
Yup, just load some of that poplar on the pile of coals and I bet that's all that you will need for the day.
One thing that's kinda hard to wrap your mind around, especially when coming from an old school burner...when it gets real cold out you can technically get more heat from pine, poplar, stuff like that, (as long as someone is there to load more often) because it makes a lot of heat fast, and you don't get the huge coal piles that you have to figure out how to burn down...
Ya once you figure out the softer woods, you can get a lot of heat from them, just over a shorter period of time. A load of poplar or pine will put out more heat over 4hrs than a load of hickory will over 4hrs: it just burns hotter. But hickory will just keep steadily putting out moderate heat for another 4-6hrs after the poplar is done. My property has a ton of mature poplar; and some years that’s basically all I had to burn. And I kept the house warm with it. Just gotta reload every 4-5hrs, atleast with my old school stove.

If I ever need to get the house up to temp quick, I’m not loading the super dense hardwoods. I’ll start off with pine or poplar and get a nice hot burn going.

Finally after 12hrs the blower stopped coming back on and the coals were burned down pretty far. I love having the grate and ash pan and not having to shovel out ash every day. What a mess that always made. I loaded it up with 12 inch long poplar splits. It’ll be interesting to see how long this load lasts. I’m going to have to get a scale to put near the furnace so I can weight the loads.

I don’t even think I’ll need white oak and hickory and all that good stuff for the coldest nights. I needed it with my old stove because it was so inefficient. But I think Ash or cherry will do the trick for the coldest NC nights. Which is good because I still have atleast 30 dead ash trees to take down. Based off what I’m seeing so far, my 3 year wood supply is probably more like 5 years now. I’m going to have to start selling alot more.
 

brenndatomu

Minister of Fire
Aug 21, 2013
7,123
NE Ohio
I loaded it up with 12 inch long poplar splits. It’ll be interesting to see how long this load lasts.
Yes, please update us on that...I bet you'll be surprised.
 
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JRHAWK9

Minister of Fire
Jan 8, 2014
1,854
Wisconsin Dells, WI
Welcome to the Kuuma family. :) They are one heck of a furnace.

Moving the low limit is advisable. The only reason they put it where it is is due to (I believe) UL certification. It has to be wired up and installed and seeing they don't include a plenum, it's the only place they can put it. I'd relocate it somewhere further up in your plenum. It will be more consistent and should solve a lot of the on/off/on of the blower.

If it were mine, I'd move it somewhere in this area. Get it up and over the furnace as best you can.

1644868084507.png
 

brenndatomu

Minister of Fire
Aug 21, 2013
7,123
NE Ohio
Oh, and I noticed in your firebox pic there that it looks like maybe you loaded the wood against the back wall...if the wood is not 20-21" long you'll want to load the wood so that it is within an inch or two of the front...it makes a difference in how the burn goes early on.
Just to be clear though, you want the red hot coals kept 2-3 inches back from the front, but the wood within 1-2"
 
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Ncguy427

Member
Oct 23, 2021
40
Greensboro, Nc
Oh, and I noticed in your firebox pic there that it looks like maybe you loaded the wood against the back wall...if the wood is not 20-21" long you'll want to load the wood so that it is within an inch or two of the front...it makes a difference in how the burn goes early on.
Just to be clear though, you want the red hot coals kept 2-3 inches back from the front, but the wood within 1-2"
Good to know. One thing I’ve been worried about is the load l collapsing when it’s well into the coaling stage, which it does sometimes, and coals fall onto the front face. What are your guys thoughts on this?

We’re 6 hours in to the poplar load. Things got a little crazy in here lol. It got up to 77 before I turned it down from just over low, to the absolute lowest setting. It’s still 76. But the outside temp is dropping fast. It was 45 during the day today and will drop to 20 overnight. Tomorrow I’ll have to do a smaller load during the day. I’m super impressed with how much of this poplar Is left. Should be due for the night load at the right time tonight in another 3-4hrs.

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brenndatomu

Minister of Fire
Aug 21, 2013
7,123
NE Ohio
One thing I’ve been worried about is the load l collapsing when it’s well into the coaling stage, which it does sometimes, and coals fall onto the front face. What are your guys thoughts on this?
Meh, no big deal, it happens...what they want you to avoid is pulling all the coals to the front right against the air distribution plate when you reload...that kind of heat can get INTENSE!
 

Ncguy427

Member
Oct 23, 2021
40
Greensboro, Nc
Welcome to the Kuuma family. :) They are one heck of a furnace.

Moving the low limit is advisable. The only reason they put it where it is is due to (I believe) UL certification. It has to be wired up and installed and seeing they don't include a plenum, it's the only place they can put it. I'd relocate it somewhere further up in your plenum. It will be more consistent and should solve a lot of the on/off/on of the blower.

If it were mine, I'd move it somewhere in this area. Get it up and over the furnace as best you can.

View attachment 292156
Ya I’m Definitely planning on moving it further up the plenum. So is it supposed to stay on low speed for as long as the firebox is over a certain temp, and then kick onto high when it calls for heat? Mine cycles between no fan and then I think it’s high speed that comes on.

I know you have a lot of data on your furnace, What kind of temp probes are you using to measure plenum and flue temps? I want to set mine up the same way.
 
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brenndatomu

Minister of Fire
Aug 21, 2013
7,123
NE Ohio
So is it supposed to stay on low speed for as long as the firebox is over a certain temp, and then kick onto high when it calls for heat? Mine cycles between no fan and then I think it’s high speed that comes on.
I doubt that it is high speed...its kinda hard to tell the difference between low n high unless they are activated back to back...just push the white button on the fan/limit switch, that should activate high speed. But yes, most of the time the blower will run on low as long as there is a fire, except for maybe a cycle or two in the beginning, and then a lil cycling toward the end of a fire, if you let it burn out.
Then obviously it will run on high when the tstat calls for heat too (if you are using it)
 
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JRHAWK9

Minister of Fire
Jan 8, 2014
1,854
Wisconsin Dells, WI
yeah, nothing to worry about if they fall into the front. My loads are always 19-21"+ long.....

It's nice reading feedback from someone who has used the old school furnaces and the real world difference in the same house. This is my very first wood furnace, so I have nothing to compare it to.

Even though you are heating a large area/volume, your climate doesn't get very cold....and it sounds like your place is somewhat efficient.

I know you have a lot of data on your furnace, What kind of temp probes are you using to measure plenum and flue temps? I want to set mine up the same way.
I have -THIS- one.

So is it supposed to stay on low speed for as long as the firebox is over a certain temp, and then kick onto high when it calls for heat? Mine cycles between no fan and then I think it’s high speed that comes on.

It's on low speed as long as the low limit is satisfied and their is no call for heat. If there is a call for heat and the low limit is satisfied, it will go to high. However, most of us don't even use the thermostat. We just manage the loadings appropriately.
 
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brenndatomu

Minister of Fire
Aug 21, 2013
7,123
NE Ohio
Hmm...I see they have the Smoke X4 on sale...tempting...my Maverick is probably due to puke another probe anytime, and its not under warranty anymore, so...I think the X4 would be nice to chart flue/supply/indoor/outdoor temps
 

JRHAWK9

Minister of Fire
Jan 8, 2014
1,854
Wisconsin Dells, WI
Hmm...I see they have the Smoke X4 on sale...tempting...my Maverick is probably due to puke another probe anytime, and its not under warranty anymore, so...I think the X4 would be nice to chart flue/supply/indoor/outdoor temps

I saw that. You'd have to extend the cables though to reach, as I thought about that too. I also think there is a max length one can extend as well.

I don't think the Smoke X series has the ability to do what I do though.

I also have the Smoke Gateway, which allows me to do all the graphing and it says it's not compatible with the Smoke X series.

 

Ncguy427

Member
Oct 23, 2021
40
Greensboro, Nc
Close to 9hrs of blower time on a load of poplar is crazy. I reloaded yesterday at 1pm, blower stopped around 10pm. And it wasn’t even a full load, all the pieces I loaded were around 12-13 inches. I didn’t reload until 12.30am.

It does not do nearly as well with unseasoned wood. Had some scraps from my saw mill that I cut up yesterday after work measuring around 28-30% moisture. Was curious on how mixing some of that in with my good wood would effect things. So my first two layers for overnight were well seasoned red oak, and the top two were this fresh red oak. When I came downstairs the computer was on 2, and quickly went to 3 and I was down to a big pile of coals, 8hrs into the burn. Similar to what the firebox looked like after 12hrs the night before with almost full firebox of seasoned red oak. Haven’t loaded it up yet, but it’s been 9hrs since I loaded last night and the blower is off.
 

brenndatomu

Minister of Fire
Aug 21, 2013
7,123
NE Ohio
I don't think the Smoke X series has the ability to do what I do though.

I also have the Smoke Gateway, which allows me to do all the graphing and it says it's not compatible with the Smoke X series.
I saw that then...oh well, I think ima just run my Maverick until she blows! ;lol
 

JRHAWK9

Minister of Fire
Jan 8, 2014
1,854
Wisconsin Dells, WI
Just drill a hole just large enough and slip it in. No need to seal, as it's under negative pressure. Mine is about 15"-18" or so from the furnace collar on TOP of the pipe. You will get lower readings if you insert it on the sides or bottom.....depending o the length of the probe.
 
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brenndatomu

Minister of Fire
Aug 21, 2013
7,123
NE Ohio
This ^ ^ ^
With my current setup I got lucky and drilled the hole the same size as the probe OD...it fits exactly...as in I can put the probe wherever I want it, it will stay put. A furnace that burns less clean would leave you with a permanently "glued" in probe if you tried to fit it this tight...but with the Kuuma, and dry firewood, the flyash that builds up on the probe after a few weeks (throwing the reading off...can be 50* off) just comes right off as you pull the probe...pull it out, put it back in, done...and yes, trying to keep the tip of the probe in about the center of the pipe will give the most accurate reading.
 
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