Kuuma VF 100 not heating my house! Help!

[bropp]

For the last five years I've been reading great things about the vf100 and have been wanting one. I finally purchased one and am very disappointed- I can't get it to heat my house! The firebox is a blast furnace but the plenum feels cool. I don't know why the heat won't leave the firebox. I can't get my house above 60 and its in the upper 50s in the morning and it's been super warm outside- lows 20 above and highs close to thirty! I have a thermometer on the registers and usually reads 72. I don't know how to get more heat from it. I insulated the plenum and put a probe in one foot above the plenum- when the furnace is roaring on the highest setting it reads 90 degrees.

I live in a 3000 sq ft house with two garage doors in the lower level. It is essentially a 1500 sq ft ranch with a Wood walled 2x6 walkout basement. The entire thing has r19 walls. The garage doors are insulated and plugged around the edges, I don't use them. House was built in 94 and has good insulation .
I've been burning wood my entire life. I am burning dry Ash and maple between 15-20 percent on the moisture meter.
6 inch class a chimney with barometric damper. I've tried every setting on the damper and just got a Dwyer mkii to check, but think its okay as i have flue temps between 200-250. Chimney goes through a thimble and is about 25 feet tall.
I made a duct system for it- not ideal but am moving it next year. Has 10x20 trunk with 4 8 in takeoffs. I've played all around with changing the static duct pressure to increase air temp. Cold air return comes from up stairs.

The air coming out just feels cold. I've talked with Dale about a dozen times and he's been very nice, but it hasn't gotten any warmer.
My wire is furious about this whole problem and wants it returned immediately. She grew up in an uninsulated farmhouse with a hot blast that was always 80 inside even when it's -35 outside. When I go there the plenum is always HOT when it calls for heat. Mine is cold.
Help! Is the Kumma actually as good as everyone says? I really regret buying it!
This has been going on for over two months
I've tried everything

 

[Gbawol42]

I am sure @brenndatomu and @JRHAWK9 will help you out when they see this post.

Something definitely sounds fishy, if it's in the 30's outside you should be cooking yourself out of the home, especially with the proper seasoned wood (which is usually the culprit 95% of the time)

I tagged two guys that are helpful for the vf100, I myself have a drolet heatmax, so little different setup. I won't be much help to ya.

 

[bropp]

I am sure @brenndatomu and @JRHAWK9 will help you out when they see this post.

Something definitely sounds fishy, if it's in the 30's outside you should be cooking yourself out of the home, especially with the proper seasoned wood (which is usually the culprit 95% of the time)

I tagged two guys that are helpful for the vf100, I myself have a drolet heatmax, so little different setup. I won't be much help to ya.

Thanks!

 

[brenndatomu]

For the last five years I've been reading great things about the vf100 and have been wanting one. I finally purchased one and am very disappointed- I can't get it to heat my house! The firebox is a blast furnace but the plenum feels cool. I don't know why the heat won't leave the firebox. I can't get my house above 60 and its in the upper 50s in the morning and it's been super warm outside- lows 20 above and highs close to thirty! I have a thermometer on the registers and usually reads 72. I don't know how to get more heat from it. I insulated the plenum and put a probe in one foot above the plenum- when the furnace is roaring on the highest setting it reads 90 degrees.

I live in a 3000 sq ft house with two garage doors in the lower level. It is essentially a 1500 sq ft ranch with a Wood walled 2x6 walkout basement. The entire thing has r19 walls. The garage doors are insulated and plugged around the edges, I don't use them. House was built in 94 and has good insulation .
I've been burning wood my entire life. I am burning dry Ash and maple between 15-20 percent on the moisture meter.
6 inch class a chimney with barometric damper. I've tried every setting on the damper and just got a Dwyer mkii to check, but think its okay as i have flue temps between 200-250. Chimney goes through a thimble and is about 25 feet tall.
I made a duct system for it- not ideal but am moving it next year. Has 10x20 trunk with 4 8 in takeoffs. I've played all around with changing the static duct pressure to increase air temp. Cold air return comes from up stairs.

The air coming out just feels cold. I've talked with Dale about a dozen times and he's been very nice, but it hasn't gotten any warmer.
My wire is furious about this whole problem and wants it returned immediately. She grew up in an uninsulated farmhouse with a hot blast that was always 80 inside even when it's -35 outside. When I go there the plenum is always HOT when it calls for heat. Mine is cold.
Help! Is the Kumma actually as good as everyone says? I really regret buying it!
This has been going on for over two months
I've tried everything

There has got to be something really wrong here...the smaller VF200 should be able run you clean out of the house with only 1500 sq ft! A VF100 should be total overkill honestly.
What is your draft set at? That 200-250 pipe temp you mentioned...is that internal or external? If that's internal, that's way too low...assuming you are measuring it before the barometric damper (baro)
You said cold air return comes from upstairs...is that ducted directly to the Kuuma blower box, or does it just flow down the stairs? What is the basement floor temp vs the ceiling?
Has Dale had you check to make sure the baffles are properly in place?
How long have you been using it?
Is the blower on high, or low? Try it the other way much?
90* in your plenum is very low...I get in the upper 90s before the fire is even properly established...110* after things have settled in...115* at the peak for a small wood load, and in the 120s at peak with a large wood load.
Something is most certainly very wrong here...

 

[bropp]

There has got to be something really wrong here...the smaller VF200 should be able run you clean out of the house with only 1500 sq ft! A VF100 should be total overkill honestly.
What is your draft set at? That 200-250 pipe temp you mentioned...is that internal or external? If that's internal, that's way too low...assuming you are measuring it before the barometric damper (baro)
You said cold air return comes from upstairs...is that ducted directly to the Kuuma blower box, or does it just flow down the stairs? What is the basement floor temp vs the ceiling?
Has Dale had you check to make sure the baffles are properly in place?
How long have you been using it?
Is the blower on high, or low? Try it the other way much?
90* in your plenum is very low...I get in the upper 90s before the fire is even properly established...110* after things have settled in...115* at the peak for a small wood load, and in the 120s at peak with a large wood load.
Something is most certainly very wrong here...

Dale said the inside flue temp should be around 225-275 and no more. I've had the barometric set every which way with nothing but cresote one way and a shorter burn the other. The cold air return is ducted right into the box. It doesn't take in hardly any basement air, I even taped it tight. I've talked to Dale and tried the baffles every which way and run the want every which way too.

 

[brenndatomu]

225-275 is too low unless that is the external pipe temp...internally mine runs in the 300s...or high 200s if it's been on pilot a long time...it will go close to, or a little over 400 if the damper is on 3 for long.
So 300 to 350 is it's normal range when it's doing it's c-1-c-1 thing during the early hours of the burn. Other owners get about the same temps...

 

[brenndatomu]

Your draft should be -0.04" to -0.06"...I usually run around -0.045"...

 

[bropp]

225-275 is too low unless that is the external pipe temp...internally mine runs in the 300s...or high 200s if it's been on pilot a long time...it will go close to, or a little over 400 if the damper is on 3 for long.
So 300 to 350 is it's normal range when it's doing it's c-1-c-1 thing during the early hours of the burn. Other owners get about the same temps...

Thanks! Just got the mark II and will check the WC today

 

[brenndatomu]

What was your main heat source before?
How much fuel did you use in a year?

 

[maple1]

Why not post the pic here that you posted on that other forum? From that one, your baro damper is installed incorrectly.

Post that pic for starters. And maybe more. You will get more overall Kuuma specific feedback here - I think.

 

[brenndatomu]

Why not post the pic here that you posted on that other forum? From that one, your baro damper is installed incorrectly.

Post that pic for starters. And maybe more. You will get more overall Kuuma specific feedback here - I think.

I agree...we need pics...from the pic you put up on AS, your return air is too small...IIRC, you need 180 sq in. on the supply plenum/ducts...and around 200 sq in for the return ducts...about 10% more than the supply.
You look to have a 12-14" flex duct there...so assuming its 14", that's only 154" sq in...and flex duct actually "flows smaller" than its nominal size.

 

[JRHAWK9]

Is it installed in your garage? Is it installed in the same heating envelope of what you are trying to heat?

What are your return temps.....the temp inside the blower box?

Back with my stock blower setup, I was sucking in 65° air and my plenum temps were 100-105° with the Kuuma on low and the blower on low. Kuuma on high and blower on high I would see 105°+° plenum temps, IIRC. I never had real high plenum temps with the stock blower setup and pulling my air off the basement floor. The one time I remember measuring my vent temp upstairs it was 90° back then.

The stock setup heated our house just fine in temps above 10°. Before heating with wood, we used to average about 1,200 - 1,300 gallons of LP a year keeping the house at 68°.

We are going to need way more temp samples and photos in order to help.

 

[bropp]

Why not post the pic here that you posted on that other forum? From that one, your baro damper is installed incorrectly.

Post that pic for starters. And maybe more. You will get more overall Kuuma specific feedback here - I think.

I am thinking that it is not drawing enough. I leveled the damper both ways to see what happens.

 

[brenndatomu]

I would straighten that stove pipe out...just use 90s so that the pipe is vertical and the baro can be installed properly...with 25' of class A chimney you will not have draft issues doing this (assuming that's why you angled it)
With the baro just taped on if you ever have a backpuff (unlikely with a Kuuma) that baro will become a projectile.

 

[bropp]

I would straighten that stove pipe out...just use 90s so that the pipe is vertical and the baro can be installed properly...with 25' of class A chimney you will not have draft issues doing this (assuming that's why you angled it)
With the baro just taped on if you ever have a backpuff (unlikely with a Kuuma) that baro will become a projectile.

Thanks!

 

[JRHAWK9]

I am thinking that it is not drawing enough.

May be part of the issue but not the smoking gun. If that was the only issue, a high return SP....meaning starving it for return air, would result in higher plenum temps due do the lack of volume of air passing through the air jacket.

All of us are just guessing at this point as we have very few data points to go off of. We need to know your return air temp and your plenum temp....so we can see what your dT is. Register temps taken at the same time of the other two. Garage temp (looks to be the garage anyway), where the furnace is located. Assuming the space you are heating is ABOVE the furnace....seeing you stated the garage is the lower level.

For some of us, wood furnaces are not just a plug and play appliance. Some setups/houses need some tweaking done to the return/supply air to get them to perform at max performance and some don't. I was one of them who did.

 

[JRHAWK9]

I would also like to know if the furnace is going to pilot ('c') at whatever burn set point (low to high) you have the computer set at? If the computer is going to pilot, it's meeting internal firebox temps for the level of burn the computer is set for and burning the wood as designed.

 

[bropp]

May be part of the issue but not the smoking gun. If that was the only issue, a high return SP....meaning starving it for return air, would result in higher plenum temps due do the lack of volume of air passing through the air jacket.

All of us are just guessing at this point as we have very few data points to go off of. We need to know your return air temp and your plenum temp....so we can see what your dT is. Register temps taken at the same time of the other two. Garage temp (looks to be the garage anyway), where the furnace is located. Assuming the space you are heating is ABOVE the furnace....seeing you stated the garage is the lower level.

For some of us, wood furnaces are not just a plug and play appliance. Some setups/houses need some tweaking done to the return/supply air to get them to perform at max performance and some don't. I was one of them who did.

I have been observing temps evey day for the last two months. They are almost always the same: living room temp 62 bedroom 64 basement 64 garage 60.
Return air temp 60-64. Plenum temp one foot above furnace 90-95. Yesterday with the barometric damper at 8 it hit 102, the highest ever. WC was .12 last night with barometric damper closed, but normally.06. normal register temp in bedroom is 72-75.
Last night the bedroom register temp was over 80 at peak burn, highest ever.
The house was 58 when I woke up, and I put my best maple pieces in last night.
Computer setting is always on the highest setting unless I'm gone more than 10 hours. It doesn't seem to produce more heat on highest setting or medium for some reason.

I was really hopeful I wasn't getting a high enough flue temp after yesterday's comments, and it did make the register temp go up by several degrees when the flue temp was 350-400 when the display read "c"
Thanks guys!

 

[bropp]

I would also like to know if the furnace is going to pilot ('c') at whatever burn set point (low to high) you have the computer set at? If the computer is going to pilot, it's meeting internal firebox temps for the level of burn the computer is set for and burning the wood as designed.

The computer goes to pilot to 1 all the time. It is set at the highest setting.

 

[woodey]

What temp do you have your lower limit switch set at and any thoughts from Brenn and JR about the placement of the switch?

 

[brenndatomu]

I have been observing temps evey day for the last two months.

OK, that answers one of my original questions...how long have you been using it?
Have you cleaned your heat exchanger area yet? If you had any crappy wood in that time (especially early on) it could have put a coat of crude on everything and it doesn't take much to start losing heat exchange efficiency...even with burning perfectly normally and just a light coat of fly ash on everything, I (and others) notice a difference in plenum temps vs exhaust temps right after cleaning...I try to clean 2-3 times per heating season. (you will notice exhaust temps drop, and plenum temps go up)

 

[brenndatomu]

thoughts from Brenn and JR about the placement of the switch?

High in the plenum...

 

[bropp]

OK, that answers one of my original questions...how long have you been using it?
Have you cleaned your heat exchanger area yet? If you had any crappy wood in that time (especially early on) it could have put a coat of crude on everything and it doesn't take much to start losing heat exchange efficiency...even with burning perfectly normally and just a light coat of fly ash on everything, I (and others) notice a difference in plenum temps vs exhaust temps right after cleaning...I try to clean 2-3 times per heating season. (you will notice exhaust temps drop, and plenum temps go up)

I have had it for two months. I cleaned it a month ago just to make sure it was a ok.

 

[bropp]

What temp do you have your lower limit switch set at and any thoughts from Brenn and JR about the placement of the switch?

I tried the switch in three places. The first switch was defective from the factory, which caused a lot of frustrating from the beginning. It's currently high in the plenum. I've played around with all the different temps and found 103 to be best.

 

[bropp]

What would really help me is the following:
What temperature is measured in the plenum one foot or so above the furnace if the fan is on low, fire is at maximum heat setting and full burn, and intake air is around 60.

When I touch the plenum it feels cool. They told me to insulate it and all the ductwork, but it's not like the very well insulated garage is hot.
Another thing- I have a Well Connect open loop Geo unit. It produces 13500 btu. I have been playing around with it some days and it will keep the house (basement, garage) WARMER than the Kuuma. So to me the Kumma won't even produce 13k btu wide open.
I think it's defective.