Kuuma VF100 produces same heat on low and high

[bropp]

Hi Folks,
I'm struggling with even heat output on my vf100. I posted before about my cold house, and I still have a cold house.
Two weeks ago I tried the setting on the lowest one, and what do you know it made the house warmer! It's not hooked up backwards, the auto damper open when I turn it up. My temp at the closest register is coming out 90 right now with cold air return is 66. It's 39 out by the way.

How much of an increase in plelum or register temp should I expect if outside temp, supply temp, and burn conditions are the same? Mine actually reads colder supply temp on high. If I could get high to be much Warner than low I'd be very happy with the vf100. Right now I hate a house that usually is 60 inside.

 

[brenndatomu]

My supply plenum temps run 110* F when first starting to get pilot burn time...with a peak of 115* commonly once the fire is at peak...or sometimes as high as 120* on a larger load (I think the highest I have ever seen was 125*)
I don't pay much attention to register temps since they will vary wildly depending on the length of the duct and how far I have it open.
Sounds like you may need to insulate your supply ducts?
Does the blower run constant on low? How about high?

 

[brenndatomu]

What is the chimney draft set at?

 

[bropp]

I had a plenum temp checked with a probe of 101 one time, but usually it's 95. I put rock wool around the entire plenum for accurate temps. I had to mount the low temperature switch in a special corner to make it run all the time. WC is .04 but I've tried everything. Dale says my supply temp are too low-60- but I tell him that's all my house usually is. 1500 ft with wood studed r19 basement. 1994 with good insulation.
I think the furnace is defective. I've tinkered with it every day.

 

[bropp]

My supply plenum temps run 110* F when first starting to get pilot burn time...with a peak of 115* commonly once the fire is at peak...or sometimes as high as 120* on a larger load (I think the highest I have ever seen was 125*)
I don't pay much attention to register temps since they will vary wildly depending on the length of the duct and how far I have it open.
Sounds like you may need to insulate your supply ducts?
Does the blower run constant on low? How about high?

Do you notice a cooler plenum temp on low vs on high? Is it considerable?

 

[brenndatomu]

Where are you measuring your return temps? And how do they compare to the house temp?
If the return temp drops much between the cold air return register and the furnace blower, you may need to insulate your return ducts too.

 

[brenndatomu]

Do you notice a cooler plenum temp on low vs on high? Is it considerable?

I've only even run it off of low once...about a year ago when we got a real cold snap I turned it up to medium and almost completely filled the firebox up...as I recall the plenum temps were higher...5-10*, wasn't a huge amount...

 

[brenndatomu]

WC is .04 but I've tried everything.

Running at -0.06" WC should make it run a bit hotter.

 

[brenndatomu]

Do you have both the baffles in place inside the heat exchanger? The long one that goes against the tubes behind the throat, and the hood that goes "over top" the throat?

 

[brenndatomu]

Dale says my supply temp are too low-60- but I tell him that's all my house usually is

What happens if you run the house temp up with the "main" furnace, and then maintain with the Kuuma?

 

[brenndatomu]

When you say low and high you need to specify if you mean the computer, or the blower.
Personally, I have always run the blower on low...well, actually I have a speed controller on it, so it self adjusts the speed.

 

[brenndatomu]

I think the furnace is defective.

I don't know how it could be...if it is burning the wood well and making a good hot smoke free fire, then IMO it is almost certainly a setup issue...

 

[brenndatomu]

I'm sure @lampmfg would appreciate an update on this one ...

Kuuma VF 100

Last year I had a VF 100 and was unhappy with the amount of heat it produced. It was not heating my house. I got a Fire Chief 1700 instead. The FC did produce a little more heat, but that was when I feed it 4x as much wood. Not only that, even though I would feed it a ton right before bed the...

www.hearth.com

And here too...

Kuuma VF 100 not heating my house! Help!

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...

www.hearth.com

 

[lampmfg]

I'm sure @lampmfg would appreciate an update on this one ...

Kuuma VF 100

Last year I had a VF 100 and was unhappy with the amount of heat it produced. It was not heating my house. I got a Fire Chief 1700 instead. The FC did produce a little more heat, but that was when I feed it 4x as much wood. Not only that, even though I would feed it a ton right before bed the...

www.hearth.com

And here too...

Kuuma VF 100 not heating my house! Help!

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...

www.hearth.com

We always try our best and know our furnace works great, so it should work fantastic. Especially in comparison to others because the test doesn't lie, well, when they are done to the same standard that is "inside joke."

In all seriousness, we appreciate you posting this follow-up @bropp.