Thread: JUCA Hi-Efficiency Wood Burning

Does anybody here use one of these? The web site makes them sound like the be-all, end-all of wood stoves...


Read about it here...

http://mb-soft.com/juca/index.html

There is a member on here that has one. I think he says they are not all the web site makes them out to be.

Something fishy is going on at JUCA, IMO.

Yeah, 046 has one. There were many debates over the thing. One of the issues was he claimed they burnt green wood with no smoke. Don't know if he still likes it. There too much bs on jucas site. Here was one of the threads.

http://arboristsite.com/showthread.p...highlight=juca

looks like a smoke dragon and an awful eye sore in a persons living room , I dont see anything about secondary burning or epa certifed approval.just another rebadged 1970's pile of scrap with a hood and blower attached

that's categorically untrue!

JUCA are not smoke dragons.... they are one of the cleanest burning stoves that I'm aware of... this includes EPA rated stoves.

yes... I can and do burn green wood with little to no creosote. reason for burning green wood is to slow the burn down while generating more heat.

how clean your wood stove burns is easily told by how much smoke your chimney is putting out. a truly clean burning wood stove will put out little to no smoke going full bore.

all wood stoves will smoke while getting up to operating temps. what counts is... does your wood stove smoke for the entire burn? if so you will have creosote buildup.

I've now gone 4+ season with almost zero creosote buildup with my JUCA. This includes burning a large amount of green wood.

Note: DON"T burn green wood. JUCA is the only wood stove that I'm aware of that can do so cleanly. there may be others, but I'm not aware of them. Juca makes no claims it's stoves can burn green. this is what I'm saying from experience.

some of the claims are BS... but most are not. the biggest fib is burntime. yes you can get the burntimes claimed.... If wood burned is PERFECT.... meaning using only seasoned Oak rounds 12in or bigger in diameter.

if you go by JUCA's calculator... I should be using 2.5 cords per season. I'm actually using 4.5 cords per season in Tulsa, OK with a well insulated 2500sf single level home. heating 99% with wood.

4.5 cords consumption is in line with EPA rated stoves for heating a 2500sq home.

what is different about JUCA is it's SUPER efficient heat exchanger.
first off... JUCA are MASSIVE... it's one HUGE hollow heat exchanger made out of 1/4in steel plate with a large blower. IMHO JUCA has one the highest deficiency heat exchanger of any wood stove.

the other main difference is how JUCA burns... it uses an open burn system. the wood fire burns fast as it wants... sucks in as much air as the fire needs. so the fire is going to get HOT! How JUCA burns is why it's exempt from EPA regulations.

this is the reason JUCA can burn green wood cleanly. it burns HOT... hot enough to vaporize wet wood into wood gas. I've done detail measurements of output air temps between seasoned and green wood. The green burns hotter... I'm convinced it's the wood gas generated.

another reason for JUCA burning HOT is it's carefully designed updraft. when door is closed, updraft noticeably increases. this increases amount of air directed to fire. effect is exactly like how some main wood furnaces uses forced air. yes fire burns hotter but consumes wood faster.

my plans was to add secondary burn tubes to my JUCA. but have not done so because I'm not convince it would improve JUCA's performance. I'll have to figure out a way to add secondary burn in a way that can be undone.

there are other differences like how JUCA does business... very weird!
but they do make a quality product for a reasonable price.

would I buy it again.... 4.5 years ago when I purchased.... without a doubt yes. but since then EPA rated stoves have made BIG improvements.

choices today are very different than five years ago. burntimes are longer than my JUCA. sure I can get 14+ hours burntimes. but I've got to pack it with perfect round Oak 12in dia. packed to it 25 cubic feet capacity.

so today... would I buy another JUCA? don't know it's a tougher choice today.
Am I happy with my JUCA... YES very much so... it's paid for it's self many times over.

Originally Posted by flotek

looks like a smoke dragon and an awful eye sore ,plus I dont see anything about secondary burning or epa certifed approval.seems to me its just a rebadged 1970's pile of crap with a hood and blower attahced

I think the red flag would be the pictures on their website are fron 1978.

not really... their design has not changed for 25+ years.
believe it or not there are old designs that are still compititive today
even when compared to latest EPA rated wood stoves.

there's another design that I'm particularly impressed with.
stove loads from the side & front. comes with catalytic converter and secondary burn. can't remember the name of that stove, but another AS member has posted loads of pic's.

it's mostly available on the east coast... out of production but comes up on craigslist out east. sure wish I could find one to play with. but when it gets down to it... probably would keep my JUCA.

Originally Posted by Ductape

I think the red flag would be the pictures on their website are fron 1978.

im still failing to see how this is high tech or super efficient with the few features it offers .if you stuff wood in about any 12 ft sq firebox 14 hour burns should be childs play doesnt mean its efficient though just means its alot of wood volume to burnup. I guess if you count a smoldering wet log as burn time it may be different .at these dimensions this must have a large cumbersome footprint aside from its poor aesthetics (looks like it is from the nixon adminstartion)when i was a kid i n the late 70's my parents had a similar insert with a hood like your juca and it damn near burnt our house down .regardless of design i would love to know how can green wet wood burn hotter than dry seasoned ? this defies all rational logicalso keep in mind secondary burn tubes need a high temperature to function correctly and burn off the smoke /gases but your juca will likely not reach those heat levels especially if burning green wood or having open incoming air .im glad your happy with it but it appears to be a campfire in a box with a hood over it for 2 grand ,i guess thats why the company is out of the wood stove business now.this is like trying to argue a 1890 steam engine is much better than a modern fuel injected multi cylinder computer controlled design

Meh.

you've obviously don't understand how JUCA achieves it's efficiency.
that's OK.. it took me awhile to figure it out too.

no it's footprint is not cumbersome... it's all sitting inside my fireplace.
how can one be so negative without even seeing one?

my JUCA was custom made for my hearth.... since I happen to have a HUGE fireplace... my JUCA was fabbed to it's exact dimension and is also HUGE.

you might read up on how wood gas works... this will help understand what's going on with the green wood. I do understand what I'm stating about burning green wood defies logic.

think in terms of wood gas and a forced air fire.
firebox is stroking with a super hot fire before green wood is added.
fire has to be already hot enough to overcome the wet wood or the fire will go out. instead of getting hot enough to produce wood gas. the secondary burn occurs right above the green wood. (pic's below) so NO the green wood is not smothering... it's cooking and putting out wood gas. so yes... JUCA is getting hot enough to generate a secondary burn as evidence by the blue flames.

I've documented this process with an IR thermometer enough times to know it works. the smoke that comes out the chimney tells no lies. when the green wood is fully burning at full temps... almost no smoke is coming out of the chimney.

JUCA's super efficient heat exchanger combined with it's super hot fire means it's putting out BTU's.

that super hot fire needs a monster heat exchanger to keep it in check. the open burn system which burn hot as it wants combined with a hyper tuned updraft... results in a forced air feed fire. this further accelerates burn rate.

if this is starting to sound like an indoor OWB... JUCA can be a monster at eating wood. how you slow it down is by feeding it LARGE ROUNDS. wood only burns on the surface, so shape/size controls burn rate. I've learned to split my wood in large chunks. the rounds that are correct size (10-12in dia) are prized. they will burn 10-12hr+ vs 6-8 hours for split wood the same volume.

unfortunately one cannot get rounds only from an Oak tree. most ends up being split wood.
4.5 cords for heating 99% of the time for a 2500 sq single level home is not bad.
wonder how much wood I would save with a current EPA rated stove.

by the way beauty is in the eye of the beholder. My JUCA is flat beautiful!!!
it's saved me $thousands each season... that's reason enough right there.

please note... in no way shape of form am I say JUCA is better than the current EPA wood stoves. what I am saying is JUCA's 25+ year old technology still works quite well.



chimney showing no smoke take same time as green wood burning below.



blue fame is the secondary burn with green wood

Originally Posted by flotek

im still failing to see how this is high tech or super efficient with the few features it offers .if you stuff wood in about any 12 ft sq firebox 14 hour burns should be childs play doesnt mean its efficient though just means its alot of wood volume to burnup. I guess if you count a smoldering wet log as burn time it may be different .at these dimensions this must have a large cumbersome footprint aside from its poor aesthetics (looks like it is from the nixon adminstartion)when i was a kid i n the late 70's my parents had a similar insert with a hood like your juca and it damn near burnt our house down .regardless of design i would love to know how can green wet wood burn hotter than dry seasoned ? this defies all rational logicalso keep in mind secondary burn tubes need a high temperature to function correctly and burn off the smoke /gases but your juca will likely not reach those heat levels especially if burning green wood or having open incoming air .im glad your happy with it but it appears to be a campfire in a box with a hood over it for 2 grand ,i guess thats why the company is out of the wood stove business now.this is like trying to argue a 1890 steam engine is much better than a modern fuel injected multi cylinder computer controlled design

yes... I can and do burn green wood with little to no creosote. reason for burning green wood is to slow the burn down while generating more heat.

Burning green wood will always generate LESS heat, not more.

you've obviously don't understand how JUCA achieves it's efficiency.
that's OK.. it took me awhile to figure it out too

Because it's not very efficient. Running with more excess air reduces efficiency, even if energy capture is higher on the back end. Modern EPA stoves run stack temperatures in the ~350 to 400 degree range and the efficiency loss through the stack/chimney caused by burning with excess combustion air is worse than the higher temperatures you see with a wood stove.

It reminds me of the old way they used to meet emissions on pre-1982 cars by just injecting more air into the exhaust to dilute tailpipe emissions.

I knew this was going to get started again...

gotta disagree... JUCA is quite efficient overall. the smoke rate going up is controlled by the damper. the amount of heat extract is in direct proportion to how long smoke stays in contact with heat exchanger.

which in JUCA's case is HUGE as measured in total cubic inches of surface area. this combined with a healthy flow of air (460 CFM) across hot surfaces. a higher percentage of this heat is captured before it goes up the chimney.

JUCA's firebox is equally hot or hotter than any EPA stove or JUCA would not burn so clean. but it's stack temps (area above firebox) are lower due the super efficient heat exchanger capturing more of the heat before it goes up the chimney.

where JUCA is not efficient is burn rate of wood. anyone knows that forced air on wood means it will burn hotter and faster (slowed down by burning Large rounds). this is why most wood stoves choke down intake air to slow the burn down. this results in a smothering fire, which resulted in lower heat output and creosote. until secondary burn solved the problem by burning up the incomplete gases, resulting in higher temps and greater efficiency.

Current EPA stoves generally have a tiny firebox with an equally small total surface area available to act as a heat exchanger. this is partially made up by the higher temps generated by the secondary burn.

the bottom line is how many BTU is put out for the amount of wood consumed. judging by the 4.5 cords consumed per season by JUCA for a 2500 sf single level home. efficiency is not that out of line with current EPA wood stoves.

Originally Posted by Cerran

Because it's not very efficient. Running with more excess air reduces efficiency, even if energy capture is higher on the back end. Modern EPA stoves run stack temperatures in the ~350 to 400 degree range and the efficiency loss through the stack/chimney caused by burning with excess combustion air is worse than the higher temperatures you see with a wood stove.

It reminds me of the old way they used to meet emissions on pre-1982 cars by just injecting more air into the exhaust to dilute tailpipe emissions.

JUCA's firebox is equally hot or hotter than any EPA stove or JUCA would not burn so clean. but it's stack temps (area above firebox) are lower due the super efficient heat exchanger capturing more of the heat before it goes up the chimney.

Heat (BTU) = Mass * Cp* dT

Higher flow even at a lower exit temperature will drive up heat lost.

I have read and reread this thread several times..

The thing I'm trying to wrap my mind around is this..

"sure I can get 14+ hours burntimes. but I've got to pack it with perfect round Oak 12in dia. packed to it 25 cubic feet capacity."

Unless my math is wrong that means a cord of wood only last about 3 days and your 4.5 cords would be gone in about 2.5 or so weeks... I'm sure you must have a longer heating season then that..do you burn 24/7.


I'm heating 2000 sq. ft. 24/7 fot 6+ months a year and burn 6 to 8 cords a year in a Lopi Endeavor. Thats not hard wood mind you, thats red fir tamarack and lodge pole. I know it's a wonder my house ain't a ppile of ashes burning al that pine , it's a PNW thing, you would'nt undersand...

so help me out here, how are you heating 2600 sq. ft on 4.5 cords, burning 25 cubic ft of wood in 14 hours, what am I missing???

Oh yea, nice looking fire can you post pictures of your stove??