Measuring Chimney Draft

[MountainHigh]

A video:
- guy puts hand through the stove pipe to show just how little heat goes up a cat stove's chimney.

 

[Marshy]

my chimney cleanout leaked some air and that slowed my non-cat stove down a bit, until I put plumber putty and foil tape around the cleanout perimeter.

Blaze King King is a great stove, but I suspect it's super efficient function just doesn't put enough heat up your chimney to crank and maintain that draft like your old fire breather used to. The fact your cat can't be kept up to temp is telling.

I'll be interested to hear your conclusions after you measure things more.

It stays active until the wood turns to charcoal, just acts like it could use more air. I can leave the bypass open and the door cracked and the thing gets piping hot (where I think it should be on high) but if it get too hot the thermostatic air damper goes closed so when I shut the door it slows back down. I'm use to the old stove where you can feel you face burn from 5 feet away and your eyeballs shrivel up into raisins if you stair at it.

I'm going to add some plumber putty to the cleanout door like suggested to try and tighten up the chimney a little more.

Here is the troubleshoot guide in the manual. I can rule out everything except poor draft and thermostat not operating properly.


If the draft checks out to be fine then I wouldn't rule out the damper being improperly set. I can hear a whistle at times like the damper is nearly closed and sucking air through the min flow air holes in the damper door. I'd hate to void the warranty but it might need calibrating.

 

[MountainHigh]

It stays active until the wood turns to charcoal, just acts like it could use more air. I can leave the bypass open and the door cracked and the thing gets piping hot (where I think it should be on high) but if it get too hot the thermostatic air damper goes closed so when I shut the door it slows back down. I'm use to the old stove where you can feel you face burn from 5 feet away and your eyeballs shrivel up into raisins if you stair at it.

I'm going to add some plumber putty to the clean out door like suggested to try and tighten up the chimney a little more.

If the draft checks out to be fine then I wouldn't rule out the damper being improperly set. I can hear a whistle at times like the damper is nearly closed and sucking air through the min flow air holes in the damper door. I'd hate to void the warranty but it might need calibrating.

>>> You might be onto something if the damper is not set right.

Looking at the King's specs, it says "51,582 BTU's/h constant output for 12 hours"
So IF that is considered running it near max thermostat temp, 51 thou BTU's/h sure won't will feel like your previous stove's power at all (no raisin eyes - lol). It's more about longer steadier burns on the King.

 

[Marshy]

>>> You might be onto something if the damper is not set right.

Looking at the King's specs, it says "51,582 BTU's/h constant output for 12 hours"
So IF that is considered running it near max thermostat temp, 51 thou BTU's/h sure won't will feel like your previous stove's power at all (no raisin eyes - lol). It's more about longer steadier burns on the King.

That is the max output but that's the LHV rating. The HHV rating is closer to real world performance and is actually 48 KBtu/hr on high (averaged over 12 hours). I can tell you after 7 hrs on high its not enough heat to maintain the house temp. It will have a very healthy bead of coals but IDK what it would be like if I waited a full 12 hrs...

I called Blaze King yesterday and had a lengthy talk about the stove, my chimney setup, wood moisture and troubleshooting. I'm starting to think I might expect too much from this stove but I have to wait to confirm draft before I make that conclusion.

Wood moisture; BK rep said a new study performed suggests hard woods don't reach <20% moisture for 3 years and that 2 years is typically not enough time even if its stored under a roof. IDK all the details of the study but I think size of the split wood might have a lot to do with how fast the wood will season. He suggested I stoke the stove full of 2x4 scraps to see how it performs. If there is a significant improvement then the moisture in the my wood is too high and is causing the performance issue.

Thermostatic Draft Control; BK rep said they are set by the factory to protect the stove and more specifically the cat from being over fired. If the cat gets too hot then the material on the cat will melt and fuse into a smooth layer visible under an electron microscope. He said they have only ever had to replace a hand full in many years (doesn't mean it could be mis-calibrated from the factor IMO). He thought that was least likely the cause of poor performance.

Chimney Draft; After discussing my chimney configuration he felt the chimney was insufficient. Being a masonry chimney approx 25 foot tall with no insulated liner was a large concern to him. He said it didn't matter if it was on an exterior wall or through the center of the house in a chase way (like mine) or not, it's just too much thermal mass for the low flue temperature of the stove (approx. 350F). He said "we have never had a customer with a king model, hooked to an uninsulated/unlined masonry chimney that has been satisfied with the performance". He said even if it drafts properly he believes I will have a significant creosote issue in the top 3' of the chimney because the flue gas will get too cold and condense.

I wish the BK rep I spoke with before I purchased this stove shared the same level of concern. I discussed the chimney dimensions with the BK rep before purchase and he did not seem the least bit concerned. In fact, at the time he said I "have the best configuration one could ask for given a masonry chimney hookup". Disappointed does not describe how I felt after hearing this...

Regardless, I have to press on and figure out a solution. I have access to a FLIR camera (infrared imaging) that I can take pictures of the stove with. My plan is to install the DP gauge and measure the draft while I let the stove burn on high with my "seasoned" wood, take IR images and share them with BK. Then I will load it up with 2x4 scraps and take images with the IR camera and measure draft for comparison. If the draft is at the required 0.05"wc and the IR images of the 2x4 scraps closely match my seasoned wood then my conclusion is this stove does not meet my level of expectation for performance. If all of that checks out ok I sill might have a creosote issue to deal with but time will tell.

I also spoke with a few local chimney sweeps and no one had the tools to measure draft surprisingly. One guy said he's never had a customer that has been happy with the output of the new EPA stoves. He did say the stove fans are necessary through (I mentioned to him that I don't have them). He said they don't radiate the heat like the old stoves and that you really need to move the are a great deal to get the heating out of them.

 

[MountainHigh]

My 2 year seasoned maple comes in around 12% to 16%+/- moisture which works great for my 3 cu.ft non-cat stove. I heard cats want really dry wood but anything lower than 12% and you're talking kiln dried mill ends in my neck of the wet woods.

I doubt you'll have much trouble selling the stove if it comes to that. BKing should take the stove back if the original sales guy misled you .

FWIW, if you conclude like I did that cat stoves are not a good fit for your chimney, my Pacific Energy is a very forgiving EPA stove on my oversize chimney (28' tall - oversize 6"x10" clay flue liner inside 5' wide brick). I tried a couple of other stoves prior to settling on the PE. For a reasonably efficient 3 cu ft EPA stove it heats like a BEAST. I get about a gallon of creosote per year after thoroughly scrubbing my chimney - similar to your chimney, most of the creosote settles on the uppermost cool area where the chimney goes into the attic and out the roof. One year I burned a dump truck full of mill ends and had zero creosote in the chimney.

Downside is I only get about to 8 to 10 hours max on a dampered down load (maybe 12hrs if I had oak or other real hardwood). But, with this large thermal mass chimney I'm happy it puts ample heat up as the chimney then acts as a heat sink that radiates warmth for several hours after the stove dies down. It's how they build their homes in the northern Scandinavia - large thermal mass chimney in centre of home.

Best of luck with your dilemma ...

 

[olyman]

Or get one of these for permanent mount. Dwyer Mark II

had me one of those long ago. first windy day, sucked the water right out of the tube!!!! chimney in center of house,,38 feet tall!! whitespidey has hell draft like I do,, and def need a dampener!!!

 

[olyman]

Wood is 2 years seasoned and the stuff I'm burning was in my basement for the last 9 months. I also have a heat pump hot water heater that keeps it dehumidied.

Draft is the suspect, I'd like to measure it to confirm or deny it's the problem. I'm not going into how my chimney is constructed. I talked with blaze King about it and they said it was the most ideal cinder chimney with clay liner you could get, it's also 8" square.

EXCEPT!!! square chimney does not like to flow..seriously...

 

[Marshy]

Unfortunately the thermal mass of my chimney doesn't provide my living space with any usable heat because its in its own chase way through the main floor and just opens into the attic. The attic get all the heat from the chimney. I could see if I can wrap the chimney in some sort of fire blanket insulation but I'm not sure that will help.

When I say maybe I expect too much from this stove, Im comparing it to the old one which could easily have 600-700F surface temps. I will take the FLIR home and see what this stove is generating. The BK rep said the new stove surfaces do not get that hot, none of them will. IDK how many BTU's/hr that stove put out but I'd bet its double the maximum capacity of the King. Learning curves always suck when its your money involved.

Because I got the bum info originally from the manufacture theres not much they can do to help me. He told me to talk with my dealer that I bought it from, maybe they can offer some suggestions. IDK how they could help me out, unless they have a stove that can produce 60-70Kbtu/hr it might not be enough heat. I'm trying the cheapest options first.

 

[MountainHigh]

Marshy ... IF it turns out the stove is not right for you, the advise you got from BK means they should speak with your dealer to make this right for you.

When I bitched to my dealer about poor performance on one stove I tried, he let me choose another at wholesale and I came out roses after selling my original - squeeky wheel gets the grease!
You may have some heavy lifting coming up swapping out stoves, but be willing to raise a little hell if they don't step up for you.

Sounds like you want a stove that can crank near 100,000 BTU.

Good luck!

 

[Streblerm]

Makes me glad I have a low tech EPA stove. My stove pipe is loose but drafts fine. Sorry about your troubles. I knew those BKs couldn't all be magical

 

[Marshy]

Poor draft has little to do with the stove and everything to do with my chimney. I wouldn't be too quick to condem the stove. It's possible for an idiot with a Lamborghini to lose a drag race to a Volkswagen.

I have a DP gauge on its way. Once I get it hooked up I will take IR images of the stove burning kiln dried 2x4's vs my seasoned wood and we'll compare the stove temps. If they are nearly the same and the draft is good then the next step is to buy the fan kit. I was told these stoves rely more on convection (air movement) vs purely radiant heat. According to some people the fans should be mandatory not optional. Where my old stove had a 6-700F surface temp this stove likely won't be above 400F. I'll share the images when I get there. Until then it's wait and see. I will say, it seems to be sippin the fuel for the amount of heat I am getting out of it. It might be too early to say but at this rate it will be easy to get 3 years ahead on the wood stash. More to follow.

 

[Streblerm]

Considering how the BK works and if moisture content is a problem then don't discount some of the lesser woods. A agree that the BK rep's assessment that oak can take 3 yrs to fully dry. Maple and others (especially soft maple) dries much faster.

I can tell the difference in my stove between sort of seasoned and truly seasoned. I can chock the thing full of 25%+ wood and it lights and burns just fine but I struggle to keep the secondaries lit. I can throw two little pieces of really dry soft maple in all by themselves and the secondaries light off almost immediately. They stay lit with less primary draft and the stove burns much hotter. Right now I'm burning mostly pine.

It's funny. When a species like oak is really, really dry the weight difference between it and other wood isn't nearly as significant. It's taken me quite a few years to figure that out (and get 3+ years ahead on firewood)

 

[Marshy]

At this point I'm convinced its a matter of getting the heat out of the stove. Moving enough air over the stove to get the necessary heating might be the key, it's not something I'm use to doing with the old stove because of the hotter stove temp and higher output. I'd be really interested in figuring out what the true output of my older stove was. I figure I could put twice the wood in the older one and it got twice as hot. Moot point I suppose. I'll let ya know what happens with the draft measurement and the IR gun and fuel test.

I talked with another chimney sweep and he said he believes my chimney is drafting just fine and everyone he's talked to that went from the old stoves to the new ones were disappointed with the heat output compared to the old stoves. Better efficiency and required less fuel but didn't radiate the same amount of heat.

I'll be going g up on the chimney to see if there is any creosote forming.

 

[Henry Fuller]

At this point I'm convinced its a matter of getting the heat out of the stove. Moving enough air over the stove to get the necessary heating might be the key, it's not something I'm use to doing with the old stove because of the hotter stove temp and higher output. I'd be really interested in figuring out what the true output of my older stove was. I figure I could put twice the wood in the older one and it got twice as hot. Moot point I suppose. I'll let ya know what happens with the draft measurement and the IR gun and fuel test.

I talked with another chimney sweep and he said he believes my chimney is drafting just fine and everyone he's talked to that went from the old stoves to the new ones were disappointed with the heat output compared to the old stoves. Better efficiency and required less fuel but didn't radiate the same amount of heat.

I'll be going g up on the chimney to see if there is any creosote forming.

Marshy, Did you do any home improvement while installing your BK stove (windows or doors possible making your house too air tight)? Did you add a chimney cap also? Sorry I didn't read all of your post if you already rule this out in the mean time. Some time after thanksgiving day I had to work nearby your area (a customer live on Route 64). If you want to use my draft gauge and take temp. reading with IR gun to see what it reading. I could swing by your place if this BK stove hasn't been solve in the mean time. Henry

 

[Marshy]

Marshy, Did you do any home improvement while installing your BK stove (windows or doors possible making your house too air tight)? Did you add a chimney cap also? Sorry I didn't read all of your post if you already rule this out in the mean time. Some time after thanksgiving day I had to work nearby your area (a customer live on Route 64). If you want to use my draft gauge and take temp. reading with IR gun to see what it reading. I could swing by your place if this BK stove hasn't been solve in the mean time. Henry

I live on rt64!

The stove is new to me, only been burning it since last weekend.

No changes to the house and the basement has a walkout basement with a drafty garage door. Chimney has a cap. One suggestion I got was to take it off and see if that helps. It would be nice to check my manometer I bought against another gauge though. I'll PM you Henry.

 

[Motorsen]

Why don't you wrap the chimney in the attic with rockwool or glasswool for insulation. That might prove to be an easy and cheap fix. Another not so easy fix would be a draft vent mounted on top of the chimney. Expensive and looks crappy.

Motorsen

 

[Marshy]

Why don't you wrap the chimney in the attic with rockwool or glasswool for insulation. That might prove to be an easy and cheap fix. Another not so easy fix would be a draft vent mounted on top of the chimney. Expensive and looks crappy.

Motorsen

I have thought about insulating the block chimney on the outside, just want to make sure it's a draft related issue before I spend money on something like that. I am unfamiliar with the available products to do that also. Havent don't any research yet but will be sure to look into those materials you mentioned. I was thinking unfaced glass insulation would be the easiest thing to do. Thanks.

 

[Hebner]

Or get one of these for permanent mount. Dwyer Mark II

Is the reading in your picture -0.5 or +0.05? Do you read the end of the red mark on the right side?

 

[Marshy]

Is the reading in your picture -0.5 or +0.05? Do you read the end of the red mark on the right side?

It's displaying +0.05" wc but I believe he has it hooked up to measure chimney draft or vacuum. Read it like a thermometer, where the red fluid ends.

 

[MountainHigh]

I have thought about insulating the block chimney on the outside, just want to make sure it's a draft related issue before I spend money on something like that. I am unfamiliar with the available products to do that also. Havent don't any research yet but will be sure to look into those materials you mentioned. I was thinking unfaced glass insulation would be the easiest thing to do. Thanks.

Hope I'm not sounding like a broken record, but to clarify for others, the BKing is a great stove, if it is on the right chimney and not tucked away in a basement!
The King throws so little heat up the chimney that large brick/clay flue chimneys are not a good fit for the BK.
I doubt if you wrap the chimney up from top to bottom it would make much difference.

After some experimentation on my 28`brick-clay liner oversize chimney, I settled on the hottest burning EPA non-cat stove I could find and it can keep my 2 story 2500 sq ft home toasty warm with just wood heat. No way i could do that with a Blaze king on my chimney, even using stove fans and chimney wraps.

My bet is on your chimney having a decent draft already, but the King's even temperament is not forceful enough to crank the BTU's you need and want.

Bring on the Draft test