Wood stove heat

Read this a good 10 years ago and it's come back to haunt me. Dang knowledge! Good explanation related to pressures and vacuums.

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Kyle if you're doing a clean slate install read all the chimney pages above. Good stuff. Wind effects etc.
 
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My Defiant has the automatic air/draft control device that helps manage airflow related to temperature. It has worked well.
I used a softer-bristle brush on the slightly-ovalized liner all these years and it has worked well.
Of course only dry, decent woods have been burnt in the stove.
 
Yep those old school Vermont Castings mechanical contolled dampners are awesome. My Tempwoods were manual , you have to pay attention. .... nobody wants a Chimney Fire
 
Burning some of the locust I cut this summer. First time I've burned any quantity of it, and it smells really good! Reminds me a bit of cooked ham. I'm digging it. Gonna have to keep my eyes open for more.
 
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There is almost endless info out there on draft if one is interested. Besides the basic theories of how a chimney works, height, size, outside air temp/pressure. I'd encourage anyone interested to look into or think about their house as a whole system. Because many of the design, use or deficiencies of a home can have a direct effect (stack effect as one) on the available draft or potential of draft at any given time. Dave has mentioned having a cold air intake for his stove which is the proper way to have a supply of air for the stove that isolates it from the homes variables. In order for air to go up that chimney(fire exhaust) air must be coming into the home to replace it. If many air exhausting appliances like dryers, bathroom or range fans, etc are running this can make it hard to establish or maintain draft. A significant leak due to a cracked open window upstairs or poor attic insulation or very commonly a attic access that is either uninsulated or not closed properly can be a cause of weak stove draft or even a backdraft of the stove. The home acts as a better chimney than the chimney itself. Conversely cracking a window or exterior door open near a woodstove can often help a finicky setup get going and establish draft by supplying the intake air needed for the stove. Even factors outside of the home become a factor like local geography, wind direction, and yup...trees. The variables for draft become almost infinite.

Autu damper add ons like the condor and stolz fell out of fashion due to it being a modification to the stove which nullified the certification because the manufacturer/certifying body never tested the stove in that configuration. I used to have a sears woodstove in my shop that had a bimetallic damper that was very effective. Still miss that stove but it had one to many extra intakes(rusted out holes) so I retired it. Many stoves employ some form of auto damper system in their secondary(the reburn part of a modern stove) air supply to moderate temps slightly. My pacific energy summit employs a flapper system which will close blocking off some secondary air when draft increases(due to increasing stove/exhaust gas temps) and open again as it weakens. This all happens behind the scenes(or underneath as it's located on my stove) but can ocassionally be heard as a light tink, tink noise when opening or closing. Most apparent if it gets 'stuck' in the middle zone of just about to hot or not hot enough. These types of systems often aren't meant to be a tool to moderate temp as much as make sure things stay hot enough for secondary combustion without causing severe overfiring.
 
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Thanks Squisher. I did a bunch of reading homework. The Hearth.com guy argues that fresh air intakes have faults and got nixed. Wind effects on the house structure/shape. Seems like cogent reasoning he presents. Apparently you can't buy draft rite meters anymore and they're not intended for install anyway. Magnahelic makes a -0.05 to +0.2 inches water vacuum gauge (bit of positive pressure scale for reverse draft) but I'm not sold on it. My Dwyer has flammable liquid - not good and its plastic. So no solution yet.

I think I'm noticing the initial draft and mixing it up with the eventual hot draft, but they intermix because poor initial draft slows the fire build up speed. I read the neutral plane stack effect stuff. Have you ever delved into that, measuring with a barometer? I figure a manometer at the stove pipe would tell me if I'm got an overall stack/neutral plane/venting etc issue at that particular moment. It would also tell me I have a strong 3/4 air valve setting that day or a weak one. Have you ever come across people with draft/flue vacuum meters? Or is that the territory of nerd excess? On a rare occasion I crack a main floor door to reverse an established real cold reversed draft for startup. My weapon of choice is a MAP cylinder to start the draft then just aim it into the kindling.

I admit to running without a flue thermometer. I aim for some secondary burn and balance heat output with getting tired of running for wood. I've got a Napoleon 1101. Run through 2 to 3 bush cords per winter.
 
I've never known anyone who's actively measured draft or seen anyone with a setup when I was cleaning systems for a couple of years. I only ever checked draft with a match after cleaning. Light a match, snuff it out and see if the cold chimney/stove would draw the smoke up. Somewhere I learned it as a simple rule of thumb that if it would,draw that bit of smoke up a fire should be able to be established without to much fussing about. I never worried about it much beyond that. People I helped with draft problems I never needed to measure I just needed to troubleshoot and change or fix their system.

In Canada all new woodstove installations are required by code to have a outside air intake, so take that for what you will. I have heard of people having issues with them in below grade basement installations where they are essentially working like a mini chimney themselves and making it very problematic to run a stove. But for the most part all installations I ever serviced with a outdoor air intake reported exceptional performance and zero issues. So that's my experience with it. None of my stoves have a cold air intake and I don't need to jump through any hoops to get draft established. I use the topdown firestarting method for my startups. Worth a Google for anyone who fights smoke escape on start up. Zero fuss and muss, four to six splits criss crossed in twos on the bottom, stuff some paper In and around through them and then kindling cabin on top. As the kindling ignites it is physically higher and so heats the top of the stove and flue pipe more readily, as it burns it drops down and in about the splits and lights them off. No opening the door while weak draft from a cold chimney is still present and getting smoke spillage. With this light off setup my stove is well up to temp by the time I have to load onto the batch of well established coals and there is established draft and no smoke spillage.
 
A magnahelic is what was recommended in the courses I took to measure draft and that's what my chimney cleaning supplier sold for checking draft but I never bought one. I didn't install only serviced and mainly sweeping, no one wanted to pay what it would take to get that involved when most of the problems people faced with drafts could be solved by simpler means. Extend the chimney, turn a 90 into two 45's, replace single wall stovepipe with doublewall, etc, etc. Often issues in the house, a poorly insulated attic entrance can really affect draft, any leaky items in the upper area of a house. Like I mentioned before running other exhausting types of appliances/fans while trying to get draft established can make firestarting a real pain for systems with marginal draft to begin with.
 
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My gf's stove has a stationary, removable baffle that wasn't fitting properly. Warping. Unbending, maybe. The slot that was meant to hold the baffle might have widened.
End result of a loss of cross sectional area for the exhaust gases.

It's been losing way too much smoke into the room.

Obsolete Danish Rais 86.

I grabbed a 1.5" long chunk of scrap pipe that had been cut off a machine, and left on my neighbor's welding table.

Two little notches ground in, with a bench grinder, and the prop has opened up the chimney well, to spec, and much better draft!
 
Sounds good Sean. The number one way to know that a modern reburn stove is burning properly is there should be no visible smoke out the stack once a load is settled in and up to temp. Steam will sometimes be present like a vapor trail(depending on the weather), it will be white and dissipate, smoke will be darker and want to settle after losing momentum. It's normal to have some smoke on light up and on reloads. I live in a fairly dry climate so often all that is visible out of my stack is some heat waves.
 
So the Hearth guy maybe is Stateside and perhaps Stateside un-required the cold air intakes, from my understanding of what he wrote. I'm still curious about the Canadian code change date because 4 or 5 years ago my last install passed WETT inspection and I figure he would have known about the code cold air requirement. Don't get the wrong impression, I do startups with a centre style cabin build, 2 side logs, big back crosser supported up, center fill with kindling structure and medium cross beams supported over the kindling structure. The center lights off the medium, which collapses into the center as the kindling finishes while the sides and back are starting, refill the center a bit and all's good. I don't have to leave the door cracked and never get start up smoke escape. I just notice slow and fast days sometimes, better and worse draft variation.
 
Doesn't surprise me one bit. I inspected and cleaned many not to code installations that had previously passed WETT inspection. CAI requirement is sidestepped around/ignored on many installs I believe. I've seen new installs without it when I was sweeping a few years ago, It adds sometimes some significant cost and effort to a installation. I had read on hearth.com too about people being unimpressed with the CAI. Somewhere online there is a video of a CAI with flames being sucked out it from some big wind event I believe.
 
So I did some more homework and came up with
  • CSA B365 Installation Code for Solid-Fuel-Burning Appliances and Equipment

Of course they want their money. Any chance you could excerpt the section about CAI? I think in Alberta they said to CSA B365 or to mfr install instructions, perhaps a nod to appliances that don't have a plumbed inlet for intake air. I don't have such a plumbed inlet, hence a quandary. The unit I installed also had no such plumbing.
 
Bart said:
So I did some more homework and came up with
  • CSA B365 Installation Code for Solid-Fuel-Burning Appliances and Equipment

Of course they want their money. Any chance you could excerpt the section about CAI? I think in Alberta they said to CSA B365 or to mfr install instructions, perhaps a nod to appliances that don't have a plumbed inlet for intake air. I don't have such a plumbed inlet, hence a quandary. The unit I installed also had no such plumbing.
Click to expand...

You tweaked my interest here. I have been over the b365 a lot in the past, had a online subscription through my WETT certification and had plenty of bits in my course materials. But it seems to me that the b365 changed its requirements on fresh air intakes from a requirement to only required without exclusion in a mobile home. As long as a depressurization test was done to the home or if a co detector was installed within a certain vicinity of the installation then a normal home no longer required them by the b365. But local/provincial building and fire codes can still require it outright which I believe was/is the case in BC. So quite possibly your install didn't require it and so passed its WETT inspection legitimately. This is going off memory, but I believe that's the gist of it.
 
I heat with two Vigilant's , a house built in 1962 ... Plenty drafty , I guess there's more than enough fresh air coming outside to inside.
 
Normally there is unless a house is super super sealed and has lots of other venting type of appliances running like hood ranges, bathroom fans etc.

The big plus is that nearly all the air that is used for the stove combustion is unheated outside air vs already heated inside air that is being replaced through draftiness by unheated outside air. Greater efficiency.
 
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Here's a nugget I found for a township in Ontario:

  1. If your house was constructed between 1990-1993, you must;
• Install a fresh air intake of an appropriate size to prevent excessive
depressurization.
  1. If your house was constructed after 1993, you must;
    • Preform a pressure test on your house in accordance with CSA-F326 and if not more than 5 Pa depressurization is found the woodstove may be installed, or
    • Provide a heat recovery ventilator (HRV) which is designed to operated so that the flow of exhaust air does not exceed the flow of intake air in an operating mode
and a bit later in the document:
Certified wood burning appliances in Canada are tested and/or listed with three agencies which are as follows:
1. The Canadian Standards Association (C.S.A.)
2. Underwriters Laboratories of Canada (U.L.C.)
3. Warnock Hersey Professional Services Ltd. (WH)
These agencies test wood burning appliances to very rigid and exacting specifications with respect to design, fabrication and safety and the clearances specified in the installation instructions for each appliance have been determined from these tests.
Any woodstove which has been tested by an agency other than the above-mentioned, or does not have any certification affixed to the unit, shall be considered unverified and installed in accordance with CAN/CSA-B365 “Installation Code for Fuel Burning Appliances and Equipment”.CAN/CSA-B365 also provides for shielding requirements which may be installed to reduce clearances to combustibles by up to 67 percent.
FIREPLACES
Construction of masonry Fireplaces and their chimney shall comply with section 9.21 & 9.22 of the Ontario Building Code.
Fireplace inserts and hearth mounted stoves vented through the throat of a fireplace shall comply with/to CAN/ULC S628 and their installation shall conform to CAN/CSA-B365.


I saw something along the lines of mfr instructions or B365 as alternates elsewhere too. God bless the world of standards. Beaurocratic CYA stuff at times. I knew a couple of guys who worked at CSA once and visited the place once. Felt similar to visiting a bank loan manager. I must be getting old because I can't think of the reason why I visited them. It'll bubble up from the depths eventually ...
 
Will a house implode if sealed too tight and no external air intake? (I'm joking) Or is it all about emissions: fire not getting enough air to burn clean?
 
Another nugget for a particular average stove, gives nominal draft values:

3.4 DRAFT
Your EPA certified Flame stove’s performance will be optimised if it is installed with a chimney (flue) system that provides an adequate draft. The draft is the force that moves air from the appliance up through the chimney and is predominantly affected by the height and diameter of the chimney, as well as the stack temperatures of the stove. If you test the draft using a pressure gauge, the reading should be between .05 - .07 inches of water column (w.c.) at a medium-high fire. A draft measure of less than .03" w.c. will cause operational difficulties while too much draft (greater than .10" w.c.) will result in over-firing of the stove. This can result in excessive operating temperatures. In this case, the installation of elbows totaliing no more than 180° (ex.: 2 x 30° elbows, 2 x 45° elbows or 2 x 90° elbows) can be installed to help reduce excessive draft. If the addition of elbows is not sufficient, a manual damper can be installed in the vertical flue pipe.

This stove mentions its fresh air intake kit as optional while quoting code everywhere else...? The soup thickens ...
 
Nutball said:
Will a house implode if sealed too tight and no external air intake? (I'm joking) Or is it all about emissions: fire not getting enough air to burn clean?
Click to expand...

It's more about efficiency(burning cold air instead of previously heated room air), and smoke and co spillage. In order for smoke to go out the chimney that air that caused the combustion needs to be replaced within the home, otherwise.....no draft. It is coming from outside the home whether plumbed in directly to the stove or creeping in through doors, windows, poor insulation, etc. But air can't go out through the chimney as stove exhaust without it somehow coming into the house through other means.

Even with a outdoor air intake it is entirely possible to burn a modern stove very inefficiently. Whether room air or outdoor air the efficiency of a wood burning system relies somewhat on the design but the largest factor is the human running it. Poor wood, poor burning practices, not knowing or understanding temperatures.

Bart I know you are quite into the draft thing and I find draft interesting too, but myself I see no need to measure it. I measure stovetop and stovepipe temperatures and those two items let me know I'm burning efficiently. The fire starts, burns, and reloads with no smoke issues. I know when it gets real cold out that the stove will pull harder so my reload burn off times might reduce a little while settling in a new load, wind etc may effect it. But never do I wonder just how much draft I have like I do wonder and obsessively monitor temperatures. How hot is hot? I need numbers, not by feel. This way I obtain long burn times and steady household temperatures.

Co monitor and smoke alarms all over the house and in close vicinity to the woodstove never go off. Off the top of my head my home has two dedicated co alarms one near the stove and the other near the upstairs insert as well as three combination smoke and co alarms. That is all I really need to know about my draft, it's pulling all the exhaust out, what's important to me after that is temps. Stoves get up to temp properly? Draft is sufficient.
 
Well, I've been tired of my crappy old woodstove for a while.
I originally bought it as a cheap backup for the wood burning furnace/central heating, but my wife loves to sit in front of it and bask in the heat radiation.

So I bought a new one and we set it up today.
It is made from concrete with an iron core, so it has mass enough to soak up a lot of heat and release it slowly.
At the same time it has a large front window, that gives off lots of radiation for my wife.

Being white, it seems a lot smaller than the old black one.
I'm pretty happy with it.

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Aduro brændeovn 9 Lux beton 6kW

Flot Aduro 9 Lux Beton brændeovn i hvid med en nominel effekt på 6 kW. Brændeovnen er høj og slank og er særligt velegnet til store rum med højt til loftet. Ovnen er beklædt med lyse betonsten, der giver den et roligt og stringent look i kontrast til ovne
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