Here's a thoughtful article by John Gulland on the subject of difficult to control non-cat stoves.
http://www.gulland.ca/florida_bungalow_syndrome.htm
http://www.gulland.ca/florida_bungalow_syndrome.htm
Why is my stove hard to control - too much draft?
- Thread starter begreen
- Start date
-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
- Status
John addresses the the problem I had on the 30-NC. Since changing to a 5.5" inch 21 foot liner from the 6" smooth-wall liner it is abated. Albeit at the cost of some spillage when the door is opened. I went from monster draft to decent draft. I will settle for "decent" any day with a firebox full of wood.
Interesting article. If I had overdraft problems my 1st choice would be a pipe damper. Tinkering with the stoves air may work, but also voids the warrantees and I wonder what insurance companies would say if you had a chimney fire?
I think he gives credence and support to the pipe damper. Often it's an easy and good solution, and smoke spillage can be avoided by remembering to open the damper before opening the stove door. However, this isn't a solution for inserts where the flue pipe is not accessible. As to stove modifications, he does warn: "Provided it is done carefully and in full knowledge of the consequences..."
You'd think so... but on the "other" group he has always argued vehemently against them!BeGreen said:
BTW, I now have the F602 running in the basement on a 28 ft. 5 inch rigid liner, which, despite it's length, has less draft than the upstairs setup (probably due to the 5 ft. of connecting pipe at 12º from horizontal...) Anyway, the F602 definitely works better with the lesser draft, though it doesn't burn quite as hot. A curious side-effect of excessive draft on this stove is that the primary air has a hard time reaching the back of the firebox. But with the smaller pipe it does so just fine. Who woulda thunk...
Given that the original 602 was designed with the metric (4.9"), it makes sense that the stove works well with a 5" chimney.
The European version of the newer one also has a 125mm flue. (smaller than 5")
I think (and you can confirm) that the actual hole in the stove is quite a bit smaller than 6", but that the flue adapter enlarges it?
Nordic model also have 125mm in Europe (100 CB)
The European version of the newer one also has a 125mm flue. (smaller than 5")
I think (and you can confirm) that the actual hole in the stove is quite a bit smaller than 6", but that the flue adapter enlarges it?
Nordic model also have 125mm in Europe (100 CB)
Man I wish I had this info when I was trying to deal with my old stove. Wheres John Gulland when ya need him? Minimum new EPA standards should have
this WEB sites address attached to the stove when ya buy it. Good stuff
:coolsmile:
this WEB sites address attached to the stove when ya buy it. Good stuff
:coolsmile:One of the best posts on stoves. John Gulland"s article " The Florida Bungalow Syndrome", is a clear explanation with possible solutions to the problems of non cat air control. :exclaim:
Let's open this up to more detailed solutions. Pre-EPA stoves, called "airtight", had air controls that could shut air off completely. Later cat stoves allowed the air to drop to near nothing; a "lit" cat would clean the smoke and control a low burn.
The Jotul Oslo is typical of most non-cat models, only allowing the air to shut down enough for some air. Even at low it burns too fast with a partial or full load, and with any variety of hardwood. Sure, it's easy to get an overnight burn with coals in the morning. I want to to be able to shut the Oslo way down, similar to say an older 602, Baby Bear, or our 2001 cat Encore.
Gulland's key damper in the pipe seems to be the simplest solution to this, but it's not the best. The best, as he says, is to "modify the ....air control." We agree. Unfortunately, it ain't so simple. And blocking up the secondary air full or partial, is no solution.
Specific ideas ? There's got to be some serious engineers/ machinists/ McIver types who like this kind of challenge.
The warranty thing is a non-issue; I'm looking for a practical, simple fix that can be done by a mechanical klutz. :blank: Schematics please.
Let's open this up to more detailed solutions. Pre-EPA stoves, called "airtight", had air controls that could shut air off completely. Later cat stoves allowed the air to drop to near nothing; a "lit" cat would clean the smoke and control a low burn.
The Jotul Oslo is typical of most non-cat models, only allowing the air to shut down enough for some air. Even at low it burns too fast with a partial or full load, and with any variety of hardwood. Sure, it's easy to get an overnight burn with coals in the morning. I want to to be able to shut the Oslo way down, similar to say an older 602, Baby Bear, or our 2001 cat Encore.
Gulland's key damper in the pipe seems to be the simplest solution to this, but it's not the best. The best, as he says, is to "modify the ....air control." We agree. Unfortunately, it ain't so simple. And blocking up the secondary air full or partial, is no solution.
Specific ideas ? There's got to be some serious engineers/ machinists/ McIver types who like this kind of challenge.
The warranty thing is a non-issue; I'm looking for a practical, simple fix that can be done by a mechanical klutz. :blank: Schematics please.
Downeast, one safe way to experiment might be to install the F500 outside air kit and put a damper in the line. That would act as a valve to control the air intake. I've toyed with this idea for the F400 as a way to control a runaway fire, but it's sitting on the way back burner. The only time I have had anything close to a runaway was the first test of the HomeFire Prest-Logs.
I've modified the air controls of every stove I've ever owned. It's not something you can draw up schematics for - they're all different, though the concept is simple. And there is more than one air inlet on EPA stoves. The only thing you can do is find the inlets and either modify them or fashion the hardware (i.e. metal) that you can add will allow you to close them. Here are links to some examples with photos:downeast said:
https://www.hearth.com/econtent/index.php/forums/viewthread/5430/
https://www.hearth.com/econtent/index.php/forums/viewthread/5715/
https://www.hearth.com/econtent/index.php/forums/viewthread/5716/
https://www.hearth.com/econtent/index.php/wiki/Add_secondary_air_control_to_stove_Morso_2110/
The photo in the Gulland article is of the primary air control of a PE stove... the stop has been modified so it can be damped down completely. That's an easy one. I find it equally important to have control of the secondary air, not only to adjust for draft but to extend burn times (keep coals alive for longer.) But the mod that has the greatest effect on the way most stoves burn is what Corie calls the "dog box", the air inlet at the front center of the firebox. For anyone who burns primarily softwoods, that hole is too big and it overstimulates the fire. Reducing it's diameter by 1/3 to 1/2 makes the stove much more controllable. The same is true for bed-level air inlets at the back of the firebox (such as most Quads have). Nothing ruins a nice front-to-back burn quicker than too much bleed air fed to the back.
So is there any consensus here on what one ought to do if they have too much draft? We have 20+ feet of chimney, it runs up through the middle of the house, and we have a killer draft. We complained early on to our dealer that we had short burn times, nothing approaching what the manual says. They gave us a bundle of dried oak to use for an overnight burn, they said maybe our wood wasn't the best hardwood. The oak lasted the same amount of time as our other wood. We add wood to our stove about every 3 hours, maybe 4 max. Some small coals remain for quite some time, but nothing giving off much heat, the wood is basically gone is 3-4 hours no matter what kind. So I have been pretty sure for a while that our draft is too strong, our fires can burn like crazy even with the primary air shut down completely. Have discussed this with hubby, we haven't done anything about it yet. I figure we could burn less wood if it didn't burn so darn fast.
I've got 25' of chimney, albeit air-cooled in an external chase. I think I'm in a similar boat; a full load brought up to a high burn will pull a ton of secondary air with the primary and base air controls fully closed. I've always wondered what it would look like if I could throttle the secondary back. It might just lead to incomplete combustion, or I might get an extra hour or two. My other problem is that once the secondary burn dies down, I need full primary air to keep the coals hot, otherwise the stove cools off too much. At least I always have plenty of coals to restart the fire with in the morning.
I'm a fan of the inline draft damper as a simple user solution that is tunable to the weather conditions. Although the trend is to treat the woodstove as an automatic appliance, I prefer having the extra control to regulate the stove. Of course this doesn't help the insert owner. There a conscious choice must sometimes be made to strike the best compromise in draft for average conditions. Bart pointed out how he made this choice by reducing his pipe diameter.
"I’ve always wondered what it would look like if I could throttle the secondary back."
Ya know....the first two years I burnt with my Jotul Firelight I was having overdraft problems. A couple things would happen. First, the backpanel that holds the cat cover in place would just glow red/dissolve when stove top temps were 500+. The second thing that would happen is that the cats would break down with great regularity. I called a Jotul rep and he told me that on most stoves the secondary air inlet is far too large. He told me to remove a few rivets on the inlet cover and block both of them off by half. That worked much better but it still ate the backpanels.
Anybody else go through stove parts under overdraft situations?
Ya know....the first two years I burnt with my Jotul Firelight I was having overdraft problems. A couple things would happen. First, the backpanel that holds the cat cover in place would just glow red/dissolve when stove top temps were 500+. The second thing that would happen is that the cats would break down with great regularity. I called a Jotul rep and he told me that on most stoves the secondary air inlet is far too large. He told me to remove a few rivets on the inlet cover and block both of them off by half. That worked much better but it still ate the backpanels.
Anybody else go through stove parts under overdraft situations?
precaud said:
Nice ideas John ( McIver). :exclaim: The Vermont Castings' and Woodstock designers and engineers did the job well in the late 80's to work EPA regulations for cat stoves making them easy and effective heaters.
The industry hasn't done itself any favors by promoting the "simple" operation of non-cats as opposed to the 'complex' procedures with cat stoves. Comments from industry people on board ? Cats will operate perfectly when operated correctly--not a big deal. The noncats unfortunately mommie users by not letting the air go too low or too high. It is simpler but at what cost for long term, clean burning ? JMNSHO. %-P
When we have a real AlGore thaw :bug: , I'll take Corie's "dog box" air control on the Oslo apart again ( to clean and graphite the slider) to look at possible adaptations for closing the air off almost completely. Right now it's below zero; need the heating. The secondary air is another matter; the Jotul schematic does not show it clearly to do any adaption without getting behind the Oslo.
Summing up: Oslo primary air is limited: not too high and not too low. Other non-cats I've looked over are similar.
Keep the suggestions coming. Thx.
I am all for having more control of the air. I have been known to adjust a carburetor for better mileage/power too depending on altitude. EPA put tamper proof plugs on the carbs too.
On the non-cat stove you can't slow the stove down too far but this isn't wasting wood is it? You are just efficiently creating more btus than you want to at low burn. If you don't need btus then let the fire die out.
The only reasons you would want to mess with these air controls is to prevent overfire and to extend burn times right?
I see the long and low burns after user mods being major pollution makers though I would sincerely appreciate a longer burn time. An inline pipe damper is easily installed and removed as a seperate little 6" pipe piece on top of the stove. Cheap too.
On the non-cat stove you can't slow the stove down too far but this isn't wasting wood is it? You are just efficiently creating more btus than you want to at low burn. If you don't need btus then let the fire die out.
The only reasons you would want to mess with these air controls is to prevent overfire and to extend burn times right?
I see the long and low burns after user mods being major pollution makers though I would sincerely appreciate a longer burn time. An inline pipe damper is easily installed and removed as a seperate little 6" pipe piece on top of the stove. Cheap too.
downeast said:
Touch'e Downeast.
My thoughts exactly Cat stoves get all the bad raps, and here is another advantage they have, more control. My cat stove is much easier to operate than all my previous non cats. No more tweeking the air every 5 minutes to find that sweet spot.
Agreed Todd.
Not many have masonry fireplaces (mass heater)--talk about it: construction, cost, use, efficiency, design, etc...? How does it compare to your Woodstock for example ?
We seriously considered a masonry stove or Russian Fireplace when building in 2001, but the cost was at least 5-8 times a wood stove, and the space required added too much space and cost to the construction and design. Wood use was not in the equation since we cut our own. One big advantage: NO issues with air control !
Not many have masonry fireplaces (mass heater)--talk about it: construction, cost, use, efficiency, design, etc...? How does it compare to your Woodstock for example ?
We seriously considered a masonry stove or Russian Fireplace when building in 2001, but the cost was at least 5-8 times a wood stove, and the space required added too much space and cost to the construction and design. Wood use was not in the equation since we cut our own. One big advantage: NO issues with air control !
- Status
Similar threads
