Tips and Techniques Q&A Archive

How to "bank" a wood stove?

How do you "bank" a woodburning stove so it will burn throughout the night?
Sara

Hi Sara,
Banking is an old term that dates back to the days of cast iron stoves with leaky joints and no gaskets on the doors. With little control of the rate of combustion, users had to use devices like flue pipe key dampers (which we no longer use) and place large unsplit, and sometimes unseasoned 'blocks' of wood at the back of the firebox in an effort to extend the burn. These were the days when stove would deliver a net overall efficiency in the 25 - 35 % range and banking was necessary to get them to burn more than a few hours without reloading.

Things have changed. New stove models are roughly 70% efficient, have glass doors that will stay clear for a week or more of full time use if the stove is operated right, and these stoves will easily burn over night while still producing a nice flaming fire. Smoldering is no longer necessary to get an over night burn.

It is still useful to load a stove carefully to get a long burn. It helps to place larger pieces more compactly in the firebox, because they break down more slowly that way.

If you can't get an overnight burn with a modern wood stove, then it is probably too small or something is wrong with it. If you are trying to use an old stove, I would strongly advise you to save up your money and plan to replace it as soon as possible. Using old stoves is frustrating and wastes a lot of wood.

John

Fireplace doors open or closed?

I have looked over your site and didn't find a exact answer for my question.  Should you close the glass door of your fireplace when burning a fire or should you leave them open?  I have heard arguments for both sides.  I heard that leaving them open you draw out more heated air then you gain from a fire and on the other side of the coin when leaving them shut you seem to not get very much heat from a fire.  Please help.  I have wondered about this for years.
Ron

Hi Ron,
Yes, that argument has gone on for a long time but the reality is it doesn't much matter whether the doors of a conventional fireplace are open or closed, it will work poorly either way.  With doors open you get direct radiation from the fire, but the warm air is sucked up the flue and the fireplace is vulnerable to smoke spillage into the room.

With doors closed, the normal tempered glass blocks almost all the direct radiation, but the doors do reduce air consumption and susceptibility to smoke spillage.  I recommend operation with doors closed, but then you risk shattering the tempered glass.

There is no good solution.  We recommend putting an EPA certified fireplace insert into the fireplace with a full stainless steel liner to the top of the chimney to make the fireplace efficient, safe and more pleasant to use.

John

A little nervous about wood heating

I have just moved into a house in a rural area where the power goes out  frequently.  The house has a wood stove.  I am concerned about the  safety aspects of using it as the only heat source during power outages.  Can I let it burn constantly for days?  Is it safe to leave it  burning while I am sleeping or out of the house?  Does it give off  carbon monoxide?  How do I know if it's time to have the chimney  cleaned.  I have been checking it w/ a mirror but don't know what the  indications of creosote build up are.  Should I burn the wood slowly or fast?  Should I shut the damper and vents before I go to sleep?  Any  info you could send me would be greatly appreciated.  Thank you.   

Hi,
The first thing you need to do is find a qualified person, like an experienced chimney sweep, to come and clean the system thoroughly and inspect it.  All you need to know is if the unit and chimney are installed exactly according to safety codes.  If they are and the stove and chimney are in good condition, then:

• you can use it as your only heat source

• you can burn hot fires constantly if you want without fear of fire

• you can burn it over night and while you are away as long as you run it carefully and make sure the door is securely latched   

Your sweep can advise about creosote build up once he sees the system.  You can find good firing instructions here.  In terms of building an extended fire, the idea is to maintain flaming combustion.  Do that and you can't go wrong.   

John

A little confusion and bad advice about flue dampers

Hi.
I found woodheat.org to be quite full of information. My first wood stove has been installed, and I'm not sure how to use the flue damper and air inlet supply on the stove.  What is the purpose of the damper and how should it be adjusted during various burn times?  How does the stove's fresh air supply and the damper work in conjunction?  For instance, if one is wide open should the other be, and vice versa?
Look forward to your response,
Rich

Rich,
I don't know what stove this is, but operating instructions are usually provided by manufacturers and those should be your main resource. In fact, we don't recommend the use of flue dampers, unless what you have is a bypass damper that is part of the stove. But I don't have enough information to help you much.

John

Rich replies:

 Thanks for the response. The stove is a Waterford Ashling Woodburning stove. It is set up with a rear horizontal flue.  Approximately 14" from the flue spigot flange is the damper.  The store I purchased the stove from included the damper.  I just assumed this was the correct procedure. As a matter of fact there is no mention in the owner's manual about using a flue damper, only the primary air settings. This seems to support the statement -"we don't recommend the use of flue dampers".  Why should I not be using the flue damper?  A friend has beaten into my head that the flue is critical in controlling the amount of heat the stove puts out.  He said if there is no damper or the damper is opened all the way, the heat just goes up the chimney.  The Ashling has a 'top air duct assembly' and a 'top plate' with (for lack of proper verbiage) baffles. My interpretation of this design is that these two items are to collect and radiate the heat built up in the firebox. Yes, No? I am very surprised that a wood stove store would promote the use of key dampers.
Rich

Rich,
A flue pipe key damper should only be used when you can't control the rate of combustion from the front end using the stove's combustion air control.  Key dampers are associated with various forms of smoke spillage into rooms, the simplest being when someone opens the loading door without first opening the key damper.  But key dampers are also implicated in cases in which, as the flue temperature falls towards the end of a burn cycle, draft collapses and the restriction offered by the key damper can produce a condition in which the easiest path for exhaust is out through the combustion air control or any other leak or opening in the appliance.  This is not very common but it does happen with cooking ranges or sidedraft wood stoves with rear exit flue collars, for example. The rear exit on your stove makes this a possibility. 

Key dampers are only acceptable for non airtight appliances, such as old cast iron "non-airtight" box stoves. Flue pipe key dampers restrict flow even when open, provide a place for creosote to build up and make the flue pipe harder to clean.  Your friend has expressed the conventional knowledge related to key dampers; that they prevent heat from being lost up the chimney.  But what counts is the rate of flow of gases through the system.  The faster the flow, the lower the heat transfer efficiency.  If you can slow down the flow to give time for heat transfer, it doesn't matter how you do it.  It is incorrect to think that only a damper downstream of the combustion chamber can 'keep the heat in'.  By controlling the amount of air allowed into the fire with the air control, you have only one control to manage and you don't suffer any of the downsides to key dampers.

I'm not familiar with the Ashling so I can't comment on the fancy terms used to describe its innards.  It could be that the first is just to keep the door glass clear and the second is to improve combustion and heat transfer.  Most modern stoves have these components, but some manufacturers like to dress them up with fancy terms.

John

Rich replies:
Thanks for your help. It's interesting how some stores are in business only for the buck. The store I purchased the stove from never asked about the original flue, nor fireplace.  They simply stated 'buy this, that and that, and we'll install it'.  After a bit of research I opted not to listen to them and had a chimney sweep install a double wall solid pack chimney.  It cost more monetarily, but provides greater safety and peace of mind.  I appreciate your response to my questions, and will control the burn rate using the stoves intake only and leave the damper wide open.
Thanks, Rich

A backpuffing woodstove

I have a fisher baby bear woodstove.  It has one draft knob in the center of the stove.  I have been heating with this stove for five winters.  This year I have noticed considerably more backpuffing of smoke around the air draft knob, especially when I am first building a fire.  Generally once I get the stove to settle down, I don't have any more trouble.  Do you have any advice on how to remedy this problem.  Any help would be greatly appreciated. Thank You,
Sam

Sam,
The backpuffing you describe is usually caused by ignition of a build up of combustible gas in the firebox.  It means there is too much smoke and too little combustion air.  When transient conditions produce rapid ignition of the smoke, the resulting increase in firebox pressure produces the puff.  Low draft and a smoldering fire is often the culprit.  You might want to have the chimney and fluepipe checked to make sure there is no obstruction limiting your draft.  If the chimney is clean, you could probably solve the problem by using more paper, more pieces of smaller drier kindling and built up to heavier pieces more slowly.  The idea in getting a fire going well is for combustion to be bright and turbulent right from the time you light the paper.  Let the stove get good and hot and wait until the wood is thoroughly charred before turning the stove down at all.  It is almost impossible to have a backpuff if combustion is bright and hot.  By the way, one good way to avoid smoldering at start up is to use the topdown fire building technique:

John

What to do with a flue damper  

We just installed an airtight wood stove and put a damper in the pipe. We  installed triple wall chimney pipe and the stove seems to burn  just fine. Our question is should the damper be left open all of the time to avoid creosote buildup or can we close the damper partially after the fire is hot enough???  
Thanks  

Hi,
A flue pipe key damper should only be used when you can't control the rate of combustion from the front end using the stove's combustion air control. This is usually only necessary for antiques.  Key dampers are associated with various forms of smoke spillage into rooms, the simplest being when someone opens the loading door without first opening the key damper.  But key dampers are also implicated in cases in which, as the flue temperature falls towards the end of a burn cycle, draft collapses and the restriction offered by the key damper can produce a condition in which the easiest path for exhaust is out through the combustion air control or any other leak or opening in the appliance.  I would suggest you remove the damper and just control the fire at the air inlet. That will keep stove operation simpler and avoid smoke spillage episodes.

John

How to start a fireplace

I have the old fashioned fireplace that is not a gas fireplace.  I am having trouble lighting it and keep it lit.  What is the best way to start a fire that will last for a long while.

Thanks
Brendie

Hi Brendie,
The key to starting a fire is to make sure the wood is dry enough and is split up small enough to ignite.  Problems starting and maintaining fires usually have to do with dryness and piece size.  Small pieces light easier than big pieces so use about 10 pieces of finely split dry kindling.  Use several sheets of newspaper to ignite the kindling.  The successful ignition of a wood fire starts with the newspaper and progresses steadily to larger and larger pieces until the full sized logs ignite.   You'll find more information in our section on tips and techniques.

Beyond that, you'll need to practice.  I'm still practicing and I've been heating with wood for 25 years!
John

If it's gross and bothersome, something is seriously wrong!

We heat with wood in my house and I find it warm yet it's smell is gross and bothersome.

You are in serious need of professional help.  There should never be the smell of smoke inside a house.  Good systems NEVER spill smoke inside.  Contact a chimney sweep or experienced retailer to get the system inspected and corrected.  Your health and that of your family are at stake.

John