Frequently Asked Questions
There are just a few questions we get repeatedly. Here they are.
- What do you think about rocket stoves?
- Unsafe firewood species
- Solutions for outside chimneys
- Improving conventional fireplaces
- Wood stoves for heating radiant floors
- Parts and info for old stoves
- What stove to buy
- Home made stove plans
Here is a response from John Gulland: I really like the rocket concept, but maybe not in the way most of its promoters do. I was first introduced to the rocket concept almost twenty years ago, shortly after it was introduced as one of many international attempts to help third world people to reduce lung disease and de-forestation by reducing smoke and wood fuel consumption for cooking. The rocket idea is to combine a small horizontal combustion chamber where sticks are fed into the fire with a vertical gas mixing and secondary combustion chamber. It sounds simple, but in actual use the rocket's performance was pretty spectacular compared to other options. I collaborated with one of the promoters of the rocket in the early 2000s and you can see some examples of his work here.
Fast forward a decade, and now the rocket idea has morphed to become the focus of a kind of cult in North America. Somehow, a humble, if clever, cooker for third world women became a do-it-yourself project for those who are suspicious of any organized industrial process of the type that produces the stoves we use for home heating. Magical properties are assigned to the rocket and claims are made that the rocket is far more efficient than EPA certified stoves. This is not true, but you can't even prove it through head-to-head testing because the rocket is an open combustion device like a conventional wood burning fireplace. EPA testing only applies to closed combustion chamber devices.
Rocket mass stoves are really just a masonry heater with a rocket elbow buried in a masonry structure. But a normal masonry heater (visit the Masonry Heater Association) produces very clean and efficient combustion without using the rocket elbow. I doubt that any do-it-yourselfer building a so-called rocket mass heater could beat the performance of a standard masonry heater. Plus, every rocket mass heater I've seen has been ugly and looks like it would deteriorate much faster than properly engineered heaters.
So, yes I like the rocket idea, but no I don't think it has any application for serious home heating in cold climates. The rocket heater fad looks to me like rank amateurism run rampant during an era of skepticism about just about everything. Speaking of amateurism, I suspect the home insurance industry has the most clout when it comes to discouraging the rocket bandwagon. I can't imagine an insurance company offering coverage to someone with a homemade rocket.
"Is ? ? ? species of firewood unsafe or unsuitable to burn? A friend told me it would produce a lot of creosote or burn too hot."
It seems like almost every species of wood has been tagged as unsuitable by someone. This is our response:
A few species of wood can produce dangerous emissions and most of them have dangerous sounding names, like poison sumac (swamp sumac), poison dogwood, poison elderberry, poison elder, poison oak. The smoke can contain the same compounds that cause allergic reactions on skin, but when airborne can cause respiratory distress if inhaled.
Aside from these few examples, we don't consider any normal species of wood dangerous or inappropriate for burning based on the idea that they produce much more creosote. There are woods with sticky sap in their bark and others that can't be split by hand and so are not as desirable as others. But creosote is a product of combustion, not a component of wood. If burned in bright, hot fires, much less creosote is formed from whatever wood is burned. This includes the pitchy bark of pine and spruce and the volatile bark of white (paper) birch.
Our advice is to try whatever firewood you have available. Make sure the wood is properly seasoned because all wood species burn poorly and produce smoky fires if their moisture content is too high. Extremely dry wood, like kiln-dried lumber, can also produce smoky fires. If you have some very dry wood available, mix it with regular firewood to avoid excessive smoke.
Burn bright, hot fires. Don't let your fires smolder.
We burn a lot of wood that others might consider junk. But maybe junk wood is the most environmentally suitable type to burn because it is useless for any other purpose. In our view, aside from the few poisonous species, no wood species is junk unless it has been painted, treated or is salt-laden from being in the ocean.
I have an outside chimney and my stove is in the basement, so I have serious backdrafting problems. What can I do to fix this?
If there were a simple and effective way to solve the problem of cold backdrafting chimneys, you can be sure it would be prominent on the web site. There is no simple solution because the problem has to do with the physics of cold chimneys and warm houses. That is why we are so adamant that chimneys belong inside houses.
If your chimney is metal, you could uninstall it and reinstall it inside using a ceiling support instead of a wall support and tee. By the way, just about every homeowner faced with the issue of where to run the chimney will claim there is no way it can run indoors. The reality, however, is that where there is a will, there is always a way.
If your chimney is masonry, you could try installing an insulated stainless steel liner. This MIGHT help to reduce the frequency and strength of the backdraft but will not entirely solve the problem.
Also, regardless of the type of chimney, the strength of cold backdrafts are always affected by the leakage pattern of the house. The leakier it is at high levels, the worse the backdraft. Therefore, you can try to reduce the strength of the backdraft by sealing attic hatches and ceiling fixtures and keeping second floor windows closed and tightly latched.
Unfortunately, there is no sure-fire solution.
Questions about conventional fireplaces: 1. "Why does my fireplace smoke?" 2. "How can I increase the efficiency of my fireplace?" 3. "Where can I get a two-sided fireplace or fireplace insert?"
Please note that we are woodheat.org, so we don't promote or support the use of conventional fireplaces because they are wasteful and polluting. If you want a conventional fireplace just for fire viewing, you won't find any support here, so please don't contact us for advice.
Also, with so many variables involved, we can't diagnose smoking problems by email. So, if your conventional fireplace smokes, as most of them do, here are the options we recommend:
- If it is a masonry fireplace, install an EPA certified fireplace insert with a stainless steel chimney liner running to the top of the fireplace chimney. Properly installed inserts almost never smoke.
- If it is a factory-built fireplace, take it out and install an EPA certified fireplace. (sorry, that's just the hard reality)
- If you live in the city, install a gas insert ( not a log set).
- Don't use it.
To increase the efficiency of a conventional masonry fireplace, install a fireplace insert. It is the only real way to boost efficiency and cut smoke emissions. Glass doors make almost no difference and accessories like tubular grates that are promoted as efficiency boosters can deliver some heat, but also run the risk of overheating the fireplace and combustibles around it. Conventional fireplaces are for decorative use only and it is unwise to try to use them as heaters.
A lot of people contact us wanting a two-sided or see-through fireplace. Two-sided fireplaces have a very bad reputation for poor performance and certainly can't be used for serious wood heating, even those few that are designed to burn clean. Therefore we don't offer advice on them, except to suggest that they are a bad idea.
We also hear from a lot of people who own two-sided fireplaces that smoke and/or don't make any heat. They always ask if anyone makes a two-sided fireplace insert. The answer is no. There is no way that an insert with expanses of glass on either side of the firebox could ever pass EPA's emissions test. That is why there are no two-sided inserts. Consider putting a good insert on one side and a fake flower arrangement on the other.
You can't. There is no way that a water coil or tank in a firebox or any kind of heat collector in the flue pipe will produce enough heat to make a serious contribution to in-floor radiant heating. For radiant heating you need a boiler.
Besides, if you take a lot of heat from the firebox, you will get smoky, inefficient combustion. If you take a lot of heat from the flue gases after they leave the stove, you'll likely compromise chimney draft, leading to other problems.
Even heating enough water for washing – that is, domestic hot water (DWH) – is a costly and complicated undertaking, and to our knowledge there is not a single EPA certified stove that has a certified DWH collector option, mainly for the reasons cited above.
We are not equipped to help with commercial questions of this type. Here are some resources that might help.
We don't recommend any particular brands or models. We do recommend that you buy an EPA certified low emission, high efficiency stove because it will give you far better performance and pay you back the modest extra cost in no time.
Visit as many wood heat retailers as you can find and listen to what they have to say. Once you have visited two or three, the ones who know what they're talking about will stand out. Here is a hint: beware of stove dealers who don't heat their own houses with wood or don't have operating wood stoves in their showrooms -- their advice is probably not worth much.
We strongly recommend that you don't attempt to build your own stove. Here's why.
You can't burn wood cleanly and efficiently without a good combustion system, and you can't design and build a one-off combustion system that is any good. One of the reasons why the price of good wood stoves start at about $1000 is because it took a lot of practice, trial and error and bucket loads of money to get them to work properly and to pass both safety and emissions test standards.
Thirty years ago wood burning technology was crude, sort of like folk-technology and anyone with a welder could call himself a manufacturer. It is not like that any more and it is a good thing. A lot of folks got burned, both literally and financially, buying stoves built by people who didn't know what they were doing.
There are no plans available for a good wood stove. If you were to find stove plans they would undoubtedly show you how to make a lousy one because no one in their right mind would suggest that a wood stove is a project for amateurs (you may be able to weld, but that's the easy part).
Here is our advice: Go out and buy yourself the best stove you can afford and invest your do-it-yourself time in getting your firewood in. Then sit back and enjoy the cozy beautiful fire.