What to Expect: Choosing Your Perfect Wood Stove

 

Our “What to Expect” series explores some of the factors to consider when you’re purchasing a new wood or gas appliance. Previously: gas fireplaces

So you’ve decided that a wood stove is right for you! Congratulations on your choice of such an environmentally-friendly heat source; Wooden Sun carries a variety of high-efficiency, low-emission stoves that will keep your home cozy and your air clean. A wood-burning appliance is a complicated system, however, and there are a lot of factors to consider when planning your stove project.

As in our last post, the first question to answer is what your goals are for your new stove. Customers sometimes ask us what our “best” wood stove is. There’s really no such thing as “best” in the wood stove world, only “best for you”. If you’re building a tiny home, for example, you’ll want to look into a stove with a small footprint (both stove size and required clearances) and a small enough heat output that it won’t drive you out of the house. If you’re looking for a stove that will give you an overnight burn, or let you bank the stove while you’re at work, you may want to consider a catalytic stove, which will let you keep the stove at a low temperature for a very long time. And, of course, you’re going to be looking at this stove for a very long time, so it’s important to consider what your aesthetic goals and preferences might be.

The first install consideration, of course – once you’ve chosen your dream stove – is where to put your stove for optimal safety and performance. Every wood stove on the market has its own clearance requirements to both protected and unprotected surfaces, as well as specifications for the floor protection required underneath the stove. These clearances can put your stove far enough into your room to eat up much of your room footprint, so consider traffic patterns and space usage in your home (many customers have found it helpful to cut out a piece of cardboard with the dimensions of their preferred stove or its floor protector, and set it in different locations around the house, observing clearance requirements, to get a better feel for it). And since a wood stove heats primarily through convection, it’s important to take into account the air movement patterns within the home. Placing your stove at one end of a narrow hallway, for example, will not heat the house as effectively as having it in a central location with lots of air movement to other rooms. If your HVAC system has a fan that will circulate the air in your home without having to run the heat, then installing a wood stove near the cold air return will make it easy to move the air from one room to another.

Venting requirements also need to be taken into consideration before you make your purchase. As we learned previously, wood appliance venting is a bit more particular than direct vent gas piping, since it relies on natural draft. If you want to put your stove in, say, a sun room or other 1-story addition, but the rest of your house is 2 or 3 stories high, you’re going to wind up with a lot of chimney sticking up above the roof (requiring a roof brace), which may be a deal-breaker for you. This is another reason a central location is desirable, since having the chimney relatively close to the peak of the roof will minimize how much stainless steel chimney is visible above the roofline. If your preferred stove location is directly underneath living space, rather than an attic, we may need to build an enclosed chase around the class A chimney, or find an alternate vent path; depending on how close you are to an outside wall, it’s sometimes possible to use a wall thimble connected to the stovepipe itself, then run the stainless steel chimney up the side of the house. Each situation is different, and initial designs sometimes have to be revised to take the specifics of your home into account.

Wood stove installed through cathedral ceiling with round support box

Wood stove installed through cathedral ceiling with round support box

A wood stove installed through the wall, with class A chimney held in place with wall support brackets

A wood stove installed through the wall, with class A chimney held in place with wall support brackets

Chimney pipe enclosed in a wooden chase

Metal chimney enclosed in a wooden chase

 

 

 

 

 

 

 

 

 

We hope that this post has given you some points to keep in mind as you plan your stove project, and will continue to help you prepare for your showroom visit and sales conversations. We look forward to seeing you, and helping you “bask in the warmth”!

Level II Inspections: What Are They, and Why Should I Get One?

In accordance with CSIA (Chimney Safety Institute of America) standards, Wooden Sun highly recommends a Level II (video scan) Sweep & Inspection for all new customers and for customers who are selling their home, have had a chimney fire or if the certified chimney sweep recommends this service. We sometimes have customers ask us why a Level I visual inspection (an assessment by one of our certified technicians from both above and below, with the aid of a powerful flashlight) doesn’t meet the industry’s highest standards for chimney safety, or show us a recent building inspector’s report certifying that the flue liners are in good condition.

The difficulty here is that, although a visual inspection will catch obvious damage to your tiles within a couple of feet at the top and bottom of the flue, even a highly-trained chimney sweep or building inspector can miss hairline cracks in a flue tile, especially if those cracks occur towards the middle of the flue. As discussed in our HeatShield post back in March, even small cracks in your terra cotta flue tiles can allow heat, sparks, and combustion gasses to escape into your home, putting you, your family, and your house at risk. In a vid-scan, our chimney technicians lower a special camera down your chimney, rotating it to get a full 360° view of the inside of your flue. This allows us to see small cracks in your flue tiles or missing mortar joints between them. We can then recommend any repairs required, before the flue tiles can degrade to the point that would require a full relining of your chimney.

Even if you have a factory-built or class A chimney, a Level II vid-scan can still be useful to you. These chimneys are put together in sections, and some brands and styles are less secure than others (Wooden Sun uses Ventis chimney components, which are held together at each joint with screws, but some brands are held together with a twist-lock system, which is less secure). A chimney sweep using improper equipment can damage these joints. A gap between chimney sections will have the same effect as a missing mortar joint in a flue tile, only a factory-built chimney is usually surrounded by wood framing, rather than brick or stone.

Bottom line: even a small crack or gap in your chimney or flue can be dangerous, and sometimes the damage is difficult to observe from the top or bottom of the chimney. Following industry safety standards, Wooden Sun recommends getting a video scan at least every two years, to make sure you’re aware of any potential problems in your chimney before they have a chance to become major hazards to your health and the health of your home.

 

Of Chimney Swifts and Chimney Caps

ChimneySwift23It’s nesting season, so that means chimney swifts are back! Chimney swifts often return to the same nesting site every year, so if you had them last year, you’ve probably got them again, cheeping away from inside your chimney. Swift nests are small, and don’t do any damage to the masonry inside your chimney; however, the abandoned nests and other debris are flammable, and can contribute to chimney fires if left during the burning season.

In 2010, the chimney swift’s conservation status was changed to near-threatened, and swifts are protected under Federal law. This means that reputable, law-abiding chimney sweeps are unable to remove the nests while swifts are still living in your chimney. However, the birds will vacate your chimney as soon as the young are old enough to leave the nest (generally by late August or early September), and we can clean your chimney out after that. Once the birds are gone and the nests have been removed, we recommend capping the flue to keep your unwanted houseguests from returning. Ideally, we recommend putting a cap of some sort on before the nesting season begins, but sometimes a family of swifts will move in and set up house before you have a chance to schedule your appointment, and we wind up having to wait until they’ve moved out again.

Single flue cap

Single flue cap

When it comes to capping the flue, there are a couple of different approaches you can take. The first is a simple single-flue cap (these are made in a range of standard flue sizes, so we’re fairly likely to have the size you need in our warehouse), which bolts onto the outside of your terra cotta flue tiles, and has both a cap to keep rain away, and a heavy stainless steel mesh to keep intruders from making your chimney their new home. A full-coverage cap, on the other hand, is custom-made to the size of your chimney, with a lid that extends slightly past the edge of the existing crown. As discussed in our previous post on maintaining your chimney crown, the full-coverage cap will not only keep rain and animals out of your flue(s), but will serve to protect the masonry of your chimney.

Full-coverage cap

A full coverage, multi-flue cap. The overhang at the edges of the chimney protects the wash.

HeatShield Flue Repair

 

As we discuss on our chimney repair page, an unlined chimney can be very dangerous. Houses built to code since the 1950s have terra cotta tiles or other flue liners, but these degrade over time, or suffer damage from earthquakes, chimney fires, or other extreme conditions. Even minor cracks in flue tiles can allow sparks, heat, and toxic flue gasses to escape into your home; the results can be anything from damage to the structural integrity of your masonry chimney, to carbon monoxide poisoning, to a house fire.

There are a variety of ways to reline a damaged flue to a masonry fireplace. Our preferred method is the HeatShield® flue repair system. Rather than a full poured liner, the HeatShield system is a high-temperature Cerfractory® material designed to fill mortar joints, cover cracks, or resurface your entire terra cotta flue. After determining the extent of repairs needed to your flue, Wooden Sun will use a foam applicator, custom-sized for your flue, to extrude the Cerfactory material into any joints that are missing mortar in your flue. If there are further cracks in the flue tiles, a second layer of the Cerfactory material can be applied to resurface the entire liner. Once dry, the HeatShield Cerfactory cement is rated to withstand temperatures exceeding 2900°F, well beyond the temperature reached by most chimney fires.

But how does the HeatShield system differ from the poured liners that Wooden Sun doesn’t install? Good question, and there are two primary differences. The first is that poured liners often require a lot more material to get a less durable liner, and a great deal of special equipment, which makes them more expensive than the HeatShield system. The application of the HeatShield Cerfactory material requires relatively little by way of installation equipment, and can therefore be installed at less expense than a full poured chimney liner. Additionally, the HeatShield system is specifically designed to address multiple levels of flue damage. Many poured or cast-in-place liner systems are intended for unlined chimneys, or terra cotta flues with such severe damage that the tiles have to be removed completely. However, most of the damaged flues we encounter during our regular service work are mostly sound, but are missing some or all of their mortar joints, or have cracks running through otherwise intact flue tiles. In these situations, our certified HeatShield installers will use only the amount of Cerfactory material needed to seal the damaged surfaces of your flue tiles, rather than creating what is essentially a new flue inside your otherwise intact chimney. While any damage to the flue presents a danger to the home and its residents, the HeatShield system gives us the flexibility to target the specific problems within your flue, without requiring you to spend money fixing a problem you *don’t* have.

Fire is a volatile thing, and not even the best sweeps, installers, or masons can ensure that nothing will ever go wrong. At Wooden Sun, we believe in taking every precaution to make sure that the heat and smoke of your fire are safely ducted outside so that the rest of your home is as protected as it can possibly be.

 

Fireplace Drafting Problems

Every fireplace season, we get calls from homeowners reporting that they can’t get their wood fireplace burning right, or that smoke spills back out into their house when the fire is going. So let’s take a look at what goes into your fireplace system, and what might be interfering with it:

Draft is the force pulling air from inside your house up through the chimney. Draft is primarily a function of the temperature differential between your fireplace and the outside air, as warm air from inside is drawn up the chimney to meet the cold air outside the chimney stack. The first implication of this is that it will be harder to start a fire on a warm day, since there won’t be a significant temperature difference to kick-start the draw of the chimney. It also means that when you first use your chimney after it’s been idle for awhile, you might have trouble getting the entry to the flue warm enough to get the smoke moving. If this happens, try holding a lit piece of newspaper or kindling up to the flue entrance right by the damper for a minute or two to quickly warm the flue and establish a draft. This can also be helpful on cold, damp days; humid air is heavier than dry air, so your chimney has to work harder to overcome that resistance.

If the flue is warm enough, the outside air cold enough, but you’re still getting smoke spilling back out into the house, the next culprit is likely to be a dirty flue or chimney cap. Creosote deposits will interfere with the airflow through your chimney, slowing it down and kicking smoke back into the house. Having your chimney cleaned and inspected every year or so helps keep this from ever becoming a problem, as well as heading off other potential chimney issues.

Sometimes, even a warm, squeaky-clean flue will refuse to draw properly, depending on how your home and chimney are constructed. A short chimney will oftenflue extenders have problems drawing properly; this can be addressed by adding a flue extender or chimney pot to the top of your flue. This flue extender can help address another cause of smoke spillage, negative pressure. We often have homeowners report that when they use their upstairs fireplace, smoke spills out of the fireplace directly below it. This is because basements, which are partially or completely below grade, are negative pressure zones, which try to pull air in from outside the house (think of it as a very weak vacuum cleaner); positive pressure zones, in upper levels of the home, are where the warm air is trying to escape to the outside. Since the two flues are directly next to each other, extending one flue may be necessary in order to get the smoke away from that negative pressure zone.

A flue extender can also combat the problem of stack effect, which occurs when your chimney termination is lower than a nearby rooftop. Hot air wants to go to the highest point in your house; if this point isn’t your chimney, the smoke will be drawn back into your home as it tries to reach the highest point in your building envelope.

Additionally, adequate replacement air can be a challenge for wood-burning appliances in newer, more energy-efficient homes. In an older, leakier house, cold air is pulled in around windows, doors, outlets, and even through the walls. While you normally want to keep that cold air outside, your wood stove or fireplace needs the replacement air to maintain combustion. In tighter modern houses, an outdoor air kit may be needed. This kit is simply a 4″ diameter duct that runs from the outside directly into your wood appliance, providing enough air to keep the fire from choking out and filling your house with smoke. An alternative to the outdoor air kit is to crack a window or door while the fire is going. For obvious reasons, this isn’t a great long-term solution, but it’s a wonderful diagnostic tool. If you consistently get smoke spillage from your fireplace, try cracking a window during your next fire; if that fixes the problem, it’s quite likely that either negative pressure or insufficient combustion air is your culprit, and an outside air kit may be the best solution.

Not every chimney problem has a simple solution, but there are often steps you can take to make it easier for your chimney to do its job. If your chimney isn’t working as it’s supposed to, it’s important to remember that it’s part of a whole-house system, rather than an isolated appliance, and the root of the problem may lie somewhere else in the house, rather than in the chimney itself.