How Large An Area Will A Masonry Heater Heat?

By Doug Hargrave

At first glance this seems to be a simple question which should have an easy answer. In actuality the answer to this question is much more complicated. There are two factors that must be quantified in order to determine if a particular masonry heater design will heat a defined square foot area.  One factor, which is relatively easy to determine, is the maximum heat output of the masonry heater. The other factor, determining the heat load (loss) of a defined square foot area under the coldest conditions, is more difficult.

While it is difficult to make an accurate claim as to the amount of space a particular masonry heater design will heat, it is possible based on the amount of wood burned, to accurately predict its BTU output and to define its heat storage capacity.  On the other hand, determining the heat load of a home requires a heat loss calculation of the floors, walls and ceiling based on their insulation properties, a determination of the homes efficiency in terms of outside air infiltration and inside leaks, and finally the heat load must be adjusted to the heating degree days for the geographic location of the home.

The following question and responses recently appeared on the members chat forum for the Masonry Heater Association of North America.

Question:

What can you expect out of a masonry heater with (the home) insulation being average to slightly above average? It would be nice to know how many Btu’s or how many square feet a typical heater will take care of.

 

Respondent A

That is a loaded question, and you can get into a lot of trouble promising a customer to heat xx square feet. We have one heater heating a 2800 sq. ft. super-insulated house in a cold climate. An identical one was built in a milder climate, and is incapable of heating a 1000 sq. ft. "poorly insulated" house. "Insulated" is a misnomer, since leakiness is often a bigger factor than insulation. "Efficiency" would be a better term, or "low energy" or even better "low heating load". 
 
You are better off to quote the heat output of the heater, and leave it be the client's responsibility to determine how much of his heating load it will cover. You can also quote some magic voodoo stuff about radiant heat. While real, it is much harder to quantify.  The generally accepted maximum output of a large heater is 20,000 BTU/hr, or 6 kW. One of those cube shaped 220V shop heaters is about 5 kW, so imagine one of those blowing continuously.  To get 20,000 BTU/hr, you need to burn about 100 lbs of 20% moisture wood at 70% efficiency. Typically, that will be two 50 lb fires per day. If you try to build a heater larger than that, you really need to know what you are doing, or be guaranteed durability problems.  Some companies up the rating of their heaters by specifying 3 fires per day. So you'd get 20,000 BTU/hr with a 33 lb capacity firebox.

Respondent B

(Respondent A) is correct: The only thing you can safely guarantee is output. If the heater is planned as the major heat source, I ask people to provide heat loss statement to compare with heater's output. I also can give them rough assessment of heater's capabilities bases on the max output for a reasonably largest possible heater at 25000 Btu/hr, extreme cases, 30000btu hr, and on rule of thumb for heat loss per sq ft related to the estimated R-value of their outside walls. The numbers for this rule of thumb were given at least a couple of times in this forum in the past. Super insulated home (R30 walls +) will have heat loss of 10Btu per sq ft or less, while a century home without any insulation may be in 40-50 Btu per sq ft.

Respondent A (additional comments)

Super insulated home (R30 walls +) will have heat loss of 10Btu per sq ft or less, while a century home without any insulation may be in 40-50 Btu per sq ft.

Using this rule of thumb, for a 20,000 BTU/hr heater:  Super insulated house: 2,000 sq. ft.  Un-insulated century house: 400 sq. ft.  You also have to factor in location.  Ottawa Canada has 8,100 heating degree-days.  Vancouver has 4,700.  A house in Ottawa with 2,000 sq. ft. is equivalent to 3,500 sq. ft. in Vancouver or 1,150 sq. ft. in Fairbanks AK in terms of heating load.

Respondent C

Generally speaking more mass means more heat capacity. Not all houses are constructed equally or in the same geographic location and not everyone burns their heater the same. Also not all heaters are placed in a central location, so the buyer must be informed that the rating may be reduced based on location.  I always tell potential buyers that no matter what, "they will always have a zone of comfortable heat output" if the power goes out. 

 

Respondent D

To be on the safe side, it is a good idea to ask the home owner to have an energy audit done on their house.   These audits are not expensive and will show where the cold spots are in the house. On the blower test, the inspector can determine the square footage of air leaving the house through leaks and can show where the leaks are. This is money well spent and will have a lifetime of positive effects.

Respondent A: +Norbert Senf – Masonry Stove Builders, Shawville, Quebec

Respondent B: +Alex Chernov – Stovemaster, Caledon, Ontario

Respondent C: +Doug Hren – Masonry Heater Design House, Hickory Corners, Michigan

 

Respondent D: +Gary Hart – Aaron’s Ltd. Alternative Energy, High Ridge, Missouri

 

Maintaining Your Masonry Heater

By Marge Padgitt

Masonry heaters require regular maintenance in order to function properly, and the flue should be swept to avoid chimney fires. Maintenance includes sweeping of the chimney flue, brushing out the flue gas channels, inspection of the chimney and heater, and doing any repairs necessary. If the masonry heater is operated properly there should be little,if any creosote in the flue, and you should find only small amounts of soot. If there is any amount of creosote in the flue proper operation and burning procedures should be reviewed. One to two very hot fires should be burned each day, or once every 12 hours for most heaters. The fire should not be “damped down” to maintain a longer burning time as is the normal procedure with a wood stove. The maximum number of fires per day should be three. For chimneys with exterior exposure, the flue will be colder than an interior chimney and will accumulate more soot.

Cleaning the flue gas channels involves using a small poly brush and vacuum. Go to the small channel doors, open them and clean and vacuum each one to remove fly ash. The chimney interior and exterior needs to be inspected, and the heater itself should be inspected for any deterioration or loose firebrick in the firebox, any cracking in the exterior heater skin or finish work, and correct clearances to combustibles. Like any masonry structure, the masonry heater and chimney will need to be maintained and repaired as needed. Get a copy of the Homeowners Safety Manual and Burning Guide for Masonry Heaters for free at www.mha-net.org.

Be sure not to use a grate inside the firebox. Fires should be built right on the firebrick floor. The door should be closed during operation, and flammable liquids should not be used to start fires. Homeowners should not burn anything other than dry cord wood in the heater. Building a top-down burn fire will provide a clean burn start up with less CO and smoke. The top-down burn is the opposite of what you learned as a Scout. Place a couple of large logs on the bottom with airspace between them, then add smaller logs on top in the opposite direction, then kindling. Try Fatwood or dry pine as a fire-starter. The fire will burn down slowly, like a candle. This method warms the flue slowly, and causes draft to establish before the fire really gets going.

Your professional chimney sweep is best qualified to sweep and maintain a masonry heater, and can likely do any minor masonry repairs needed needed as well. Find a professional chimney sweep at the Midwest Chimney Safety Council Website at www.mcsc-net.org or at the Chimney Safety Institute of America site at www.csia.org.

For more information visit www.mha-net.org or call Executive Director Richard Smith at 530-883-0191.

Masonry Heater Association Encourages Preparedness with Wood-Burning Heating and Cooking Appliances

Masonry heater and bake oven with heated bench by Max Edelson of Firespeaking

Press Release

Masonry Heater Association Encourages Preparedness with Wood-Burning Heating and Cooking Appliances

November 14, 2012

The Masonry Heater Association of North America encourages homeowners to be prepared for any type of disaster with an alternative source of heating and cooking. The recent flooding and lack of electricity in the Northeast United States during cold temperatures is a reminder that everyone should be prepared to be self-sufficient in a disaster or power outage.  

Masonry heaters are site-built wood-burning appliances constructed with natural materials that radiantly heat a home with the renewable resource of wood. Masonry heaters are efficient and use relatively small amounts of wood to heat without the use of electricity, gas, fans, or ducts. These appliances heat the home through burning wood in a firebox, which connects to channels inside a large thermal mass. After the fire is out the heater gradually radiates heat to the living space for many hours without causing large temperature fluctuations or drafts. Many homeowners prefer masonry heaters rather than gas, electric, or wood-stove heating methods for regular use, not just during power outages.

Outdoor oven by Martin Pearson

Masonry heaters can be built with an oven, which can be used anytime, but is especially important during times of disaster when electricity or gas may not be available.  Stand-alone outdoor brick ovens are another option. These are site-built using a pre-cast oven kit or built with firebrick.

Masonry heaters and bake ovens are appliances that masons should get specialized training in before building. The Masonry Heater Association of North America trains heater masons and oven builders.

For more information or for a list of builders in the U.S. and Canada contact Richard Smith, Executive Director, at 520-883-0191, e-mail execdir@mha-net.org or visit www.mha-net.org. 

Your house might be making you sick

By Marge Padgitt

As people close up their homes for winter, sealing every open gap, and installing thermal windows and insulation, they may be doing more than making their home energy efficient. They might be doing things that can make their family ill.

Houses need at least six air exchanges per day, according to the Environmental Protection Agency. These air exchanges are necessary in order to move out tobacco smoke, Carbon Dioxide, Carbon Monoxide, Nitrogen Dioxide, Radon, and a host of other chemicals such as Formaldehyde that off-gas from furniture, carpet and woodwork. These air exchanges bring in fresh air for the occupants to breathe.

Exacerbating the problem are appliances that take air out of the house such as attic fans, range hoods, bathroom fans, clothes dryers, and central vacuums. If the house is tightly constructed replacement air needs to be introduced somehow.

Appliances such as furnaces, hot water heaters, fireplaces, and wood-burning stoves need air for combustion, and they take house air for this purpose. Open fireplaces are only -10 - +10% efficient, and use heated air from the home, causing the furnace to work harder. Even if an outside air source is supplied to a fireplace in an attempt to use less house air, this is often inadequate, and is not the best solution. Cold air dumped on a hot fire cools it down, causes it to burn inefficiently, and to produce more CO.

High-efficiency gas fireplace inserts are 75% + efficient and use no indoor air for combustion, and wood-burning fireplace inserts and freestanding stoves are 70%+ efficient and use much less air for combustion than traditional open fireplaces do. These are good choices whether a home has inadequate air for combustion or not. Other methods to improve fireplace efficiency include installation of glass doors, use of a grate heater, and improvement in design. A Rumford style fireplace is a better choice than a standard style fireplace because it uses less air and is more efficient. Efficient fireplaces or inserts use less wood than standard fireplaces to produce the same amount of heat, so an added benefit is lower energy cost.

Health effects associated with poor indoor air quality are unexplained flu-like symptoms, headaches, dizziness, fatigue, confusion, eye and nose irritation, and in more serious cases, inability to wake up, asthma, cancer, irreversible brain damage, or death.

Another problem that can occur in larger homes or homes that are tightly constructed is unbalanced house pressure. Symptoms of negative house pressure are moisture condensation on cold surfaces, smoking fireplaces or wood-burning stoves, difficulty lighting a fire in a fireplace, CO backup from gas and wood appliances, back-drafting of appliances (and CO), CO detector alarms frequently, and cold air infiltration through leaks. Children and pets may be more affected than adults. If a person feels ill when at home, but better when outside the home, this is an indication that something is wrong with the house.

A good solution is the PlusAire whole house ventilator, which mixes cool outside air with warm air before sending it on to the furnace and the rest of the house where it is used as combustion air and fresh air for the occupants to breathe. 

Strategies to improve air quality:

1. Install portable air cleaners
2. Maintain humidifiers and dehumidifiers and empty water trays
3. Replace air filters on schedule
4. Turn on whole house fans or bathroom and kitchen fans with doors or windows open occasionally in Spring and Summer (not during cold weather)
5. Install a heat recovery ventilator (HRV) to the furnace (assists the furnace only)
6. Install a whole-house ventilator such as Plus-Aire to bring in make-up air for appliances and fresh air to breathe
7. Install EPA Certified high-efficiency gas or wood-burning inserts in fireplaces
8. Be sure clothes dryers are properly vented outdoors and vents are cleaned twice per year
9. Use a vented gas space heater or stove rather than an un-vented gas appliance
10. Never use kerosene heaters inside the house
11. Have a trained licensed HVAC contractor clean and tune-up furnaces annually
12. Have a professional CSIA Certified Chimney Sweep inspect and clean furnace, fireplace, masonry heater, and wood stove flues annually
13. Have an energy specialist do a blower door test on the home, which will indicate leaking areas and negative pressure issues

Sources:

www.epa.gov

www.csia.org

www.ncsg.org

www.acca.org

www.plusairplus.com

www.wikipedia.com

www.chimkc.com

www.coheadquarters.com

Masonry Heater Workshop Oct. 26-31 or Oct 28-31, 2012

Masonry Heater Workshop Oct. 26-31 or Oct 28-31, 2012

  

Masonry Heaters are clean-burning heating appliances that use the renewable resource of wood for fuel. They are site built, with a core that is hand-built or pre-cast.  Masonry heaters use no electricity, gas, fans, or duct work, and work by storing heat in a thermal mass, then emitting radiant heat to the living space. Find out why Masonry Heaters are the best heating option today! Masons, skilled homeowners, and contractors interested in learning new skills will want to attend this intensive training session. 

  

The Heater Mason Development Program(HMED) has proven to be an excellent tool to learn more about masonry heaters. The curriculum is designed as an introductory course for masons or homeowners who want to know more about the heating appliance. This course may be used as a "professional credential" good towards the Certified Heater Mason program.

  

The workshop is being held October 26 - 31, 2012 near Sullivan Missouri, near St. Louis. Workshop participants will learn how masonry heaters work, and participate in the the basics of heater building,  hands-on heater core building, and hands-on oven core installation. A heated bench and wood-burning cook stove are also part of the program. This workshop is an approved HMED program for those wishing to become Certified Heater Masons.

  

The class schedule is as follows:

October 26-27: Intensive classroom training with HMED approved credit towards Certification (Certified Heater Mason). Heater builders who wish to be Certified Heater Masons can apply credits for this course. Other builders are encouraged to attend in order to learn the basics of Masonry Heaters which is extremely important! 

October 28-29: Hands-on workshop- build a contra-flow masonry heater with bake oven and heated bench.

October 30 -31: Hands-on workshop bonus- Build a wood-fired cook-stove!
.

Those wishing to stay longer to assist with the exterior finishing work are welcome.

  

The project instructors are Jerry Frisch, owner of Lopez Quarries in Everett, Washington, Gary Hart, owner of Aaron's Ltd. Alternative Energy in High Ridge, Missouri, and Gene Padgitt, Vice President of HearthMasters, Inc. in Kansas City, Missouri. All three are Certified Heater Masons. Jerry Frisch is a master heater builder.

  

Cost for the four-day HMED workshop is $795 for MHA Members and $900 for non-members, plus bonus two-day cook stove workshop.  ALL 6 days!

Or 

$400 for non-HMED participants: attend any four days from Oct 28 - 31!

  

CEU's have been approved for CSIA and NFI. 

Visit www.mha-net.org or call Richard Smith, Executive Director, at   520-883-0191 for more information or to register for the workshops. Get your motel reservations in now! E-mail mha.association@yahoo.com  

Masonry Heater Workshops Coming Soon!

  LEARN HOW TO BUILD MASONRY HEATERS!

October, 2012
February, 2013
April, 2013

May, 2013

If you are a mason or very handy homeowner interested in learning more about Masonry Heaters, there are some opportunities for education coming up.  First, is the HMED Class sponsored by the Masonry Heater Association of North America in Sullivan, MO near St. Louis  October 26-29, 2012.  You will learn how masonry heaters work, the basics of heater building,  hands-on heater core building, hands-on oven core intallation, and buld a heated bench.  Instructors are Jerry Frisch and Gary Hart assisted by Gene Padgitt. Visit www.mha-net.org or call Richard Smith, Executive Director, at  520-883-0191.

You may also want to attend the annual workshop by the MHA near Asheville, NC in April of 2013, where you can participate in a variety of hands-on workshops all week long.  Visit the website for more info.  You must be a member of the MHA to attend.And for masons only, The World of Concrete/World of Masonry Expo in Las Vegas is Feb 5-13, 2013, where the MHA will have a booth and will be demonstrating masonry heaters and will present at 3-hour class. Visithttp://www.worldofconcrete.com/ for more info.Also coming in the spring of 2013, HearthMasters Masonry School opens in Kansas City, MO. We will be teaching beginning to advanced masonry skills, chimney restoration, brick oven building, and masonry heater building. Watch this list for more details soon. Visit www.chimkc.com for more info.Sincerely, Marge PadgittPresident, HearthMasters, Inc. Host, Wood-Fired RadioKansas City, MO www.chimkc.com

2012 MHA Contest Results

2012 MHA Contest

The MHA sponsors an annual Design/Build contest with three categories: Masonry Heaters, Bake Ovens, and Masonry. Three expert judges assign points to each entry without knowing who the entrant is. Judging was done based on aesthetics, skill in craftsmanship, creative use of materials, and overall design. Thank you to judges Stephen Bushway, current president, and Glen Overk, and Norbert Senf, both past presidents of the MHA.The following are the winners of the 2012 Contest:

Masonry Heater Category

Custom designed stone heater and bake oven by Dan Givens

First Place: Dan Givens Stonecastle Masonry, Ltd. Ester AK

stonecastle@gci.net
______________________________________________

Custom designed tile masonry heater by Jessica Steinhauser

Second Place: Jessica Steinhauser, Stonehouse Pottery, Guelph, Ontario, CA
www.stonehousepottery.com
_____________________________________________________

Third Place: Custom stone masonry eater and bake oven by Paul Anderson, Dale Anderson Masonry, Inc., Allenton, WI 53002 www.damasonry.com

____________________________________________________________________________________

Bake Oven Category

First Place: Historic oven rebuild by project by Mike Wurzbacher and Walt Kelly
Mike Wurzbacher, Squirrel Tail Ovens, Red Lion, PA www.squirreltailovens.org mikross53@yahoo.com and Walt Kelly, Fire and Stone Masonry, Danville, PA 17821 PH 570-275-2619 fireston@ptd.net _________________________________________________________

Second Place: Adobeand brick finished wood-fired bake oven by Max and Eva Edleson, Firespeaking, Deadwood, Oregon Ph 541-964-3536 www.firespeaking.com

_______________________________________________________________________________________

Masonry Category

Outdoor Kitchen: Masonry design/build project by Hendrick Lepel

First Place: Hendrick Lepel, Kinsale, Co.Cork, Ireland
Ph 00353 86 8838400

_________________________________________

Second Place: Dan Peltier and Jay Krabel, Design Masonry, LLC., Tomah, WI 64660 PH 608-387-9449 www.designmasonryllc.com
_________________________________________
 __________________________

Stone stream and waterfall by Dan Givens, Stonecastle Masonry, Ltd.

Third Place: Dan Givens, Stonecastle Masonry, Ltd, Ester AK 99725 PH 907-474-3465 www.damasonry.com
______________________________________

Other Entries worthy of mention:

Custom designed stone faced masonry heater by FireSpeaking, Deadwood, OR

Masonry heater/bake oven by Max and Eva Edleson, Firespeaking, Deadwood, Oregon 541-964-3536 www.firespeaking.com
________________________________

Masonry fireplace by Gene Padgitt, HearthMasters, Inc. Independence, MO

Man-made stone two-sided circulating fireplace by Gene Padgitt, HearthMasters, Inc.Kansas City, MIssouri www.chimkc.com

_____________________________________________________

Visit www.mha-net for more information

Wildacres Poem

A Poem by Tom Marc
Wildacres

It’s the time to think about Wildacres

Learning from the worlds’ best fire makers

Convection, radiation, thermal mass and unburned gas

This is the only place you’ll get this class

Getting the most heat from a piece of wood

Less pollution, less cost, more heat- all good.

Our gracious hosts Kathryn, Kiva and Mike,

making sure that everything is just right

Listen for the bell- 3 squares a day in the mess hall

So good, you want to eat it all.

You’ll learn from the best, with bricks, limes, and clays

From master masons, you’ll see the best ways

To build beautiful heaters of stone, mortar and bricks

You can be sure to learn a few tricks

Top down fires, refractory clay, cement and the EPA

All these and more at the annual meeting of MHA

With Soapstone, bricks, sand, and clay

Shovels, trowels and levels, grown men and women play

In 6 days you can build a Contraflow

Man, you should see that thing glow.

An then there is also the five run

A big honkin’ heater, what fun.

And don’t forget the Tulikivi,

So velvety smooth, blue and pretty.

Wild contraptions like the Rocket stove

Seen a 30’ horizontal chimney bench before?

There’s also a giant bake oven for Pizza Party Day

Thin crust pizzas and beer, there’s no better way

The amazing pizza, thin crisp and chewy

You can be sure there’s always plenty

Five heaters all a glow, drinks – free flow

Warms your heart, body and soul,

Heaters yes, surely Works of art

Keeping fires burning in our home’s hearts

A crazy beautiful cast of characters from all over the world

Gather to see smoke from chimneys unfurl.

Marty, Lars, Norbert, Pat, Tom, Worm and Jeff

Your sides gonna hurt, when too much you laugh

The Blue ridge Mountains, fog, mist, rain, and sun

You’re guaranteed to have some fun

Sweet music has filled the hollow the last few years,

Radiant Heat Ramblers sweet strings, candy for the ears

The MHA, it’s about wood, not coal

Chopping renewable resources is good for the soul

Camaraderie up on the Airy Mount

For 15 years, too many good times to count

Learn About Guatemala and Masons on a Mission

Building clean burning cookers, reducing disease and pollution

Times are tough, it’s true

Wildacres will be a rewarding break for you

A talented group of masons will inspire

To once again connect to the “ Spirit of the Fire”

High-Performance Masonry Heating

By Stephen Bushway
Deer Hill Masonry Heat

(This information is based on emission test results done with a Finnish contraflow heater design with a grate and air supply from under and in front of the grate) Whether you're a seasoned masonry heater owner or are reading this as a new owner, there are some newly discovered firing techniques you will want to employ to get the most out of your hearth. Use regular cordwood! Yes, it is not necessary to burn sticks 2" to 3" across to get the rapid, complete combustion that masonry heaters are noted for. Actually, 4" to 6" pieces such that 9 to 12 pieces will fill your firebox when cross hatched will provide better air/fuel ratio for complete, and more usable combustion. The bigger pieces allow more time for the masonry mass to soak up the fire's heat - yielding better heat transfer to your home. Place smaller wood, kindling and paper on top of this load and light from the top! The revolutionary top burn greatly reduces emissions during the dirtiest part of a firing - the first 10 minutes or so. Lighting the load from the top of the pile yields a candle-like burn, allowing the firebox to heat up as the volatile gases are being more evenly released. Take a little extra care in laying up your fire. A good "fuel load configuration" is well balanced and won't topple over prematurely. Allow a 1" airspace between pieces, placing the largest pieces first and the bottom row running "front to back" in the firebox. Don't admit air from below the grate until the fire is down to coals. Use the air slots in the door, if provided. If not, cut scrap dimensional lumber so that a piece will cover the grate and air is admitted from the front. With a top burn fire the piece will block grate air until it is burned through - well into the firing. Alternately, you can adapt your doors so that they will 3/4 inch of air between them but can not be accidentally be opened further. This modification was lab tested for emissions with excellent results. During the coal burning phase, rake the coals so they evenly cover the grate with air coming from below. It is more efficient to have one full firing than 2 fires half as large. If you've been burning small pieces kindled at the bottom in your contraflow heater, chances are there is soot in the heat exchange channels. This can effectively be cleaned from the cleanout door usin a rod and brush designed for cleaning pellet stove chimneys. This will better allow them to absorb heat from future fires. Burning cordwood has so many benefits, economy-wise. And as you're probably aware, masonry heaters provide the cleanest burning solid fuel appliances available. Now, following these simple practices you can be assured that you are providing yourself and your loved ones simple, yet state-of-the-art heat more cleanly than ever.

High-Tech Old World Technology Latest Trend in Heating

By Marge Padgitt
HearthMasters, Inc.

Sometimes old things are better than new, like old houses, historic buildings, and castles. The latest trend in home heating fits into that category. Masonry heaters have been around for hundreds of years in Europe, but are just recently catching on in the U.S. And the great thing about heaters is that they are GREEN. People needed to heat their homes in an efficient manner in olden times just as today in order to save their forests. Inefficient open fireplaces took too much of their valuable resources, so another method had to be developed. No one knows who the first mason was who came up with the idea of devising something that would retain heat for long periods of time, then radiate it into the home while using less wood, but whoever he was he was a genius.

Masonry heaters have been redesigned and altered over the years by different masons in Finland, Russia, Germany, Austria, and the United States. But heaters all have the same characteristics with complex channels to slow down and trap heat from flue gasses, and a mass of masonry to retain that heat, then radiate it to the living space over a period of up to 20 hours. By the time the products of combustion get to the exit of the flue, the smoke is white, and the particulate emissions are very low. One load of wood can usually provide heating for the average size home for 8-12 hours. Compared to even the best high-efficiency wood–burning stoves on the market today, gas and oil-fired furnaces, and certainly inefficient open fireplaces, masonry heaters can’t be beat.

Custom granite masonry heater
Courtesy of HearthMasters, Inc.

Another benefit masonry heaters offer is that they don’t require electricity, gas, or ductwork to distribute the heat. In a properly designed home with an open floor plan and the heater in the center of the home, the heat will radiate evenly throughout. Ideally, heaters are built in new home construction, but they can be added to existing homes if the layout is right. Heaters require a suitable foundation to support the massive masonry, which weighs three to six tons by the time all of the firebrick, block, cast iron doors, dampers, and exterior masonry facing is installed.

Heaters can be enhanced with heated benches to sit on, mantels, wood storage bins, and even bake ovens. Pizza and bread from a wood-fired bake oven has an incredible and unique taste that is not to be missed, and entire meals can be cooked in the oven if desired. An experienced heater mason can not only design and build the right size and type of heater for a home but make it beautiful to look at as well. An exterior finish of soapstone, tile, sandstone, or brick can make a dramatic statement. Heater masons will work with the homeowner to come up with a custom design that suits the home or use one of many masonry heater kits that are available from several manufacturers (usually incorporating soapstone) in a variety of designs.

Use of natural non-toxic materials and the renewable resource of wood make masonry heaters the perfect solution for a green home.

The trade is very specialized, with only a few heater masons scattered across the U.S. Fortunately, most of these masons will travel to do installations. Some have even traveled to Japan, China, and South America to build heaters. Often several heater masons will help each other out since these are big projects. In days of old, the heater masons kept their trade secret, even to the point of not leaving the room until the heater was completely finished so no one else could see how the interior was built. At that time, the livelihood of the masons was dependent on this secrecy. The trade is so skilled that the only way to learn is to do hands-on assistance with an experienced heater mason, and that is part of the reason the Masonry Heater Association was formed. The older masons do not want this to become a lost art, so they help train others. The Certified Heater Mason program was developed by the experienced MHA members in order to assure that the knowledge is not lost.

In the U.S. many people are not yet aware of masonry heaters, so it is a challenge for a heater mason to make a living out of just building heaters. Most heater masons also build other types of projects such as fireplaces, chimneys, outdoor bake ovens. Some are timber frame or log home builders or own brickyards. Most are very aware of the green building trend and are interested in sustainable living. Many heater masons will travel to build a heater because they love doing it and love the satisfaction they get out of building something that is very specialized.

Pricing for heaters is what most would consider being on the high end, and a long-term investment. The average cost a homeowner may expect to pay is from $15,000 to $30,000, with price depending on the complexity of the heater, material costs, and labor. The expected time to get a return on your money is approximately 10 years. The time to build a completed heater may be up to four weeks or more, depending on how many skilled craftspeople are working. Many homeowners will elect to be an assistant on the job in order to lower their costs. In some cases, if a heater mason is traveling the homeowner will put him up at their house or a local hotel. When traveling the masons usually work long hours in order to get the project done sooner.

Mark Twain discovered masonry heaters while traveling through Europe and wrote about them: "All day long and until past midnight all parts of the room will be delightfully warm and comfortable … Its surface is not hot: you can put your hand on it anywhere and not get burnt. Consider these things. One firing is enough for the day: the cost is next to nothing: the heat produced is the same all day, instead of too hot and too cold by turns… America could adopt this stove, but does America do it? No, she sticks placidly to her own fearful and wonderful inventions in the stove line. The American wood stove, of whatever breed, is a terror. It requires more attention that a baby. It has to be fed every little while, it has to be watched all the time: and for all reward you are roasted half your time and frozen the other half... and when your wood bill comes in you think you have been supporting a volcano. It is certainly strange that useful customs and devices do not spread from country to country with more facility and promptness than they do."

Find out more about masonry heaters, including technical specifications and testing results, photos of heaters, manufacturers, and a list of heater masons, contact the Masonry Heater Association of North America through www.mha-net.org. There is a chat list set up for anyone interested in masonry heaters at http://groups.yahoo.com/group/MasonryHeaters.

Marge Padgitt is a past board member for the MHA.  She is president of HearthMasters, Inc. in Kansas City, Missouri. Her husband, Gene Padgitt, is a Certified Heater Mason.

When the Wind Blows - its Cold: The indoor wind chill factor

By Doug Hargrave
Mid-Atlantic Masonry Heat

Everyone has experienced the cooling effect of a strong wind or breeze while engaging in some outdoor activity. The extent of the cooling effect is determined by the speed of the wind and the temperature of the air. For example, a warm breeze has to be significantly stronger than a cool breeze to produce a cooling effect. The cooling effect of wind can be moderated by the use of insulation and/or a wind breaker. Someone is more comfortable wearing a wind breaker in a strong breeze. In a strong winter breeze one would have to add a sweater (insulation) under the wind breaker in order to achieve the same relative comfort. When weathermen talk about outdoor temperature condition they often refer to the wind chill factor. The wind chill temperature is always lower than the air temperature. The movement of air indoors is not generally referred to as "wind", however, the effect of air movement indoors is the same as outdoors - it has a cooling effect - it does not make you warmer. Air movement is often introduced into indoor living areas in a number of different ways; a few of the prime examples are as follows: Outdoor air infiltration that causes noticeable drafts through leaky doors, windows and other openings. Forced air systems and fans that mechanically move the air Natural convection of air from a hot radiator surfaces in the primary living areas. The most uncomfortable type of indoor air movement (draft) is outdoor air infiltration that causes noticeable drafts. Just as you would wear a wind breaker for comfort in windy outdoor conditions you want the shell of your home to act as a wind breaker for indoor comfort. No amount of insulation will help if you have drafts from the outside blowing in around it. The only way to counteract the effect of this type of indoor wind chill is massive amounts of hot air which will mask the effect of the infiltration. However this is accomplished at a high energy cost and only marginal improvement in personal comfort. The first line of defense in any home heating plan is reducing the air infiltration so that drafts from the outside are not noticeable. Only after this problem is fixed should someone turn their attention to other issues in the home heating plan. In the United States the use of forced air heating systems is so pervasive that it is difficult for most people to imagine any other way of heating their home. The fact that these systems produce indoor wind chill is accepted as a necessary evil. These systems typically force heated air into a room at the outside walls (usually under the windows) and then extract return air from locations high on interior walls. This forced air ducting arrangement results in relatively strong drafts at the ceiling level while minimizing drafty conditions at floor level. In a room with standard eight foot ceilings the movement of the heated air at ceiling level mixes fairly well with the cooler air lower in the room but there is always a marked temperature difference between the warm ceiling and the cold floor. In rooms with higher ceilings (especially vaulted ceilings) the mixing results of warm air near the ceiling and cooler air near the floor is compromised by the greater separation and larger volume. In order to compensate for this, more heated air is required and more mixing of air is required. This results in more air movement and more indoor wind chill. It is not unusual for someone seated in a vaulted ceiling room during cold weather to wrap a blanket around them self as a shield from this intensified indoor wind chill. Hot radiators cause air movement through natural convection which is then felt as indoor wind chill. The best known example of this is the wood stove where surface temperatures often run between 400 - 600 °F. At these temperatures when the air in the room makes direct contact with the stoves surface it expands dramatically and quickly rises to the ceiling. Other air follows behind creating a draft at floor level in the direction of the stove. This draft is quite cool because it comes off the coolest surfaces in the room usually the least insulated window areas. The wind chill effect from the combination of hot stove surfaces combined with cold window surfaces is very noticeable. Less noticeable wind chill is felt from electric resistance or hot water radiators placed on outside walls (usually under windows). These radiator heat systems send heated air up along the cooler surfaces in the room to the ceiling level. Cooler air to replace the heated air is drawn along the floor toward the radiator but it comes from warmer areas of the room resulting in less indoor wind chill than with a wood stove or other centrally located radiators that would tend to draw air from the outside walls and windows. The question is often asked, "Wouldn't it be a good idea to use a ceiling fan to blow the hot air near the ceiling down to the floor or reverse the fan and draw the cool air up to the ceiling?" On close examination, this solution, could come right out of the pages of Alice in Wonderland. When the ceiling fan is used in the winter time to "blow" the warm air down you almost always can see the slowly turning fan blades, which means it is not really blowing the warm air down but rather just stirring it up at the ceiling level. If the fan were actually run at a high enough speed to blow the air down (or draw the air up), the wind chill factor in the room would increase substantially and your comfort would decrease. On the other hand, in the summer time, when you have hot air at the ceiling and relatively cooler air at the floor, you can turn on the ceiling fan, force the hot air down on you and the indoor wind chill will make you feel cooler and more comfortable. The fan cools in winter and it cools in summer - period.

Types of Heat Transfer

By Doug Hargrave

Mid Atlantic Masonry Heat
radianthomeheating.org

Radiant heat is transmitted from a warm object to a cooler object through infrared radiation. This is the same type of heat transfer that takes place when the rays of the sun shine on the earth. The distance between objects, their surface area and their temperature difference affect the rate of the radiant heat exchange. A good example of radiant heat transfer is the warmth you feel when you sit close to another person. Another example would be the way a radiant heater warms the surfaces and objects inside a home rather than the air.

When the distance between two solid objects of differing temperatures goes to zero and they come into direct contact, the heat exchange between them is then called conduction. Conduction between solid objects results in a faster rate of heat exchange than that of radiation. A good example of this difference is the amount of heat one would feel holding their hand just above a hot stove (radiation) versus actually touching the stove (conduction).

Heat transfer within solid objects is accomplished through conduction. The heat storage capacity and the transfer rate will vary with different solids. For example, the higher density of soapstone allows it to absorb and then radiate more heat per unit volume than common brick which has a lower density. The heat transfer rate within metals is much faster than the transfer rate within masonry materials.

Heat transfer within gases is quite different from heat transfer within solids. Gases have relatively little mass (weight) and very little density (weight per unit volume) when compared to solids. Unlike solids gases can dramatically expand or contract their density. Their density expands when they are heated and contracts when they are cooled. Warm gases that are expanded are lighter than cool gases that are contracted. The difference in weight causes warmer gases to rise and cool gases to fall creating movement within the body of gas. This movement is called convection. The speed of the convection (movement) is largely determined by the how much and how quickly heat is introduced into the body of gas. For example, a 600 degree wood stove causes much more convection (air movement) than a 200 degree masonry heater in the same living area.