Warming Up To Outdoor Wood Heaters
Humans have been burning wood as a primary source of heat for many
centuries, and its use has evolved greatly over time. Along with demand
for new applications and means of increasing the use of inexpensive and
renewable wood heat, environmental concerns have also grown. The wood
heat sector has responded by producing cleaner and more efficiently
designed units for a multitude of applications, from residential-sized
outdoor wood boilers for heating swimming pools to commercial-sized hot
air pellet furnaces for heating poultry farms.
Current trends in the small-scale wood heat sector lean toward
indoor wood chip and pellet boilers and stoves, but traditional outdoor
wood boilers, or hydronic heaters, are still widely used today, despite
the units being amongst the most heavily scrutinized appliances in the
wood heating sector. This likely spurred the outdoor wood industry to
approach the U.S. EPA requesting more regulation, to move away from the
wood heat pollution poster child it had become.
The EPA’s New Source Performance Standard for residential wood
heaters has been around for years, but proposed changes place pressure
on all manufacturers to redesign wood heaters to become cleaner and
lower emitting. Many manufacturers are embracing the proposed emission
standards and have produced models certified by EPA’s phase-two
voluntary program, which requires no more than 0.32 pounds of fine
particles per million Btu of heat with a maximum individual test run of
18.0 grams per hour. These furnaces virtually shatter every preconceived
notion about emissions and efficiencies of wood heating. Non-EPA
qualified, traditional outdoor wood furnaces that are purchased before
the final rule will be grandfathered in.
The final rule is expected to be announced in 2015, and although
the heat is on, many manufacturers are optimistic about adapting to the
changing standards. Northwest Manufacturing Inc. WoodMaster and Central
Boiler Inc. are two of the manufacturers working with the EPA to set new
testing standards, and have EPA qualified models available for
purchasing. Lee Energy Solutions LLC is another manufacturer in the
sector creating carbon neutral, commercial pellet furnaces in the U.S.
South, for use predominantly at poultry farms and greenhouses.
The environment and customers are meant to benefit from the
standards; they may even be warming up the public to the idea of the
units as an option for clean, safe and efficient energy. John Ackerly,
president of the Alliance for Green Heat and board member of the Biomass
Thermal Energy Council, believes the way to move forward is to have
restrictions. “These regulations help the industry maintain standard,
public support for the technology, and it makes us have a higher
priority on clean air,” he says.
Clean air is something outdoor wood and pellet heating systems
can offer. According to studies posted by Central Boiler Inc., there are
more than 16 million fireplaces used in homes in the U.S. with
reportedly only 200,000 outdoor wood furnaces. Many wood boilers can
actually heat a home with less wood burned and far fewer particulate
matter (PM) emissions than heating the same home with fireplaces. This
is because the number of fireplaces or wood stoves required to heat the
home would have comparable emissions to those from a single outdoor wood
furnace heating that same home.
When choosing between these indoor and outdoor options,
manufacturers say outdoor models work better to uniformly heat the
entire home without a mess. “Outdoor is typically designed for home
heating to keep the mess and fire hazard outside, and have the option to
heat multiple buildings,” says Chuck Gagner, president of Northwest
Manufacturing Inc. WoodMaster.
Minidistrict heating is what Gagner is referring to, or the
ability to heat multiple buildings. The wood heat sector sees this as
one of the best applications of the technology, in which two or more
buildings are heated from the same boiler in the yard.
If an outdoor boiler is a desired option, there are a few
considerations to take into account; the type of application should be
the first. After determining the application, time must be dedicated to
understanding details of how to operate the machinery, as well as
weighing the pros and cons of each unit. And because of policy changes
surrounding the units, what manufacturers are doing to improve the image
and efficiency of their products may be something to consider.
The type of application and surrounding conditions will help
determine whether the desired benefits are attainable. Ultimately,
outdoor furnaces should be considered as a replacement when wanting heat
for an entire building. “An outdoor wood furnace is a good choice for
replacing fossil fuel energy when the goal is to replace the entire heat
load with wood-fired energy that can be thermostatically controlled
heat for entire homes and other applications,” says Rodney Tollefson,
vice president of Central Boiler Inc.
Outdoor wood heating has primarily been applied in rural, colder
climates where end users can source their own wood. Central Boiler’s
main applications are for home and domestic water heating. “Other
applications are resorts, lodges, swimming pools, greenhouses, brooder
barns, dairy farm water heating, warehouses, small businesses,
aquaculture and snow melt,” Tollefson says.
Often, use of these units derives from identifying the need for
it personally. Suppliers to the industry are no exception. “I had a
need, personally, for an outdoor furnace, and living and working on the
farm with access to equipment, I just built my own furnace,” Gagner
says. “I built the first furnace and then started the company and
partnered with my brothers.”
Warmer climates have also been brought into the sector looking
for an alternative. “We were agricultural guys looking for an option
held hostage by propane,” says Wes Cumbie, Lee Energy Solutions vice
president of sales and marketing.
The use of biomass such as wood chips and pellets is one way to
loosen dependence on fossil fuels and foreign oils. “Wood pellets are
much more stable on a cost per million Btu basis, probably the most
stable fuel, whereas propane and fuel oil are the most volatile fuel
sources,” Gagner explains.
Although a stable fuel source, people in the wood heat sector
stress that the treatment of the fuel will determine the success and
amount of smoke of the wood heating system. According to Cumbie, Lee
Energy’s dry heat furnace, “when running at 100 percent burn rate, a
cigarette puts off more smoke.” One reason for the disparity in smoke is
how the unit functions. In a nut shell, the company’s furnaces heat
air, and then a blower motor moves the warmed air through a duct system.
A boiler heats water, which then flows through a network of pipes in a
building or home. When it comes to boilers, successful fueling of the
system boils down to the enduser. One of the keys is to use dry,
seasoned wood. “Seasoned wood is by far cleaner, more efficient, uses
less fuel and is less corrosive,” says Jeremy Hanson, Northwest
Manufacturing Inc. WoodMaster commercial sales representative.
“If you want to get the most out of your wood, you should be
cutting and seasoning it a year before you burn it,” Tollefson adds. “It
will reduce your wood consumption by 20 to 30 percent; when you have
unseasoned wood about 50 percent of the weight is water.”
Users also “need to be absolutely confident that whatever boiler
they choose it’s properly sized,” says Charlie Niebling, chair of BTEC
and consultant with Innovative Natural Resource Solutions LLC. Properly
sizing the unit will ensure even heat throughout the home, as well as
achieving the highest efficiencies possible. When properly sized, many
wood heating systems burn for 12 hours before they need to be reloaded.
Efficiencies range based on the model of the furnace.
Manufacturers will agree that some of the older models lack in
efficiency, but that the EPA phase two certified models are
demonstrating efficiencies as high as 90 percent. “Central Boiler
furnaces can operate with efficiencies between 60 and 90 percent,”
Tollefson says. “The Central Boiler E-Classic furnaces have been tested
at 80 to 90 percent efficient.”
WoodMaster has similar ranges with their EPA certified
gasification models in the 80 to 90 percent efficiency range. Lee Energy
also demonstrated comparable efficiency at 80 to 82 percent with the
unit capability of 66 pounds of pellets an hour, at 540,000 to 550,000
Btu. The combustion of WoodMaster and Central Boiler furnaces were more
difficult to estimate with the wide range of units. “Normally, the
heaters we sell are for heat loads of 50,000 to 350,000 Btu per hour for
residential applications,” Tollefson says.
Beyond the sizing of the furnace, the installation of the unit is
important to ensure efficiency. “The furnace is usually installed 30
feet or more from the building or buildings being heated,” Tollefson
Lee Energy’s commercial pellet furnaces are typically set on
concrete pads outside the structure to be heated. “We will set our
heater on that pad and then right next to the heater will be a 15 to 20
ton storage bin that pellets go into in bulk, and they are automatically
loaded through an auger feed system,” Cumbie explains. A customized
collapsible duct system is also installed.
The outdoor hydronic heater is designed to work with any existing
heating system. Water-to-air or water-to-water heat exchangers or
direct circulation conveys the heat into the structure’s forced-air
furnace, radiant baseboard or radiant floor heating system. This allows
for normal thermostatic temperature control.
While it is important for customers to know the basic set up of
their desired wood heating system, what many direct their attention to
are the major benefits and drawbacks.
Pros and Cons
The main drawbacks to wood-burning systems result from
maintenance and user error. Ash buildup needs removal every week or so,
depending on how much wood is being burned. Lee Energy’s BIO pellet
furnace needs cleaning just about every day if burning hard. Beyond
general ash removal, some are deterred from the labor of manually
loading many of the outdoor furnaces once or twice a day.
The biggest drawback comes with the customer’s capacity of
misusing the technology. “It is very difficult to control how people
choose to use the equipment, namely what they choose to burn,” Hanson
says. “If they are burning wet wood or nonbiomass materials, emissions
are a concern.”
Although there are a few setbacks to the technology, it is the
benefits that increasingly draw customers to the products. “The No. 1 is
fuel savings, significant fuel savings,” Hanson says.
The prices of Central Boiler and WoodMaster units are comparable.
“The units themselves run from about $5,500 for residential on up to
about $12,000,” Tollefson says. “You are going to have anywhere between
$1,000 to $4,000 in labor and parts involved in installing them.”
Commercial sizes run higher. “The typical layout of what a
customer buys for turnkey ducting, manufacturing, installation, brings
the unit to around $17,000 to $21,000 depending on where you are,”
Many units last for 20-plus years, with fuel savings offsetting
the purchase price and installation of the units usually within the
first three years. “After that, it is in effect generating money
compared to fossil fuels,” Tollefson says. “We find more than 50 percent
of the people that own our furnaces cut their own wood, which results
in eliminating their heating costs. If purchasing wood, normally, they
save 80 percent of the heating cost.”
In addition, some insurance companies prefer outdoor wood burning
furnaces over indoor wood stoves because all combustion is removed from
the home or building. This removes the fire hazard and carbon monoxide
Beyond keeping a thicker wallet, the environment is another big
draw. Wood is renewable and considered carbon neutral, conserving fossil
fuels for the future and reducing greenhouse gas emissions.
Rectifying an Image
Innovation and collaboration with the EPA is at the forefront of
the change in image. Some manufacturers have worked closely with the EPA
in helping to set performance standards. WoodMaster’s gasification
models and Central Boiler’s E-Classic models both meet EPA’s voluntary
phase-two program standards, and are ready for the drafted NSPS. “There
has also been an effort to educate consumers of proper installation and
operating practices when using outdoor wood furnaces for the best
performance,” Tollefson says.
This education comes from many groups in the wood heat sector.
“BTEC, Pellet Fuels Institute, Heating the Northeast, and Heating the
Midwest do a great job of educating the general public and raising
awareness of the benefits of heating with biomass,” Hanson says. Best
burn practices have been developed in conjunction with EPA, Hearth,
Patio and Barbecue Association and manufacturers, he added.
Although the heat is on for manufacturers to produce cleaner,
more efficient units, it seems that the resulting innovation will
ultimately warm customers and the general public to the prospect of
outdoor wood heat, and spur advancement throughout the entire sector. “I
give a lot of credit to manufacturers, they’ve come a long way and have
worked very hard to improve the efficiency, combustion and
performance.” Niebling says.