* How Do Pellet Stoves Work?

* What types of pellet stoves are available?

* What size stove is best for me?

* What stove features should I ask about?

* What factors determine appliance location?

* What are my choices for floor protection?

* What electrical requirements should be checked?

* What are the purposes of venting systems?

* What materials and products can be used to vent pellet stoves?

* What are my options for venting layout?

* Besides appliance requirements, what other factors may be considered in specifying pellet venting systems?

* How should pellet venting components be assembled and joined together?

* What's a good starting point for learning to operate a pellet stove?

* How do I start a fire?

* What if the stove doesn't start properly?

* What do I do after the stove starts?

* What are signs of performance problems?

* How do I shut the stove down?

* What happens in an unexpected shutdown, such as a power outage or component failure?

* What are the routine things that I do to keep my stove working right?

* What are some of the more advanced maintenance tasks?

*   How Do Pellet Stoves Work?

            Stove diagram Pellet appliances automate as many functions as possible. The most significant is fuel delivery. The heat setting made by the operator controls an auger or similar feed device that delivers regulated amounts of fuel from the hopper to the fire (Figure 2). The upper part of the picture show a Top Feed Stove, while below shows a Bottom Feed Stove.                  

                Automatic fuel delivery from the hopper frees the operator from frequent attention and loading, while providing clean burns and the desired comfort level. The amount of air needed for optimum combustion efficiency is delivered automatically or with minor manual adjustments. In most designs, a fan delivers air to the fire and blows exhaust by-products out of a vent pipe that is smaller and typically less expensive than a chimney (Figure 3). 

In most designs, a fan delivers heat to the home by blowing air through heat exchangers in the stove and out into the home. Heating efficiency is greatly enhanced by removing the heat from the appliance before it can exit the system.

*   What types of pellet stoves are available?

Pellet stoves come in a wide range of style, size, and finish. The first choice is the basic configuration of the appliance. Freestanding pellet stoves (Figure 4) offer great flexibility in installation choices. Supported by a pedestal or legs, they are designed to be installed in almost any living area of the home (restrictions may apply to sleeping areas). Freestanding stoves are placed on a non-combustible floor protector. They are installed a specified distance from combustible surfaces that is usually smaller than that required for comparable cordwood appliances. 

 Fireplace inserts (Figure 5) are installed in existing, working fireplaces.  A decorative panel covers the space between the insert and the fireplace opening. Some pellet inserts are approved only for use in masonry fireplaces, while others can also be installed in approved factory-built metal fireplaces. 

Built-in appliances (Figure 6)

 are an economical choice that offers homes without an existing fireplace the look of an insert in a fireplace setting. A unit tested and listed as a built in can be boxed in with close clearances to combustible framing. Noncombustible materials like brick can be applied to the area around the front of the unit to give the appearance of a fireplace. A noncombustible floor protector is required, sometimes with spacers to provide an air space under the unit. Pellet furnaces are large units designed to heat an entire house through duct work. They are usually installed in a basement or other non-living area of the house. Like pellet stoves, furnaces require venting to the outside.

          Pellet stoves are also categorized according to their method of delivering fuel. Top feed stoves deliver pellets from a tube or chute above the fire, and bottom feed stoves deliver pellets from behind or beside the burn pot directly to the fire (see Figure 2). There are many variations within these categories, but in general, bottom feed stoves tend to perform better with the wider range of ash content in standard grade fuel because the feeding action moves ash and clinkers away from the burn area. This action helps keep air inlets open and thereby reduces the frequency of cleaning the burn pot. Top feed stoves may have some advantage in overall heating efficiency since pellets remain in the burn pot until they are completely burned, and exhaust gases tend to move slower, allowing improved heat transfer. Special grates or rotating burn pots in some top feed designs can also move ash and clinkers from the air inlets to reduce maintenance frequency. If only standard grade pellets are available, or if there is a desire to burn a higher ash or special fuel like corn or nut hulls, special attention must be paid to the issue of fuel delivery, ash content, and stove compatibility. Otherwise, design differences are less significant considerations of relative degrees of efficiency and maintenance frequency.

*   What size stove is best for me?

The wide range of heat output possible with pellet stoves reduces the number of different stove sizes needed for most heating situations. Within the range of pellet stove sizes, choices involve input from different sources. Information from manufacturers is of necessity general in nature given the many variables in climate, home construction, and personal comfort. Btu output and efficiency ratings must be qualified to be useful. Overall efficiency, a measurement of the percentage of the energy available in a fuel that is actually delivered as heat in the home, is more important than combustion efficiency, a measurement of the percentage of available energy that is converted to heat (some of which escapes through the vent). A knowledgeable dealer is the best source of information about sizing. You can help the dealer by providing information about factors that affect stove sizing:

* Your intended purpose:   primary or backup heat source for the 

                                                   entire house or a selected area
* House size and layout:    sketch with room and house size estimate

                                                   or building plans very helpful
* Heating characteristics    insulation and tightness

                     of your home:   of construction
* Your idea of comfort:        day and night.

*   What stove features should I ask about?

Stove size, type, and appearance generally begin the process of appliance selection. The choice may then include considerations of performance, convenience, and cost. Operational convenience is affected by a number of design features. Hopper capacity, which ranges from under 40 to over 100 pounds, plays a role in loading frequency. Hopper size should match heating needs on a reasonable loading cycle, typically once daily. The means of adjusting controls affect convenience also. Manually controlled stoves require occasional adjustment of air inlet dampers as the fuel feed rate is changed. Stoves with more sophisticated controls are able to monitor burn conditions and make these adjustments automatically. The choice may focus on the lower cost of manual stoves versus the value of minimal interaction with stove operation. Some owners prefer the reduced attention of automatic air controls while others enjoy more active participation in tending the fire. Features which affect ash tolerance and fuel compatibility may influence both performance and convenience, particularly in regions where fuel grade choice is limited. While many newer stoves perform well with increasingly wider ranges of fuel, some designs are better at extending good performance with longer intervals between routine maintenance. Bottom fuel feeding moves ash and clinkers away from air inlets. Specially designed grates in top feed designs either allow heavier ash and clinkers to fall through to the ash drawer, or they rotate themselves to move ashes and keep air inlets open. In both stove designs, a larger ash drawer reduces ash removal frequency, and grates which can be dumped without stopping operation add convenience. As long as a compatible pellet fuel is available, the issue of ash tolerance is one of convenience, not the acceptability of stove design. Ease of maintenance is enhanced by features that make routine cleaning tasks easier. The heat exchanger can be cleaned by simply moving an external rod handle back and forth on some stoves. Other designs demand a more involved cleaning procedure. Ask the dealer to demonstrate heat exchanger cleaning as well as access to ash traps, receptacles behind the fire chamber designed to separate fly ash from the exhaust. Although pellet stoves are safety tested as a solid fuel heater by an accredited laboratory, stoves safety tested to ASTM Standard E 1509 undergo stringent testing specifically designed for pellet appliances to assure their safety and performance reliability . Other features bring added convenience and enjoyment:

* Automatic ignition. Offers simple, reliable startup. Typically more desirous on stove used intermittently than on one used continuously.
* Remote thermostatic control. Controls heat output based on room temperature. Ensures even temperature from unattended stove regardless of changes in the weather. Discuss with the dealer the merits of thermostats and stove startup design: automatic ignition stoves cycle on and off according to heat demand; manual start stoves keep fire at low setting and return to high.
* Large glass view and air wash system. Offers fire viewing, particularly enjoyable in living area installations. Air wash keeps glass clean by directing warm air over the glass during combustion.
* Imitation log sets (stove manufacturer approved only). Improve aesthetics of the fire. May increase frequency and difficulty of maintenance; ask if removable.
* Blower quietness. A concern in some areas of the house, depending on room use and personal preference.
* Backup power source. Consideration for primary heat stoves in areas subject to frequent power outages. Should automatically switch from utility power to battery and back again.
* Extended warranty for components. Low cost, high value extension of warranty on components (from normal one or two years to as many as five).

*   What factors determine appliance location?

For maximum enjoyment and heating effectiveness, a major living area where the family spends leisure hours and which provides heat flow to other areas is usually a strongly preferred location for the stove. The pellet heating professional considers the factors that determine whether installation requirements can be met in the homeowner's preferred location:

     * Venting.  May be limited by factors like obstructions

                         above vertical venting through the ceiling and

                         roof or by the distance to an outside wall for

                         horizontal venting.

     * Outside air for combustion ( if needed). Must be drawn 

                                                      from an approved location.

     * Space requirements.  Must meet minimum clearances

                                                 between the stove and

                                                 combustibles. More space than

                                                 the minimum required may be  

                                                 desirable to provide room for

                                                 convenient operation and

                                                 service.

     * Electrical requirements.    Proximity to properly

                                                        wired  outlet.

*   What are my choices for floor protection?

The floor must be protected according to manufacturer's instructions. The minimum size of the noncombustible floor protector is clearly specified in installation instructions. The choice of suitable materials usually requires professional assistance if a suitable hearth is not already available in the home. Built in appliances may require additional protection such as an air space between the appliance and the floor protector.

*   What electrical requirements should be checked?

The dealer or installer should check the intended appliance outlet for proper voltage, ground, and polarity. The electrical circuit to be used should have a properly rated circuit breaker.  Are there special requirements for mobile home installations? The model you choose must be approved for use in a mobile home. The U.S. Department of Housing and Urban Development (HUD) makes additional requirements for solid fuel burning appliances installed in mobile homes (Figure 7), which are listed in stove manufacturers' installation

*   What are the purposes of venting systems?

Proper venting is an essential for proper appliance performance, dwelling safety, maintenance frequency, and indoor environment. Pellet stoves produce little or no visible smoke after startup, but exhaust gases, fine ash, and water vapor must be removed safely from the appliance to the outdoors without leaking into the house. The purpose of all vents is removal of combustion by-products during normal operation. For most designs, the exhaust is mechanical: a fan blows the combustion by-products out and pulls air needed for combustion into the fire. A few stoves operate without a combustion air fan and use natural draft both for exhaust and combustion air intake. Some heat also moves through the vent. Protection of nearby combustibles is essential. The minimum clearance between the vent and combustibles, as specified in the vent installation instructions, must be met or exceeded to assure safety.

*   What materials and products can be used to vent pellet stoves?

The product specifically tested and listed for use with pellet stoves is PL vent pipe, labeled as tested to UL 641. PL vent pipe is double wall pipe; the stainless steel inner pipe that carries the exhaust products is separated from the outer wall by an air space. Pipe joints must be sealed gas tight to prevent exhaust products moving through the vent under pressure from leaking into the home. Stoves tested and listed requiring PL vent must use no substitute venting materials.

Venting materials and products that MUST NOT BE USED TO VENT PELLET APPLIANCES include:

* Dryer vent
* Gas appliance (Type B) vent
* PVC (plastic) pipe
* Single wall stove pipe (unless clearly approved by the installation manual and local codes)

Pellet fireplace inserts and freestanding stoves are often vented into existing masonry and factory-built fireplace and woodstove chimneys (Figure 8). The chimney- should be inspected before installation to ensure that it is clean, mechanically sound, and meets local safety code requirements. The appliance manufacturer's installation instructions may require relining the chimney with an approved metal liner, pipe, or PL vent. Vents or grilles on the face of factory-built fireplaces which provide cooling air to the outside jacket of the fireplace must not be blocked. Cleanout access for future maintenance should be considered.

*   What are my options for venting layout?

Mechanical Exhaust:

* Sidewall horizontal venting (Figure 9). Invariably the least expensive venting system. Disadvantage of potential smoke spilling into the house in the event of a power outage or component failure, or house depressurization (see discussion of next question).

* Horizontal vent with backup vertical venting (see Figure 10). Preferred horizontal method that avoids venting problems associated with unexpected appliance shutdown.

* Vertical venting through

   the ceiling and roof  

(Figure 11). Has the advantages of keeping vent gases warm and of providing natural draft to prevent problems in an unexpected shutdown.

* Venting into existing chimney (see Figure 8). Stove manufacturers provide recommendations for venting into masonry and factory-built chimneys, which may include partial or full chimney relining.
* Natural Draft: All vents for appliances designed without mechanical exhaust fans must meet stove manufacturer's requirements for minimum draft and must terminate above the roof.

* Vertical (Figure 12) Extends up from the stove and penetrates the ceiling and roof . Horizontal and vertical (Figure 13). Extends from the top or back of the appliance, penetrates the wall, turns up to penetrate the eave and roof. · Venting into existing chimney (see Figure 8). Follow manufacturer's recommendations for venting into masonry and factory-built chimneys, which may include partial or full chimney relining.

*   Besides appliance requirements,  what other factors may be considered in specifying pellet venting systems?

The following factors may play a role in 

     the designation of the venting system:

          * Altitude: High altitude installations, generally higher

                              than 2500 feet above sea level, may require

                              special venting options to provide adequate

                              combustion air and/or draft.

                   
          * House Pressure:  Extremely tight house construction

                                               or strong kitchen, bath, or other

                                               exhaust fans may create a

                                               negative pressure within the home

                                               that decreases venting

                                               effectiveness. May necessitate an

                                               approved outside air source.

          * Windy Conditions. Unpredictable effects of high

                                                 winds or prevailing wind

                                                 conditions may necessitate the

                                                 addition of vertical venting

                                                 extending above the roof and/or

                                                 special termination caps.

          * Cleanout and Maintenance: The venting system

                                                                  must be designed with

                                                                  normal maintenance in

                                                                  mind.

*   How should pellet venting components be assembled and joined together?

Appliance manufacturer's instructions should be followed closely regarding sealing joints and seams, particularly of pressurized mechanical exhaust vents. It is imperative that they be gas tight so that they cannot leak. Proper application of an approved sealant or sealing band is typically required. Appliance manufacturer's instructions for pipe sealing which exceed vent manufacturer's instructions must take precedence. You can get a sense of what heating with pellets involves through an introduction to the principles of operation and the reasons for maintenance that you will come to understand as an experienced operator. 

*   What's a good starting point for learning to operate a pellet stove?

The rule here is When all else fails,   "Read the instructions." 

    Operating a pellet stove is not difficult, but it is a new technology that calls for basic knowledge. Training videos accompany some stoves, and hands on demonstrations by many dealers and installers. Find a dealer that carries your type of stove, or try finding an operations manual online from your stove's manufacturer's.    

    We at All Basics Stove Shop provide further support by having an informative   OPEN HOUSE   each spring for our pellet stove customers. 

*   How do I start a fire?

         Small dry fuel (pellets) and combustion air provided by a fan on most designs make startup easy. Operating instructions provided with the stove give the specific steps to follow. Manual ignition stoves call for the owner to apply an approved gel or solid starter material (no liquids), light the pellets, and monitor the fire to see that the fire catches and the flame gradually grows. On automatic ignition stoves, pushing the start button feeds pellets to the burn pot and heats the self-igniter device.

*   What if the stove doesn't start properly?

           A safety device monitors startup and stops fuel feed if operating temperatures are not reached within a specified time period. If startup fails, the operator makes sure that the hopper has fuel, that fuel is feeding, and restarts the stove. Repeated failed lighting cycles indicate the need for maintenance or professional service.

*   What do I do after the stove starts?

          After control panel or air inlet adjustments and a quick performance check, the stove is set to provide hours of even, comfortable heat. Stoves equipped with a remote wall thermostat respond to owner setting and room air temperature by cycling on and off or by cycling from a low to high burn, depending on stove startup design.

*   What are signs of performance problems?

          Properly operated and maintained pellet stoves experience few, if any problems. Most of pellet stove operation is automatic, but sometimes combustion air adjustment is needed. A lazy, orange, sooty flame or dark smoke coming out of the vent (after startup and before shutdown) may indicate the need for more air. An overactive, "blow torch" flame calls for less air." Performance problems are more likely to be caused by neglected maintenance than by operation. Lazy flame, dark smoke, unusual sooting of glass, unexplained smoke spillage, and reduced heat output all point to the need for maintenance of appliance components and/or the venting system or for remedies for house depressurization. Problems related to mechanical failure usually result in safety switches shutting the appliance down. Appliance shutdowns may, however, indicate nothing more than owner forgetfulness (empty hopper) or hurry (improper startup), or intermittent power failure. Unexplained, repeated appliance shutdowns call for professional advice and service.

*   How do I shut the stove down?

          Shutting the stove down is typically a matter of simply setting the control to the Off position according to operating instructions. The fuel feed stops delivering fuel right away, and after the stove cools sufficiently, all motors and blowers cease operation. The stove should NOT be shut down by unplugging the power cord.

*   What happens in an unexpected shutdown, such as a power outage or component failure?

             Although fuel feed stops in a power outage, the pellets in the burn pot may continue to burn or smolder. The duration of this condition can vary with appliance design from a few minutes to an hour or more. The resulting smoke and hot gases rise, seeking the path of least resistance. If the exhaust vent does not have vertical sections to provide natural draft, smoke may spill into the home (Figure 14).

*   What are the routine things that I do to keep my stove working right?

Routine maintenance tasks are essential to peak stove performance:

* Burn pot (Figure 15). Checked daily and cleaned periodically to keep air inlets open. Frequency of cleaning depends on fuel type, grade, and content.
* Ash drawer (see Figure 15). Emptying recommended before starting new fires and occasionally by interrupting stove operation. Frequency depends on fuel and stove design. Typically once or twice a week, but monthly in some new designs.
* Heat exchanger (Figure 16) On some stoves, simply a matter of moving a rod that scrapes the tubes inside the stove. May require professional service on others.
* Ash traps. Chambers located behind the fire chamber which prevent excess fly ash in the exhaust from exiting the stove. Easily accessed for ash removal by owners in some designs; on others requires professional service.
* Glass. Cleaned with glass cleaner when the glass is completely cool on stoves with effective air wash systems. May require more vigorous methods on others.
* Hopper. Checked for accumulated sawdust materials (fines). Fuel in the hopper and auger tube should be run out occasionally to prevent auger blockage by fines.

*   What are some of the more advanced maintenance tasks?

   Cleaning the venting system is usually performed by professionals (see below), but can be tackled by the handy stove owner with thorough knowledge and the right equipment. Motors and fans need occasional cleaning and may require lubrication. The wrong lubricant or wrong amount of lubricant can damage components. Some components which call for removal for service require replacement of a gasket . Gaskets for the fire chamber door, ash pan door, and hopper lid (on some designs) may need occasional replacement to assure a tight seal.

*   What professional maintenance and repair services will I need?

         Most pellet stove owners depend on professional service for cleaning and preventive maintenance on at least an annual basis. Many dealers offer service plans that offer reduced costs and convenient scheduling. 

Cleaning and maintenance services usually performed include:

          * Emptying ash traps and cleaning exhaust passages 

             behind the fire chamber.
          * Cleaning and lubricating fans and motors.
          * Cleaning the hopper and fuel feed system.
          * Cleaning the heat exchanger system.
          * Cleaning exhaust pipes and resealing the venting system 

             if needed.
          * Verifying and adjusting the stove settings with proper 

             gauges and meters.
          * Mechanical and electric components may eventually wear 

             out and need repair or replacement.

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