Consumer Guide to Heating with Pellets

As you choose the appliance, you will be asked to provide information and make decisions about installation details. Professional guidance in these matters is both helpful in choosing the optimum system for your needs and essential to proper performance and safety. Knowing installation basics can help you communicate your preferences and understand professional recommendations.

The Placement

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.

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 instructions.

Venting

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.
  

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?