Pellet Stove Pipe

Pellet stove pipe, or PL vent is specially made for pellet stoves and is specified by most manufacturers in their installation instructions. Pellet pipe comes in internal diameters of either three or four inches.

The actual diameter of the pipe will be larger than this depending on the size of the air gap between the inner and the outer walls favoured by the manufacturer.

Pipe with a larger air space between the walls often has a better rating for clearance to combustibles which is normally three inches but can be as little as one inch.

If you are considering using pellet stove pipe with an enhanced combustible clearance rating, check your local building codes to make sure that you will be able to use the enhanced performance.

From the US Pellet Fuels Institute: -
"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 Stove Pipe Explained

The air gap incorporated into pellet stove pipe is there because the flue gases from a pellet stove are cooled when they pass over the heat exchanger and exit at a lower temperature than a woodburning stove.

The air gap helps to stop the exhaust gases cooling and condensing water vapor in the flue. The water contained in the exhaust combines with the flue gases from burning to form a corrosive acid which can rot the inner flue. This is even more likely if corn is being burned. For this reason, it's best to keep the run of the pellet stove venting inside the building where the flue will not become chilled.

If you are considering burning corn either by itself or mixed with wood pellets, it's best to go for a multi-fuel vent pipe with increased corrosion resistance.

An additional benefit is that this insulation keeps the outer pipe cool and allows it to run closer to combustibles than a single wall flue. In the UK, building regulations still require a pellet stove to be vented with the same type of flue as a woodburning stove.

PL vent inner pipe is made from stainless steel of varying grades to combat this corrosion. The outer tube is made from galvanized steel, aluminized steel, or painted with high temperature paint. The pipe is tested to 300¡C. / 570¡F.

A system of PL vent pipe is available which uses the air gap between the inner and outer walls to introduce outside air to the stove. On the face of it, this is a neat solution and avoids having a separate outside air pipe. The downside is that chilled air from outside the building will chill the inner vent pipe and may cause unwanted condensation.

Pellet Stove Pipe Manufacturers

Different manufacturers use various methods of making the joints between sections of pipe airtight. This is important because the venting system is pressurized by the combustion blower and if the joints are not airtight, smoke and fumes might enter the living space.

Most PL vent sections lock together with a screw action, but this is not enough by itself. Some systems incorporate a silicone 'O' ring, a ceramic fiber gasket, or a manual application of high temperature silicone to each joint.

American Metal Products produce 'Amerivent'
BDM make 'Bio Vent'
ICC produce 'Excel' pellet vent
Lennox Hearth Products offer 'Security Chimneys'
Metal-Fab inc. make 'Biomass Chimney'
Selkirk produce pellet stove pipe under the names MetalBest, SuperPro, SuperVent and Energy Vent
Simpson Dura-Vent make PelletVent and PelletVentPro

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