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Harman pellet stove low draft set point adjustment cited & discussed at Inspectapedia.comDraft Adjustment on Pellet Stoves & Heaters
Several adjustment controls & methods

Pellet stoves usually operate using a forced draft that supplies combustion air and effects the exhaust of combustion products, but to readers unfamiliar with these devices it can come as a surprise that a typical pellet stove heater has at least two and some more than two adjustments to the stove's draft and to its heat output.

Here we describe various methods used to control the draft and airflow through wood-pellet burning stoves or heaters.

This article series catalogs and describes all types of air and draft regulation devices used in buildings where control of heating appliances is needed.

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Pellet Stove Draft Measurement, Settings, Controls

Lopi AGP Pellet Stove from Travis Industries at InspectApedia.comPellet stoves usually make use of a draft fan for proper burning, though in event of a power failure some models permit limited operation using natural draft.

A separate blower fan helps extract heat from the pellet stove and transfer it to room air.

Using Castle Pellet Stove's Serenity Pellet Stove as an example, here we illustrate examples of controls on pellet stove heaters, all of which ultimately affect the stove's exhaust draft.

Illlustration: The AGP Pellet Stove from Lopi, Travis Industries, excerpted from the company's instruction manual cited below. Travis Industries recommends a minimum vertical vent of 5’ to ensure adequate draft
during a power outage.

Other pellet stove installation manuals, for example the Harman Pellet Stove cited below, specifically describe using a manometer to check the appliance draft and may provide a mechanical adjustment of the combustion motor speed.

Harman specifies a normal pellet stove "high" draft (for their model) of -0.50 to -0.60 inches of W.C. (Water Column) and normal pellet stove "low draft) of -0.35 to -0.45 in. W.C.

Pellet Stove Exhaust Voltage Adjustment

From our same example pellet stove, the Serenity model, the manufacturer explains another control over pellet exhaust draft, the exhaust fan voltage.

Excerpt: Increasing the exhaust voltage, and thereby increasing the amount of air in the burn pot, will also assist in burning lowerquality fuels that may otherwise cause unwanted buildup.

The user can set the exhaust voltage, called "Stall voltage" at an of five settings between about 85V and 110V that in turn regulate the stove's blower.

Setting a higher voltage causes the fan to run faster, extracting more heat from the pellet stove.

Pellet Stove Exhaust Fan - Draft Fan

Serenity pellet stove control adjustment - Castle pellet stoves cited & discussed at InspectApedia.comFor example here is an excerpt from the Serenity Pellet stove produced by Castle:

Your stove is equipped with an automatic ignition system that should ignite the fuel within 3-5 minutes of pressing the On/Off button.

As pellets fill the burnpot and ignite, outside air is drawn across the fuel and heated during the combustion process which is then pulled across the heat exchanger by the exhaust motor or the draft fan.

As the stove reaches operating temperature, room air is then circulated around the heat exchanger by a room air blower, distributing warm air into the room. 

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Because a forced draft pressure is required for the combustion process inside your stove, it is extremely important that the exhaust system be properly installed and maintained.

Also, the doors must remain closed while in operations and the seals on the doors must be properly maintained. 

Watch out: implicit in the instructions just above is a mistake about which we warn with other heating appliances: woodstoves and coal stoves: leaving the combustion chamber ajar beyond during initial stove lighting procedures is very dangerous and can lead to severe stove overheating, damage, or even a house fire.

Pellet stove Airflow Gate Adjustment

Pellet stove air gate adjustement Serenity Pellet stoves by Castle cited & discussed at InspectApedia.com

This same Serenity pellet stove model from Castle includes an additional airflow or "draft" adjustment, the stove's airflow gate - shown below.

The airflow gate for this pellet stove is explained by the manufacturer:

IMPORTANT NOTE:

ADJUST THE AIRFLOW GATE BEFORE INCREASING THE EXHAUST VOLTAGE.

If you are having issues with getting enough air to your fire, FIRST try to adjust the air flow gate. SEE FIGURE 27. This will also adjust the air flow to the stove.

The exhaust voltage (controlling the combustion motor) allows you to adjust the stove for the fuel you are burning or compensate for inadequate ventilation situations.

In less than optimum venting situations, you can increase the exhaust speed for additional air circulation through the stove should ventilation be an issue.

Below: Illustrations from Harman's Pellet Stove IO manual showing how a manometer or draft gauge is connected to a service tee on the pellet stove to measure the stove's draft level, and a second illustration of the manual setting of the stove's low-draft set-point.

How to measure draft on a Harman pellet stove adapted, cited & discussed from Harman Pellet Stove manual cited at InspectApedia.com ... Harman pellet stove low draft set point adjustment cited & discussed at Inspectapedia.com

Pellet Stove Draft Adjustment Sources

 


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PELLET STOVE DRAFT CONTROL at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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