Symptoms: Lazy flame, pellet buildups in the burn pot, and dark black ash or soot on the glass are clear indications of limited airflow.
Resolution: This video demonstrates the airflow circuit, and why it is important:
Cause: There are two main problems that lead to limited airflow.
- Negative pressure leakage - This is where the stove is drawing air incorrectly. Instead of pulling air through the pellets, it is pulling air around them. Common places where this occurs are:
- The bottom ash pan drawer - make sure that both side latches are snug and have even pressure.
- The burn pot itself - Make sure that the burn pot sits completely flush on the cradle. (this is very important) You want to avoid gaps around the bottom of the pot where air could spill out around the pellets instead of up through.
- The front door seal - Ensure that the gasket did not flatten or wear out, causing a leakage of air to be pulled in from this loose seal.
- Restrictions - this could occur when a buildup or clog starts to restrict airflow, and not as much volume of air is able to be drawn through the pellets, and thus slows the burn down.
- There are videos that may help illustrate the common areas that need to be cleaned that can lead to these sorts of restrictions.
- Refer to the “Maintenance Videos” section at: https://comfortbilt.net/pages/our-videos for more information on proper cleaning for your stove model.
- Or, you can check out the written guides here: https://cdn.shopify.com/s/files/1/0411/0670/2486/files/Guide-to-Stove-Cleaning.pdf?v=1597605162
Pellet quality will also play a huge role. If there is a lot of dirt or impurities in the pellets, there is a much higher chance for clinkers and blockages to occur in the pot.
How to tell if pellets are good: https://www.instructables.com/5-Easy-Ways-To-Determine-Quality-Of-Wood-Pellets-W/
How to test vacuum pressure/airflow within diagnosis menu:
- Press and hold the Enter button (left arrow) until the set data menu appears.
- Scroll down to #6 Diagnosis and press Enter.
- Once in, you can select the simulated combustion level H01-H05 (1-5 bars)
- Press the Enter button twice to select Exhaust
- Press Up arrow to engage the exhaust fan.
Now that the exhaust fan is engaged, as long as the ash pan and front door are sealed, it should create a vacuum pressure inside the main chamber.
Take a 1/2 sheet of standard printer paper, (torn in half width-wise), and hold it to the 2" intake pipe behind the stove. (You will need to remove your outside intake pipe if installed)
There should be enough pressure created by the exhaust system to hold the weight of that 1/2 sheet of paper. If you do not have any or very limited pressure, it could indicate a vacuum leak or blockage in the exhaust system.
While performing this test, you can open up the Tee cap at the base of the piping and then retry the test. If the pressure returns and holds the paper, it indicates the problem is up inside the piping between the Tee and the top exhaust cap. (usually a buildup at the bends, or at the cap itself).