April 13, 2014

Boost Your Breckwell- Run on Heat Level 1 without Re-adjusting the Damper

 Breckwell Pellet Stoves sometimes have trouble running on heat level 1, especially when they get older. Older stoves have a buildup of calcium, iron and carbon deposits on the inside walls of the internal ash chambers. This is exacerbated at 3 AM when the diurnal variation of pressure is at it's nightime low. The control board does have an auger trim to increase the fuel feed on heat level one which feeds more pellets to keep the fire going but does not vary the combustion blower speed during this period to help increase the air pressure requirements to keep the vacuum switch closed and the stove running. The vacuum switch is a necessary safety device that cuts power to the auger and shuts the stove down when the combustion blower quits or dies so the house does not fill up with smoke. When Hi/Low mode is selected on a thermostat connected to a Breckwell stove, the temperature drops from the selected high heat level to low when the desired thermostat temperature is reached. The control board does not increase and decrease the combustion (exhaust) blower speeds so a the damper may have to be re-adjusted for the low setting or the stove may die out. The air inlet damper can only be set for heat level 1 or 3, not both at the same time. If you wanted to run the stove on heat level 1 and then change it  back to 3 you would have to adjust the damper again. I know a few people who own this stove and none of their stoves run well on heat level 1, especially if the altitude of the installation makes it hard to set the damper. Different air pressures at different altitudes make it difficult.  However, since the combustion blower always runs on high speed,  there is a way to boost the combustion blower and make up for this discrepancy and keep the same damper setting!

Pic 1 shows the new Breckwell control panel with the red backgound behind the On/Off button and the Fuel Feed button. The older panels have a yellow background. Also, On the new panels the heat level auger trim button labeled "Low Feed Adjustment" is labeled "Reset Trim" on the old panel even though the functioning stayed the same.

In the midst of rebuilding a Breckwell Big E, I found way of running the stove on heat level 1 especially in Hi/Low mode as well as all the other heat levels with the same damper setting. The stove I worked on needed a new exhaust blower and housing. I have a lot experience installing exhaust blowers for many stove brands. I found that Magnum Baby Countryside stoves using their upgraded exhaust blowers with large impellers burn wood pellets better. The original Baby Countryside stoves using blowers with small blades were installed for the stoves to burn corn . Quadrafire pellet stoves and small Travis stoves use large blades as well. With that in mind, I installed a combustion blower with large petal blades in the Breckwell Big E. I discovered when the stove started that it defaulted to heat level 1 and remained on after the initial damper setting! The real test is Hi/Lo mode. The next morning was cold 32 Degs outside. The workshop was 53 Degs F inside so I started the stove in Hi/Lo mode and set the T-Stat for 65 Degs. The stove started and the Hi setting was set to 3. The workshop slowly warmed up and when the T-Stat hit 67 Degs (It has a 2 Degree swing) I heard the click and the T-Stat contacts opened up. I saw the pellet feed slow and the height of the fire die down to the level 1 setting. The control panel light does not change, it still had the 3 heat level lit but I could hear the convection fan speed drop to the heat level 1 speed. The was still one catch. I did this test twice, the 1st time with the default auger trim setting at medium which is the middle of the 3 choices, the stove died out from not having enough pellets. Before the second test I set the stove to manual, heat level 1 and set the auger trim to show lights 1 & 4 which is the high setting. Finally on this second test, when the T-Stat was satisfied and the heat level dropped to heat level 1, the stove kept running fine! Therefore, adjusting the heat level was no longer an issue. No need to adjust the damper. I also observed that the stove lighted up more quickly after installing the new blower with larger impeller blades compared to the smaller impellers. The pellets also seemed to burn more completely. There were no unburnt pellets in the ash pan. See below for a comparison of impeller petal size. Left: Small. Right: Large

To gather some more data, I used my friend's stove as a baseline. To test his stove, I connected the manometer to the nipple on the back left side of the firewall and connected an AC cord to the original exhaust blower. I got -0.43 WC. WC measures Air pressure in Water Column, which is what is used to measure draft level. I went back to my shop and made the same measurement with the large petal impellers and got -0.72 WC. This is an increase of 0.29 WC. Usually, the controller sets the draft fan to operate on high during start up and when the stove is set to the highest heat level, but the Breckwell always runs the combustion blower on high. The AC test cord provides full draft (120 vac) voltage to the exhaust blower so my tests are the same as if the stove is running. A hotter fire on higher heat levels creates more air pressure. Therefore when the stove is on heat level 1 with lower air pressure, the large petal impellers maintain a higher air pressure. Thus, the vacuum switch will remain closed and the stove will keep running. Testing this stove shows it running all day on heat level 1 (approximately 200 Degrees F out of the heat exchangers).The higher heat levels put out effective heat as well. 

Left - WC measured with small impellers. Middle - WC measured with large petal impellers. Right - Heat output on heat level 1.

In summary, the large petal fan blades make the stove run well on heat level 1 as well as increase the overall performance. Please take note that the housing that comes with the stove I worked on is 1-1/2 inches deep, so the large petal blades fit. This may not be true for all models so larger housing may be needed. In that case, a new housing can be bolted on and the large impellers can be installed. Sometimes, you can transfer the original snap disc to the new housing. Occasionally, you may need a replacement depending on the size and condition. If the blower housing has a 3/4" hole, then a 3/4" F-120 snap disc with airstream mount will work fine. Also, a surface mount F-120 snap disc will work regardless of whether there is a hole or what size the hole is. If there is a hole, it will cover it. Most large impeller blowers come with a motor that has more current capability. I have seen motors from 1.35 amps up to 1.75 amps. Check your motor tag.


Here is an exhaust blower with the large petal blades that will fit the Breckwell:


F-120 Snap Disc for exhaust blower above
http://www.eastcoasthearth.com/collections/universal-pellet-stove-parts/products/low-limit-snap-discs-diameter-air-stream - for 3/4" hole

Updated Control Panel


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