Harmon P68 Fired With Grass
Ashoken Center
There have been several requests for me to explain our experiences burning grass pellets in the appliances being used the Catskill Grass Bio-Energy project.
(Please note: any mention of brand names is for informational purposes only, and is not intended as an endorsement of a particular product.)
Our first purchases were two Quadrafire Mt. Vernon pellet stoves. One was quickly installed and the other put in storage for later installation. We also purchased two Central Boiler Maxim pellet hydronic furnaces. One was sited at the Town of Franklin NY Town Garage where the first Quadrafire was installed in the Town meeting hall in the same building. We were able to secure the services of a local plumber who completed the installation by the end of December that first year. Initial operation of these first units had a steep learning curve. The Maxim furnace burned well after the operator at that site tried many combinations of feed rates and blower settings. The manufacture nor the local dealer were of little help tailoring the settings to burn grass.Luckily the operator at the site had a lot of experience in the heating industry and had interest in making the unit work to it's potential. As the season grew colder we found that if the unit was pushed to produce maximum heat it had a tendency to melt the aeration paddle on the end of the feed auger. The original was mild steel but the replacements were made of stainless steel. They did last longer but eventually failed as well. We kept replacements on site after the third failure. Another shortcoming of this unit is the size and position of the ash drop. Ash has to be removed by scooping the ash out daily also the unit has to be shut down weekly to clean the interior of the burn area and the heat exchanger. If this is neglected the unit pushes smoke back into the hopper on top of the furnace leaving a creosote type of condensate in the hopper.Another problem with the design of this unit caused two burn backs into the top hopper. We are not sure the reason for he first but the second was the result of a power outage lasting six hours. The unit needs a supplemental power source to run a clean out cycle if high heat is experienced or a power outage is experienced.By the way the unit was burning wood pellets at the time of the power outage.
As to the Quadrafire at this site, the operator tried all season to burn grass with little success. Any of the settings on the control unit did not dump the ash fast enough and the fire was snuffed out. We purchased these stoves based upon the success of Dr. Cherny at Cornell University. We knew we needed specific tables to burn grass successfully.Dr. Cherny supplied us with he tables that the manufacture had supplied. We were unable to install the grass tables. We sought help from several Quadrafire dealers and the manufacture and were told multiple times that Quadrafire does not support burning grass pellets even though we knew grass tables existed. After that initial season we pulled the unit and replaced it with a Harman P68 which has been burning well ever since. The Harman has analog controls for feed rate and also has a unique burn system where the pellets are pushed up a burn ramp and the ash is pushed off the ramp in to a very ample and removable ash pan.
We have four Harman stoves on site at this time, Two P68 and two P45s.These units are working well burning grass pellets but like all appliances burning grass they all require frequent cleaning. Anyone wishing to burn Grass with appliances that are not specifically designed to handle grass will need the owner/operator to be conscientious about operation and cleaning.
More about the Quadrafire saga (we are using them satisfactorily) and our other appliances and installations next time.
Keep Warm!