Comments and Progress Reports:
For a description of the current test heater setup in our lab, see 2006 - 2007 Heater Testing at Shawville
Because of the non-typical floor level entry into an outside insulated chimney, it is not possible to take stack temperature measurements at the standard height of 8' above floor level. Since there is a damper at this height in the chimney, the first 8 feet of chimney is normally masonry, and is considered part of the heater system rather than the venting system.
For recent tests, stack temperatures have therefore been measured immediately upon leaving the heater. This results in somewhat elevated temperatures, typically around 400F (200C). This represents a small but significant hit on overall efficiency, when calculated by the stack loss method.
We decided to do a variation on Kuznetsov's, and add a couple of small in-line "bells" between the test heater exhaust and chimney entry to see how much of a drop there would be in stack temperature, and to see if combustion is affected adversely.
The idea for this came from an observation on the 2007 test heater at Wildacres. Somewhat to everyone's surprise, when the gas path was set directly from the exit of the downdraft channel to the chimney, the three vertical flues still heated up all the way to the top, even though they were dead ends.
May 3/07: Teardown.
Floor is covered with sheetmetal. 1x2 steel tubing is used as a spacer and a sheet of cement board is laid on top.
October 15/07: Testing commenced on Oct 10. 5 runs so far, ironing out various glitches. We are using white birch with 20% moisture, which we will be using in Alaska shortly. Some dirty burns, due to various phenomena with the flammable bark during startup. Useful, since we will need some dirty burns as a reference for establishing what the limits are for clean burning.
Sept 16/07: This week, we are installing a heater where we have added a "bell" heat exchanger en route to the exhaust. Footprint sketch.
We are also shipping one to California where a channelled heat exchanger between the heater and chimney has been reconfigured to the much simpler, and easier to build, FGM design. Old heat exchanger design.
This page was updated on
October 15, 2007
This page was created on May 3, 2007