I'd also like to know, when they re-tested, and for the Cat I burn, if they did so w/o the combustion air blower on (no call for heat). The test requires it to burn at the lowest possible BTU output, which would be a loaded firebox burning with no call for heat by a thermostat....meaning no combustion blower.
I looked through this giant file, and they do show when the simulated thermostat comes in on the tests using a "green" color and when the thermostat is off using a "salmon" color on the test charts for each category. Cat 4 is the exception it all shows salmon or off, but the cat 4 written test procedure has the draft blower locked on the whole time, so the simulated thermostat is probably just not used at all on that test. On Cat 3 they kicked it on at 54 minutes, and on the cat 2 test at 254 minutes. On the cat 1 test it would seem detrimental to the test to run draft too much, as getting the furnace under the 35% BTU is tough enough - turning on the draft too much would make it blow its load too fast so to speak and push the average BTU too high. They burned 37 lbs. on the cat 1 test in 6 1/2 hours, which in my experience on an idled load that size is probably within reason, maybe a little faster than what I see when I'm trying to stretch out the burn time.
They run the draft for 20 minutes to start the fire on cat 1 according to the test procedure, which is about right to get the furnace to temperature and would be how it should be used by an end user per the directions, and then operated from there at the lowest rate. The first and longer of the two cat 1 tests as required by the ATM the thermostat table coloring shows an engagement at minute 381 out of a 394 minute test. The flue temperature data doesn't reflect any increase though, so it might just be a coloring error like on the cat4 test when it shows salmon/off when green/on would be more accurate to display - maybe on those two tests they just didn't pay attention to the colors in the spreadsheet and left them at whatever they were on the last data entries since the simulated stat was not in the circuit...?
Cat 1 test procedures:
• Test Load: approximately 37 lbs. Red Oak Cordwood.
• Place test load North/South.
• Place test load to the rear of firebox.
• Draft inducer engaged at start of test.
• Position Fuel and Ash doors open approximately ½” open at start of test.
• Leave Fuel and Ash doors open for approximately 5 minutes or a flue temperature of 850* f
whichever occurs first, then close.
•
Disengage draft inducer at 20 minutes from start of test.
•
The Draft Inducer shall remain disengaged for remainder of test.
• Reference ATM issued to HY-C on July 26th 2018 for operating to Cat. I
Category I- “Operate at the lowest delivered output that the unit is able to operate at, which
may be a higher delivered output average BTU than the test method allows. Using two test runs
at this low output (averaging the two runs), operating the heater at the intended lowest “real
world” operational mode