Fahrenheit Technologies Endurance 50F Information

So...did some futsing around and tried to insert my probe, but was giving me fits so went down a different direction...using my IR temp reader. Picked a spot on the door just above the viewing glass and also took readings on my booster (pretty far downstream)...took readings with blowtorch flame (about 30% damper opened) and somewhat lazier flame (about 10-15% open)...I was very surprised by the results:

Blowtorch door reading - 135 degrees (level 5)
Blowtorch booster reading - 84 degrees (level 5)

Lazier flame door reading - 175 degrees (level 5)
Lazier flame booster reading - 89 degrees (level 5)

I find these readings confusing but confirmative at the same time. Initially, without measuring actual flue temps, it would appear that having the lazier flame does indeed heat the box more than having a bright white blowtorch flame...I find that confusing, but confirms what other more experienced individuals have been saying all along.

So now the big question is how "lazy" do you go? What's the right mix? Is the highest temp the objective? Too many questions!!!

 

I lost a little temperature with damper at 40%
Gotta try less than 30% and see what gives
It's mild out today so it might be a day or two when I get to it

 

Got to find the sweet spot and not dirty the stove too fast is key to success

 

Dirty glass to boot! 30% air opening.

 

On the small Francesca stove here (which about 3 of would fit inside the Fahrenhiet 50F) to tune it, I start with the very brisk (torch) flame in your vids, record the setting, then dial down air until "lazy" flame appears, record the setting, then adjust back up to about mid-point between the (2). Then fine-tune from there.

( This is done by adjusting combustion blower RPM settings in the stove settings here, not w/ a manual damper. )

Best burns here are when glass is starting to get hazy after 4-6-8 hours of operation, ash is light to medium grey, cleaning cycle runs every 15 minutes for 20 seconds to kick any excess ash out of the burn pot (no mechanical cleaning mechanism on the stove), stove glass should be easy to clean / wipe off when cleaning.

The longer you can hold heat in the stove -> Heat Exchanger assembly : the more heat is transferred into the home, and not going out the flue.

The objective here is always the most heat output possible from the Heat exchanger, without choking the stove (burn pot) with ash / requiring excessive cleaning.. Regardless of feed rate / setting.

Our stoves are very different: but the objectives are the same, hope the info on how it's done here helps.

 

I'm rethinking the engineering on those exchange tubes and the blast plates that cover them. The idea that the heat needs to stay in the box longer might indicate an inefficient heat transfer to the exchange tubes. Gonna see how much room I have to play with on those blast shields (my theory being that a blowtorch on a bolt should heat that bolt far more efficiently then throwing the bolt into an oven to achieve the same temperature) as I don't think they are "vented" adequately to allow the hotter flame to actually heat the exchange tubes before the heat is pulled out due to the increased air flow to achieve the blowtorch flame. Space between the plates and the tube scrapper will be a significant design factor (I'll want more heat up past those plates faster, but still not allow direct flame contact to maintain service life)...

I'm basing this off what I feel are more efficient designs (Harman Quardafire comes to mind). My neighbors Quadrafire burns incredibly efficiently (like mine now does when in blowtorch mode), but also throws a ton of heat...I think the heat exchange is now the difference...but just a theory (although my frame re-design theory worked out pretty damm good)...

 

I understand what you're saying Maximus, but there will be a finite point of return where increasing combustion air will not transfer to the Heat Exchange tubes (it will pass through the Heat Exchange assembly too quickly), and will exit the stove as a higher flue stack (gas) temperature.

Hotter temps held inside the fire box -> Heat Exchange assembly at a given feed rate = better heat transfer to room air, based on my experience here. Not disputing or preaching - just sharing gained experience on our particular stove here.

If you have the ability to measure -> monitor flue stack temp. immediately before or beyond the Combustion Blower, that will aid greatly in tuning your 50F - to achieve the highest room air temp. output (room air temp. measured at the Heat Exchange assembly exit), vs. lowest flue stack exit temp., while ensuring the stove is operating efficiently.

Empirical data that can be measured, recorded, and verified is always best.

Harman stoves do the above with the ESP (Exhaust Sensing Probe) in conjunction with the room air temp. probe, and adjust / throttle the stove's Combustion air, and feed rate accordingly. Harman folks here got some smart stoves.

re: better Heat exchange assembly / design - fully agree, much the same here - there's always room for improvement..

But tuning to current design (and limitations of) with verifiable data, would seem to be a logical first step.

 

I've work in a steam plant for many years and seen what fly ash does to a air exchangers and it's not pretty. Those shields are there for a reason among directional path flows for the heat exchange of the furnace. Mind you we were burning red liquor which had different chemical make up so different mess and we had a few passes to collect the ash along with sootblowers and it wasn't adequate to prevent the mess but only delayed it
Retention is a important factor to not ignore, we are trying to heat a vast area and not a bolthead

 

Damper at 40% and long pellets broken down and 166*F

 

Your steak shows medium well on the thermometer.

Nice clean burn going there ivanhoe ! Congrats!

 

Thanks
Trying to dial in my different pellets, I'm noticing a difference with the newer furnace

 

Well said and the issue at hand. We are trying to heat air that heats metal tubes...that's where my analogy of using the oven to heat the bolt is perfect...the current design heats air around the tubes...heating air (which is difficult in the realm of efficient heat transfer) IS the problem. It is ridiculously inefficient to heat air to heat another substrate as it takes considerably more energy to excite the widely dispersed air molecules then it would to heat the far more compacted molecules in a solid substance (metal). I'm not questioning the need for the exchanger plates, but rather how efficiently the current design heats the air that heats the tubes above it. When I look at my neighbor's Harman I noticed the exchange plates are placed at not less than a 30-40% angle. I'd assume that's done to allow any ash to fall to the bottom and not collect as easily (think pitched roof & snow) on the tubes (ash buildup would be an insulator), but I'd also bet that those angled plates are significantly closer, if not touching, those exchange tubes...so, even though the flame (or upward heat) is contacting the plates at a less than efficient perpendicular intersection, the heat transferred from those plates to the tubes is far more efficient given that the volume needed to be heated must be significantly smaller and/or the heat is most efficiently transferred from the plate directly (touching) to the tubes.

All theory mind you, but (in theory) a more efficient engine should result in more usable power...I think my engine is working perfectly, far superior compared to stock, so now I think the transmission (transfer of that energy) needs an overhaul as well

 

Something I have noticed also,My Stove Likes clean pellets .No fines. Ive got a vac step-up almost nailed down,I'll share if anyone interested.The Fines make soot ive noticed....

 

We like to share ideas to improve the functionality of our stoves. Fines can be a nuisance. Knowing the quirks and whistles of our stoves is beneficial on efficient operation. The heat exchange tubes are thick for durability and somewhat less so for efficiency we could use more of.

 

Im still Working on the air adjustment, What should be the air temp be coming out of the stove ,I know it will vary (Pellet type ,air,etc) whats a good base line?Thanks fellas.

 

What temps are you getting? from where are you getting your readings?
My temp probe is 27" up the 10" duct.
Keep adjusting your air damper until temps start to go back down, watch out for false readings so let it ride for a awhile.

 

Don't overlook your blower thermostat switch...I recall futsing with mine in the past...if set differently then stock then you might get different temp readings in the 10" vent...I think I set mine to come on at lower temps...need to validate...

 

The trick is to burn at a higher setting so the blower doesn't shut off. That way your temp reading will flat line and be more accurate, in my case I was burning on level #5

 

I'm on a thermostat...so it's #1 or #5

 

I'm the same.
Depends how cold outside it is and the swing on the thermostat which dictates the length of time the furnace stays on #5 heat level.