Harman feed adjuster dial / One more time please

[jbmaine]

Hello everyone. Thanks to all the great info. everyone contributes on this forum,I have gained alot of knowledge about running and maintaining our P68 and pellets/ pellet burning in general. One thing I am still not 100% clear on though is the feed adjuster. If I understand it's function correctly, the higher the settings, the longer the auger runs, putting more pellets in, to keep the fire further up the burn pot. Does it also shut the auger down for a longer time? In other words do you use more pellets with a higher setting?Does it function the same in room temp and stove temp settings?
I know this subject has been covered before and I've read the past posts ( and the stove manual) but I'm still haven't fully grasped how this works. If you could help me to understand this better I would really appreciate it.
Thanks
JB

 

[cac4]

just set it to 4, like the manual says, and forget it.

it sets the "maximum" time that the auger can run in a given minute. not the amount of time that it "will" run. The computer will decide how many seconds the auger runs, based on the amount of heat that is being called for...via the room temp probe if in room temp mode, or the exhaust temp if in stove temp mode.

 

[summit]

just set it to 4, like the manual says, and forget it.

it sets the "maximum" time that the auger can run in a given minute. not the amount of time that it "will" run. The computer will decide how many seconds the auger runs, based on the amount of heat that is being called for...via the room temp probe if in room temp mode, or the exhaust temp if in stove temp mode.

+1

 

[jbmaine]

just set it to 4, like the manual says, and forget it.

it sets the "maximum" time that the auger can run in a given minute. not the amount of time that it "will" run. The computer will decide how many seconds the auger runs, based on the amount of heat that is being called for...via the room temp probe if in room temp mode, or the exhaust temp if in stove temp mode.

+1

I don't doubt what you're saying, but if the dial "is set it and never touch it", why have a dial at all? You would think Harman would have hard wired that setting at the factory.
JB

 

[rickwa]

not all pellets burn the same, also you can adjust so you get max burn time instead of coming on at high for 10 min, meeting tstat then kicking off the on then off. you can tweak feed to size of the area you are heating.

 

[cac4]

it doesn't work that way. ("high, then off, then high, like a hot-air furnace). In either mode, the computer adjust the feed rate for a steady temperature output. If you're using low-grade (non-premium) wood pellets, which might burn too fast, or have a low btu/lb, you may need to turn up the feed rate for the stove to maintain a high enough temperature.

why they don't just hard-code the maximum possible feed rate, and let the computer adjust it down as necessary...all I can think of is that the computer is making its decisions based on input from sensors...which could fail. If that happened, and you were using premium (high-btu) pellets, the thing could over-fire. kind of like a run-away train.

 

[Dougsey]

it doesn't work that way. ("high, then off, then high, like a hot-air furnace). In either mode, the computer adjust the feed rate for a steady temperature output. If you're using low-grade (non-premium) wood pellets, which might burn too fast, or have a low btu/lb, you may need to turn up the feed rate for the stove to maintain a high enough temperature.

why they don't just hard-code the maximum possible feed rate, and let the computer adjust it down as necessary...all I can think of is that the computer is making its decisions based on input from sensors...which could fail. If that happened, and you were using premium (high-btu) pellets, the thing could over-fire. kind of like a run-away train.

The computer doesn't know if unburned pellets are being pushed over the edge.

The idea is to set the max feed rate so that no less than 1" or so of ash is at the front edge of the burnpot.

The adjustment compensates for variables in size of pellets and how quickly they burn.

Setting and forgetting at 4 is good advice.

 

[AndrewChurchill]

I've got my PB105 pellet boiler set at 6 and I don't have a problem with unburned pellets being pushed out the burnpot. That doesn't mean that it won't happen, just that it hasn't happened yet. Last year I burned Energex hardwood pellets and this year I'm burning Energex softwood pellets that I bought in bulk form.

I had them blow 11 tons into a bin in the basement. It took about 45 minutes and my back was very relieved it didn't have to hump them into the basement!

 

[jbmaine]

Thanks for the replies everyone. I believe I have a better understanding now.
Thanks again
JB

 

[Centurion]

Speaking of pellet feed rate, it makes sense to me that you must have some adjustment capability to compensate for the length of the pellets. Small, short pellets would feed more completely, filling the auger fully where a long pellet would not compact as easily in the auger hence not getting the same amount of pellets in the burnpot per cycle. The exhaust sensor would however prevent the unit from overfiring by adjusting how many pellets are in the pot. No, it can't tell how full the burnpot is but the fuller the pot is the higher the flame and consequently the higher the internal temperatures would be. The sensor would then cut back on the pellets to regulate the fire/heat.
In regards to pellet length, it would seem that a long pellet, 1.5 to 2.0 inches would cause increased wear and tear on the auger motor/gears. My PB105 crunches right through them, never jamming the auger, but I wonder if they are putting stress on the auger/motor causing perhaps premature failure?

 

[dingees]

I've got my PB105 pellet boiler set at 6 and I don't have a problem with unburned pellets being pushed out the burnpot. That doesn't mean that it won't happen, just that it hasn't happened yet. Last year I burned Energex hardwood pellets and this year I'm burning Energex softwood pellets that I bought in bulk form.

I had them blow 11 tons into a bin in the basement. It took about 45 minutes and my back was very relieved it didn't have to hump them into the basement!

what type of storage system do you have to recieve 11 ton of pellets? what were the savings vs. bagged fuel? what was the delivery charge?

 

[AndrewChurchill]

I built a 8' x 16' bin in the basement that is capable of holding 17 tons of pellets. This year the savings was $25 P/Ton which was a little surprising since last year the savings were close to $100 P/Ton. No delivery charge it was built into the price of the pellets.

 

[Former Farmer]

Price difference from where I get my pellets from is around $25 per ton more for bags than bulk. That is the pick-up pricing.