P68 controls

[Rockbase]

Greetings, I have 2 questions.
1) Does the P68 dist fan vary by its-self. I notice that when I have it in room temp, auto, and the blower switch on high (All thee way) the fan runs on a reduced speed, maybe even varies speed and I do not notice it. However, turn the switch (pot) back slightly (Still in the high range) and the fan speed kicks up. Is this maybe a min max switch where in high the fan speed varies based on room temp?

2) My feed rate is all the way down at 1. Even when up higher, I can get a 1" ash lip but pellets seem to bunch up. Once this occurs the flame tilts towards the glass door and deposits ash on the top of the glass. Open the door and knock the ash down and the flame is straight up again. Is this normal.

And to give you some feedback on my use. Its in a non finished cement floor and cement wall basement. Between the basement and upstairs we are at 3,400 + sq feet with 10 foot ceilings down below and 15 to 18 fooot ceilings upstairs. As long as the winds are min and temps at or above freezing, it keeps the house warm at about 73f. When it get down below 20 and in the neg temp ranges outside (Oh yeah this winters cool ) then the best I get is that it keeps the basement warm and reduces the electric heat upstairs.

I keep my machine clean on a regular basis with a complete cleaning every 2 weeks (Im anal/engineer). I just think it can put out a little more.

Any help would beappreciated. I do like the unit.

Doug.

 

[Enigma869]

I can't comment on your question about the distribution fan, but I've never heard of anyone running their stove with the feed rate on 1. I know some tweak the feed rate a bit, depending upon pellets. That said, it seems that between 3 and 4 is about the right setting on these stoves. Even according to Harman, the feed rate should be at about 4. I have the P68 and have always had my feed rate at about 3.5.

John

 

[Rockbase]

I can't comment on your question about the distribution fan, but I've never heard of anyone running their stove with the feed rate on 1. I know some tweak the feed rate a bit, depending upon pellets. That said, it seems that between 3 and 4 is about the right setting on these stoves. Even according to Harman, the feed rate should be at about 4. I have the P68 and have always had my feed rate at about 3.5.

John

yes, being a engineer i would think that i could control the pellet feed with this. but even at 1 it achieves a 1 to 1.5 ash lip.

 

[Harman Lover 007]

yes, being a engineer i would think that i could control the pellet feed with this. but even at 1 it achieves a 1 to 1.5 ash lip.

But above, your complaint is you want more out of your stove. A feed rate of 1 is severely limiting your P68's performance. Since you reference the 1" ash lip, I'm going to assume you've read the Harman sticky above (or click on the link in my sig). If not, it's a must read. The Harman feed rate doesn't work the way your engineering brain wants to think it does.

 

[Rockbase]

But above, your complaint is you want more out of your stove. A feed rate of 1 is severely limiting your P68's performance. Since you reference the 1" ash lip, I'm going to assume you've read the Harman sticky above (or click on the link in my sig). If not, it's a must read. The Harman feed rate doesn't work the way your engineering brain wants to think it does.

Yes, you are correct, it does not. I have done the following test(s)

Since Harman states in its owners manual, to set the stove to max stove temp, auto, and feed rate of 4 (I think), run for 1/2 hr and adjust feed rate up/down to obtain a 1" ash lip. I assumed (silly me) that this meant the stove was running in max condition, and if you achieved this 1" ash lip you would never waste pellets by overfeeding, and likewise would run the max pellets when in the worst (Coldest) conditions. My test shows their setup is flawed, let me explain....

1) I set the stove (P68) in stove temp, max setting and adjusted the feed rates as followed. Note next to each feed rate I used a stop watch to time the auger motor (Feed motor) duty cycle.(on/run time)

Feed Rate Time motor ran
1 15 out of 60 seconds ---------------------------------------\
1.5 20 out of 60 seconds each 1/2 adjustment change equals 5 seconds so far
2.0 25 out of 60 seconds---------------------------------------/
2.5 30 out of 60 seconds with some variance........................
4.0 30 to 40 seconds out of 60 seconds................................Looks like something is over-riding timer, prob internal temp thermocouple !!
6.0 30 to 35 seconds out of 60 seconds................................

Other tests; I used a 3m $2000.00 infrared pyrometer and a $100 std thermocouple pyrometer to measure temp at the black flange which protrudes
from the rear of the unit (Exhaust) and the silver exhaust pipe is attached to. The infrared read basically 200f +/- 5 degrees and the touch
pyrometer read 170f +/- the same. the touch is a pinpoint where as infrared takes in a larger are. Over these tests this varied little meaning
the timeframe was not long enough or it was well insulated.
Air temp blowing out of the unit (Not true air temp, pyrometer thermocouple was laid into air distribution vents touching steel) was about 265f
and the sides of the stove using infrared was 265f.

I also tried this test, albeit abbreviated, in room temp with temp setting at max also. Same basic results on feeder runtime.

What this seems to tell me is that the feed rate setting is a maximum setting or in other words, a governor. (one of two).
When you adjust this timer, the auger will feed (once each minute) UPTO the amount of time you set on the feed-rate adjusting pot.
Here's my assumption, it will feed pellets until the timer times out, or until a max temp (I believe exhaust) is reached at which point it over rides the timer.

So what's this mean in English?

Lets say that you do the setup per Harman and end up at a feed rate of 5, at which point you still have a 1+" of ash lip. The truth is that the stove may have been over riding your feed setting giving you a 3 feed rate.
Now when it gets real cold out, the feed rate timer is not over ridden, and it ends up using the full setting of 5 and pushes unburned pellets over the edge wasting fuel.

I understand Harman's predicament. If they gave you full control and you could over-ride the max temp safety (Short term) you could really set a max feed rate. But, some one would over heat the unit and burn down the house, and
of course blame the Mfg. for this.

At least I think I understand the reason why it feeds the way it does now. And if I ever get time, maybe Ill write a little software that would improve this, and send it to the Mfg. as a simple suggestion.

Now, How about the distribution Blower? Any answers on that ?

BTW, I will look at the authors article (Harman lover 007) as it may provide even more insight.

Doug.

 

[Ctcarl]

But above, your complaint is you want more out of your stove. A feed rate of 1 is severely limiting your P68's performance. Since you reference the 1" ash lip, I'm going to assume you've read the Harman sticky above (or click on the link in my sig). If not, it's a must read. The Harman feed rate doesn't work the way your engineering brain wants to think it does.

^^^^Agree

 

[camdids]

Yes, you are correct, it does not. I have done the following test(s)

Since Harman states in its owners manual, to set the stove to max stove temp, auto, and feed rate of 4 (I think), run for 1/2 hr and adjust feed rate up/down to obtain a 1" ash lip. I assumed (silly me) that this meant the stove was running in max condition, and if you achieved this 1" ash lip you would never waste pellets by overfeeding, and likewise would run the max pellets when in the worst (Coldest) conditions. My test shows their setup is flawed, let me explain....

1) I set the stove (P68) in stove temp, max setting and adjusted the feed rates as followed. Note next to each feed rate I used a stop watch to time the auger motor (Feed motor) duty cycle.(on/run time)

Feed Rate Time motor ran
1 15 out of 60 seconds ---------------------------------------\
1.5 20 out of 60 seconds each 1/2 adjustment change equals 5 seconds so far
2.0 25 out of 60 seconds---------------------------------------/
2.5 30 out of 60 seconds with some variance........................
4.0 30 to 40 seconds out of 60 seconds................................Looks like something is over-riding timer, prob internal temp thermocouple !!
6.0 30 to 35 seconds out of 60 seconds................................

Other tests; I used a 3m $2000.00 infrared pyrometer and a $100 std thermocouple pyrometer to measure temp at the black flange which protrudes
from the rear of the unit (Exhaust) and the silver exhaust pipe is attached to. The infrared read basically 200f +/- 5 degrees and the touch
pyrometer read 170f +/- the same. the touch is a pinpoint where as infrared takes in a larger are. Over these tests this varied little meaning
the timeframe was not long enough or it was well insulated.
Air temp blowing out of the unit (Not true air temp, pyrometer thermocouple was laid into air distribution vents touching steel) was about 265f
and the sides of the stove using infrared was 265f.

I also tried this test, albeit abbreviated, in room temp with temp setting at max also. Same basic results on feeder runtime.

What this seems to tell me is that the feed rate setting is a maximum setting or in other words, a governor. (one of two).
When you adjust this timer, the auger will feed (once each minute) UPTO the amount of time you set on the feed-rate adjusting pot.
Here's my assumption, it will feed pellets until the timer times out, or until a max temp (I believe exhaust) is reached at which point it over rides the timer.

So what's this mean in English?

Lets say that you do the setup per Harman and end up at a feed rate of 5, at which point you still have a 1+" of ash lip. The truth is that the stove may have been over riding your feed setting giving you a 3 feed rate.
Now when it gets real cold out, the feed rate timer is not over ridden, and it ends up using the full setting of 5 and pushes unburned pellets over the edge wasting fuel.

I understand Harman's predicament. If they gave you full control and you could over-ride the max temp safety (Short term) you could really set a max feed rate. But, some one would over heat the unit and burn down the house, and
of course blame the Mfg. for this.

At least I think I understand the reason why it feeds the way it does now. And if I ever get time, maybe Ill write a little software that would improve this, and send it to the Mfg. as a simple suggestion.

Now, How about the distribution Blower? Any answers on that ?

BTW, I will look at the authors article (Harman lover 007) as it may provide even more insight.

Doug.

Its not a pellet stove you need buddy. Give NASA a call.

 

[Rockbase]

Its not a pellet stove you need buddy. Give NASA a call.

Maybe your right. I am anal about efficiency

Now, does the blower adjust its speed ? (Dist blower), or do I have a flaky pot?

Doug

 

[camdids]

In Room Temp it will vary somewhat to maintain the set temp. I never use Stove Temp, but I understand it should remain constant.

 

[Rockbase]

In Room Temp it will vary somewhat to maintain the set temp. I never use Stove Temp, but I understand it should remain constant.

well that would make sense. If I had it on the second floor vs the basement, I could see it overheating the rooms. In my case, im am heating at the stoves max ability. On real cold weeks, stove temp would probably be a better option for me.
Thanks everyone for the help. I understand my unit a lot better now.

Doug

 

[Harman Lover 007]

Yes, you are correct, it does not. I have done the following test(s)

Since Harman states in its owners manual, to set the stove to max stove temp, auto, and feed rate of 4 (I think), run for 1/2 hr and adjust feed rate up/down to obtain a 1" ash lip. I assumed (silly me) that this meant the stove was running in max condition, and if you achieved this 1" ash lip you would never waste pellets by overfeeding, and likewise would run the max pellets when in the worst (Coldest) conditions. My test shows their setup is flawed, let me explain....

1) I set the stove (P68) in stove temp, max setting and adjusted the feed rates as followed. Note next to each feed rate I used a stop watch to time the auger motor (Feed motor) duty cycle.(on/run time)

Feed Rate Time motor ran
1 15 out of 60 seconds ---------------------------------------\
1.5 20 out of 60 seconds each 1/2 adjustment change equals 5 seconds so far
2.0 25 out of 60 seconds---------------------------------------/
2.5 30 out of 60 seconds with some variance........................
4.0 30 to 40 seconds out of 60 seconds................................Looks like something is over-riding timer, prob internal temp thermocouple !!
6.0 30 to 35 seconds out of 60 seconds................................

Other tests; I used a 3m $2000.00 infrared pyrometer and a $100 std thermocouple pyrometer to measure temp at the black flange which protrudes
from the rear of the unit (Exhaust) and the silver exhaust pipe is attached to. The infrared read basically 200f +/- 5 degrees and the touch
pyrometer read 170f +/- the same. the touch is a pinpoint where as infrared takes in a larger are. Over these tests this varied little meaning
the timeframe was not long enough or it was well insulated.
Air temp blowing out of the unit (Not true air temp, pyrometer thermocouple was laid into air distribution vents touching steel) was about 265f
and the sides of the stove using infrared was 265f.

I also tried this test, albeit abbreviated, in room temp with temp setting at max also. Same basic results on feeder runtime.

What this seems to tell me is that the feed rate setting is a maximum setting or in other words, a governor. (one of two).
When you adjust this timer, the auger will feed (once each minute) UPTO the amount of time you set on the feed-rate adjusting pot.
Here's my assumption, it will feed pellets until the timer times out, or until a max temp (I believe exhaust) is reached at which point it over rides the timer.

So what's this mean in English?

Lets say that you do the setup per Harman and end up at a feed rate of 5, at which point you still have a 1+" of ash lip. The truth is that the stove may have been over riding your feed setting giving you a 3 feed rate.
Now when it gets real cold out, the feed rate timer is not over ridden, and it ends up using the full setting of 5 and pushes unburned pellets over the edge wasting fuel.

I understand Harman's predicament. If they gave you full control and you could over-ride the max temp safety (Short term) you could really set a max feed rate. But, some one would over heat the unit and burn down the house, and
of course blame the Mfg. for this.

At least I think I understand the reason why it feeds the way it does now. And if I ever get time, maybe Ill write a little software that would improve this, and send it to the Mfg. as a simple suggestion.

Now, How about the distribution Blower? Any answers on that ?

BTW, I will look at the authors article (Harman lover 007) as it may provide even more insight.

Doug.

Holy Crap, Doug, I think you've already got too much time on your hands if you went through all that to find out what the Harman sticky would've told you. The feed rate is, in fact, an adjustment/limit of how much your stove "can" feed at a desired setting...not how much it "will or does" feed. You are correct, it is a governor and if you are trying to get the max out of your P68 with yours set on 1, you have your governor set at the lowest setting and are pinching the fuel line with a pair of vise grips. To say it another way, you've got a brick under the accelerator pedal. Humor us and try setting your feed rate at 4 and see how she performs for you.
To answer your other question...yes, it sounds like you have a pot going bad. Hope this helps.

 

[Rockbase]

Holy Crap, Doug, I think you've already got too much time on your hands if you went through all that to find out what the Harman sticky would've told you. The feed rate is, in fact, an adjustment/limit of how much your stove "can" feed at a desired setting...not how much it "will" feed. You are correct, it is a governor and if you are trying to get the max out of your P68 with yours set on 1, you have your governor set at the lowest setting and are pinching the fuel line with a pair of vise grips. To say it another way, you've got a brick under the accelerator pedal. Humor us and try setting your feed rate at 4 and see how she performs for you.
To answer your other question...yes, it sounds like you have a pot going bad. Hope this helps.

Its solid ice out, no where to go. So ust a quick test to see what makes it tick. FYI, i have it set on 3.5 now. Thanks for the help, and replies.

 

[Harman Lover 007]

OK great! Rock on and let us know what happens....

 

[Rockbase]

How do I upload a 15 second video clip to see / show if my stove is running normal. Once the ash lip has formed, the flame tilts towards the glass which may or may not be ok.

 

[Ctcarl]

How do I upload a 15 second video clip to see / show if my stove is running normal. Once the ash lip has formed, the flame tilts towards the glass which may or may not be ok.

My new harman p35i with the flame guard does that when it's cranking nothing to be concerned.

 

[P38X2]

Prob not the most efficient place for the flame to be. It's saying "shave my beard"

 

[jslinger]

I would seriously consider getting some insulation in that basement. If I recall correctly, that cement has an r-value of .8. Those walls are absorbing all of your heat.

 

[Rockbase]

My new harman p35i with the flame guard does that when it's cranking nothing to be concerned.

Well I used to have, years ago, a lopi wood stove. The flames never touched the glass. Im not used to that and while I know the glass is tempored, it just seems strange to me. Thanks for the reply.

 

[Rockbase]

I would seriously consider getting some insulation in that basement. If I recall correctly, that cement has an r-value of .8. Those walls are absorbing all of your heat.

Yes, I know this to be true, the walls and floor are all concrete. However, if you take the cost of insulating the walls and floor, and the assumption that you will cut your costs for pellets in half, it would take 15 to 20 years to break even. So the payback is to low. But a good thought.

 

[Rockbase]

Prob not the most efficient place for the flame to be. It's saying "shave my beard"

when the ash lip iscleaned, flame goes straight up, when the ash lip builds up (Quickly at 4 setting) heat is great but flame touches glass in door. Ive been told this is ok. Im just not used to seeing that.

 

[P38X2]

when the ash lip iscleaned, flame goes straight up, when the ash lip builds up (Quickly at 4 setting) heat is great but flame touches glass in door. Ive been told this is ok. Im just not used to seeing that.

I'm sure it's OK. I'm just thinking the exchanger will be heated less evenly and cause a loss of effiency, however slight. You may notice that if you continue to let the ash build, it will start deflecting the flames back to where they should be, however at that point, it's definitely time to scrape the pot as you'll start losing combustion efficiency due to the ash blocking the air from the pot holes.