Anyone with a p68 getting anything close to 68,000 btu's out?

[J1809]

Hi,

Here's my problem, and I would love to hear from anyone who is getting close to 68000 btus out of their p68: I installed a p68 this Fall, and in the highest settings--stove temp 6, feed rate 7, distribution blower all the way high-- I burn a little more than 3 bags/day. This is true of the $5/bag pellets that the stove dealer sells and the $4/bag pellets from home depot.


If the pellets are about 8500 btus/lb and I burn 3 bags/day or 120 lbs/day, I burn 5lbs/hr so I'm inputting about 42500 btu's. This is at the max settings, so clearly I'm not getting anything like 68,000 btu's out.


I've spoken with the dealer and with Harman, and although draft test pinned when it was installed, both the dealer and Harman have said that my exhaust set up has some restrictions in it so the ESP won’t allow the stove to run hotter.


I kind of believed it until this week when temperatures got to minus 10 and I used an online engineering calculator to figure out that the pressure in my flue was twice what it is when the outside temperature is 30 degrees. I'm still only able to burn the same three bags/day even though it's much colder outside and the natural draft is twice as strong.


So I am suspicious of the 68000 btu rating or of the 8lbs/hr burn rating and so I really wonder if anyone is able to burn more than 3 bags/day with their p68? I figure that if you could run the stove at 8lb/s hr, which the manual says is possible and the pellets were 9500btu's/lb and the stove really is 89% efficient then you might get to that 68000, so it's pretty pie in the sky, but my 5lbs/hr regardless of ambient temperature, is so far from that number that I really wonder.


Please let me know and thank you in advance.

Jared from western NY

 

[Enigma869]

 

[P38X2]

As silly as this sounds, put it on "room temp" mode and crank it. Make sure the sensor is not too close to the stove. Report back. A friend of mine was obsessed with keeping his stove in "stove temp" mode and was never happy with the heat. He wouldn't listen to me, but finally our dealer convinced him to use "room temp" mode. Sure enough he calls me and says "holy chit, this thing is brutal". Why there is a difference in max output in the 2 modes is odd. I'd think max stove temp would be the same as room temp, assuming the setpoint was never close to being satisfied, but it isn't. I've read other posts of peeps complaining about stove temp not yielding the same max output as room temp.

 

[Enigma869]

As silly as this sounds, put it on "room temp" mode and crank it. Make sure the sensor is not too close to the stove. Report back. A friend of mine was obsessed with keeping his stove in "stove temp" mode and was never happy with the heat. He wouldn't listen to me, but finally our dealer convinced him to use "room temp" mode. Sure enough he calls me and says "holy chit, this thing is brutal". Why there is a difference in max output in the 2 modes is odd. I'd think max stove temp would be the same as room temp, assuming the setpoint was never close to being satisfied, but it isn't. I've read other posts of peeps complaining about stove temp not yielding the same max output as room temp.

This is interesting to read, as I've noticed the same thing. I always ran my Accentra in room temp mode. This is my first season with the P68, and I thought (wrongly) that stove temp gave me much more control over the stove. I felt on the very coldest days (of which, we've had more than I can even count) that the stove temp mode simply wasn't throwing off nearly as much heat. The second I switched to room temp mode, there have been zero issues with getting enough heat. Hell, I've had to turn the thing down in room temp mode, because it's getting too hot. Not sure what the story is with the very noticeable difference between the two modes, but it's quiet noticeable to me. I'd love to hear Harman's take on this.

John

 

[P38X2]

Perhaps Harman set the parameters of stove temp mode using very short pellets? The stove doesn't know exactly how many pellets are in a pound. "8" lbs of pellets an hour could only be 5 pounds if they're 1 1/4" long on average. Less input, less output.

Set it to room temp and now its gonna feed whatever is required to get the job done, while the ESPs primary objective becomes to assure the stove doesn't overheat.

Just some thoughts. Probably flawed.

 

[flybmw02]

Enigma869 We must of had the same Massachusetts high school teacher somehow that makes sense.
John

 

[saladdin]

View attachment 123371

I have never seen that before. That is funny stuff.

 

[Hoot23]

This is interesting to read, as I've noticed the same thing. I always ran my Accentra in room temp mode. This is my first season with the P68, and I thought (wrongly) that stove temp gave me much more control over the stove. I felt on the very coldest days (of which, we've had more than I can even count) that the stove temp mode simply wasn't throwing off nearly as much heat. The second I switched to room temp mode, there have been zero issues with getting enough heat. Hell, I've had to turn the thing down in room temp mode, because it's getting too hot. Not sure what the story is with the very noticeable difference between the two modes, but it's quiet noticeable to me. I'd love to hear Harman's take on this.

John

I tired stove temp for a little while at the beginning of the season. I couldn't get it dialed. Room temp fits us best. Steady temps throughout these last few weeks with no sign of the stove struggling.

 

[SmokeyTheBear]

Orange with pink polka dots.

There is no such thing as an average pellet and that 68 may mean only input (or in other words doesn't take the system's efficiency into account).

There are some pellets that reach 9,000+ BTUs per hour under ideal conditions which makes 5 pounds per hour worth 45,000+ BTUs per hour and an 8 pounds per hour worth 72,000 BTUs per hour.

The stove would need proper air flow through it and the temperature sensor would have to be set so it was never satisfied.

 

[Heat Slinger]

I think I could easily burn 3 bags/day...in fact, I struggle to burn less than 2-2.5 bags/day. My P68 is a basement dweller, and it heats a total of almost 3000 sqft. I run it in Room Temp, usually set for 72-75°F. I've never had to turn it above 75°F, and it throws a ton of heat. I can't imagine running it on MAX, I think it would melt my face off. I haven't really tried Stove temp, I always assumed running in Room temp would burn less pellets.

I LOVE my P68...I installed it in September, and over Christmas we lost power for 3 days during the ice storm. My P68 and Champion generator kept us warm and toasty while some of my neighbors were forced to leave their homes for Christmas.

 

[J1809]

Thanks for the reply. I've run it in all the different modes, cleaned it, run different brand pellets etc etc. I still max out at a little more than 3 bags/day. I wonder if anyone is burning more on their p68?

 

[J1809]

The ESP sets the maximum burn temperature at abuot 600 degrees. The max the stove can burn is governed by the ESP. Maybe I have a 'overly sensitive' one. I'd love to hear from someone who is getting close to that 68000 btu rating.

 

[J1809]

Orange with pink polka dots.

There is no such thing as an average pellet and that 68 may mean only input (or in other words doesn't take the system's efficiency into account).

There are some pellets that reach 9,000+ BTUs per hour under ideal conditions which makes 5 pounds per hour worth 45,000+ BTUs per hour and an 8 pounds per hour worth 72,000 BTUs per hour.

The stove would need proper air flow through it and the temperature sensor would have to be set so it was never satisfied.

Thank you. Harman says it's 68000 out and that it can burn 8lbs/hr. I've run a bunch of brancds including the fancy stuff the stove store sells and my burn rate at the max settings--the setting governed by the ESP rather than the thermostat etc, is always about 120lbs/day--this is also regardless of the outside temperature.

 

[SmokeyTheBear]

Thank you. Harman says it's 68000 out and that it can burn 8lbs/hr. I've run a bunch of brancds including the fancy stuff the stove store sells and my burn rate at the max settings--the setting governed by the ESP rather than the thermostat etc, is always about 120lbs/day--this is also regardless of the outside temperature.

Where does Harman say it is 68,000 out?

You could Private Communication Delta-T he knows a little bit about Harmans.

Harman's website (broken link removed to http://www.harmanstoves.com/Products/P68-Pellet-Stove.aspx) shows it to be input.

 

[J1809]

I think I could easily burn 3 bags/day...in fact, I struggle to burn less than 2-2.5 bags/day. My P68 is a basement dweller, and it heats a total of almost 3000 sqft. I run it in Room Temp, usually set for 72-75°F. I've never had to turn it above 75°F, and it throws a ton of heat. I can't imagine running it on MAX, I think it would melt my face off. I haven't really tried Stove temp, I always assumed running in Room temp would burn less pellets.

I LOVE my P68...I installed it in September, and over Christmas we lost power for 3 days during the ice storm. My P68 and Champion generator kept us warm and toasty while some of my neighbors were forced to leave their homes for Christmas.

Where does Harman say it is 68,000 out?

You could Private Communication Delta-T he knows a little bit about Harmans.

Harman's website (broken link removed to http://www.harmanstoves.com/Products/P68-Pellet-Stove.aspx) shows it to be input.

Thank you. Harman's glossy brochure calls it an output...hmmm from:

(broken link removed to http://hearthnhome.com/downloads/brochures/HAR-1110U.pdf)
....P68 PEllEt StovE
the award-winning p68 is a home heating
powerhouse. it produces up to 68,000 BtUs—...

I agree the spec sheet you link to show sit as an input number though. So if we assume it's an input number ,and we find a pellet that's even 10k btu's/lb, then we'd still need to put roughly 7lbs/hr in so about 168 lbs/day or something a little over 4 bags/day. I'm wondering if anyone is doing that.

Granted my LP furnace is ducted, but it's not huge and it's rated 100k btu's out. So I would think that there are people with open floor plans or heating big insulated space etc, that would max the stove out like I'd like to. It's possible that my exhaust set up does not allow enough airflow over the ESP to cool it to get to those higher BTU numbers, But again, I'm really curious to hear from anyone who gets there before I punch into my masonry chimney to change the T to 4" all the way..

If you google Harman P68 4 bags/day ot 5bag/day there are no hits at all.

I really appreciate all the responses.
Thanks, Jared

 

[SmokeyTheBear]

Thank you. Harman's glossy brochure calls it an output...hmmm from:

(broken link removed to http://hearthnhome.com/downloads/brochures/HAR-1110U.pdf)
....P68 PEllEt StovE
the award-winning p68 is a home heating
powerhouse. it produces up to 68,000 BtUs—...

I agree the spec sheet you link to show sit as an input number though. So if we assume it's an input number ,and we find a pellet that's even 10k btu's/lb, then we'd still need to put roughly 7lbs/hr in so about 168 lbs/day or something a little over 4 bags/day. I'm wondering if anyone is doing that.

Granted my LP furnace is ducted, but it's not huge and it's rated 100k btu's out. So I would think that there are people with open floor plans or heating big insulated space etc, that would max the stove out like I'd like to. It's possible that my exhaust set up does not allow enough airflow over the ESP to cool it to get to those higher BTU numbers, But again, I'm really curious to hear from anyone who gets there before I punch into my masonry chimney to change the T to 4" all the way..

If you google Harman P68 4 bags/day ot 5bag/day there are no hits at all.

I really appreciate all the responses.
Thanks, Jared

No it doesn't, the glossy also says input. No where does it say output.

 

[Hoot23]

Is the 68 not giving you enough heat or are you just doing it for SAG?

 

[J1809]

No it doesn't, the glossy also says input. No where does it say output.

P68 PEllEt StovE
This is the harman brochure:
(broken link removed to http://hearthnhome.com/downloads/brochures/HAR-1110U.pdf)
Go to the 5th page:
<<the award-winning p68 is a home heating
powerhouse. it produces up to 68,000 BtUs—
enough heat to fill the largest of spaces. Mirrored
glass provides distinctive style and fades when the fire
is lit to expose intense flames.

The description says "it produces up to 68,000 btu's"

 

[J1809]

Is the 68 not giving you enough heat or are you just doing it for SAG?

No, I want more heat out. It's not an academic exercise.

 

[J1809]

P68 PEllEt StovE
This is the harman brochure:
(broken link removed to http://hearthnhome.com/downloads/brochures/HAR-1110U.pdf)
Go to the 5th page:
<<the award-winning p68 is a home heating
powerhouse. it produces up to 68,000 BtUs—
enough heat to fill the largest of spaces. Mirrored
glass provides distinctive style and fades when the fire
is lit to expose intense flames.

The description says "it produces up to 68,000 btu's"

 

[J1809]

P68 PEllEt StovE
This is the harman brochure:
(broken link removed to http://hearthnhome.com/downloads/brochures/HAR-1110U.pdf)
Go to the 5th page:
<<the award-winning p68 is a home heating
powerhouse. it produces up to 68,000 BtUs—
enough heat to fill the largest of spaces. Mirrored
glass provides distinctive style and fades when the fire
is lit to expose intense flames.

The description says "it produces up to 68,000 btu's"

I didn't mean to put that face there meant to put in '' anyway

 

[J1809]

I didn't mean to put that face there meant to put in '' anyway

 

[SmokeyTheBear]

P68 PEllEt StovE
This is the harman brochure:
(broken link removed to http://hearthnhome.com/downloads/brochures/HAR-1110U.pdf)
Go to the 5th page:
<<the award-winning p68 is a home heating
powerhouse. it produces up to 68,000 BtUs—
enough heat to fill the largest of spaces. Mirrored
glass provides distinctive style and fades when the fire
is lit to expose intense flames.

The description says "it produces up to 68,000 btu's"

It sure can inside the firebox not into the room.

If you look at the little boxes you'll soon discover it is 68,000 BTU input.

 

[Mt Bob]

Output is irrevelent.68k is input.8500 per lb. is potential,not output out of the heat exchanger.If that stove could do that,conservative measurement would be 4.5 to 4.8 40lb bags in 24 hrs.Just my 2cents worth.

 

[Delta-T]

I'm sure in a lab we can get that stove to really hit 68k, but you'd need a seriously cold space to strip off enough heat from the unit to tell the ESP to tell the CB to "eat more pellets"...in the end, its still a max temp at the ESP that tells the stove what to do. Making more BTUs without either, more surface area, or more convection air, the internal temp doesn't drop enough to make the stove work any harder. You also have a max auger speed of 6RPM (i thinks) and pellets are pretty oddly shaped so there might be a "theoretical" ability that is just prohibative to acheive...like MPG on cars...its nice pretty numbers, just not always that realistic...and of course YMMV.