Auger continues to feed after shutdown - new Harmon XXV

[jimmie ray]

Did a startup on a brand new Harmon XXV today. After the burn pot was initially filled, but before the ignitor had any pellets glowing, it seemed odd that the auger added more pellets once or twice. Not that the burn pot overflowed, but the fire was high up the back wall, I believe I had the feed adjustment at #3, if that makes a difference? Then during the trial shutdown, with the room / stove temperature dial (room sensor utilized)manually set to "off", the auger periodically fed more pellets over a 15 minute period - maybe came on for a few seconds about 8 times. The status light for the auger was lit each time this happened, the combustion blower ran steady with it's indicator light on, no error blinking light was shown, and I did not observe the ignitor light come on during the shutdown. I experimented with turning the feed and temperature dials down, which did not seem to have an immediate effect. Eventually, the auger stopped completely, and the pellets burnt up as you normally observe - but it took about a half hour for the shutdown to be complete. I am still learning, but this seems weird - any thoughts?

 

[tinkabranc]

Sounds normal to me.

My stoves take anywhere from 30 mins to an hour to shutdown completely.
Congrats on your new stove, nice choice ;-)

 

[lecomte38]

I've had mine continue for hours. I just open the hopper and it will stop feeding with no vacuum.

 

[imacman]

I've had mine continue for hours. I just open the hopper and it will stop feeding with no vacuum.

To have a pellet stove continue "for hours", and requiring you to "open the hopper and it will stop feeding" seems to be quite ridiculous, IMO. What's the sense in even having an on-off button.....oh, I forgot <insert serious sarcasm here>....it's a HARMON.....it has to be the right way to shut down a pellet stove...just because! :shut:

 

[exoilburner]

My Harmon pellet furnace does the same thing. I can see why the combustion blower would continue to run for a while but don't understand why they keep feeding pellets. Maybe it takes it a while for them to get in to the shut down mode. Who knows? But it appears they have been designed to run that way.

 

[gbreda]

LOL, I think asked the same question after mine was insalled last Sept.

Normal shutdown process. Mine takes about 20-25 minutes. If I do a quick scrape of the burnpot, it sometimes takes less time.

Atlthough "HOURS" does not sound normal.

 

[jimmie ray]

Thank you all for confirming this is normal. I just spoke to a Harmon tech service guy, and he explained the reason for this is to prevent the possibility of burnback through the feed tube. He also took the time to discuss the feeding of extra pellets during the ignition, and the seemingly high flame. Excessive draft effects the pellet ignition time, and flue temperature sensor - causing the additional feeding. I will do the draft test and potentiometer adjustment, but need to get the right equipment. However, I don't have the manual handy, and forgot to ask him about the specifications of the equipment. I thought since others may not be aware of the critical need to perform the draft test, and obviously one of our members is also having a problem, let me inquire here:
1- Pressure gage - Magnehelic 0-1" w.c. range sound appropriate?
2- Tubing - 1/4" I.D. Tygon or equivalent?
3- Barb fitting(s) 1/8" NPT x 1/4" hose for the gage (use low pressure side for negative pressure reading)?
*Any special connection or thread for the stove? I assume a hole, possibly tapped and plugged, is there?
I think Grainger is the best bet for getting these parts, and have one locally...

 

[seige101]

Just my ramblings here. Is the harmon a dual auger system? Could it be the lower auger is clearing out the pellets to prevent the burn back the tech explained?

 

[jimmie ray]

Just my ramblings here. Is the harmon a dual auger system? Could it be the lower auger is clearing out the pellets to prevent the burn back the tech explained?

Didn't get that far into it, but I'd guess the apparently somewhat vertical slant of the feed tube allows heat from combustion to migrate up that way. I'm just a burnin', burnin' chunk, huh, huh - currently. Thank you, thank you very much...

 

[Delta-T]

single auger system

 

[jimmie ray]

Here's all the information on the equipment needed for the draft test, from what I found talking to the Harman people. They do offer a test kit, but the gage only has a range of 0-0.5" w.c., which the actual pressure in the firebox commonly exceeds (huh???).
So I found the more appropriate Magnehelic gage (0- 1" w.c.) and accessories (3/16" I.D. Tygon tubing, 1/8" NPT x 3/16" I.D. hose barbs, and 3/8" x 1/8" NPT bushing) at Grainger, anyway.
The test port is supposedly behind the left leg, and has 3/8-16 bolt in it. I think the 3/8 NPT (tapered) bushing will go in a thread or two, and will be adequate for this low negative pressure. From that I will attach the hose barb, and tubing to the gage (low side).

 

[jtakeman]

Does Harman use a timer to control shutdown, Or a snapdisk?

My Enviro has a snapdisk and as soon as the temp drops to 90ºF it shuts down. Usually around 20 mins to cool down. Seems like a waste of energy to cool it down any longer. Most stoves use the Poof of Fire snap disk as there shutdown trigger.

If Harman has a Poof of Fire snap disk, I would check it to see if its stuck closed.

 

[tinkabranc]

The combustion fan is supposed to stay on until the ESP probe in the exhaust reaches 90
degrees, thats how it knows the fire is out.

Snippet from the manual:

Shut Down Procedure
The best way to shut down the stove is to simply let it run out of pellets, the stove will shut
down automatically. Alternatively, you can turn the Mode Selector to “off”. This will cause the fire to
gradually die down and go out. The fire will not go out immediately and may take more than
an hour to fully shut down.

 

[jtakeman]

Thanks for explaining tink, One of these days I will figure out these Harman's. I bet that big burn pot takes a bit to cool down. Makes sense to just clean out the hopper and let it burn out the remaining fuel. Pretty sure the colder weather would also help in the cool down time. More if its got an OAK.

I am just trying to understand them tis all! I wont knock them Harman's, there's just too many out there and the owners aren't complaining all that much. Haven't seen a stove that hasn't had a quirk or 2! Bet if we did a little pole on owner hapiness, Harman would have a good shot at number one! Hope I didn't start some Chevy, Ford, Toyota stuff here! hehe :lol:

peace!

 

[Boom]

if we did a little pole on owner hapiness, Harman would have a good shot at number one! Hope I didn't start some Chevy, Ford, Toyota stuff here! hehe :lol:

peace!

Dodge!

Another idea (or how I avoided mandatory testing) with the Harman's low draft adjustment...
From a Harman Advance manual: "The low draft voltage should be adjusted to achieve the most efficient burn on low burn or "maintenance"... yada yada ...This adjustment should be done by the installer during set up because a draft meter reading is required to insure proper set up.

If the unit is not adjusted properly, it does not cause a safety concern. If the unit is adjusted too high, only effiency is lost. If the unit is adjusted too low, the low draft pressure switch will not allow the feeder motor or the igniter to operate."

Therefore, If I adjust it to it's lowest point and increase it until it until the feeder motor runs reliably on low... :coolsmile:

Jay
Darn Happy with...
Harman Advance
Maybe I'll light her up tonight with the windows open?

 

[tinkabranc]

Thanks for explaining tink, One of these days I will figure out these Harman's. I bet that big burn pot takes a bit to cool down. Makes sense to just clean out the hopper and let it burn out the remaining fuel. Pretty sure the colder weather would also help in the cool down time. More if its got an OAK.

I am just trying to understand them tis all! I wont knock them Harman's, there's just too many out there and the owners aren't complaining all that much. Haven't seen a stove that hasn't had a quirk or 2! Bet if we did a little pole on owner hapiness, Harman would have a good shot at number one! Hope I didn't start some Chevy, Ford, Toyota stuff here! hehe :lol:

peace!

too funny... :lol:

 

[jimmie ray]

If the unit is not adjusted properly, it does not cause a safety concern. If the unit is adjusted too high, only effiency is lost. If the unit is adjusted too low, the low draft pressure switch will not allow the feeder motor or the igniter to operate."

From what I've learned so far, a high draft adjustment can reduce ignitor temperature, causing a prolonged ignition time and excessive pellet feeding. This accounts for the high flame I observed, which would most likely soot up the unit (impingement), and possibly even cause stress or warping from temperature elevation in the upper firebox area. Too low a draft adjustment might also cause ignition complications, and sooting from a hazy flame. I'm guessing about worst case schenerios, but none of this seems desireble to live with - just to save spending a few minutes on testing or a few bucks on the proper equipment. I'd also guess the reason for the installer to do the draft test, following completion of the flue pipe installation, is so he can address any venting issues if the draft cannot be adjusted to the specifications.

 

[Boom]

Thank you Jimmie Ray for helping me clarify cutting corners at the expense of safety or potential damage to a stove was not my intention. My failed attempt at humor may have misled. My intention was to help people understand their stoves better by studying the manuals, asking questions and thinking about how their stove works. I do not suggest anyone do anything with a stove that is not in their manual without through understanding.

I have a Harman Advance which may not have the same text as your Harman XXV manual. The quote you included above were not my words but verbatim from three separate manuals for the Harman Advance (R1, 12 & 14).

What I did took more time and careful thought not less. There is often more than one way to the desired result. My method should not result in too high a "Low Draft Voltage Adjustment" on my stove. My stove burns efficiently and starts in 3.4 to 5 minutes.

Another thought, very cold pellets may take longer to ignite than warm ones. Shorter pellets perhaps quicker than long ones. As always YMMV.

Congratulations on your purchase and many happy warm winters with your new Harman!

Jay

 

[smwilliamson]

Here's all the information on the equipment needed for the draft test, from what I found talking to the Harman people. They do offer a test kit, but the gage only has a range of 0-0.5" w.c., which the actual pressure in the firebox commonly exceeds (huh???).
So I found the more appropriate Magnehelic gage (0- 1" w.c.) and accessories (3/16" I.D. Tygon tubing, 1/8" NPT x 3/16" I.D. hose barbs, and 3/8" x 1/8" NPT bushing) at Grainger, anyway.
The test port is supposedly behind the left leg, and has 3/8-16 bolt in it. I think the 3/8 NPT (tapered) bushing will go in a thread or two, and will be adequate for this low negative pressure. From that I will attach the hose barb, and tubing to the gage (low side).

A length of 3/8 hose up to the testing hole is fine. You can hold the hose thereof fit it into the opening. Also to note, the draft should be set after the unit has come to high temp, running for at least 1/2 hour and the unit should be completely clean. This is usually, under most circumstances, a one time adjustment. My Harman pulls .62 totally clean and hot.

 

[smwilliamson]

I've had mine continue for hours. I just open the hopper and it will stop feeding with no vacuum.

To have a pellet stove continue "for hours", and requiring you to "open the hopper and it will stop feeding" seems to be quite ridiculous, IMO. What's the sense in even having an on-off button.....oh, I forgot <insert serious sarcasm here>....it's a HARMON.....it has to be the right way to shut down a pellet stove...just because! :shut:

Ok, new rule, anyone with over 5000 posts needs to spell Harman correctly or you are banned.

 

[smwilliamson]

Does Harman use a timer to control shutdown, Or a snapdisk?

My Enviro has a snapdisk and as soon as the temp drops to 90ºF it shuts down. Usually around 20 mins to cool down. Seems like a waste of energy to cool it down any longer. Most stoves use the Poof of Fire snap disk as there shutdown trigger.

If Harman has a Poof of Fire snap disk, I would check it to see if its stuck closed.

Harman uses the ESP sensor in the exhaust port. If you have hot coals in the burn pot it takes a while as it is measuring the actual air temp and not the metal temp caused by the air temp.

 

[smwilliamson]

Thank you all for confirming this is normal. I just spoke to a Harmon tech service guy, and he explained the reason for this is to prevent the possibility of burnback through the feed tube. He also took the time to discuss the feeding of extra pellets during the ignition, and the seemingly high flame. Excessive draft effects the pellet ignition time, and flue temperature sensor - causing the additional feeding. I will do the draft test and potentiometer adjustment, but need to get the right equipment. However, I don't have the manual handy, and forgot to ask him about the specifications of the equipment. I thought since others may not be aware of the critical need to perform the draft test, and obviously one of our members is also having a problem, let me inquire here:
1- Pressure gage - Magnehelic 0-1" w.c. range sound appropriate?
2- Tubing - 1/4" I.D. Tygon or equivalent?
3- Barb fitting(s) 1/8" NPT x 1/4" hose for the gage (use low pressure side for negative pressure reading)?
*Any special connection or thread for the stove? I assume a hole, possibly tapped and plugged, is there?
I think Grainger is the best bet for getting these parts, and have one locally...

You can use an inclined manometer too, but it's not as accurate. How about calling your dealer??? They want to sell, sell, sell but no one wants to service, service, service. Why should you have to set the draft? Isn't this supposed to be set by the installer toconform to warranty requirements? I always set the draft while I'm doing my 1 hr long setup/ homeowner instructional.

Here is the manometer: http://www.grainger.com/Grainger/items/2T650?Pid=search

 

[smwilliamson]

Thank you all for confirming this is normal. I just spoke to a Harmon tech service guy, and he explained the reason for this is to prevent the possibility of burnback through the feed tube. He also took the time to discuss the feeding of extra pellets during the ignition, and the seemingly high flame. Excessive draft effects the pellet ignition time, and flue temperature sensor - causing the additional feeding. I will do the draft test and potentiometer adjustment, but need to get the right equipment. However, I don't have the manual handy, and forgot to ask him about the specifications of the equipment. I thought since others may not be aware of the critical need to perform the draft test, and obviously one of our members is also having a problem, let me inquire here:
1- Pressure gage - Magnehelic 0-1" w.c. range sound appropriate?
2- Tubing - 1/4" I.D. Tygon or equivalent?
3- Barb fitting(s) 1/8" NPT x 1/4" hose for the gage (use low pressure side for negative pressure reading)?
*Any special connection or thread for the stove? I assume a hole, possibly tapped and plugged, is there?
I think Grainger is the best bet for getting these parts, and have one locally...

You can use an inclined manometer too, but it's not as accurate. How about calling your dealer??? They want to sell, sell, sell but no one wants to service, service, service. Why should you have to set the draft? Isn't this supposed to be set by the installer to conform to warranty requirements? I always set the draft while I'm doing my 1 hr long setup/ homeowner instructional.

Here is the manometer: http://www.grainger.com/Grainger/items/2T650?Pid=search

 

[imacman]

Ok, new rule, anyone with over 5000 posts needs to spell Harman correctly or you are banned.

Actually, the rule is that anyone with over 5000 posts gets a pass on the occasional typing mistake. Second rule, is that any young pellet punk with less than 500 posts will keep their keyboard silent about such things! ;-P

 

[imacman]

....Isn't this supposed to be set by the installer toconform to warranty requirements?.....

Hmmmm....the pot calling the kettle black......that couldn't be a mistake there, could it, pellet punk???