Harmon Accentra Trouble Shooting Help and Information

[skipp025atyahoo]

Harmon Accentra Trouble Shooting Help and Information

Hello everyone,

I found this forum while searching for information related to problems I was having with
a Harman Accentra Insert Pellet Stove. I've been able to repair the Accentra and it's again
happily running through its latest bag of pellets.

I read a lot of other member information request posts related to trouble shooting their
specific problems. I thought I might be able to give back to the group by contributing some
Harman Accentra (in my example Insert) pellet stove trouble shooting suggestions. Let's
just say for this thread I'm fairly well experienced regarding the electronics and control
computer board operation.

First and obvious... cleaning. You've got to clean the darn thing out really well. Even as a
long time owner user, I've recently learned there always seem to be places where one needs
to clean and remove ash and fines. A large barrel vacuum cleaner with a fine particulate
filter is a must have. I also bought 3 feet of a small clear plastic (fuel line type of) hose, that with
one end held in to the larger vacuum cleaner hose, will allow me to extend ash and fine removal
suction up in to the internal square exhaust ports (where you also use the factory/dealer supplied
square body wire brush). Be sure to also use the square wire brush, inserting nearly the entire
brush less a few inches in to the lower left port. Most people seem to prematurely stop at
the first lower left port turn/angle.

Second. You must remove the combustion blower from its mount and clean everything
associated with it and inside the mount body.

Caution, unplug the stove from any AC mains and back up power source and be sure to
watch and prevent any wiring harness pinching or damage as you service the stove.

Another must do is to remove or slide the entire insert (in this example) stove forward, away
or pulling out from its main installation mounting frame to expose the gasket interface area
above the combustion blower. This is is the location where the chimney pipe mounts to the
main frame, the main frame area transitions from the round chimney tube to the square box
that below becomes the mounting box for the combustion blower. Sliding or pulling the insert
out/forward exposes a mounting frame/combustion box interface area that over time, really
becomes clogged with ash.

Then be ready with the handle of a hammer and your large vacuum cleaner to tap on the
exhaust chimney pipe, then watch the surprisingly substantial amount of ash (after a few
tons of pellet operation without cleaning this area) rain back down toward the stove. Again,
clean everything as indicated in the owners manual. A small wooden handle paint brush will
help you clean hard to reach areas and the blower body and fins. Need anyone remind you
to be careful and not bend any of the blower fins while you have it removed from it's mount.
Be sure to properly tighten the combustion blower mounting (thumb type) screws, prevent any
wire harness pinching and then slide the insert completely back in to it's frame, properly securing
it with the insert to mounting frame mechanical mounting latches on each side (down low).

Now, on to some of the electronics.

There are differences between Accentra stoves and their internal parts (numbers) by date
of production. At least one revision/update to the micro controller computer board (firmware,
aka software inside the chip) seems to have occurred between 2006 and 2008.

You must not replace any electrical parts without being totally sure the new part
is the exact, proper replacement part. I would also recommend anyone brave enough to
access the micro controller "computer" board, upon access, immediately photograph and even
also draw on paper, a copy of the micro controller board before anything is touched/changed/
done. You want to know and retain all the original wire connection locations and the as-delivered
small on board dip switch settings.

*The Owners Manual for at least some of the 2006 Harman Accentra Inserts, don't show
the top hopper door-open magnetic switch. Later on-line pdf versions of the owners manual
do include the electrical wiring system with top hopper door switch shown.

Trouble Shooting.

Let me address the distribution blower problem that started me on this most recent quest.

After starting and what I call "ramping up" to normal operation, the distribution blower would
suddenly stop. This full on stove operation, less the distribution blower is not good and could
potentially lead to a dangerous excessively high heat or runaway condition. Note if the pellet
feed auger and combustion blower remain in operation when this condition occurs.

After considerable testing, the following information was important to note. With the stove
running, if the distribution blower LED indicator is on and when on, the distribution blower
does in some capacity (or speed) run.

An even more interesting and completely misleading symptom occurs when the fire box door
is opened during the above mentioned condition, and with the fire box door open, the distribution
then blower returns to service (comes back on). A short time after then closing the firebox
door again shuts off the distribution blower.

Don't be mislead by the firebox door open/closed pressure difference , replace your ESP
probe.

The part number of the 2006 year insert was owners manual listed as 3-20-00744, however,
the replacement part supplied by the original dealer arrived with 3-20-11744 and has included
information on the label stating "REV F OF 3-20-00744"

Replacing your ESP in most common cases, should resolve what I call the stove fully on,
distribution blower stopping problem.

Blowers that don't shut off.

Blower speed control is handled by the small micro controller board. A test might be the
blower being combustion or distribution is running at any speed is indicated by the LED
(lights) on the controller. Related to the problem of a blower running even with the stove
off or cold, is the LED indicator for that blower lighted (on)?

The sad part of the above problem, is how a blower constant run problem is probably tied
to a micro controller board electronic part. It's beyond the scope of this post to try and tell
you how to service the board, while it is possible and in many cases relatively easy for the
proper electronics person to service... finding that proper and reasonable electronics
person (with the available time and an honest pulse) is not easy. It might be more cost,
time effective and truly easier to just replace the micro controller board.

If the LED and blower remain on with a cold stove, the micro controller is probably still in
a run condition. This is quite different from the blower remaining on with the LED off, often
indicating a specific controller board part(s) problem.

The blower and LED on, controller possibly still in a run condition is probably related to one
of two choices. First is a bad ESP, which is the cheapest first replacement choice. Second is
a glitch or old firmware within the micro controller firmware or the board itself. Replacing the
micro controller (computer) board is about a $200 cost (as of late Dec 2014).


Blowers and feed motors that don't run at all.

Simply put, the problem is (obviously) electrical or mechanical. Mechanical problems often
cause electrical problems, with excessive current draw (blowing fuses) and damaged
connections/connectors.

A good service technician with some common sense, a bit of experience and a good
quality Multi-Meter ("if it's a good meter, it must be a Fluke") shouldn't need the IMO
excessively high priced Harman Test Box... every device can actually be tested in place with
the proper interface connection to the stoves white Molex style wire harness plug, when
the plug is removed from or off the micro controller (computer) board.

Once again: Caution, unplug the stove from any AC mains and back up power source
and be sure to watch and prevent any wiring harness pinching or damage as you
service the stove.

The individual blowers, motor and control parts paths can be tested using a Mult-Meter
resistance function, which doesn't help a lot related to operational current draw. It's a bit
more involved to trouble shoot the Auger Motor, pressure sensor and ignition path, but
a good electronics person using the proper diagram can go through each leg to find
the failure.

It is very possible and relatively simple for the proper and experienced electronics (or even
a really good appliance) technician to externally power on and test the blowers, auger motor
and igniter directly from the main wire harness white Molex style plug. But the mentioned
external source testing process is potentially dangerous to the uneducated, untrained
and ill equipped service person. I will write the properly applied test process can quickly
isolate and locate problems without having to first remove a blower, motor or igniter. This
test is where the current consumption (draw) of each device is easily measured for its
proper value (within reasonable limits).

Those darn Ingniters.

Once you've replaced your second or third igniter in the same season, it might seem easy
to just start using the wonderful invention of Gel Starter. I like and use the large size One
Match brand and then simply get on with my life.

Early pre 2008 / 2010 Accentra stoves seems to suffer from rapid igniter failures. There
is an improved replacement igniter available if you have to have it. Consult your Harman
Dealer if they have a pulse regarding reasonable part ordering/replacement/cost or simply
do the proper homework and find it on line (Ebay has them offered).

One last thing about the room temp sensor, located underneath the area just below the
micro controller door access (area). When possible, note and record the room sensor
individual wire colors as they exit their larger jacket, just before making connection with the
main stove wire harness leads. I've never experienced a bad room temp sensor unless
the connection was damaged by the owner/operator. They seem to otherwise be a fairly
reliable sensor.

So...

That's about it for this rather windy post, I hope some of you will get some ideas about
different things that can happen with your Harman Accentra Pellet Stove. Now that I've had
an in-depth look at the stove, I can say relative to some of the other brands I've serviced,
the Accentra is relatively well thought out and much more robust that many other brands.

Good luck in the contest (an old radio term)...

Regards,

Skipp

skipp025 at yahoo period com

 

[notch]

Thanks for the thoughtful post. Might be the best first post ever . As a 2006 Accentra insert owner, I found this information interesting and useful. Most of it was not new, but some of your thoughts on the various fan issues were. I suspect this will be helpful for many. Good Christmas present .

 

[F4jock]

In room temp mode my distribution blower cycles if the room temp is satisfied and the stove feed backs down to at or near min. At night when outside temp falls it ends up running pretty much constantly.

 

[Tim_M]

Thanks Skipp, for the detailed post. I've only had my 2006 Accentra insert for 3 mos, and due to our unusually warm fall here it hasn't really seen a lot of heavy use yet. But so far it's been working well other than having to replace the ignitor which I knew about when I bought it. I've bookmarked your post for future reference.

 

[skipp025atyahoo]

Thanks Skipp, for the detailed post. I've only had my 2006 Accentra insert for 3 mos, and due to our unusually warm fall here it hasn't really seen a lot of heavy use yet. But so far it's been working well other than having to replace the ignitor which I knew about when I bought it. I've bookmarked your post for future reference.

Hello back,

You are very welcome and thank you to you and the others for the kind words. I'll be around if you or
anyone else have other questions or comments. I had to break down and reverse engineer out the entire
Accentra system because of the bizarre problems occurring with my stove. Something I would rather
have not been forced to do during the middle of winter, but the completed repair process was very
interesting and educational.

I've come to appreciate the seemingly very mild winters we have in Northern California, where our temps
might get as low as the 20's for short periods. I can't imaging what it would be like living in an area where
it's just plain cold, with snow on the ground for months a time.

Aside from all the repair work...

I've had a casual interest in making an amateur steam boiler... during my research for information about
the pellet stove, I came across Youtube videos of folks who have converted their stoves to boilers... I've
got an old wood stove to experiment with if I want.

And...

If my stove ever becomes problematic again, I will make a test control box that could be connected to
the main harness plug (removed from the micro controller board). The cost to make one would be fairly
reasonable (under $50 cost for all the parts). Part of that test box function would be the ability to plug
on to the micro controller and simulate the blowers, sensors and switches... Something to consider if
there was ever a need...

cheers,
skipp

skipp025 at yahoo dot com

 

[skipp025atyahoo]

In room temp mode my distribution blower cycles if the room temp is satisfied and the stove feed backs down to at or near min. At night when outside temp falls it ends up running pretty much constantly.

Hello again,

The difference from what you describe as normal distribution blower cycles once the stove arrived near
the desired/set temp and what I was experiencing.... with my room still in the 60 degree range and the
stove just coming on line toward full temp, my distribution blower would completely stop and not come
back on. The stove would become very hot with the auger and combustion blower still running as
normal. So this was not the normal expected cycling of the distribution blower.

The distracting part of trouble shooting the problem was how the distribution blower would
restart if I opened the front firebox door. I can only suspect what the pressure or temp change was doing
to the intermittent ESP (probe) and the combustion chamber area around it. I will admit to not having
as clean a combustion blower box area as I thought, but I did clean it out real well and the problem
didn't go away. Only when I replaced the ESP (probe) with a truly clean stove, did the stove assume
a completely normal operation.

thanks

skipp

 

[skipp025atyahoo]

More Harman Accentra Trouble Shooting Help and Information in January 2017

Hello again everyone,

Seems like we blink our eyes and the years just blow past us; it's currently January of 2017
and as you can see by my absence, our Harman Accentra has been behaving itself relatively
well since my flurry of posts back in December 2014.

A recent problem that's actually appeared in the past has occurred and my description and
"work around" might be helpful to some of you.

The stove has been working relatively well, we still use gel-starter because the igniters were
always unreliable for us... always failing in a very short period of time.

The other day I walked in and noticed the stove ramping itself down as if we were
turning it of... this seemed kind of strange because I wanted it to stay on. To save a lot of
time, let me just tell you the stove was actually in a detected fault condition, safe power down
control mode because the micro controller lost one of it's expected input signals.

I have actually witnessed this fault condition in the past... here's the cause, the test for,
the temp work around and the eventual fix.

The temperature control knob is a common electronics potentiometer, also commonly known by
many older people as an older radio volume control. Inside the "pot" is a carbon resistor/resistive
surface and the center contact a movable wiper that makes physical contact on to the carbon
at some point within its normal range.

The Cause:

The stove vibrates, the vibration continually bounces the pot's center metal wiper are on the
carbon surface and eventually over time actually causes an intermittent connection at this
location. If you leave the temperature control at the same setting, this setting location within the
control will start to cause trouble. The micro controller board losing the temperature control
connection will start the forced shut down protection mode.

The Test:

Simply move the temperature control to any different location/position. I rotated my control
clock-wise from 70 degrees, up to about 74 degrees and the stove resumed normal
operation. Counter Clock-wise rotation would also be a valid test, any control pot position
other than where it normally is placed probably has not suffered the internal carbon surface
vibration damage.

The Work Around:

It's cold here on the left coast of the US (California), a bone chilling 50 degrees during the day.
(I just wanted to give some of you colder area folks something to laugh about... "Was I funny?"
So we really don't want to have the Accentra off line right now. I don't have to have the stove
coasting along at my normal 68 to 70 degree set-point, so I increased the temperature range
up to the 72 degree position and the stove is back in regular operation.

The eventual fix:

The temperature control potentiometer on the micro controller board needs to be replaced
next spring or summer. It's probably marked, it can be replaced with an exact type or
even with a better quality part. The vibration issue isn't going away, the new control might
also suffer from this problem, but it's easy enough to fix once you know what's going
on. Do yourself a favor and find a quality part through a known electronics supplier. A
good quality control potentiometer might cost you $5 to $25 dollars each, where as cheap
low cost pots are less than $1 and you do get what you pay for.

There are control pot spray cleaners and special control pot lubricants that do work, but
they also tend to quickly degrade with heat... and you have a stove here... with adjacent
heat. So any cleaner/lube spray fix is at best temporary.

None of the other controls appear to exhibit this vibration damage issue yet, but I wouldn't
be surprised if and when they do... I would imagine the micro controller (computer board)
will also detect a fault and (hopefully) ramp the stove down and off as a protection mode.

There you have it for January of 2017... thank you to everyone who has written very kind
follow up replies to my previous posts. Once again, I'm happy to answer your direct Email
Harman Accentra questions.

I'm very mixed bag opinionated about buying a second Accentra.. I really like the one I
have, it's very strong and robust in the weight, size and heat delivery department. But
the electrical system has been modestly problematic and I can't imagine how many other
owners of Harman and even other brand pellet stoves are pulling their hair out trying to
solve these seemingly stupid electrical, micro controller system problems. I guess that's
where these forums are so valuable to the public at large.

That's about it... best to everyone and I'm looking forward to keeping my Accentra in service
for many more years to come.

cheers,

skipp

skipp 025 at yahoo dot com

Harman Accentra Trouble Shooting Help and Information

Hello everyone,

I found this forum while searching for information related to problems I was having with
a Harman Accentra Insert Pellet Stove. I've been able to repair the Accentra and it's again
happily running through its latest bag of pellets.

I read a lot of other member information request posts related to trouble shooting their
specific problems. I thought I might be able to give back to the group by contributing some
Harman Accentra (in my example Insert) pellet stove trouble shooting suggestions. Let's
just say for this thread I'm fairly well experienced regarding the electronics and control
computer board operation.

First and obvious... cleaning. You've got to clean the darn thing out really well. Even as a
long time owner user, I've recently learned there always seem to be places where one needs
to clean and remove ash and fines. A large barrel vacuum cleaner with a fine particulate
filter is a must have. I also bought 3 feet of a small clear plastic (fuel line type of) hose, that with
one end held in to the larger vacuum cleaner hose, will allow me to extend ash and fine removal
suction up in to the internal square exhaust ports (where you also use the factory/dealer supplied
square body wire brush). Be sure to also use the square wire brush, inserting nearly the entire
brush less a few inches in to the lower left port. Most people seem to prematurely stop at
the first lower left port turn/angle.

Second. You must remove the combustion blower from its mount and clean everything
associated with it and inside the mount body.

Caution, unplug the stove from any AC mains and back up power source and be sure to
watch and prevent any wiring harness pinching or damage as you service the stove.

Another must do is to remove or slide the entire insert (in this example) stove forward, away
or pulling out from its main installation mounting frame to expose the gasket interface area
above the combustion blower. This is is the location where the chimney pipe mounts to the
main frame, the main frame area transitions from the round chimney tube to the square box
that below becomes the mounting box for the combustion blower. Sliding or pulling the insert
out/forward exposes a mounting frame/combustion box interface area that over time, really
becomes clogged with ash.

Then be ready with the handle of a hammer and your large vacuum cleaner to tap on the
exhaust chimney pipe, then watch the surprisingly substantial amount of ash (after a few
tons of pellet operation without cleaning this area) rain back down toward the stove. Again,
clean everything as indicated in the owners manual. A small wooden handle paint brush will
help you clean hard to reach areas and the blower body and fins. Need anyone remind you
to be careful and not bend any of the blower fins while you have it removed from it's mount.
Be sure to properly tighten the combustion blower mounting (thumb type) screws, prevent any
wire harness pinching and then slide the insert completely back in to it's frame, properly securing
it with the insert to mounting frame mechanical mounting latches on each side (down low).

Now, on to some of the electronics.

There are differences between Accentra stoves and their internal parts (numbers) by date
of production. At least one revision/update to the micro controller computer board (firmware,
aka software inside the chip) seems to have occurred between 2006 and 2008.

You must not replace any electrical parts without being totally sure the new part
is the exact, proper replacement part. I would also recommend anyone brave enough to
access the micro controller "computer" board, upon access, immediately photograph and even
also draw on paper, a copy of the micro controller board before anything is touched/changed/
done. You want to know and retain all the original wire connection locations and the as-delivered
small on board dip switch settings.

*The Owners Manual for at least some of the 2006 Harman Accentra Inserts, don't show
the top hopper door-open magnetic switch. Later on-line pdf versions of the owners manual
do include the electrical wiring system with top hopper door switch shown.

Trouble Shooting.

Let me address the distribution blower problem that started me on this most recent quest.

After starting and what I call "ramping up" to normal operation, the distribution blower would
suddenly stop. This full on stove operation, less the distribution blower is not good and could
potentially lead to a dangerous excessively high heat or runaway condition. Note if the pellet
feed auger and combustion blower remain in operation when this condition occurs.

After considerable testing, the following information was important to note. With the stove
running, if the distribution blower LED indicator is on and when on, the distribution blower
does in some capacity (or speed) run.

An even more interesting and completely misleading symptom occurs when the fire box door
is opened during the above mentioned condition, and with the fire box door open, the distribution
then blower returns to service (comes back on). A short time after then closing the firebox
door again shuts off the distribution blower.

Don't be mislead by the firebox door open/closed pressure difference , replace your ESP
probe.

The part number of the 2006 year insert was owners manual listed as 3-20-00744, however,
the replacement part supplied by the original dealer arrived with 3-20-11744 and has included
information on the label stating "REV F OF 3-20-00744"

Replacing your ESP in most common cases, should resolve what I call the stove fully on,
distribution blower stopping problem.

Blowers that don't shut off.

Blower speed control is handled by the small micro controller board. A test might be the
blower being combustion or distribution is running at any speed is indicated by the LED
(lights) on the controller. Related to the problem of a blower running even with the stove
off or cold, is the LED indicator for that blower lighted (on)?

The sad part of the above problem, is how a blower constant run problem is probably tied
to a micro controller board electronic part. It's beyond the scope of this post to try and tell
you how to service the board, while it is possible and in many cases relatively easy for the
proper electronics person to service... finding that proper and reasonable electronics
person (with the available time and an honest pulse) is not easy. It might be more cost,
time effective and truly easier to just replace the micro controller board.

If the LED and blower remain on with a cold stove, the micro controller is probably still in
a run condition. This is quite different from the blower remaining on with the LED off, often
indicating a specific controller board part(s) problem.

The blower and LED on, controller possibly still in a run condition is probably related to one
of two choices. First is a bad ESP, which is the cheapest first replacement choice. Second is
a glitch or old firmware within the micro controller firmware or the board itself. Replacing the
micro controller (computer) board is about a $200 cost (as of late Dec 2014).


Blowers and feed motors that don't run at all.

Simply put, the problem is (obviously) electrical or mechanical. Mechanical problems often
cause electrical problems, with excessive current draw (blowing fuses) and damaged
connections/connectors.

A good service technician with some common sense, a bit of experience and a good
quality Multi-Meter ("if it's a good meter, it must be a Fluke") shouldn't need the IMO
excessively high priced Harman Test Box... every device can actually be tested in place with
the proper interface connection to the stoves white Molex style wire harness plug, when
the plug is removed from or off the micro controller (computer) board.

Once again: Caution, unplug the stove from any AC mains and back up power source
and be sure to watch and prevent any wiring harness pinching or damage as you
service the stove.

The individual blowers, motor and control parts paths can be tested using a Mult-Meter
resistance function, which doesn't help a lot related to operational current draw. It's a bit
more involved to trouble shoot the Auger Motor, pressure sensor and ignition path, but
a good electronics person using the proper diagram can go through each leg to find
the failure.

It is very possible and relatively simple for the proper and experienced electronics (or even
a really good appliance) technician to externally power on and test the blowers, auger motor
and igniter directly from the main wire harness white Molex style plug. But the mentioned
external source testing process is potentially dangerous to the uneducated, untrained
and ill equipped service person. I will write the properly applied test process can quickly
isolate and locate problems without having to first remove a blower, motor or igniter. This
test is where the current consumption (draw) of each device is easily measured for its
proper value (within reasonable limits).

Those darn Ingniters.

Once you've replaced your second or third igniter in the same season, it might seem easy
to just start using the wonderful invention of Gel Starter. I like and use the large size One
Match brand and then simply get on with my life.

Early pre 2008 / 2010 Accentra stoves seems to suffer from rapid igniter failures. There
is an improved replacement igniter available if you have to have it. Consult your Harman
Dealer if they have a pulse regarding reasonable part ordering/replacement/cost or simply
do the proper homework and find it on line (Ebay has them offered).

One last thing about the room temp sensor, located underneath the area just below the
micro controller door access (area). When possible, note and record the room sensor
individual wire colors as they exit their larger jacket, just before making connection with the
main stove wire harness leads. I've never experienced a bad room temp sensor unless
the connection was damaged by the owner/operator. They seem to otherwise be a fairly
reliable sensor.

So...

That's about it for this rather windy post, I hope some of you will get some ideas about
different things that can happen with your Harman Accentra Pellet Stove. Now that I've had
an in-depth look at the stove, I can say relative to some of the other brands I've serviced,
the Accentra is relatively well thought out and much more robust that many other brands.

Good luck in the contest (an old radio term)...

Regards,

Skipp

skipp025 at yahoo period com