Pellet stove heat decreases daily

[LuvMyStove]

Hi Guys - We've had an Austroflamm Integra since 1995 (it was a one year old floor model). We've had some issues over the years, but generally it's been a very good stove. For the past week or two, we've noticed that the stove starts putting out less heat the day after I clean it. If I let it go two days before shutting it down and cleaning it, the heat output is even more diminished.

At first I thought it was the convection fan. It makes a slight rattle, which increases in volume when I go from 3 to 4 (out of six) on the user control board. When I replaced the convection fan/motor 7-8 years ago, it was because the bearings were squealing and the blades were noticeably slower - almost seized. This is a different sound, but could mean the same thing. Does anyone know if I can replace or lubricate the bearings? I hate to spend another $220 for a new fan assembly.

Even if the convection fan is an issue, it doesn't explain why the heat output reduces the way it does. When I start the stove up after having cleaned it, we get plenty of hot air. The next day it's really warm air and the day after that, just warm air. The combustion fan seems to be running fine, although I have no way of measuring the rpms of either fan. There does seem to be quite a bit of clinker in the burn pot, but we've been using the same pellets (Hamers Hot Ones and Barefoot) the whole winter so I ruled the pellets out. I also can't figure out how the high and low limit switches could be involved. My one thought is to adjust the air/pellet balance, but haven't done that since we first got the stove and am sort of worried I might screw it up. The flames seem - to me - a pretty dark yellow. They decrease in size every day. A very small amount of pellet ash is popping out of the burn pot, but really not much at all.

Following is my maintenance schedule, as it might rule out some of the possibilities. Thank you in advance for any help you might offer.

I remove the sides and cast iron every 6 weeks or so and vacuum it out (both from around the tubes and the smoke exhaust chamber behind the tubes that leads to the combustion fan, as well as the square holes that connect the two). I even remove the combustion fan and suck out the ash before and after the fan blades. I clean the stove pipe at the same time. As I noted above,I replaced the convection fan/motor 7-8 years ago and we had to have the main board replaced after a brown-out maybe 12 years ago). I keep a new combustion fan and auger motor on hand for when if/when they will be needed.

 

[SmokeyTheBear]

Every minute that goes by after you clean the heat exchanger surfaces the ash builds up on the surfaces, this interferes with heat transfer to the convection side of the stove. More ash, better insulated less heat transfers, convection system has less heat to blow into the room.

If your convection fan is dirty less airflow into the room, the higher the temperature in the convection side of the heat exchanger, and less heat transfers from the firebox side of the stove.

 

[LuvMyStove]

Thank you for responding. Are you saying that I should remove the convection fan, vacuum the fins on it and then reinstall it?

 

[summit]

I believe that is exactly what he's sayin... and check the venting all the way to it's termination as well, sometimes it's at the other end.

 

[SmokeyTheBear]

Clean the convection fan, however that is only one half of the system. A lot of stoves have a heat exchanger tube scrapper that in some cases can be used while the stove is in operation to remove ash from the fire side of the heat exchanger system. Your manual should speak to the proper use of any heat exchanger scrapper system (some stove manuals tell you to only use it when the stove is off).

 

[LuvMyStove]

Thank you both. With regard to the second post, i thoroughly cleaned the heat exchange tubes recently when i serviced the inside of the stove. I made special cleaning tools that let me remove ash from behind the tubes and we use the "tube cleaners (scrapers)" several times a day while the stove is running. I'm sure some ash has attached itself to the tubes since I had the cast iron out two weeks ago, but it should - hopefully - be minimal.

With regard to the previous post, I will remove the convection fan and motor - but I have a stupid question. You'd think I would know this after 16 years, but where is the air intake for the convection fan? Is it on the front of the stove underneath the combustion chamber door? Or does it get air through the air intake that feeds the fire (which I believe is the round hole on the back side of the stove)? In either case, i'm not sure how to clean it out. I looked through both the User Guide and the Tech Manual and neither seemed to show where the air comes in. Thanks again guys.

 

[SmokeyTheBear]

Have you ever cleaned the air intake side of the stove?

That is the area between the intake and the burn pot. Over time crud has been known to get into some strange places. Stuff like dog and cat hair, kids toys, etc ...

It is also possible that the damper got hit and the stove is crudding up faster than it used to.

If you have a leaf blower that can be used as a leaf vacuum do a search on leaf blower trick. That might get some hidden ash that your cleaning method still leaves behind.

 

[SmokeyTheBear]

Usually the air for the room blower comes from inside the stoves shell, there are a lot of slots or holes in some of the panels. It doesn't come through where the fire gets its air.

 

[Flammam]

Hi there nice stove you have. Here a couple of things to try. Carefully remove the intake air sensor and clean it off, after 15 years it may be a little cruddy and will affect how the stove runs. It is located on the round tube the air gets sucked into the stove through, behind the control knob panel. Take it out and blow it off with air and get all of the dust off of it. While you have the right side of the stove off pull the small square cover off of the bottom of the heat exchanger(held in by 4-5mm screws) and vac the heck out of the exhaust passages.
Removing the convection blower is pretty simple. Its held in by 4 5mm screws 2 on the right side of the stove and 2 on the left side. It comes out the left side after you remove the wires. I use a compressor and a soft brush to clean out the fins on the squirrel cage. The bushings can be lubricated on both the motor and the other end of the fan assembly. I lubricate mine every year at the begining of the season.

I will say the only time I had this problem it was bad pellets.(cornith from 3 years ago) I would get good heat for a couple of days then it would get colder and colder
Let me know how this works out for you

Your COMBUSTION AIR comes in through the round tube with the sensor, the convection air comes from the bottom of the stove

 

[LuvMyStove]

Thanks everyone.

I'll remove the convection fan assembly and clean the fins, but need to know what kind of lubricant to use on the bushings: silicon, 30W motor oil, grease, 3 in 1 oil, WD40? I imagine it has to be somwhat heat resistant?

Once I have the fan assembly out, how do I get into the air exchange chamber behind it to clean it out? Grills cover the opening on top and bottom so I can't get a vacuum nozzle in there to clean out the dust.

I'll also try to remove and clean the air sensor from the air intake tube.

I cleaned out the smoke exhaust chamber two weeks ago (I do it every six weeks or so) so that should still be pretty clean.

 

[SmokeyTheBear]

On the fan assembly there may be a makers plate that will specify the oil to use.

It may also be in the installation manual and is likely in the service manual.

Usually 3 in 1 Blue and White can which is SAE #20 non detergent oil is used on electric motor bearings, the manufacturer of the motors and assembly is the authority as to what gets used.

Grills are a pain usually all you can do is use the vacuum on the grill holes (unless you can remove the grills). You should be able to snake a rubber hose attached to a crevice tool into most areas you open up by removing the blowers.

Make certain that any of this work is done with the stove off, cold, and unplugged. One doesn't want an oops moment followed by the release of the magic blue smoke from the electronics.

 

[Flammam]

You can get into the "non smoke side" of the heat exchanger tubes from the bottom of the stove, its NOT easy. I bought a really long flexible brush and jamb it through the grills and into the tops of the heat excahger tubes. Run it up and down a couple times and it should clean the dust out of there. I would clean the intake air sensor first(2-5mm screws). I used 3-1 oil on the convection blower bushings only a couple drops you dont want to be attracking dust.

 

[Stovensen]

Luvmystove,

Your Austroflamm Integra stove made me curious, simply because it looks so much like my Whitfield

Did a little homework and was surprized that it's not made in the US, but in the EU ( Austria ).
Here in Europe, however, these stoves have a different name ( Rika ).
Inside, the Integra is technically somewhat different from an old Whitfield.
An example is the air sensor... as mentioned by Flamman and from studying the service manual, an unstable air sensor certainly could make the heat output fluctuate the way yours does.
Also, the combustionmotor is monitored by a Hall sensor connected to the control board. The service manual suggests that an unstable Hall ic could make the heat output fluctuate as well.

I found the service manual.pdf in english for free download here. It's very detailed, but still straightforward.

http://pelletstoverepair.com/IntegraTechManual.pdf

Good luck
Bo

 

[LuvMyStove]

Thanks Bo. It's a coincidence that I found and downloaded a free copy of the Tech Manual yesterday (after having the stove 16 years!). I didn't even know one existed; and I was always disappointed by how little the Owner's Manual tells me. A lot of the electrical testing they mention in the Tech could probably narrow my search for the problem, but I'm really not good with electronics and wouldn't even know what to get (a voltage meter?) to do the testing.

As I said in a previous post, I'm going to start with cleaning the convection fan (and any other mechanical parts of the stove I can reach) and - if that doesn't help - work my way through the solutions that will cost us money, starting with the cheapest first. My wife doesn't want me to start surgery on it until it warms up a little in April. Probably a wise move. The stove is working; just not efficiently.

Thanks to all of you who suggested solutions. I'll let you know what happens (unless I do something REALLY embarassing).

 

[SmokeyTheBear]

...
I'll let you know what happens (unless I do something REALLY embarassing).

Don't let that stop you. If geek can admit to hooking up his shop vac to blow instead of suck and applied that to the exhaust system with the stove door open, there likely isn't anything you can do that hasn't already been posted here ;-P .

 

[LuvMyStove]

p.s. The same thing happened last night. I cleaned the stove yesterday at 3 pm. An hour or two later, the air coming out of the top of the stove was so hot I couldn't hold my hand in front of the vent for more than a few seconds. Now the air coming out is just warm - barely enough to keep the house liveable. I'll have to shut it down and clean it again this afternoon.

 

[LuvMyStove]

p.p.s. Sorry to keep posting as I think here, but that's why I thought the burn pot might be getting clogged too quickly with ash/clinker. That would seem, to me, anyway, to explain the gradual decrease in heat output. Could adjusting the pellet/airflow make a difference? And if so, which way would I turn the adjustment? I don't think that it's bad pellets, since I'm alternating between two brands (Hamer's Hot Ones and Barefoot). We did have a bad time with the brand we used last year, which produced an enormous amount of ash, but the new pellets seem to burn pretty efficiently.

 

[SmokeyTheBear]

p.p.s. Sorry to keep posting as I think here, but that's why I thought the burn pot might be getting clogged too quickly with ash/clinker. That would seem, to me, anyway, to explain the gradual decrease in heat output. Could adjusting the pellet/airflow make a difference? And if so, which way would I turn the adjustment? I don't think that it's bad pellets, since I'm alternating between two brands (Hamer's Hot Ones and Barefoot). We did have a bad time with the brand we used last year, which produced an enormous amount of ash, but the new pellets seem to burn pretty efficiently.

Increase your airflow a bit and wait. If you can keep the ash from staying in the pot and the temperature from being just right you may be able to prevent clinker formation. Since this deals with airflow, I'd make certain that the sensor in your intake air path is clean as was suggested by flammam. This could be the reason things are happening the way they are.

 

[LuvMyStove]

I guess my last post didn't fly.

Thanks again and one more question: if I can get the air sensor out without damaging it, how can I safely clean it? It looks like a circuit board and I've been told not to use anything like a vacuum cleaner because it would destroy the circuits. Even a soft brush sounds dicey. Any tips?

 

[SmokeyTheBear]

I guess my last post didn't fly.

Thanks again and one more question: if I can get the air sensor out without damaging it, how can I safely clean it? It looks like a circuit board and I've been told not to use anything like a vacuum cleaner because it would destroy the circuits. Even a soft brush sounds dicey. Any tips?

Send Flammam a PM and ask.

 

[LuvMyStove]

Thanks to everyone who responded to my post. Flammam got me to remove the air sensor, the business end of which was badly melted. Neither of us could believe it was still working. We'll be replacing that and see if it makes a difference. Thanks again.

 

[SmokeyTheBear]

If that was in the air intake you might want to investigate how that much heat got there.

 

[imacman]

....Flammam got me to remove the air sensor, the business end of which was badly melted. Neither of us could believe it was still working......

Maybe you could post a pic of the air sensor, and show what melted....I'd be interested in seeing it.

Make sure to post a follow-up after new sensor is installed and run for a while.

 

[Flammam]

Looked like a possible component failure on the end of the temperture sensing circuit. Caused the board to overheat and burn up/char some of the circuit traces. Belive it or not I have seen boards with even more damage still function although at a degraded performance.

 

[Stovensen]

$140 at Wood Heat Stoves:

http://woodheatstoves.com/austroflamm-integra-air-sensor-p-512.html

The components on the circuit board, are they standard on the shelf types or special custom types?

If standard types and you're handy with a soldering tool it might be possible to repair.

I'm not able to identify the components from this photo: