Harman Six Blink Part-time Problem

[slheinlein]

I have a XXV thats roughly I got in the fall of 2007. I've started to have a six blink problem with it recently and it will shut itself down. However, if I keep it in stove temp with the dial < '3', then it will run fine. The six blink trouble happens only when the stove gets to a certain temp. It seems if it stays at a relatively low temp, everything is fine. I replaced the ESP not too long ago for a separate problem. Done thorough cleanings so I don't believe that is the issue. I'm thinking it could be the differential / draft switch but thought I would check out here to the experts for advice. Thanks.

 

[Bioburner]

Have you tested the door gaskets? Stove 5 seasons or so old could have some compressed gaskets not working as well as they should. I replaced the ones on our 45 last fall and have had no more sporadic 6 blink codes so far this season.

 

[Former Farmer]

From Harman manual

#6 status blink: A 6 blink control board status indication is caused by poor or incomplete combustion. The Automatic Ignition circuit board has the ability to track the combustion through feed settings and ESP temperatures. When the control board has calculated poor or incomplete combustion, it will shut down the unit as a safety feature. (Poor or incomplete combustion is a contributer of creosote which may cause a chimney fire)
A 6 blink status may be caused by several things:
1. Blocked or partially blocked flue.
2. Blocked or partially blocked inlet air.
a. Backdraft damper on the inlet pipe may be stuck closed.
b. If outside air is installed, the inlet cover may be blocked.
3. The air chamber under the burnpot may be filled with fines and small bits of ash.
4. The holes in the burnpot may be getting filled with ash or carbon buildup.
5. Combustion blower fan blades may need cleaned.
6. There is no fuel in the hopper.

Did the problem start shortly after installing the new ESP probe? Possible bad probe?
Did you install the correct ESP probe? I know for the PB105, there are several different ones. They have different wire colors.

 

[Bioburner]

If air is not going through the pot properly can lead to improper combustion. Is the stove showing any sign of soot?

 

[F4jock]

Farmer and Bio have it right. When you crank it are there true signs of incomplete combustion such as partially burned pellets?

 

[slheinlein]

Thanks for the responses.
I replaced the seal last season so it should be good.
I haven't noticed soot or unburned pellets but do think it is a air inlet problem. After the six blink trouble, the igniter doesn't work so I've had to manually start the fire. Its very difficult to start the fire, very slow to start and get a good burn going so I'm thinking the airflow into the burn pot may not be sufficient. Is there a way to check the air flow in the burn pot? The inlet hose looks fine and the valve isn't stuck so I think the air coming in is good but not sure how to check.

 

[F4jock]

Maybe a silly question but is the igniter chamber clean? Where is the voltage pot for the combustion blower set? Have you tried setting it higher?

 

[rickwai]

A partly blocked feeder will cause this also. Empty pellets and check for obstruction in bottom of hopper. When starting up does it auger in a full pot of pellets so the stove starts without having to do a second push?

 

[Bioburner]

You say you replaced seal. Both door seals? Rick talks about partially blocked feed too. Ive seen stuff wrapped around auger not allowing full feed.

 

[slheinlein]

Just wanted to follow up on this. I took the board and probe in to have it tested. Both tested fine at the store. A service technician came to my home to check it out. He initially didn't come up with any problems and was about to give up when the probe started acting crazy. The temp the probe was recording was around 200 degrees when the stove was obviously hotter than that. In fact, the temp went from 400 degrees down to 200 degrees in an instant.
He replaced the probe and everything has been working for about 3 weeks now. So the problem was a intermittent bad probe, which was tough to diagnose. Technician said this is very unusual. Usually probes work or not but don't do intermittent.