Thelin Parlor Fail to light

[Aughtago]

I have been working to resolve the frequent failure to light on my Thelin Parlor pellet stove. I purchased it new in 2008 and later upgraded to the new firebox (per recomendation from Jay) My stove runs on T-stat with battery backup and is run on Low 24/7 cycling on the t-stat which is in another room. (it gets to about 85 in the kitchen where the stove is, but comfortable in the rest of the house.

I have TWO other issues with this stove , OVERFEEDING after fail to light(I believe is temp sensor issue and think I have a solution), and if power fails while stove is off it turns on the auger and fills the stove with pellets-As designed acording to Jay) but Iwill focus on the fail to light with this post.

The problem seemed less frequent at first, then got worse. I spent ALL last winter working with Jay to troubleshoot it and have replaced EVERYTHING except T1 sensor. I am an electrician with access to high tech test equipment and monitored it with an 8 channel digital chart recorder. I was unable to pinpoint any electrical problems with the stove.

Jay finally decided my problem was due to too many bends(T, 90, T) in the exhaust pipe too close to the stove(within first 6'-see attached pdf). I DONT BELIEVE IT. I think it is more to do with TOO much draft(due to 15' rise of 4" pipe through an old chimney. I believe this because I watched the flame get blown out from too much air, or just spew sparks untill all pellets near the ignighter were burnt away. If I cracked open the door and throttled the airflow during startup I could get it to every time.

I have closed my intake completely and raised the min fan speed during run cycle to try to compensate for the closed damper. This helps the situation a lot but did not solve it completely. It still fails to light probably 5 times per week. This setup also results in quick sooting of the glass.

Anyone else with a Parlor had this issue? If so, Have you found a solution yet?

 

[Monkey Butler]

I have a Thelin Echo which I beleive has similar internal works as your stove and it behaves the exact same way.

I have determined that there is just too much air velocity during startup. The volume of air flowing over the igniter cools it to the point where it doesn't get hot enough to ignite the pellets.

I did two things to confirm this. First, if I leave the door open about an inch so that the air velocity through the burn pot and past the igniter is reduced the stove lights without any problem. Second, I put a separate temporary speed control on the blower and reduced the speed to about half the normal speed. Stove lights no problem.

I see two possible solutions. One is to try to find a higher wattage igniter, which are commonly called cartridge heaters if you want to do an internet search. Trying to figure out what the next step up from the Thelin supplied part is the challenge.

The other is to disign a circuit that would reduce the voltage to the blower motor whenever the igniter relay is energized.

This is my first season with the stove and I bought it used knowing that the igniter was an not working. Once heating season is over I'll be able to do a little more testing and come up with a permanent solution.

 

[Aughtago]

Sounds identical! 1" door gap is about where I was, I would then slowly shut it as the flame developed.

Before I realized it was airflow issues, I also suspected the igniter was not getting hot enough. It seems to fail more in the wee hours 3-5 am and I thought that it may have been due to lower voltages on the power grid at night. I tried last year was to install a buck boost transformer in-line with the igniter and it helped tremendously. I believe this will also shorten the life of the heater element. I removed the transformer when Jay and I were playing the parts replacement game to narrow down the problem. I have been tempted to put it back on.

The ideal solution would be If we could adjust the programming of the PIC chip we could set a lower blower voltage during start-up. I have a PIC chip reader/programmer and tried to download the existing program. Thelin however has enabled the write protection and the program cannot be read. Jay had indicated a willingness to modify the program for me but he has been out of contact since last year and all my emails come back return to sender- "users mail folder is full" apparently he has finally retired. maybe I'll try the Thelin technical support to see if they will share the code, but my experience is that they wanted nothing to do with this stove and left any troubleshooting up to Jay.(even though he sold the company and was retired)

I also designed an add on circuit that would shut the stove down on failure to light OR on loss of power IF it is not currently running. I just haven't had the time to find the parts and build it. This circuit could probably be modified to include a start-up fan control.

 

[SmokeyTheBear]

What does the area around the igniter look like and can the position of the igniter be adjusted either forward or backward ?

 

[Aughtago]

The igniter is threaded into a tube. the tube is welded to a bracket that screws onto the outside of the firebox support/air duct. When the fire pot is placed in the support, the igniter barely protrudes into the pot. There a a couple small holes in the tube that allow air to be drawn past the heater/igniter and into the fire pot creating a miniture heat gun.

There is no adjustment possible without welding a new tube/bracket design. see attached photos of igniter installed in air duct/support, fire pot installed, and one with the ignitor removed and rolled upside down for view of bracket.

 

[Aughtago]

here is the igniter without the fire pot

 

[Aughtago]

and the igniter unbolted and rolled over to see bottom of bracket and tube

 

[Monkey Butler]

Aughtago, if you could reprogram the blower speed during ignition that would be the answer I do believe. Way beyond my knowledge though. The dealer that I bought parts from seemed to indicate that he was still able contact Jay directly. I'll email him with your idea and see if he can get a response from Jay if that is okay with you.

Smokey, the bottom of the burn pot has a "grate" of 1/4' rods running lengthwise across the bottom. A cross section would look sort of like this:

O O
O O
O

and that bottom rod is the tubular shaped igniter. It slips thru holes drilled in the end plates of the burnpot and there is no adjustment. Shouldn't need any as pellets sit right on top of it. It's just that there is too much air velocity across it that carries away too much heat and actually blows out the fire before it gets started.

 

[SmokeyTheBear]

So if you can't slide the igniter in and out in the tube (from the picture you provided I'd say it needs to go backward in that tube).

How is the igniter secured in the tube?

Perhaps a shorter cartridge heater is called for.

Misfires are fairly common and frequently the area around the igniter is blocked with ash but there are cases where the blockage is actually the igniter being to close to the tube exit.

 

[Monkey Butler]

Different igniter layout, same problem, same cause, both stoves use the same control board. Solution would seem to be a new program.

Aughtago, I have emailed Thelin and gotten answers from Jim Blocker [email protected] but they were usually short and sweet, "replace something". If you do contact them feel free to mention me as another disgruntled customer.

Steve Pawlowskis
steve AT monkeybutler DOT com

 

[Aughtago]

Fire God: The igniter is screwed into the tube. Your theory is opposite of what I had in mind, I wanted to get it closer to the pellets. I do not think it is an ash problem, I have had it fail frequently just after cleaning the stove. In fact it seems to work better when it's dirty(blocking air flow?), it would be relativly easy to try your theory sometime when I have the stove apart.

Firestarter; Sounds like you have the original firebox design. Jay convinced me to upgrade to the new design. I did have the same problem with the original design. It seemed to improve when I installed the new firebox, then degrade agin over time, but that just may be my perception. It seems like every thing I try makes it less frequent for awhile, but that is just from memory/perception, I should probably log every failure to light to get an acurate idea if improvement occurs. One thing for sure nothing I have tried has eliminated the problem.

 

[SmokeyTheBear]

Fire God: The igniter is screwed into the tube. Your theory is opposite of what I had in mind, I wanted to get it closer to the pellets. I do not think it is an ash problem, I have had it fail frequently just after cleaning the stove. In fact it seems to work better when it's dirty(blocking air flow?), it would be relativly easy to try your theory sometime when I have the stove apart.

Firestarter; Sounds like you have the original firebox design. Jay convinced me to upgrade to the new design. I did have the same problem with the original design. It seemed to improve when I installed the new firebox, then degrade agin over time, but that just may be my perception. It seems like every thing I try makes it less frequent for awhile, but that is just from memory/perception, I should probably log every failure to light to get an acurate idea if improvement occurs. One thing for sure nothing I have tried has eliminated the problem.

Yes I understand the counter intuitiveness of the igniter being positioned further away. But it is in fact a hot air gun and it really does need a lot of air flow but that doesn't always mean a lot of air pressure.

 

[wwert]

I may be wacked but isn't there a new eprom chip that goes along with the new burn pot design. That program chip should be the current one for the new pot. They are available at Stove King in Danielson, CT and he has a great website for all Thelin parts. I would make sure you have the latest chip.

 

[Aughtago]

Yes really Hot, the firebox came with a new program chip, with different timings, but I don't believe it affected the fan speed at startup.
Then when working with Jay to solve this issue , I replaced the board, the chip, the T2 sensor, the fan motor, the auger, and the igniter. Everything except T1 and the relay, control transformer, and control panel. No change when I replaced any of these except we created another problem (overfeeding) when working on T2. I now believe that problem may be due to loose insulation and tape around T2 and plan to open her up again to repair that.

The overfeeding occurs after a failure to light, and the stove keeps shoving pellets in. Twice the smoldering pellets in the ash (from previous failure to light) eventually caught the entire fire chamber full of pellets on fire and bagan to burn up into the feed chute. Fortunatly I caught it both times and was able to prevent the fire from spreading to the hopper. Jay didn't seem to concerned with this symptom, but it really scared me. I'll try to post some pics of overfeeding and the resultant fire.

You can see by the photo Overfeed fire 1 that the fire actually started outside of the fire pot, on the left side. I think that a previous failure to light(FTL) caused pellets to build up in the ash. Then a succesful ignition and run cycle started these pellets smoldering. On the next attempt to start it failed, and overfed more pellets onto these smoldering pellets eventually catching on fire. It was about 3 am when I found it after I got up to tend to my dogs who either wanted to go outside OR knew there was something wrong (they woke me up both times this stove caught fire in the early am). On another occasion I had a FTL and overfeed, I cleaned out the stove and found a baseball size pocket of smoldering pellets in the ash pit to the left of the firepot. Now after a FTL I completely clean out all ash and pellets from the stove and thus have prented any more fires like this.

 

[Aughtago]

This is the aftermath of one of the overfeed fires

 

[jtakeman]

Scary! I wouldn't be running it!

You say new control chip? Did it do this before the upgrade?

 

[Monkey Butler]

FWIW,the place where I bought all my parts was Stove King. It seemed like Matt still might know how to get in touch with Jay.

 

[Aughtago]

It has always failed to light, the overfeed condition started right after inspecting and relocating the T2 sensor (following Jay's recomendation) It was BEFORE we replaced all the other items including the T2. However, just last week I took the stove apart and inspected the T2 in close detail. I found the foil tape and insulation had loosened up. I got the sensor apart far enough to read the part number on the transistor package. I put it all back together, and tried to tuck the original inulation back on.
After re-searching the part number online I discovered that this type of sensor will average the temperature sensed on the transistor package with that of it's electrical leads. It is imparitive to keep the leads and board insulated. The stove worked well for 2 days, shuting itself down after every FTL. Then it began to act up again. I suspect the foil tape and insulation have loosened up again. I plan to dissasemble it today and try to repair/replace the high temp tape and insulation.

I may look closer at the igniter to see if I can move it back in the tube as suggested. If I can solve the FTL, it also solves the overfeed condition. I then would only have to fix 1 other design problem which is the auto-feed on power failure.

 

[SmokeyTheBear]

Snip ...

I may look closer at the igniter to see if I can move it back in the tube as suggested. If I can solve the FTL, it also solves the overfeed condition. I then would only have to fix 1 other design problem which is the auto-feed on power failure.

Not exactly as the controls should always detect a failure to light and respond by shutting down any possible way for it to continue or restart fuel flow under any condition including a power failure until the error and condition causing it are cleared by operator intervention.

The stove is in an unsafe state after a failure to light.

 

[Aughtago]

The stove is in an unsafe state after a failure to light.

Yeh your right, I do want to solve all three problems. The overfeeding after FTL being the first. Then the FTL, and the overfeed after a power failure.

According to Jay the power fail symptoms are normal, it's the way they designed it. If power fails, it bypasses the thermostat and turns the fan and auger on even if the stove was not running when the power went off! This results in filling the combustion chamber with pellets. It seams to me it would be a simple program change, to allow the following logic. If the stove is hot (T2) and running and the power goes off, continue to run(bypass T-stat. If the stove is cold and the power goes off, lock the stove out until the controls are cycled off by the user or until the power returns.

You mentioned a shorter heater, it seems to me maybe a longer tube could also help, the tube stops short of the fire pot.

 

[wwert]

This is probably obvious but there is also an auger trim that should be turned all the way down in your case.

 

[Aughtago]

If you mean the one on the control panel, it is as low as it will go. That is a minor nusiance that if I had access to the program I would tweak. During the 10 minute start up it completly fils the little fire pot. Even if the stove shuts down at 20 min as designed it has then completly overfilled the fire pot. I think the feed rate should be much lower during start up, OR off longer during start up.

 

[SmokeyTheBear]

They can run the fan all they want but if there was a failure to light that auger should be off until the error is reset by a person.

Design needs to change.

As for the igniter tube it looked to me that the tube was piercing the plane of the burn pot wall, basically you want to have a nice really hot relatively slow air flow in front of that tube.

Anyway, good luck in your endeavors and please keep us in the loop.

 

[wwert]

iI am grasping at straws here but there are also 3 different cups that fit the end of the auger, or feed discs if you will. I saw this on the Easyfire website as the guts of their stoves are all made by Thelin.

 

[AlsThelinStove]

Hi,

I bought my stove in '08 as well. Lots of problems too. I am electronics tech and did all necessary troubleshooting as well. Also replaced: circuit board, fan motor, auger motor. It should be noted I have the same remote tstat. I burn the best quality hardwood pellets.

After all said & done I had the same problem and realized I had a $3600 ornament that was worthless.

Until I discovered the root problem. Whenever you have problems with flame out or soot (blackening of the glass) it is caused by restrictriction of the exhaust airflow. This restriction is caused by two things. One, the exhaust pipe is longer than 15 feet or build up inside the pipe. (which is why when you turn up fan speed it helps, but only temporarily).

Clean out pipe, problem goes away.

Hope that helps.

Al