I'm a NEWB / L250 Manual Reset

Tim M. · Dec 31, 2012

Hey gang ---- been searching online for a while now trying to find best approach to this issue but found this online forum and it appears the the best place on the WEB for answers on these types of things - extremely grateful I found this site.

So I have a FLAME FP-45 pellet stove ..... appears to be very limited info on this forum regarding this brand or model. My wife and I bought our home last year and this was left behind from prior owner, I have not alot of info on how he serviced or maintained it. Last year we had it professionally cleaned and used infrequently last year due to the mild winter in New England. I went through approx 1.5 tons of pellets last year. It ran fine last year with no issues at all.

This year again we had it cleaned again from a different person. It started off OK but within first 4 - 5 weeks of use it started shutting down constantly with the high heat warning, overheat etc etc from the manual L250 switch. It seems to run completely fine on setting 1 or 2 with no issues, I have run it for 48 hours straight on setting 2 with no problem at all. As soon as I turn it up to 3 or higher the heat sensor trips within 30 minutes.

I assume first course of action should be to have a sevice call made seeing as I dont really know much about these stoves. I thought possibly the sensor could be bad so I ordered a new L250 switch from the manufacturer on friday last week and expect to have it delivered on Wednesday 1/2/13.

If that doesnt work any suggesstions, I cant find much online about this model or brand ..... only info I can seem to find is that constant tripping of the L250 could be a bunch of things, exhaust vent clogged, convection blower bad, bad sensor etc etc.

Any thoughts or can anyone give me some direction if the swapping out the new sensor doesnt work. We have an pil furnace but man do I HATE turning that thing on ... it's like burning $20 bills every time we have to use it as a backup. Last night was the coldest night of the year for us so far at about 17 degrees overnight ..... at heat setting 2 it kept the house at 60 which isnt terrible for us but we have a 10 month old son and thats just too cold for him.

jtakeman · Dec 31, 2012

Pellet stoves rely on the air moving through the unit to keep them cool. If for any reason the air is reduced they will overheat. Cleaning and lubing the convection fan usually fixes the issue. While you have the unit out to replace the high limit switch. I would get the vacuum and clean the convection fan blades. Use an old tooth brush to assist in getting all the dust bunnies off the fan blades. Also while its down give the unit a thorough cleaning. If you haven't cleaned the venting lately it could also reduce the air flow through the stove and cause it to over heat. Giving the unit a complete top to bottom cleaning will usually fix over heating issues.

SmokeyTheBear · Dec 31, 2012

While it isn't unknown to have a high limit fail it is not the root cause of your problem.

The basics apply in this case, you have to remove the heat being produced fast enough to stop the temperature at that high limit switch from exceeding its trip point.

A pellet stove has two means of getting rid of the heat produced, one is into the room and the other is up the flue.

Both paths through the stove have to be clear and both fans have to be operating properly for this to happen.

Any restriction will cause the temperature at the heat exchanger to rise eventually tripping the high limit.

The primary cause of a high limit trip is as jtakeman has mentioned is usually the convection fan. It only takes a slight amount of dirt on the cage blades to reduce the air flow through the convection air system. So this is the first thing to clean.

Having a fan running slower than it could because of hot bearings or bushings is another cause of a reduction in airflow so a bit of oil (consult the blower motor makers plate for type) and hand spinning to work it in will usually correct this issue.

Then there is dust in the blower motors shell and cooling fan, this needs to be kept clean as well (this will cause the convection blower to thermal off followed very quickly by the high limit tripping).

The other air path is your combustion air path and if that is ashed up or if the damper is set such that the air flow is too restricted the exhaust gases are slowed down to the point that they can dump a lot of the heat they carry out the vent into the heat exchanger instead that the convection fan may not be able to remove fast enough causing the high limit to trip (opening up the damper a bit more helps in this case as would cleaning the exhaust paths of the stove if there is ash in them)..

DexterDay · Dec 31, 2012

When was the air filters cleaned or replaced in the back of the unit?

Where is the damper set on your stove? 25% open? 50%?

Because it has Combex burn technology, it has both combustion air (pushed through the pot and also exhaust, pulled through the stove).

After reading the manual (which is a very imformitive one by the way) it goes into great detail on how often the ash traps need cleaned, where they are located, how to clean combustion blowers, how often, and where those ports are located.

Having a slowing or dirty convection blower, dirty filters, damper position either closed to much (slow moving air through stove is to hot) or to much air (to hot or to active of a flame).

DexterDay · Dec 31, 2012

Also, make sure that BOTH convection blowers are working and there filters are clean, squirrel cages are free from dust and motors are lubed if applicable.

heat seeker · Dec 31, 2012

And a "professional" cleaning sometimes leaves a lot to be desired. My local guy charges $45 extra to remove the combustion blower for cleaning, "if the Magnehelic vacuum gauge results" warrant it. Their letter makes no mention of pulling the convection blower for cleaning.

SmokeyTheBear · Dec 31, 2012

Hey Tim,

Welcome to loony land.

Clean your stove and pull a chair up near the fire and tell us all about your stove. We just love stove stories and pictures showing them in operation.

Watch out for the flying pellet pigs, they frequently have control issues (I think it is related to being a bit over limit in the tonnage department, but others have different explanations for the matter)

Tim M. · Dec 31, 2012

Alright gang so got home from work today at 2:00 and started taking this thing apart to the point I was comfortable with. I had this serviced by a "pro" back in May, all I can say is I had it done in 2011 and the guy spent 5 hours here doing it ..... the guy that came this year was here for 90 minutes and $160 later he was gone.

After taking the back off and some panels I could get a good look inside the combustion fan chanmer .... opening the damper 100% I could see about 50% of the fan inside, spun it several times and it was clean as I thought it could be. I was able to get the shop vac hose in there somewhat and left it on there on high for about 5 minutes trying to suck out anything I culd. Next I looked at the two blower fans on the side of the hopper ...... the screens on the outside of those were filthy, I'm talking about an 8th of an inch of dust caked on them .... looked like it would have been hard for any air to get through those screens at all. Took those off and cleaned them ... no dust left at all on those.

Next I pulled the stove from the wall and removed the "chimney pipe" ( that about the only thing I can think to call it" ... it vents through the wall horizontally outside. when I removed the stove from that pipe there is a I think a pot on the part that is connected to the pipe leading out (ont he boottom) - I am giessing this is there to collect ash??? It was full .... it is the same width pipe that goes outside but goes down about 4 inches and then is capped at the bottom. It was FULL of ash, vaccumed that out and put everything back together,

I've had it on heat setting "6" for about 30 minutes now with no L250 shut off ...... the air coming out of the tubes seems to be much more forceful than before I cleaned this. My wife and I are going out in 45 minutes for New Years. I am going to let her rip on heat setting "4" while we are out and if it is still on when we get home and hasnt shut off from the L250 then I will assume this was successful and it just needed to be cleaned better. Suffice to say I wont be using that pellet stove cleaning gy ever again, sounds like I got duped.

SmokeyTheBear · Dec 31, 2012

Once most people discover where everything is and what has to be done they can figure they can handle the job themselves.

A lot of the folks on here do their own service and cleaning work. The key to a good cleaning job is to get familiar with your stoves air passages those need to be cleaned regularly, then any device that is part of those passages also has to be cleaned and maintained.

These stoves are nothing anymore than air pumps. One pump handles the combustion air and the other pump handles the convection air all of the heat transfer takes place in the exchanger where the two air pumps air flows go by each other.

Once you realize that everything else falls into place.

Tim M. · Jan 1, 2013

Well - she's been cranking all nightlong on "4" which we werent able to do before, like I said previously anything over the heat setting of "2" up until yesterday would trip the overheat sensor and shut the pellet stove off. Been going for about 15 hours now on 4 keeping my 2500swft house at a very comfortable 68 degrees !!!

I am a happy guy.

DexterDay · Jan 3, 2013

Congrats.

A ill deeper than what you did, and you can save yourself about $200 (cleaning) and spend it on Pellets

Mike Page · Oct 6, 2013

Hi there guys, I just read this entire thread cause I have the same problem, and I'm hoping to get a little extra insight from somebody
. I took the motor and fan assembly out in order to clean it and I was having a problem with one of the interior fan blades
... the small ones... rubbing up against the motor because it would slide on the shaft and bump into the motor or exhaust blower... so I took it apart and tighten it up and it doesn't make a noise anymore but when I put it back together I started getting same error message when I ran a stove on a setting higher than two with the heat switch tripping off. Now I have cleaned the entire stove but the one thing I realize that when I put it back together the seal on the exhaust fan side was not in perfect condition and I did not have a replacement for it, so I put it back as best I could and I was thinking of putting the red high heat silicone that I used on the chimney pipes to seal around there but I didn't want to permanently stick it closed. So, does anyone think that that might be the reason my high temp switch is going off and if so should I go for the exact seal or can I use the high temp silicone? Just asking what you guys think...you all seem to be very knowledgeable... so I defer to your wizdom...Thanks!

imacman · Oct 7, 2013

To the OP.....next time you have a chance, and the stove is cold, do a search on this forum for the "leaf blower trick". That should get any remaining "hidden" ash out of the inner, non-reachable parts of the stove. It's very easy to do on a stove with a simple horizontal exhaust.

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I'm a NEWB / L250 Manual Reset

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