Harman P68 Slow Startup

Guys, this topic has already been discussed extensively, in this thread: Shoulder pellets or?? | Page 3 | Firewood Hoarders Club starting at post 43, however I wanted to start a new thread for it.

I have been experiencing what I would consider a slow start time on my P68. By start time, I mean the time it takes between turning the power on and when the distribution blower turns on. Over the last week or so, I have been watching this each day when I power on the stove. I have seen times ranging from 5m 15s to 23m 30s, and everything in between. To be fair, the 5m 15s incident the pot was pre-loaded with pellets from me doing a test cycle on the stove. Most of the time, the stove tends to take more toward the 20m start time.

I have checked all the usual suspects. Flue is clean, ESP is clean, gaskets are tight, fines box is clear, the area beneath the burn pot and in particular the igniter and cradle are clean, burn pot and holes are clean, hopper and slide plate area are clean, hopper lid gasket is tight. The stove makes no unusual noises and in all regards appears to be operating normally, except what I perceive as slowness.

Last night, I saw flame at 3m 20s but the stove didn't get heated up enough to trigger the blower until 12m 30s. Tonight I saw flame at 3m 30s, but the blower didn't kick on until 18m. It seems like the fire starts quickly enough, but then just smolders until the stove goes through umpteen additional feed cycles before it pushes the pellets out far enough into the pot to really get enough combustion air moving through them to create a decent flame, triggering the ESP to kick on the dist blower.

You guys know I burn a lot of different pellets, and I can say for sure that some pellets definitely take longer to fire up than others. What has been other's experience in this area? Am I over analyzing or is there a real problem here?

 

TT, just a thought. Over the years I got into the habit of scraping my entire burnpot clean before I started the stove. This year, totally unintentionally, I started the stove without scraping it clean and it actually started faster. Now when I start it, I just scrape out the ash and leave the partially burnt pellets and the stove starts great. Maybe try that?

 

Have you checked the air intake flapper? If you are getting flame and then a slow burn after that it sounds like air flow might be an issue? I have had similar slow fires in the past now and then, so maybe its the pellets too?

I checked start time on my P68 last night and again tonight. I screwed up last night and would have estimated, but tonight is accurate

Initial flame at 5 min 10 seconds-burn pot had pellets to maybe the 2nd row of air holes. Dist blower at 7 min 25 seconds. This is from a scraped pot and using Corinth soft/hardwood mix from last year. My igniter is original and on its 7th burning season averaging 4-5 ton/season.

 

First thing I would check is draft, making sure it's within spec....why we like initial readings on a new stove. If the exhaust has been impinged, or the dampers sticking, a new reading will tell you that.
Subbie is correct, in that I have also noticed they start faster without totally cleaning out the burn pot.
Could be the pellet, but not to the degree you mention. Snatch up a bag or two of a different brand, see if it makes a difference.
Igniters don't really get weak, they just fail.
Would be nice to see what the ESP is reading as well. It determines when your dist blower comes on. I know it's clean, but is it reading accurately? Only way to tell is a DDM
What about venting? Is it a simple pipe out, or into a chimney?

 

Thanks for the though Sub. What you described is how I have been doing it since day one. When the stove is at the end of it's shutdown sequence, and while the combustion fan is still running, I pull out the chunks of ash, scrape, and leave the un-burned and charred pellets (and obviously a little ash too) in the pot. It's for the same reason you describe, I think those leftover charred pellets help it to startup more quickly.

Yes I checked the air intake flapper too. It moves freely, no issue there. You made me think of something though. When the stove is in it's shut down sequence, or reaches a point where it's running at a maintenance burn, I notice that I can hear the "ting ting" of the air intake flapper as if the combustion fan has slowed down and isn't drawing as much air as it normally would at a strong burn. This has always been the case, and I assume you guys know what I'm talking about here? Well it could be just that I have this thing under a microscope, but I'm noticing I hear the same "ting ting" sound at startup time too, like the combustion fan is running slower at startup? It may be normal, not sure because I've never really payed attention this closely before. If that's not normal, then I will start looking for deeper evidence of air flow restriction.

My igniter is also original and entering the 8th season now.

I definitely know what you mean about some pellets starting more slowly than others. I plan to start testing different pellets in my stash to see how much of a difference I see. This will take some time to do.

 

The "ting ting" usually happens on startup in a chimney system, and it's the intake flapper opening and closing.....which tends to indicate poor draft at that moment in time

 

The venting is 3" straight out the back into a 3" - 4" adapter tee and then 4" flex all the way up to the top. The flex runs inside the old 8" SS fireplace flue - about 27' up. This is in the center of the house, not an outside wall. I would like to think it's not the venting, only because the slow startup issue has not always existed and after the stove gets running, it's runs fine. I notice the "ting ting" most often when it's warmer outside - 40s / 50s, at shutdown and maintenance burn. When it's colder, like 30s or below, I don't notice the "ting ting". I don't have a draft meter to check it and I also don't have a DDM (pretty hard to come by, for me, but I would LOVE to own one...). I will look into the draft meter to see if I can get a proper reading.

 

Is there a way to test the combustion fan motor without a Magnehelic?

Have you tried playing with the draft adjustment?-just make sure you note the original position

 

The ting ting is a temporary draft thing, nothing to be concerned about, but it's due to changing draft....almost certainly not got anything to do with you're slow starting issue.
Draft meter? I dunno, ya get one and you'll rarely use it. Nice though for diagnosis....we use them a lot, but we do this every day.
The DDM is nice, but on borrowed time. The new controls, like in the Absolute, have all that info on the touch screen. P63 will be next to have them, out in early spring or so.

 

No,can't really test the comb fan without a gauge. Really not a big fan of messing with comb blower voltage without a draft gauge tho.
Also, you do know you can vary the feed time on startup with you dip switch settings on the board, right?

 

Good point

Never had too, but care to elaborate?

 

The dip switches on the CB can be set to do different things. We all know switch 5 is for the ESP type, but the other switches do different things. There are like 5 different iterations of that board though, and it would be tough to tell you how to mess with it without knowing exactly which board you have.....off the top of my head, it's switch 1,2,3 which controls startup feed on/off times, but can't recall the settings.....need the cheat sheet

 

Yes I know about the dip switches, and you have it right. Switches 1-3 can be set to adjust the feed time down by ~60 seconds or up by ~80 seconds. I am hesitant to take this route, only because it feels too much like covering up / masking the problem, and I would rather exhaust all other avenues trying to really fix first, you know what I mean? If I had messed with the dip switches before and landed in this spot, I would gladly adjust them back to default values. Let me see what trying some other pellets gets me.

LW, one other thing I want to mention. To me it honestly seems like the feed cycle isn't pushing enough fuel into the pot. I spent a lot of time earlier in the week observing the slide plate movement, and the way the wheel on the auger assembly pushes the arm that moves the slide plate in both directions. It seems to me that the slide plate simply isn't moving enough to push sufficient pellets into the auger chute. I have removed the slide plate twice and checked for freedom of movement and there doesn't appear to be an issue there, it moves freely. Having said that, when the wheel pushes the slide plate arm, on the return movement, it does not seem to be moving the arm all the way back, I can move it further with my finger after the auger loses contact with it, and when I do that it seems to push more pellets into the auger chute (I hear a lot more tinkling of pellets dropping). Have you ever heard of this before? Is there any type of adjustment in this mechanism to better ensure the slide plate is moving it's full range of motion in both directions? The wheel pushes one end of the arm all the way (pushing pellets into the auger chute), then the wheel loses contact with the arm for a few seconds, then it very briefly (just barely) touches the other end of the arm, pushing the slide plate back, but not all the way. Man I hope this makes sense.

 

Makes sense, but there is no adjustability in the slide plate. The tongue of the feeder arm engages into the slide plate slot....and yea, you likely can move it a bit more by hand...normal. Dumb question.....you did put the slide plate back in with the step UP, right? If it's down, you'll get less feed. Any gummy deposits in your feeder? Under the slide plate? I've seen the goo hold pellets, which causes less pellets to get to the auger.
Agreed, if it ran fine without messing with the switches, that's a last resort.
Maybe it is the pellets....what are putting thru that thing now?

 

Yes the slide plate went back in the right way

No gummy deposits, this thing is really clean. I mean, really the only thing I have not done yet is pull the auger out to see what it looks like inside there. Really don't want to either, but I will if it comes to it. Most recently, I have been burning Platinum Pellets and MWPs. The Platinum Pellets take longer to start than the MWPs. I'm going to switch to some Energex next, and probably try two other brands after than and compare results to report back.

 

Like I said, try different pellets.....easy

 

So, this is more about slow time from flame to blower starting. Mine will take a while to actually start a flame, but the blower comes on within a minute or so (certainly not the 9 minute difference you got last night). Leads me to think about exactly how many pellets are fed after the flame starts up. What do you have the feed rate set at? It probably has nothing to do with it, but curiosity over this issue is killing me, so figured I would cover different ground than others have.

 

TT I just timed both of mine again today Accentra with Sets went off at 4 min + blower on at 6 min .
p43 with T Heats flame off at 3 min + blower on at 6 min. Pots not totally scraped ,but ash removed .

 

not the feed rate....that's just kinda like a maximum timing, worst case scenario thing....

 

if its time from flame to blower starting, the blower starting is controlled completely by the temp the ESP sees.....or thinks it sees. OP said he cleaned it.....the only way to TEST it is to put a DDM on it, and monitor when the blower comes on versus what the ESP is reading...cant recall the temp, but its somewhere between 150 and 155 degrees (on the DDM).