Back-fires, feed rate/ DIP switches and smoke ??????? Harman PB 105

[taperk600]

I'm trying to get used to my PB and all the little quirks it seems to have. I've posted on a few topics as some of you have seen. On Wed (11/12) my dealer had me move my #1 & #2 DIP switches to UP to try to lessen the amount of smoke I'm getting on restart. Said it would slow the feed rate of the pellets at restart. Well, it seemed to cut the smoke by a lot, but I noticed the flame was a lot lower over the burn pot after restarting and trying to recover... reaching maybe 1/3 of the distance from the pot to the exchangers, and it seemed to be taking longer to recover and shut down. I turned up my feed rate from 4 to 6, but flame and recovery time seemed to stay the same. Then I started to get "backfires" (for lack of a better description) on restart and a very un-even burn for the first few mins .... AND A LOT MORE SMOKE than before. Also started getting a few unburned pellets spilling over into the ash pan with some full charcoaled pellets too. Called the dealer back on Fri, but he had left for a week vacation (which I knew he was leaving for).

So I reset the DIPs back to down and put the feed rate back to 4. Took 2 or 3 cycles to go back to what was "normal" before. Flame is back to reaching up into the exchangers, recovery time is "normal" and have stopped getting unburned and charcoaled pellets. But I am back to the heavy smoke at restart. The one thing I did notice right after moving the switches to UP was that the burn pot wasn't filling up very much before I got ignition. And it would ignite a lot faster too. Made sense to me that less pellets would start to burn quicker, smolder less and make less smoke. But after a few restarts, when the backfires started, when I watched it start the ignition process, the burn pot would get completely full before I'd even start to see any sign of an attempt to ignite. Then it would just billow smoke around inside the chamber for what seemed like 45-50 seconds before it would start to flame.

So I guess I'm wondering if any of you have any ideas or suggestions. I'm waiting for my dealer to get back from vacation to call to get his input, but wouldn't mind hearing from you guys.

 

[AndrewChurchill]

It sounds like you need to figure out which option is less annoying to you.

All my dip switches are in the down position and I get about 30 - 40 seconds of smoke on start up. The smoke doesn't bother me and once winter sets in I don't think I'm going to have a lot of restarts during the day.

 

[taperk600]

well, today I spent some time watching it again. Moved the #2 Dip to UP and left #1 down. Seems to be starting quicker and with less smoke. Pot filling about half way before ignition. Flame seems to be going right up to the exchangers once underway. So far no unburned or charcoal pellets and no "backfires" or uneven burning. Keeping my fingers crossed that this might be the right setting for my stove with the pellets I'm burning now. Subject to change I'd bet if fuel was changed.....

Would be nice if we were able to get a real answer to what these switches actually did................

 

[787MH]

On startup or relight with dip switch 2 on, the auger runs 2 min 41 seconds.
On startup or relight with dip switch 2 off, the auger runs about 3 min 24 seconds.
With all dip switches off we have a hotter start. We are getting 43 more seconds of pellets.
I believe this was the way the PB 105 was shipped last year.
This and making sure the slider plate is modified per Harmon hopefully will fix the relight problem.
I also am beginning to think that proper draft is a must.
When my PB 105 was installed the exhaust pipe was clean, the blower was clean and I had a low draft of -.38. I had relight failures whenever there was low demand on the PB 105. ie warm days.
Today 70 bags of pellets later and having never cleaned the exhaust pipes or blower, my low draft is down to -.30. Harman says -.25 to -.35 is good. In the middle I have an ideal draft.
I also have had no relight issues in 10 days

 

[alaz]

I have a PB105 that was dated 9/08. The second dip switch is on the rest are down. My flame has been incosistent. On a feed rate of 3 my neighbors flame reaches the heat exchangers at the top and then bends around to touch the ones on the right. My flame progresses, but then shrinks, enlarges and shrinks. It does not seem to maintain itself and consistently as my neighbors. (Both of our boilers were installed in Sept.) How did you test the draft? I am wondering if that is the issue. Is there a draft adjustment? Are there any areas that need to be checked, or tightened? I have noticed some half burned pellets "hopping" out of the burn pot. I have cleaned the fan, the horizontal exhaust pipe and the burn pot. We use the same pellets: Barefoot.

 

[nmerrill]

Alaz,
You can test the draft with a manometer - either buy one, or build a simple home made version. Check google. Mine is a glass U tube, a good ruler, and some tube.
There is a draft setting adjustment on the control board - a small flat head screw driver is needed to turn the pot.
Draft will be determined by the flue vent size/configuration, the intake pipe configuration, the amount of soot in the system, and the combustion fan's setting (via the daft adjustment screw).

Besides draft, the total amount of pellets in the burn pot at a time is another (only?) factor in overall flame size. Are both boilers set at the same feed rate? Are the dip switch settings both the same? Could be that the controllers are calculating different feed amounts based on the inputs they get from the ESP and aquastats which may not be the same under the same conditions (within a standard error).

Nat

 

[alaz]

Thanks for the feedback. I spoke with the dealer and he said he will schedule a time to check the draft. Hopefully this helps the flame. We'll see...

 

[ratfink]

I bought my PB and had it installed in November. It's been a more of a headache than anything. I've been searching for people with similar problems with very little luck. You mention the flames reaching up and around the exchanger tubes. NEVER SEEN IT HAPPEN! Was it installed improperly? I also don't know any of the draft settings or if it was even done. The PB really struggles to put out heat when both zones of the house call for heat. It's temp drops to 100-120. I've never seen the PB temp go over 150 despite OB reading 180 when there isn't a heat demand. I called my dealer and he said the 2nd dip switch should be off, 1st and 3rd dip switches should be on and the others off. This was the exact opposite of how it was shipped. My house is only about 2100 sq ft and I don't use a hot water coil. I still use 2-3 bags a day. I was recently up in the middle of the night and it took just about an hour to bring the upstairs zone of the house up from 67 to 68. I'm very dissappointed. I'm desperatley looking for any and all help I can get. It's tempting to go back to OB with prices dropping the way they are, but not after the money I've put into this new system. Please help.

 

[nmerrill]

ratfink,
There are several pb105 users on various boards who have satisfactory performance from their boilers.
In order to get any help from people at places like this, you need at least a basic understanding of how your system works, or is set up, and provide some more information.

For starters, what type of distribution do you have - baseboards, radiant floor, radiators...
any idea what your heat loss on the house is? Well insulated modern house, old farm house with no insulation... etc.
burning 2-3 bags per day is a lot.

You say you have never seen the pb105 above 150F? What is the high temp setting set at? Are you using the outdoor air sensor?

Basically, we need more info!
hope that helps!

Nat
pb105 #389

 

[wil lanfear]

I bought my PB and had it installed in November. It's been a more of a headache than anything. I've been searching for people with similar problems with very little luck. You mention the flames reaching up and around the exchanger tubes. NEVER SEEN IT HAPPEN! Was it installed improperly? I also don't know any of the draft settings or if it was even done. The PB really struggles to put out heat when both zones of the house call for heat. It's temp drops to 100-120. I've never seen the PB temp go over 150 despite OB reading 180 when there isn't a heat demand. I called my dealer and he said the 2nd dip switch should be off, 1st and 3rd dip switches should be on and the others off. This was the exact opposite of how it was shipped. My house is only about 2100 sq ft and I don't use a hot water coil. I still use 2-3 bags a day. I was recently up in the middle of the night and it took just about an hour to bring the upstairs zone of the house up from 67 to 68. I'm very dissappointed. I'm desperatley looking for any and all help I can get. It's tempting to go back to OB with prices dropping the way they are, but not after the money I've put into this new system. Please help.

If the fire is not reaching the exchanger tubes, its easy to understand why the boiler is not reaching the preset high temp of ???*. All my dip switches are down (off). I would guess that the feed should be turned up so enough pellets will create a fire large enough to make this possible. The fire has to make contact with the exchanger tubes. I run mine on 5 or 6 , 5 seems to be working at the present time. I have three zones of heat, 2060 sq ft of living area, 625 sq ft of work shop space, mine heats all areas with stats set at 70*, plus suppying DHW for seven people, not a problem even when the temp dropped to -2*F the other night. I average a tad bit more than 2 bags a day since it turned cold.

 

[ratfink]

I have baseboard heaters in one area and radiators in the other. The house is about 60 years old and is fairly well insulated. We put new windows in the house last year also. The PB is set at 160 for a min. and 180 for a max. If I have the feed rate up to 5 won't I go through more pellets?

 

[ratfink]

I forgot to add that the outdoor sensor is connected. Should I turn all of the switches off? The PB circulates to the OB and then it has circs to send to each zone as it is called for.

 

[alaz]

If your settings are 160/ 180 and you have never seen above 150 something is reading wrong. The first step is to see why your boiler is not reaching temp. As for the zone taking an hour to heat one degree was that the case with the OB? At a feed rate of 3 I can get to 180 with the boiler. My neighbor who is heating around 2700 sq (well insulated) uses a feedrate of 2.5. You have a circ pump between boilers; is that correct? Right now, myself and my neighbors (there are 4 of us) are getting better performance from the PB than our OB and I still feel I have kinks to work out. The dealer can check operation by plugging into control panel. My temp gauge is off (by approx. 14 degrees, reads high), just as an aside. My point is the dealer can confirm all temps, feed rates, etc. Don't give up. Last thing, my 2 dip switch is in the on position the rest are off.

 

[ratfink]

What's strange is I spoke to my dealer twice. The first time was to ask about the difference in temps between boilers. The PB read 155 on was set on 4. The OB read 180. He had never heard of it, but thought everything was ok. The second time was because the heat output seems low. He told me to "turn dip switches 1 and 3 on, 2 off, and leave the rest off". I have no clue on the draft settings because the installer never told me or never did it, I'm not sure. What are the outdoor temps around there and would that impact it? It seems like some day I go through 2.5 to 3 bags and it isn't even that cold out yet. My dealer seems uninterested in doing business maybe because he is an hour away and there is a closer dealer. However, in June the closer dealer couldn't get a PB until after the first of the year. I had no choice but to go the the one farther away. That's why I'm here now in search of any and all help I can get from anyone.

 

[alaz]

I do not go through my OB, I cut directly into my supply and return and bypass the OB so I cannot account for the temp diff. Are you sure the OB is not firing at all? Could there be any back flow?

 

[alaz]

I have an odd question, sorry to break the thread, but being that we seem to be talking about anomolies: I have had a consistent build up of ash along the farside of the burnpot. It is building up there (within a relatively short time of cleaning it) and begins to form over and hang off the burn pot. Any similar observations out there. :-S

 

[wil lanfear]

The PB is set at 160 for a min. and 180 for a max. If I have the feed rate up to 5 won’t I go through more pellets?

Your installation is the same as mine, I think, supply of PB to supply of OB, return of PB to return of OB, circulator on return of PB to circulate heated water in the PB to the OB, returns from heat zones to OB, heated water for heat zones from supply of OB. I found with the feed rate on a lower setting that the fire would really never bring the boiler to operating temp in a short period of time where as a higher setting on the feed rate dumps more pellets into the burnpot, resulting in a larger fire, heating the boiler water faster. My settings are 165* min., 180* max.

Something to try if you haven't already, turn all the dip switches to the off position, turn the feed rate to #5, watch to see if in fact the flame wraps itself around the exchanger tubes, fill the hopper with pellets, let it run for 24 hrs, refill the hopper to see how many bags you used in a 24 hr period.