If it doesn't cause problems just using the indoor air for your stove...why mess with the outside air kit? I have a Quadra Fire pellet stove, and I had a local chimney sweep company do the install for me. He also does all of the installs for one of the local pool & stove places that sells Harman stoves.

I was going to buy the outside air kit for my Quadrafire stove also...but he told me that in the hundreds of pellet stoves he's installed, he's only installed the outside air kit once or twice...and that was because the homeowner absolutely demanded it. I figured that he was the stove professional, so I took his advice. We've been using our pellet stove for 2 years now, and have never had any problems.

Actually on the issue of using "warm air vs cold air" for combustion, the amount of air you are "sucking in" for combustion is relatively minimal. It's nowhere near the amount that a bathroom or kitchen fan would draw; and it has no impact on energy efficiency as far as I can tell. Our electric bill went from $235/month to $135/month by adding the pellet stove and doing some additional air sealing work around the house. (brand new house; well-insulated but very leaky).

This string is a bit old, but I have a similar problem and had a thought about the cause.

I have a Harman Accentra with outside air hooked up. The stove is in the basement with about 8 feet or so of both inlet and exhaust pipe. I get hopper smoke, and frequent 6 blink incomplete combustion warnings. I've been through the thing several times looking for causes, and I'm down to the outside air pipe - which is clear. I just disconnected it.

Here's my theory about hopper smoke. Even a clean outside air pipe will restrict flow as compared to no pipe - pretty much universally understood. During high draft running, this restriction would cause a greater vacuum to be created inside the stove including the hopper. When the stove cuts back to idle, and the draft drops to low, this will relieve the vacuum in the hopper. As that happens it will suck smoke right back through the auger and into the hopper. Switching back to high draft won't clear it out because the hopper gasket seals out any incoming air flow - until you crack the lid.

Does that make any sense?

The solution is tricky. Draft, as measured with a meter as per the installation instructions, is a function of vacuum. The amount of vacuum also depends on how much replacement air can get into the stove. You can have high draft... and no air flow at all. If the stove is tuned to have a given airflow at a given draft... that airflow will not be present with an outside air pipe installed. So with outside air, the stove chokes and you get hopper smoke and incomplete combustion. I don't see any way out other than disconnecting the inlet pipe.

I would have to agree with you completely, now all we have to do is convince Harman, except they won't talk about it to my dealer and they won't talk to me.They basically told the dealer I must be doing something wrong, they did however replace my stove after several e-mails to them but they just won't respond on the issue, All I want to know is what causes it, if Harman say's- yes, it is the outside air causing it, then I will have to run it without the outside air, what else can I do ??? But they won't admit it because then they opened a can of worms ... the stove does not do what it was advertised to do.

You've about summed it up. You also happen to be blessed with a dealer that has better customer service than Harman does. Unfortunately I don't.

The stove must not have been designed to work with the amount of restriction created by the outside air pipe (perhaps it would if the pipe were 2 feet long straight out the back). To design the draft quality, you'd have to figure in the pull of the fan and then the freedom of incoming airflow. The added pipe is a new variable. Given that, the only solution is an increase in fan strength, or a marked increase in pipe size.

We are between a rock and a hard place. We can't modify the stove.. it'll void the warranty. At the price of the stove, I want to keep the possibility of complete replacement - which they will do, to their credit. Since they won't do anything to help us... about all we have in our control is pipe size. I suppose if we swapped out the 2 3/8 flex pipe to something like a 4 inch smooth wall metal dryer duct, it MIGHT work. The constriction down to the stove inlet would not be a problem flow wise. I don't really want to look at two chimney sized pipes running up the wall... so I guess I'll just run without outside air this season, and ponder the problem while I shovel the snow.

A possible cheat would be to introduce a leak in the hopper lid gasket by slipping a thin shim or something under it. That would act as an auxilury intake. It might even whistle a jaunty tune.

Perhaps if you pass these thoughts along to your dealer, he might go back to Harman.

SBWM:

Where in Mass is your Harman dealer ? I am from Mass also. I know there is one in North Dartmouth and Mansfield which is 30 mins from me.

The one I purchased the stove from is in Springfield, I think there is another which just opened up in Bernardston.

I was less than impressed with the installer, but I tend to be picky when it comes to contractors and how things are done in my house. I called the dealer at one point last year about a door gasket leak and incomplete combustion and got the run around on both. So I fixed the gasket myself, and the jury is still out on the combustion.

I also noticed that the book says to test the high and low draft with a meter and adjust the controller if needed. This was not done during installation. I get the feeling this is routinely blown off, and I don't really care to fight with them about it. It's one of those things that you make a big stink about and then turns out not to be a problem.

Had my Harman Advance installed last month. For the past two weeks I have gotten smoke in the feed hopper when the pellets are about 1/3 or more down. It happens with both Economy and Premium pellets. I called my dealer yesterday to explain what was happening. He stopped by to check it out and was at a loss to explain it. He said he would call Harmon today (Friday) and inquire. I'll let you guys know if he gets any info as to why this happens. In the mean time I'm simply keeping my hopper full and not letting it drop to more than half since there is no smoke if kept filled. I also have outside air intake because of my small heating area. Other than the smoke in hopper issue I'm just loving the Harmon, but like anything thats new it may need some tweaking.

Toastyinri,

I'm willing to bet that you get smoke in your hopper when it's full too. You just can't see it. I could be wrong though, if smoke billows out when you open it, you'd know when it was smoky and when it wasn't.

You should try running without outside air just to see if there's a difference. I think I've come up with a way to go back to using it with my stove in the basement. The problem is the length of the pipe - about 8 feet. At some point in the future I will be replacing the paneling with drywall. At that time I'll install a 3"x8" or so duct in the wall. I'll hook that to something like a 4 inch dryer vent at the top and pipe the stove into it at the bottom. That way most of the pipe is oversized. How long is your outside air pipe?

I have also found in the past few days that the stove and burn pot stays much cleaner running on "stove temp." It seems like the crust builds up when the stove is idleing between firings on "room temp". I'm going to try room temp now without my outside air hooked up and see how that goes. It may have been starving for air.

No smoke billows out at full or just below half when I open the hopper to refill. Also I noticed that the pellets don't have a "smoky" smell to them as before when I did get smoke at lower levels. The need for outside air, as it was explained to me, is because of my small heating area and the Advance's proximity to a window,,,just beyond 18". I too have noticed the difference in the burn pot when running on stove temp vs. room temp. Have you noticed a buildup of soot on your glass without the outside air? My outside air pipe is approx. 3 FT. My whole setup goes out the side wall and is installed per Harman's instruction.
Haven't heard from my dealer yet, I'll give him a call towards the end of the week to see if he got an answer.

I know what you mean about the smokey smell when you open the pellet door. I suppose your right about the 'billowing out.' It doesn't really do that.

I do get soot on the glass without the outside air, but far less than I did with it. And it is more grey brown than dark brown. I have also set it on Room temp without outside air for the past few days. It runs cleaner than before but not as clean is in stove temp.

Not sure what to tell you about the need for outside air in your situation. Don't know the codes down there. Seems strange that the window plays into it... I thought the exhaust had to be 4 feet from a window... so the stove proabbly would be too. Anyway, I wouldn't guess that room size would matter. I would think more about the airtightness of the house/room and if there are other competing appliances which might create a vacuum in the house. Like a woodstove or fireplace etc. But again, I don't mean to argue, I can't quite picture your situation. Also, I wouldn't expect that 3 feet of pipe would be much of a problem.

I hope your dealer gets back to you.

My dealer got me a new stove and I don't want to trash this one, so I am just going to disconnect the outside air.Continually getting smoke in the hopper is going to wreck the stove, If you look down into the area where the pellets drop (when hopper is empty) you are going to see a sticky soot build up,this is also building up on the auger and the auger housing, eventually this is going to cause problems with your stove.You will also start getting a smokey / soot on the hopper lid. I know... I've been there and and am still awaiting an answer from Harman, going on 1 1/2 years now, but they simply don't want to talk about it. If I were you, I would ask your dealer for a new stove, or else ask them why you can't run it with outside air hooked up and not get smoke in the hopper ?? afterall, isn't that how they advertise it to work ?? And isn't that what you paid for. Good Luck....

Thanks for all the suggestions. I'm going to disconnect the outside air and see what happens. I'll also be doing a complete cleaning of it in the next couple of days and will check for soot build up on and in the auger area. So far there has been no build up on the hopper lid.

My Dealer contacted Harman. Their first suggestion was for the dealer to check the seals...again. Since my dealer was actually here when the smoking occured in the hopper and checked it throughly a few days ago, there can be "no way" Harman can claim improper usage. I've made it clear to my dealer that if a solution and fix is not possible within this heating season that I will be requesting that Harman replace the stove. I asked my dealer if the problem could be related to the air intake and he said he didn't think so.
I don't know if it's coincidence or not but when the outside air was 40 and above, there was no smoke in the hopper for the first two weeks. When temps dipped below 30 and more,,,it smoked. Does anyone think outside air temp might be the culprit? The intake flex hose sometimes has frost build up or condensation on it in the morning, which I've been told is normal. My dealer will be coming by again to recheck whatever Harman told him to do within the next few days. Update will follow at that time.

Outside air temp... that's a good question. No idea. Outside air pressure might also have an impact... but that should balance out because the fan works against it at the exhaust end too.

I had another thought about the possible resistance in your short 3 foot run of intake pipe - if this whole theory is correct... If you have the stock outside vent cover for the intake, that could be the problem. Mine is like a little metal house with a grill on the bottom. If I remember correctly, the grill is made of heavy wire welded close together. I would bet that it cuts the opening down by at least 2/3s or maybe by half. That's a lot of resistance all by itself. Might be interesting to take that off and see what happens..

Cold air is denser... might add resistance that way.

There is a plate behind the stove that seals the back of the auger with a wingnut. Harman is saying that if it isn't on tight it will cause smoke in the hopper. My dealer is away for the holidays and doesn't want me to touch it until he sees it for himself. If it turns out that the plate is not secured tightly, it would have to be Harmans factory assembly, so I'm not touching anything until he inspects it.

I noticed there are "additional" instructions to cleaning the Advance on their website and it shows the plate and wingnut in back of the auger as an area that needs to be cleaned out of fines at the end of the season. It's nowhere in the instruction manual that comes with the stove.

After 1 1/2 years I started getting smoke in my hopper like many others here in my Harman P38.I am using outside air. I let it go for a while and was seeing a residue on the slide plate in the hopper. I kept cleaning it up and did a total clean of the stove to no avail. Finally the stove refused to feed pellets and was clunking at times like there was a jammed pellet or something jammed in the feed area of the stove --
Cleaned the stove and saw nothing jammed. I called my dealer Ace Swim and leisure and they sent a tech the next day. He pulled the auger on the stove and said the stove was history and needed replacement. He showed me the auger and said that the ash should go no farther than the second ring on the auger and mine went all the way to the back of the auger. He said that there were problems with some of the harmans. The tech said that he a had a stove in stock but had to get Harman approval for the replacement and modification. I questioned him on the modification. He told me that they had to send the new stove to a machine shop and modify the burn pot and pressure relief chamber tube. I thought this was odd that Harman had an issue and the new stoves were not corrected. I finally got the stove and they had drilled 10 extra holes at the bottom of the burn pot. I do not know what they did to the Pressure relief chamber Tube on the stove but now there is a real good vacume in the hopper compared to my old stove. So far no problems with the stove and no smoke in hopper. The tech also said that outside air was not the cause of this. I guess I was lucky to get a good tech that knew the issue. He said that my stove is the 3rd one to get this mod no problems with the others. Just thought I would update you all since I have read many posts and seems like all run to a dead end and no resolve. I'll keep you updated if any problems arise with the mod but is looking real good so far...