starving for air

May want to check out the fine tuning Biomass thread.

Not familiar with the Biomass, but maybe air intake into boiler partially blocked, or not enough chimney draw?
Then again possibly the nozzle, couple of good threads on patching/fixing them. Might be worth a try. Some of he guys took a fire brick and cut a nozzle in it and laid in over their old one. That may be quicker just to see.

Since it's seen a few years of use - are you absolutely sure that all the air passages are clean & clear?

davem3261 said:

I have been having issues with my first season with the biomass 40. First of all I don't have storage yet. I will get the fuel message when I get up in the morning and there is still wood in it. If i just release the upper door handle so a little more air gets in it burns great. When it's shut like normal I get a weak yellow flame and I can't seem to ever get a coal bed. Doesn't matter if I'm burning 2x4's or hardwood. Setting are primaries all the way open. Secondary air is almost shut all the way. Fan 100%. With the door cracked I had a blue flame this morning which turned yellow after closing the door for a minute. What should I do differently?

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I brought my new Biomass 80 on line a couple of weeks ago and although I have had a gasser for 7-8 years (Econoburn) the 80 is a whole different animal. Two things I have learned. One from the helpful folks here is to split your wood small (end of splits no larger than a playing card). The other, which may be your problem, is that there is a flap on the inside of the air distribution box that is prone to sticking shut with the creosote generated if you're not burning hot. My 80 exhibited similar symptoms to your 40, and this was the problem. If the counterweighted flap on the blower housing isn't opening, open up the inner door and you will find this flap stuck closed.

davem3261 said:

I have read that a couple times. My air settings are at the max and it seems to me that it wants more. The only thing I can think of is it may need a new nozzle because I didn't buy this new. It's about 4-5 years old.

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If you are getting air the other things I learned here on the forum, that made a huge difference in my burn, is to cut the fan speed down (I reduced mine to 60%) and open the secondary air, I have mine set to about the halfway point. I am burning elm at 12%-14% moisture and it maintains an awesome bed of coals if I throw in 3-4 splits every few hours. With only half filling the wood box at night I still have a good bed of coals in the morning.

Check the secondary air slider, sometimes it is not tight against the boiler body and lets a lot of air in even though it looks like it is mostly closed. It must be absolutely tight otherwise air comes in behind. One symptom of this is when you open the upper door a bit and let more primary air in it starts jetting again nice and closing the door kills it. A wide open secondary ends up keeping the primary air from getting thru even if the primaries are all opened up. I have seen some Biomass boilers that came from the factory with a wide gap behind the secondary adjustment and it wasn't until it was adjusted so it was tight to the boiler body and then adjusted with a 1/8 to 1/4 gap that any other adjustments could be made.