Your thoughts on these gasser readings

ohbie1 · Dec 16, 2014

I'm running an INNOVA 30 with 1k gal storage. (There's no damper; the Innova is made to run full out.)

I put a length of black pipe with a cap into the sight hole (bottom chamber). Inside the pipe is a K couple hooked to a pyrometer. The pipe protrudes about 3" (relatively not far) into the chamber.

When I run as specified with top (load) door clamped shut, The pyro. reading is 500-600 degrees.

When I run with the top door very slightly ajar, the pyro reads 1000 - 1200 degrees.

The stack temps are actually a bit lower with the door ajar than when locked. 300-400 vs. 400-500.

I noticed that the boiler temp goes to 180-190 with the door ajar, but 170s with it locked.

With the door ajar the boiler consistently takes my tank (top reading) from 140s to 170s on 1 load of wood.

With the door locked...140s to mid to high 150s. (one load of wood)

Any thoughts on this data?

kopeck · Dec 16, 2014

My guess is your are simply pushing more air through. More volume, less time for the heated air to be transferred to water which equals higher stack temps.

K

Clarkbug · Dec 16, 2014

Sounds like you might need to adjust your air settings some if your tank temps vary that much. Does the Innova have a primary air adjustment?

And how long has your wood been seasoned? Any hissing when it burns? Same type of wood between the two scenarios above?

ohbie1 · Dec 16, 2014

kopeck said:
My guess is your are simply pushing more air through. More volume, less time for the heated air to be transferred to water which equals higher stack temps.

K

That would make sense...BUT, the stack temps are lower with the door ajar.

ohbie1 · Dec 16, 2014

Clarkbug said:
Sounds like you might need to adjust your air settings some if your tank temps vary that much. Does the Innova have a primary air adjustment?

And how long has your wood been seasoned? Any hissing when it burns? Same type of wood between the two scenarios above?

Same wood, 20-30% moisture content. I've played with the pri and sec air settings for many yrs., but can never get the heat output as high as the ajar scenario. I think you're on to something with the wood moisture content. Could the extra air be making up for the moisture content of the wood?

tom in maine · Dec 16, 2014

When the door is ajar, you have excess air coming into the system . This dilutes the hotter exhaust and makes it cooler. It also steals energy from your system.

An ideal system operates with minimal excess air.

heaterman · Dec 16, 2014

ohbie1 said:
I'm running an INNOVA 30 with 1k gal storage. (There's no damper; the Innova is made to run full out.)

I put a length of black pipe with a cap into the sight hole (bottom chamber). Inside the pipe is a K couple hooked to a pyrometer. The pipe protrudes about 3" (relatively not far) into the chamber.

When I run as specified with top (load) door clamped shut, The pyro. reading is 500-600 degrees.

When I run with the top door very slightly ajar, the pyro reads 1000 - 1200 degrees.

The stack temps are actually a bit lower with the door ajar than when locked. 300-400 vs. 400-500.

I noticed that the boiler temp goes to 180-190 with the door ajar, but 170s with it locked.

With the door ajar the boiler consistently takes my tank (top reading) from 140s to 170s on 1 load of wood.

With the door locked...140s to mid to high 150s. (one load of wood)

Any thoughts on this data?

With the loading door cracked open you are introducing more air into the fire box and you are getting some secondary combustion that is not happening otherwise. 5-600* in the secondary chamber is way too low.
You're not in gasification range at those temps.
Part of this may be air adjustments and finding the balance between primary and secondary settings but I think a larger factor is moisture content. It takes more excess air to burn wet wood than is does dry stuff. Also, when using fuel that is a bit on the high side, it's difficult to get primary combustion temp up in the range where it will gasify enough to support secondary burn when hit with "fresh air" in the secondary tunnel.

Introducing excess air into the firebox is getting the flame temp up to where you are actually getting some gasification burn up in that area rather than all down below.
If you had a flue gas analyzer you would see your excess air percentage and O2 % jump way up while CO2 would go down when you crack the door open. This will drop overall efficiency. CO is probably off the chart under those conditions also.

ohbie1 · Dec 16, 2014

heaterman said:
With the loading door cracked open you are introducing more air into the fire box and you are getting some secondary combustion that is not happening otherwise. 5-600* in the secondary chamber is way too low.
You're not in gasification range at those temps.
Part of this may be air adjustments and finding the balance between primary and secondary settings but I think a larger factor is moisture content. It takes more excess air to burn wet wood than is does dry stuff. Also, when using fuel that is a bit on the high side, it's difficult to get enough primary combustion temp up in the range where it will gasify enough to support secondary burn when hit with "fresh air" in the secondary tunnel.

Introducing excess air into the firebox is getting the flame temp up to where you are actually getting some gasification burn up in that area rather than all down below.
If you had a flue gas analyzer you would see your excess air percentage and O2 % jump way up while CO2 would go down when you crack the door open. This will drop overall efficiency. CO is probably off the chart under those conditions also.

I understand your and Tom's references to the efficiency... BUT... why does the boiler heat my storage water to a higher temp (all other things being equal) with the door cracked open under this assumed inefficient running

kopeck · Dec 16, 2014

Sorry, fouled up what I meant. Tom got it right.

I think you don't have your primary air set correctly. It also sounds like your wood is on the wet side.

K

tom in maine · Dec 16, 2014

Excess air allows for a leaner burn, usually with more turbulence, so storage temp goes up because the burn is hotter. It also is burning faster and it is likely the efficiency is down.
Is always easier with a combustion analyzer to show you what is actually happening. Then you have a chance of properly balancing primary and secondary air.

AroostookDave · Dec 17, 2014

20 to 30 % moisture is too high for efficient gasification. To get a good moisture reading you also need to split a piece of wood to get interior moisture content. Also, have you split your wood small enough? Large chunks lose moisture slower than smaller pieces. Another thing to be sure to do is to cross stack wood, so that air circulates better through the stack.
My innova is always used with doors closed, 75% open on the air intake setting, flue temps usually in 300s, water tank temp gets up to 180+ after a few hours. If the flue temp gets into 400s it is time for tube cleaning.

flyingcow · Dec 17, 2014

I agree your wood is too wet. I have the Inova 30.if my wood is about 20 to 25 percent it performs like you're talking about.I've got some stuff right now its in the 16/17 percent range. Almost night and day compared to 25 percent wood. I've been told there is nothing better than goodwood

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Your thoughts on these gasser readings

ohbie1

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kopeck

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Clarkbug

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ohbie1

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ohbie1

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tom in maine

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heaterman

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ohbie1

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kopeck

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tom in maine

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AroostookDave

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flyingcow

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