LL AA-220 Max Draft Burn With Power Vent Please Help!

swyman · Post by **swyman** » Mon. Nov. 30, 2015 11:27 pm

KLook wrote:The combustion fans are low cfm's, just enough to fire up the coal. The vent is much more about volume so it doesnt produce a lot of suction and just pull air in by the combustion blowers. It is a balancing act for sure and something is not doing its job.

Kevin

Not sure how low the combustion fans are but just messing around if I open them wide open they will blow almost all the coal/ash right off the shelf into the ash pan!

swyman · Post by **swyman** » Mon. Nov. 30, 2015 11:31 pm

KLook wrote:
Your combustion blowers are forcing air right into that baffle between the 2 different sized pipes. That, I beieve will cause all kinds of back pressure in the flue system. Looking at it this way, I can understand the drop in your draft from .035 to .02.
He is pulling on the firebox, that is the issue. He is using a power vent sold by LL to handle all the combustion blowers will put out.

How about that power vent? I had one once and it could be shut down on the outside to prevent backflow of air to blow out a pilot light. I installed my bro in laws Pioneer from LL, before they bought the company, and it was power vented. I do not remeber how it handled the backflo issue. Could it be not running at maximum velocity because of settings?

Kevin

Matt from LL had me bypass the rheostat so the fan gets full voltage and did not make a difference. Even when I put foil over the barometer opening didn't make much of a difference but temps went really high in idle fire due to pulling at full capacity through fire area. Pulled foil off and temps settled down.

lzaharis · Post by **lzaharis** » Tue. Dec. 01, 2015 1:20 am

swyman wrote:
KLook wrote:The combustion fans are low cfm's, just enough to fire up the coal. The vent is much more about volume so it doesnt produce a lot of suction and just pull air in by the combustion blowers. It is a balancing act for sure and something is not doing its job.

Kevin
Not sure how low the combustion fans are but just messing around if I open them wide open they will blow almost all the coal/ash right off the shelf into the ash pan!

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You have opened the air shutters and had this happen,
this in itself tells me that the fans are working properly.

If you have opened the air shutters and achieved this amount of combustion air blowing under the fuel bed of both stokers that tells me a lot as the power vent is working properly as you would not be able to blow the coal off the twin stoker beds unless the fire door is open.

Now all you have to do is leave the air shutters open at the recommended distance and slowly adjust the
air shutters-opening them slightly with the pusher plates at the lowest stroke/coal feed rate as it is burning
for both units.

I think your going to find that by cutting the feed rate in half for both stokers while you have the air shutters
opened to their proper width with the stroke at its lowest setting you will be able to run both burners and provide the heat you need.

Its best that you talk to Matt or one of his folks while you do this even starting with no fire and starting from there-

1. reduce the stroke of the pusher plates to the minimum/lowest thread setting on each stoker

2. start a fire on both coal beds
a, be sure the power vent is running and fully open
b. open the air shutters to the recommended width which I believe is one third the distance across the air inlet for both stokers
c. have the minimum required number of threads on the stoker for the starting point check with matt for the number of threads on the stroke mechanism for the minimum feed rate, but I believe its 12 threads.
3. start the fans.

4. check the manomometer reading at both fan inlets-remember that if the air damper doors are not equal in opened width
one blower may be working harder than the other.

4. wait to see how the fire looks and increase the coal feed a bit

5. wait for an hour or so and check the fire and if the boiler is not burning well meaning all the coal is burned well before it reaches the midway point on the stoker bed increase the feed rate.

6. check the fire an hour later to see how it is doing and go from there.

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7. I would rather see you do this with one stoker for now as you have not ironed out all the problems yet.
by fine tuning one stoker at a time you will become more familiar with how your boiler operates.

a. by running one stoker first it will let you accomplish several things:
1. the air shutter will be set to the correct width for the air volume needed for combustion
2. when you have one stoker running very well you can slow down the feed rate slightly
and begin to get the second stoker dialed in over a longer period so that you can uses both burners.
3. having one stoker working properly you will be able to duplicate the results on the second stoker by
adjusting the second stoker which is at the minimum feed rate in the beginning which is the basic starting point for the
Pocono stoker.

Telling us that you have opened the air shutters fully open and had coal blown off the firebed or firebeds tells us a lot and Matt needs to know this to help you.

swyman · Post by **swyman** » Tue. Dec. 01, 2015 3:14 am

Iza, you did it again!!! Excellent post and that all makes perfect sense to me. One thing with this design is I cannot look at the fire without having the door open. I have to lay on the floor and look up to see the flames. Cannot wait to get home now and get this straightened out. Before reading this I was going to get home this morning and shut one side down and run the other at minimal temp and turn my propane furnace back on. At least this thing should be able to heat my domestic hot water and act as a supplement heat for my home but that is not the intention. I cannot keep tossing 4 bags of coal per day at 30-38* outside temps. My neighbor has also sold his Central Wood boiler and bought the same LL AA-220 with direct vent but he does not have it up and running yet. Will be nice when he does so we can help each other out. I really thought I would get some replies on this forum from those that have this boiler but I guess there isn't? Anyways, thank you for your reply and will give feedback after adjustments and talking to Matt!

SWPaDon · Post by **SWPaDon** » Tue. Dec. 01, 2015 5:04 am

swyman wrote:Yes you guys are exactly right, the direct vent will not pull enough exhaust out for me to maintain the correct draft. I cannot open the combustion blower doors even half way. I cannot believe that this setup will not support the boiler as this was a package deal through the company. I did not get a call back from LL all day so maybe they are out of town? At this point I think it will be best if I just install a chimney and I hope they give me my money back from the direct vent. Another thing I don't like about the direct vent is it is always running wide open. That pulls a lot of air out of the room when the boiler is in idle fire. The baro door is wide open and still immediately pegs the manometer. Hope I can talk to Matt in the morning. Burned another 4 bags last 24hrs with temps in the 30's.

I agree.

KLook · Post by **KLook** » Tue. Dec. 01, 2015 8:18 am

Positive you will get it, even without other owners of the 220 chiming in. It is early in the season and the forum isn't up to speed yet.

Not sure how many people have the 220 also. It is a big unit. Also positive Matt will get it straight, unusual for them to not communicate, they must be swamped or something. LL customer service is first rate.

Kevin

swyman · Post by **swyman** » Tue. Dec. 01, 2015 9:32 am

Well talked to another gentleman from LL this morning and he told me to adjust the direct vents fan so that it is right up close to the housing (which Matt told me to check but didn't). I moved it forward around 1/4" and still wasn't hitting but put it together and had to get inside...raining pretty hard here and got soaked! So I shut off one side and turned on the propane furnace to ease up on my consumption and will work with one side at a time like Iza suggested. Not sure if the fan made much difference, will tell once I fire up both burners. Will adjust fan blades some more once it dries off. So I have one side running at factory recommendations and what a beautiful fiery inferno! Here's a pic.....I know I was blowing hot coals off the end but have it adjusted now.
Editors note: I thought this would be easier than burning corn?????

lzaharis · Post by **lzaharis** » Tue. Dec. 01, 2015 9:58 am

swyman wrote:Well talked to another gentleman from LL this morning and he told me to adjust the direct vents fan so that it is right up close to the housing (which Matt told me to check but didn't). I moved it forward around 1/4" and still wasn't hitting but put it together and had to get inside...raining pretty hard here and got soaked! So I shut off one side and turned on the propane furnace to ease up on my consumption and will work with one side at a time like Iza suggested. Not sure if the fan made much difference, will tell once I fire up both burners. Will adjust fan blades some more once it dries off. So I have one side running at factory recommendations and what a beautiful fiery inferno! Here's a pic.....I know I was blowing hot coals off the end but have it adjusted now.
Editors note: I thought this would be easier than burning corn?????

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About the fan blades on the power vent-If the pitch/angle is adjustable like high thrust propellers or reversable turbine blades that's the other item we/I did not know about power vents and your issue in particular.

if the fan blades are set at the minimum pitch you are only moving a very small amount of air through the throat of the power vent per minute.

I am not happy that they did not ask you this or suggest it to begin with in the LL manual as you have no chimney.

Please put this at the front of the list:

angle the fan blades to the maximum pitch before you do anything else tomorrow/today etc.

this does two things for you; it increases the cubic feet per minute of flue gasses exiting the firebox in total to 65CFM and increases the amount of theoretical and potentially available combustion air to at least 32.5 CFM PER stoker using both stokers
for a total of 65 CFM .

YOU have to go back and set the damper door on one squirrel cage fan to start the process AFTER you increase the pitch on the fan blades of the power vent and measure the draft setting with the manomometer to obtain the proper "HG" setting (water gauge reading).

Post by **franco b** » Tue. Dec. 01, 2015 12:17 pm

As Rob mentioned way back the only place a draft reading is meaningful or critical is over the fire. Through the loading door. If no hole then drill one. Adjust baro for .02 reading. Just holding a match to the hole would indicate if draft is negative or not. If positive it would also burn your finger if held there.

Stack temperature within a foot of breech even if only surface would also give an idea if too much excess air is being used. Matt should give you an idea of what temp. to expect. My suspicion is that too much combustion air is being used.

Gradually increase burning rate with what you feel to be minimum air until draft begins to turn positive over the fire. At that point you have reached the maximum output of the system. Excess air will certainly account for the problems you experienced including excess consumption.

swyman · Post by **swyman** » Tue. Dec. 01, 2015 4:39 pm

Iza, the fan has only flat blades and the only way to adjust is sliding it on the motor shaft closer to the inlet shroud.

Franco, I will drill a hole in the door and check that fire box draft. Right now my stack temp right out of the elbow at the boiler exit before the barometer is 170's. The manual states to set unit up for max burn then lock the settings down and that's it. So trying to do as Iza suggested and get one burner set then move to the other.

Post by **franco b** » Tue. Dec. 01, 2015 6:13 pm

With the hole in the door you can also measure the difference in draft between over fire and at breech area. Large drop would indicate too much resistance within boiler and you would look for things like a baffle out of place or anything blocking flue passages. Having the hole also allows a quick test by holding your finger close to it to see if it it pushing heat out and burning your finger.

170 stack temp. seems good to me, but that is at a lesser firing rate than you want.

Presumably you have held your hand in the exhaust outside and can verify a pretty good blast of air? Also verify that the vent has no other place to draw air from than the smoke pipe, some have a diverter vane.

Once you have reached a maximum firing rate while still maintaining negative draft over the fire, no matter how small, the baro flap should be closed at that point, and that's as far as you can go.

Burning 3 forty pound bags should give you roughly fifty thousand BTU net per hour.

swyman · Post by **swyman** » Wed. Dec. 02, 2015 8:53 am

New report.... Ran 24hrs with a single burner set as close to max burn (as far as I can tell?) and the boiler was in idle fire mode which is a great sign considering it's 26* but no wind. Still, that to me is progress in the right direction! I have the rheostat on the direct vent turned down to maintain .04wc draft. How hot are you guys running your boilers? I'm set at 180-190* on the aquastat with 200* high limit? Would I consume less if I turned it down 15-20*? I still burned about 1 1/2 bags from 10pm till 8am, would like that to get better. I may have found another breakthrough, I had put a vault in my yard next to the pool with my lines running through it. I noticed this morning that there was no frost on the lid so I opened it up and lots of steam going on. I had foam insulation around the pex to insulate and separate them, then that sticky pipe wrap insulation wrapped around that, and fiberglass insulation on top of that, then a piece of 1" foam board covering that then the vault lid. Well the fiberglass insulation looked like a dead, wet animal! I removed everything and dug out around everything by 4" and am going to spray foam 4" thick around it all encapsulating everything. I haven't hooked up the pool in the 8 years it's been there so I guess I am safe in doing this! Doing it in layers as I don't know if the "great stuff" foam will cure if I just make a mountain all at once? So I laid one can down and it covered the 4" under everything so when I wake up I will do another can, then probably another. I like lot's of insulation!

Oh, I noticed one other thing with burning at max fire is the ash...instead of most all the coal having a popcorn like consistency in the ash pan, there was a lot of fine powder and less popcorn (if that's a good explanation?). I hope that means I am getting more out my coal?

KLook · Post by **KLook** » Wed. Dec. 02, 2015 9:02 am

How deep is that line and where did the water come from to soak the insulation?

Could you have a leak that is robbing your Btu's?

Kevin

Post by **Rob R.** » Wed. Dec. 02, 2015 9:08 am

Wet insulation in underground piping will have a significant impact on the amount of BTU's donated to the soil.

lzaharis · Post by **lzaharis** » Wed. Dec. 02, 2015 10:55 am

you have better burn with the indications of a fine powder ash which is commonly referred to as fly ash
in the coal burning biz(electric power and steam generation)

The steam coming from your vault is never a good sign.

The other issue is the age of the PEX and its condition.
The wrapped PEX has had problems over the years as I have come to understand it.

As far as your coal consumption goes you should seriously think about lowering
your high limit to 160 and setting the low limit to 140 and your boiler will recover faster.

My other question is whether you have a boiler bypass line?
The boiler bypass line diverts a certain amount of hot water back to the boiler base to keep the
water in the steam chest hotter and reducing the amount of time the boiler burns by keeping
the water hotter at all times.

The other worry is of course the amount of heat lost to the ground as has been mentioned.

The 15 per foot Thermopex has a heat loss rate of one degree per one hundred feet if I
remember correctly.

The thing is that the wet insulation you found tells me you have may have a hole in the solid
drainage pipe letting the water enter the tubing

About the temps, I have had my high and low limits set at summer temps(140-160) for years and
I have a drafty old house and the hand fired Switzer it has kept up with the heating load.
If its really cold I just bump up the thermostat a bit.

You will burn less coal per hour/per day which I realize is your major concern.

I would seriously look at the PEX you have now and replacing it as the insulation surrounding the pex
is damaged and of little heat value and the heat value of the water is being lost to the ground over time.

It may be worth your while to invest in a handheld infrared thermometer to check the ground temperature
and if it is above 52 degrees along the trench route for the Ppx pipe its losing way too much heat.

Think of it in this way. every foot of your pex is losing heat through the wet insulation to the tubing and
then to the surrounding earth.

The new thermopex is so good many folks have left it on the ground if they did an install in the crap weather
season all winter and the thermopex snow never melted the snow that buried it due to the foam insulation surrounding the
oxygen barrier pex lines sitting on the top of the ground. you have to be careful of course to not run over it with a tractor if you are clearing snow.

You will be able to heat your pool more efficiently as well if you install the new pex.

I would lower your boiler temperatures to 140-160 add a bypass line with a control valve to allow the bypass line to deliver a set number of gallons per minute back to the steam chest to keep the boiler hot and your boiler will come up to the high limit faster, cycle less and reduce wide wild temperature swings to a minimum as you will not have any due to the use of the lower summer
temperatures of 140 low and 160 high.

As mentioned your current tubing is already compromised and having steam in your piping vault is not a good thing
at all as you are losing both heat and boiler water.

I am sorry If I have not been much help, but I think your already stuck with a bad pex loop that is compromised due to a leak or wet insulation and you should invest in a new run of the oxygen barrier thermopex from the boiler to the home and pool.
As you have invested in the new boiler installing the new thermopex will only help to reduce your coal use and reduce you heat loss to 1 degree per one hundred feet of buried thermopex.

LL AA-220 Max Draft Burn With Power Vent Please Help!

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