Coalgun- Puff backs & Explosions

rychw · By: **rychw** On: Wed Jan 11, 2012 9:38 pm

I had a large puff back yesterday. The outside temps were @ 55 degrees, so boiler demand was low. I cleaned out my horizontal stove pipe today, it was 50% filled with fly ash and that is normal for the last 5 heating seasons. I am considering lowering my thermo ash dump temp to 90 drgrees from the current 95. The boom occured right when the boiler fan shut off so there was too much new coal added to the boiler. The next plan is to try to get a device to have the fan run at slow speed after it shuts off to evacuate the coal gas. Yanchee suggested this idea and I will try to find an economical device.

macdabs · By: **macdabs** On: Wed Jan 11, 2012 10:13 pm

It is official... I found the bottom of my field controls RC damper lower flap 20 ft from my boiler!! :mad:

I guess my boiler had a puff back sometime during the day and when I walked into my shop my damper was wide open. I guess now I am in the puff back club

Then after I fiddled with the damper to try to make it work, 20 minutes later a small puff back occurred and shaked the whole flue and slammed the damper forward again!! :mad:

What the heck!
I was so happy with zero issues since fire up over two weeks ago even on the warm days we had . The only thing I changed in the last few days is I was mixing nut coal with my pea to get rid of it and today I filled the hopper with all pea. Could this be the problem ?
My baro damper now seems to be sticking and not working the same with a oval instead of a round shape now. What is scary is my main electrical panel was wide open for wiring breakers and if that piece of the baro would of flew into that who knows what could have happened. I am wondering if I should go back to mixing with nut again?

Not to mention the cost of the baro damper is pissing me off.. Sorry for the vent.

ValterBorges · By: **ValterBorges** On: Wed Jan 11, 2012 11:07 pm

I use pea, keep my SV @ 120, the hopper always full, have plenty of combustion air available, my hysterisis diff @ 10, the boiler temp between 145-165 or 160-180 depending on the weather, getting .04 wc on the dwyer and around 180-200F inside stack temps when dormant, and 1-1.2 wc when blower is on and stack temps rise to 450-500F. No problems at these settings. Loading and ashing is snap now that i got a different tub that fits a contractor size bag, lift tie, dump (good bye vacuuming, and ash dust).

As soon as I try SV @ 130 the booms start.

Keep an eye on the height of the fire if you're dumping too much coal on top and buring the coal you'll have booms.

I've also thought about mixing Nut figuring the larger spaces would allow the flames to come thru and burn off those gases.

Yanche · By: **Yanche** On: Wed Jan 11, 2012 11:37 pm

rychw wrote:I had a large puff back yesterday. The outside temps were @ 55 degrees, so boiler demand was low. I cleaned out my horizontal stove pipe today, it was 50% filled with fly ash and that is normal for the last 5 heating seasons. I am considering lowering my thermo ash dump temp to 90 drgrees from the current 95. The boom occured right when the boiler fan shut off so there was too much new coal added to the boiler. The next plan is to try to get a device to have the fan run at slow speed after it shuts off to evacuate the coal gas. Yanchee suggested this idea and I will try to find an economical device.

I don't think you will find a suitable variable speed controller for your existing single phase induction motor. The controllers you will find will be single phase input (110 or 220 VAC) input but the output will be 3 phase. This will add considerable expense because you will also need to replace the motor. Do you have the belt drive or direct drive blower?

A much less expensive experiment would be to slow down the coal feed. This would put a speed controller on the ashing motor. This motor is a shaded pole motor and can use an inexpensive ceiling fan motor controller. The idea would be to move the grate so slowly that coal feed occurs over a long time period, ideally so slowly that the grate is every so slightly moving whenever the combustion blower is running. This would eliminate a big gulp of fresh coal.

macdabs · By: **macdabs** On: Thu Jan 12, 2012 6:35 am

My draft has been .04-.06 for the last two weeks with no issues. The boiler as of now has over 3200 sq ft to draw fresh air from with 20 ft ceilings and is placed near a steel exit man door. I think you have a constant draft near the panic hardware on that type of door compared to a home style door not to mention three overhead 12'x 12' garage doors.

Now my ash rate is still at the factory setting at 140* with a constant load of two pumps to my oil boiler that is 245' to my house. The temp yesterday was colder than several previous days we had this month so far. The only thing that I changed was no nut coal mixed with the pea in the last day in a half. Now I have had the sight door closed since the stove has been fired up should I crack it open? I average a good 100to 150# easy per day ,but I am heating 6300-6500 sq ft per day on average .

Mac

Pa papa · By: **Pa papa** On: Thu Jan 12, 2012 9:16 am

That would be my vote. Since opening the vent port on mine half way, no more woof's or kabooms. I burn all pea and have the SV at 130 and it works just fine.

dchartt · By: **dchartt** On: Thu Jan 12, 2012 3:37 pm

changed my ashing temp from 120 to 130 and heard her burping this morning, none of that while it was at 120, burning buckwheat

rychw · By: **rychw** On: Thu Jan 12, 2012 7:11 pm

Yanche wrote: Do you have the belt drive or direct drive blower?

I have the belt driven model. Can I just go to the discount hardware store and buy a cheap ceiling fan control to work with my ash grate motor? Thanks

ValterBorges · By: **ValterBorges** On: Thu Jan 12, 2012 8:20 pm

Yanche wrote:
rychw wrote:I had a large puff back yesterday. The outside temps were @ 55 degrees, so boiler demand was low. I cleaned out my horizontal stove pipe today, it was 50% filled with fly ash and that is normal for the last 5 heating seasons. I am considering lowering my thermo ash dump temp to 90 drgrees from the current 95. The boom occured right when the boiler fan shut off so there was too much new coal added to the boiler. The next plan is to try to get a device to have the fan run at slow speed after it shuts off to evacuate the coal gas. Yanchee suggested this idea and I will try to find an economical device.

I don't think you will find a suitable variable speed controller for your existing single phase induction motor. The controllers you will find will be single phase input (110 or 220 VAC) input but the output will be 3 phase. This will add considerable expense because you will also need to replace the motor. Do you have the belt drive or direct drive blower?

A much less expensive experiment would be to slow down the coal feed. This would put a speed controller on the ashing motor. This motor is a shaded pole motor and can use an inexpensive ceiling fan motor controller. The idea would be to move the grate so slowly that coal feed occurs over a long time period, ideally so slowly that the grate is every so slightly moving whenever the combustion blower is running. This would eliminate a big gulp of fresh coal.

I've noticed that even with no ashing the hooper/gravity still dumps quite a bit when the burnt coal below collapses.

coaledsweat · By: **coaledsweat** On: Thu Jan 12, 2012 10:57 pm

rychw wrote:I have the belt driven model.

Could you post a picture or description of the pulleys and belt?

ValterBorges · By: **ValterBorges** On: Thu Jan 12, 2012 11:28 pm

I think this has what you're looking for. pg 34+

Yanche · By: **Yanche** On: Fri Jan 13, 2012 12:29 am

coaledsweat wrote:
rychw wrote:I have the belt driven model.

Could you post a picture or description of the pulleys and belt?

Here's the previously posted picture of my AHS S130 with the belt drive blower. The motor is a capacitor start 1/2 HP induction motor. It could easily be replaced by a three phase motor. A variable frequency speed controller would control the speed.

For anyone planning to do this make sure you purchase a three phase motor intended to be used with variable frequency speed controllers. The motor insulation is upgraded from standard three phase motors. Also buy a controller that has external speed control inputs. This control can be an analog voltage or digital. This external speed input would be in addition to the controller's panel speed settings. I suspect any puff back solution based on adjusting the combustion air will require external control logic.

ValterBorges · By: **ValterBorges** On: Fri Jan 13, 2012 12:41 am

No Image

Yanche · By: **Yanche** On: Fri Jan 13, 2012 1:00 am

ValterBorges wrote:No Image

That's strange I see it. Used previously in one of my postings. I just wrapped Img tags around it. Try it using this link.

http://nepacrossroads.com/download/file.php?id=5695

coaledsweat · By: **coaledsweat** On: Fri Jan 13, 2012 8:58 am

Yanche wrote:Try it using this link.

http://nepacrossroads.com/download/file.php?id=5695

The selected attachment does not exist anymore.

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