Comfortmax Instructions Deficient in the Coal Burning Dept.

ddahlgren · Post by **ddahlgren** » Sun. Jun. 14, 2015 7:30 am

If you open the ash pan door you are getting max air possible open MPD max draft possible. So max burn possible to wake up the coal.The coal you put in steals heat from the coal burning as generally room temp or outdoor temp and has a long way to go to get to burning temp too much cold coal and burning coal goes out. You can't take what is not there. I have a grain scoop that holds 5 or 6 lbs of coal and add one at a time leaving about 1/3 of the coal bed exposed. I work from home and need to go from the shop to house every now and then so when I walk by the stove throw a scoop or two in and get on with what I need to do so tending for me is more about shaking down ashes. The overnight burn recovery the more exciting one as coldest part of the day so need the most heat and may need to rethink that though the house takes days to get to temp with the plaster walls but once warm no drafts at all.. The 5 am open ash door and MPD and add a scoop at a time game goes on for about 20 minutes while I make breakfast and a cup of tea. When 30 lbs or more burning time to shake and let ashes cool before dumping. If things real desperate will throw some kindling in to add some heat and get draft going anything to not start from zero fire out. We had a week last year of nights -17 to -20 and several near nothing burning as asking too much from the 404 Rebuilt daily a bed of coals from almost bare grates and might have been easier to start over again. Reminds me need to get the sweep over here to do the chimney and be ready for next year and order 2 1/2 tons of Blaschack from Branford any news on the TSC Kimmels coal? Would love to have a couple tons on hand of that too great for starting and super cold nights. A couple scoops of that will bring any fire back from the dead.
'

KingCoal · Post by **KingCoal** » Sun. Jun. 14, 2015 7:45 am

SWPaDon wrote:
lsayre wrote: The secondary air control is the small knob situated midway between the two doors at the center of the stove. For wood burning it is to be moved more to the right, and for coal burning it is to be moved more to the left. The primary air control is the dial regulated bimetallic air inlet flapper in the back of the stove that lets air into the ash pan area beneath the grates.

This has me thinking. Most of the stove guides I've been perusing say that to liven up the stove you open the ash pan door. But these stoves do not have the bimetallic air inlet. Instead of opening the ash door, could not essentially the same be accomplished simply by dialing the bimetallic air inlet flapper wide open?
That would work, but not nearly as quickly as opening the door. as the area for air to enter will be much larger.

on the other hand, you have a fire pot that is 18x12 and about 9 deep, that's a fair amount ( say 65 #) of settled ash and coal sitting there and you have the combustion chamber and the whole exhaust path above that. what I found with the circulator was that if I opened the ash door much the system would seem to equalize and take a while to get moving again.

i then started to open the primary air with the bi metal. that seemed to keep the velocity up and things moved along quicker. the point here is that you will find that the bi metal keeps the flap open about 1/8" during most cruise burns so opening it wide open isn't really nec. I found 1/2 was plenty and, it willl keep you from having a run away if you go "senior" for a few minutes cause it will close itself back down.

in the end, it became obvious that I was putting way too much thought and effort into it. while I was using the stove as a circulator I found that if I was running with or with out the hopper all I needed to do was walk up to the stove, shake the grates till I had the glow I want, make sure the top of the fire isn't totally covered and walk away.

no opening the MPD, no opening the primary or ash door, no poking or slicing, just shake the grates, fill to satisfaction and go. the stove just kept on keeping on. no temp. drop, no spike, just constant even heat.

these stoves couldn't be any easier in this respect and honestly I expect that your stove will run very much the same and quite nicely. i'm very concerned about the construction and exhaust path being the best for heat transfer to the living space but, we've covered that before in other threads.

since it was my understanding that this unit is pretty much a space heater and not carrying the demand of the whole house the efficiency issues may not even be of much concern.

you're biggest issue will probably be clearing the ash pit and carrying ash out of the furnished portion of the house. make sure to get some long welding gloves for messing around in the stove and a hard hat to stave off broom stick attacks from behind

lsayre · Post by **lsayre** » Sun. Jun. 14, 2015 8:11 am

Very good advice there KingCoal!

SWPaDon · Post by **SWPaDon** » Sun. Jun. 14, 2015 8:17 am

KingCoal wrote: on the other hand, you have a fire pot that is 18x12 and about 9 deep, that's a fair amount ( say 65 #) of settled ash and coal sitting there and you have the combustion chamber and the whole exhaust path above that. what I found with the circulator was that if I opened the ash door much the system would seem to equalize and take a while to get moving again.
i then started to open the primary air with the bi metal. that seemed to keep the velocity up and things moved along quicker. the point here is that you will find that the bi metal keeps the flap open about 1/8" during most cruise burns so opening it wide open isn't really nec. I found 1/2 was plenty and, it willl keep you from having a run away if you go "senior" for a few minutes cause it will close itself back down.

in the end, it became obvious that I was putting way too much thought and effort into it. while I was using the stove as a circulator I found that if I was running with or with out the hopper all I needed to do was walk up to the stove, shake the grates till I had the glow I want, make sure the top of the fire isn't totally covered and walk away.

no opening the MPD, no opening the primary or ash door, no poking or slicing, just shake the grates, fill to satisfaction and go. the stove just kept on keeping on. no temp. drop, no spike, just constant even heat.

these stoves couldn't be any easier in this respect and honestly I expect that your stove will run very much the same and quite nicely. i'm very concerned about the construction and exhaust path being the best for heat transfer to the living space but, we've covered that before in other threads.

since it was my understanding that this unit is pretty much a space heater and not carrying the demand of the whole house the efficiency issues may not even be of much concern.

you're biggest issue will probably be clearing the ash pit and carrying ash out of the furnished portion of the house. make sure to get some long welding gloves for messing around in the stove and a hard hat to stave off broom stick attacks from behind

With all the different stoves I've used over the years, I've never experienced anything like that.

lsayre · Post by **lsayre** » Sun. Jun. 14, 2015 8:19 am

In thinking of how to minimize the potential for setting up puff-back scenarios, I came up with this ditty as I was sitting here and openly typing my thoughts on this matter. Please evaluate this and let me know if there is any merit to it, or if I can improve upon it (correct it) before printing it out for the wife and I to use as a guide:

After loading and closing up the stove and setting its air controls for a long burn, do not subsequently go back and open the doors (ash or feed) on your load of freshly added coal, and particularly more so for the case of where there is no sign of openly blue flames dancing to burn off the volatile gases. This will likely lead to an immediate (or nearly so) puff-back condition. If anything, at this juncture if you are not seeing any dancing flames open the over the fire air control. The over the fire air inlet should allow for air to enter and ignite the gases.

The reason why you can open these two doors safely after 12 hours of burn time (give or take) is that by then essentially all of the volatile gases that can ignite and explode have been burned away and only pure carbon is left burning.

Side note: My spell checker did not like the word "gasses", but it accepts "gases". Which is correct?

SWPaDon · Post by **SWPaDon** » Sun. Jun. 14, 2015 8:27 am

lsayre wrote:In thinking of how to minimize the potential for setting up puff-back scenarios, I came up with this ditty as I was sitting here and openly typing my thoughts on this matter. Please evaluate this and let me know if there is any merit to it, or if I can improve upon it (correct it) before printing it out for the wife and I to use as a guide:

After loading and closing up the stove and setting its air controls for a long burn, do not subsequently go back and open the doors (ash or feed) on your load of freshly added coal, and particularly more so for the case of where there is no sign of openly blue flames dancing to burn off the volatile gases. This will likely lead to an immediate (or nearly so) puff-back condition. If anything, at this juncture if you are not seeing any open flames open the over the fire air control. The over the fire air inlet should allow for air to enter and ignite the gases.

The reason why you can open these two doors safely after 12 hours of burn time (give or take) is that by then essentially all of the volatile gases that can ignite and explode have been burned away and only pure carbon is left burning.
Side note: My spell checker did not like the word "gasses", but it accepts "gases". Which is correct?

Either spelling is correct according to this: http://dictionary.reference.com/browse/gasses

KingCoal · Post by **KingCoal** » Sun. Jun. 14, 2015 8:51 am

lsayre wrote:In thinking of how to minimize the potential for setting up puff-back scenarios, I came up with this ditty as I was sitting here and openly typing my thoughts on this matter. Please evaluate this and let me know if there is any merit to it, or if I can improve upon it (correct it) before printing it out for the wife and I to use as a guide:

After loading and closing up the stove and setting its air controls for a long burn, do not subsequently go back and open the doors (ash or feed) on your load of freshly added coal, and particularly more so for the case of where there is no sign of openly blue flames dancing to burn off the volatile gases. This will likely lead to an immediate (or nearly so) puff-back condition. If anything, at this juncture if you are not seeing any open flames open the over the fire air control. The over the fire air inlet should allow for air to enter and ignite the gases.

The reason why you can open these two doors safely after 12 hours of burn time (give or take) is that by then essentially all of the volatile gases that can ignite and explode have been burned away and only pure carbon is left burning.
i agree with this. another thing that can happen when using more secondary air in the conditions you mention is that it will sweep excess volatiles up the flue and will lower the chance of puff back and encourage the fire bed to perk up. it can impede the heat transfer from the stove but it should be short lived since you will be shutting it back down after things are perking.

Side note: My spell checker did not like the word "gasses", but it accepts "gases". Which is correct?

lsayre · Post by **lsayre** » Sun. Jun. 14, 2015 9:05 am

I intend to burn pea, since that is what I stock for the AHS boiler. The Crane literature suggests 9" deep beds are for nut and 6" deep beds are for pea. My bed is 9" deep to the top of the firebricks. Should I fill it up, or short fill it to closer to only 6"?

Sunny Boy · Post by **Sunny Boy** » Sun. Jun. 14, 2015 9:50 am

KingCoal wrote: ...............................................

you're biggest issue will probably be clearing the ash pit and carrying ash out of the furnished portion of the house. make sure to get some long welding gloves for messing around in the stove and a hard hat to stave off broom stick attacks from behind

If you fashion a removable lid for the ash pan,......... it should help eliminate the need for you having to wear a lid .

Paul

lsayre · Post by **lsayre** » Sun. Jun. 14, 2015 10:00 am

Sunny Boy wrote:If you fashion a removable lid for the ash pan,......... it should help eliminate the need for you having to wear a lid .

Paul

I can't see why the manufacturers don't provide slip over lids for these things. If Freddy is still in the business of making ash pans, perhaps he could fab up two of them with covers for me at a reasonable cost?

Sunny Boy · Post by **Sunny Boy** » Sun. Jun. 14, 2015 10:02 am

I do believe Freddy is still "pan handling".

lsayre wrote:I intend to burn pea, since that is what I stock for the AHS boiler. The Crane literature suggests 9" deep beds are for nut and 6" deep beds are for pea. My bed is 9" deep to the top of the firebricks. Should I fill it up, or short fill it to closer to only 6"?

Likely the reason the Crain literature says that is, because if you fill it to the top with pea coal, it may not be able to breath well enough to generate the heat output you want. ??? There are ideal depth ranges for the size of the coal being burned in naturally aspirated stoves. The smaller the coal size the tougher it gets to make it breath by just the draft strength alone. That's why so many rice stoves have forced air through the firebed.

However, if you find that your set up has a rather strong draft on very cold days, adding to the depth of coal bed and/or using smaller sized coal mixed in, can help hold back that overly strong draft.

I can't change the depth of the firebed much on my range, but by changing what size ratio that I dig the coal from various parts of the coal bin, I can slow, or speedup, the draft and thus have a rather big impact on the heat output.

Size does matter !

Paul

KingCoal · Post by **KingCoal** » Sun. Jun. 14, 2015 3:16 pm

lsayre wrote:I intend to burn pea, since that is what I stock for the AHS boiler. The Crane literature suggests 9" deep beds are for nut and 6" deep beds are for pea. My bed is 9" deep to the top of the firebricks. Should I fill it up, or short fill it to closer to only 6"?

the DS info listed on Messsick stoves says your stove will burn egg, stove, nut and pea. i'd say how deep to load each one is a question for DS directly.

my experience based view would be that the 6" depth for pea in that stove would probably be about right. esp. if you don't have an atomic leaf vac flue.

Post by **Lightning** » Sun. Jun. 14, 2015 3:20 pm

Wow, lots of great stuff on this thread, and you can see that people have developed their own routine for quickest recovery after loading and avoiding the ominous puffback

.. There really isn't one particular way that is more right than someone else's way. It's a process of trial and error of what you find works, you feel confident with, and that you are comfortable with. The variables at play with your particular set up have impact on how you discover your "iron clad" shake and load routine.

At the top of the priority list are (not in any particular order),

#1 Not to kill the fire. Its an easy mistake is to let too much of the fuel burn up before shake and load time. This is contingent of course on heat demand between tendings. On my set up, I watch my stove and pipe temp for a drop in temperature. For 90% of the burn, the temps hold quite steady (thank you barometric damper) when I see the temps begin to fall, I know the stove is near its time for refueling. As you've read, coal fires don't like to be fiddled with. It injures the happy community of burning coal in the fuel bed. Shaking ash out must be done, but it also injures the fire. This is why it's important to give it a 5 minute rev up. It gets all the available coal in the fuel bed burning nice and hot which helps with recovery time too. To do this, I open the ash pan door for 5 minutes.

#2 Loading. Like mentioned, best case scenario is to have the same amount of burning coal left after shaking as you plan to load. This will provide the quickest recovery without a heavy drop in heat output for an extended period of time. In my case, when I see my temps start to fall (as described above) its a signal that I'm nearing that point. This is the time that I'll have 50 pounds of burning coal left after shaking and I can add 50 more fresh. There have been times that I couldn't get to it and it went past this point. The most dramatic loading I've done, was with having about 20 pounds of healthy, hot burning coal after a shake down and then loading on 85 pounds (maybe it was 90, not sure lol). It took about and hour and a half to get the fire back to producing good heat again with the ash door wide open. If you are caught in a situation like this just keep in mind that as long as there is good draft with an orange glow radiating down thru the grates and you have fresh coal on top - it will catch, just give it time. I had one unrecoverable fire last year. The missing component was the orange glow after shake down. IN this particular instance the shake down injured what was left of the fire to the point of becoming lethal.

Edit - I also saw that layering was mentioned. The only time I use the layering method is during a brand new fire. Build up to the top of the fire brick with layers. After a new fire is established, I just add the whole charge after a shake down.

#3 Recovery and puffback. After shake and load, the most desirable thing is to get the stove back up to it's needed heat output. I do this by leaving the ash pan door open. Others that have the bi metallic regulator let it do it's thing instead. While the fresh load is baking, it starts to release it's hydrocarbon based volatiles. What you don't want are these volatiles to reach the proper fuel/oxygen ratio to where they can flash. This is accomplished by keeping the mixture either too rich or too lean. Keeping it too rich would be dangerous since when it does finally lean out to the point of ignition, you basically have a bomb waiting to detonate. ESPECIALLY if the whole stove AND chimney have an abundance of this mixture. So, the safest thing is to keep it too lean. I accomplish this by cracking the load door. By just cracking the load door I maintain pull under the grates. Also, it dilutes the volatiles that are up above the fuel bed beyond flash mixture ratio until a flame can peek up from below and ignite the gases right at fuel bed level that are reaching the proper mixture. Once they ignite, leave everything alone for a small period of time (10 minutes or so) before closing everything up. Closing up early while the mixture is fragile can cause the blues to vanish and then we're entering flash territory with nowhere for the flash pressure to go, other than blowing out the baro door. It may seem like I do an excessive amount of fiddling, but its what I've discovered that works for me, I'm confident with and comfortable with. There are others that load and go by just leaving a corner of burning fuel bed exposed with the banking tecnique, and that's fine. Personally, I haven't been brave enough to do that. Maybe I'll try it sometime.

lsayre · Post by **lsayre** » Sun. Jun. 14, 2015 3:55 pm

Thanks Lee! I printed that out for reference.

lsayre · Post by **lsayre** » Fri. Jun. 19, 2015 8:27 pm

What is a good solvent free (or at least very low VOC) protectant with which to coat the metal parts of a coal stoves innards with for the summer months?