Why not Burn coal over 50 degrees

[coldinnj]

Have heard different views on burniong coal if outside temperature is over 50 degrees F.
Is there any definitive evidence / facts or informative points that can be presented on it?
Many have said you cannot unless the temp is under 50 deg.
Others show where they have been using it over 50 deg for years and in fact heat their water with it also all summer long when temps can hit 90's and even 100 with no problem at all.
Some do it in the times of year when the temps may be 60's by day and 30's at night but don't want to rebuild their coal fire so it keeps runnig 24 /7
Possibilities of differences if blower is used for draft control at furnace / stove.

 

[MountainStoveGuy]

less draft in warmer weather can cause carbom monoxide to spill. Coal emits a lot of bad stuff and you want to have proper draft.

 

[Corie]

Yep. Moreso than that, coal combustion in the stove is generally a bit more efficient, resulting in lower stack temps.

In my stove, a load of coal will produce a stove temp of 350F and a stack temp of 150-200F, nothing like that in a wood stove.

The lower stack temps mean the temperature differential at outdoor temperatures about 50F are too low to maintain a good draft.

 

[Michael6268]

Ditto. Lower stack temps make it harder to draft. Handfired/natural draft units are more of a problem than stoker stoves. Stoker stoves use an exhaust blower to aid in the draft. Two summers ago I had to use my stoker in July when it was 90+ out for hot water when the water heater went. It burned fine.

 

[ansehnlich1]

I burned a baker coal stove for 7 years. If I'd burn when temps were warm outside, 60+, this is what would happen. I'd shut the air to the stove down real far, having the coal smolder, but not really put out much heat. Sometimes I'd lose the fire, sometimes I'd come home to that God awful odor of coal fumes throughout the house, sometimes it would just smolder all day with no problem. I'd come home, throw open the draft, sometimes the ash door, and it would take a couple hours to bring the coal back up to burn. A BIG RISK is this, when coal smolders, and the fumes build up in the stove, and then those fumes light off, WHAMMO, you'll think the whole house just went up. (speaking from experience of course) Now, if you know your stove, you know when it's time to shut 'er down, and rebuild the coal fire when cold weather returns.