Boiler Firing Via Room T-Stat's , or Via Internal Aquastat?

AHS Coal Guns fire (initiate their fan motor) only when their own aquastat monitored internal temperature falls to or below a pre-selected level. Other boilers seem to fire primarily based on a room (zone) T-Stat's call for heat (with a high limit aquastat delaying/preventing this firing as necessary to avoid dangerous boiler overheating situations from ever occurring), and secondarily from the boilers internal temp falling to a pre-selected level. What potential advantages or disadvantages are there for either of these firing methods? Is one method potentially more efficient than another?

One disadvantage I can see for the Coal Gun method is that with coal recovering slowly from its slumber between firings, it seems advantageous to have the T-Stat initiate firing so by the time the boilers temp starts to drop internally it is already firing and starting to catch up, whereas for the Coal Gun this does not occur.

One advantage I can see for the Coal Gun is that occasionally a T-Stat heat call is satisfied without the boiler needing to fire at all, or with the boiler hardly needing to fire at all, and this could potentially save coal.

The traditional and conservative way is to have the thermostat control the circulator only. The aquastat starts the burner. Starting the burner as well as the circulator is an advantage with slow recovering systems.

franco b wrote:The traditional and conservative way is to have the thermostat control the circulator only. The aquastat starts the burner. Starting the burner as well as the circulator is an advantage with slow recovering systems.

Thanks! Perhaps the Coal Gun is wired more traditionally than I thought.

Another way to greatly boost overall system efficiency is to bring in outside combustion air. With each pound of coal burned needing 123 cubic feet of air, that becomes a lot of air infiltration that brings cold air that must be heated right into the rooms of the home. My electric resistance boiler did not draw in any air as it didn't need it. So even if my boiler truly is 80 percent efficient, my overall system efficiency is only about 65%, with at least some of that being due to having to heat so much outside air that the boiler is dragging in from sources throughout the home.

What somebody needs to get working on is a control that "learns" how your system works to heat your house based on changing conditions outside,ie temp change , wind speed /direction , atmospheric pressure , maybe even % cloud cover and adjusts your system settings based on historical data. It may sound complicated but I gotta believe with today's technology its within easy reach. Maybe the gains in efficiency (savings) to be had arent yet great enough ,but thats only at current energy costs. Somebody here needs to get crackin'

outdoor reset controls == somebody needs to to invent this -- Seriously???

I installed my first electronic reset control in the early 70's - very simple device compared to the junk now in production
bulb / mechanical versions were in use before I was a twinkle in my daddies eye!
HUMANS/ Dirty men covered in wood - oil and or coal dust- employed as boiler tenders ----slaved at this since water circulated heat energy in buildings - they were the first out door reset controls

an autonomously temperature controlled boiler is a happy boiler

So this animal already exists. It "learns your system" and makes adjustments based on the history of its experience? What is the name of this unit, speak it ...please! I know there are things (tekmar controls) that will adjust your boiler but I thought it did so based on settings you the operator provide and not based on its own observations of system efficiency. Damn I gotta get out more Please advise as to a website and any personal experience. Maybe this should be its own thread, Rob this may be a place for some moderator wizardry ... standing by...

I just ran some numbers indicating that my system efficiency could increase by roughly 4% to 5% overall if I brought in combustion air from the outside instead of having my boiler suck in air from the various leaks, nooks, and crannies all over the home.

If each pound of coal requires 123 cubic feet of air supply to properly burn, and that same 123 cubic feet of air weights about 9.5 lbs (give or take), and that 9.5 lbs are coming in through the homes various leaks at say 20 degrees and in need of being heated to 70 degrees, then each pound of burned coal is causing the homes BTU demand to rise by 50 x 9.5 = 475 BTU's. If you burn 45 lbs of coal per day, then on average that represents 21,375 BTU's that you are wasting every day of the heating season just to heat the cold air that the boiler (stove, furnace) is dragging in, or nearly 2.5 lbs of coal. 2.5 lbs. of wasted coal for each of the roughly 200 heating season days per year is 500 lbs. of coal wasted annually heating air infiltration unnecessarily. Not to mention that the comfort level of the house is reduced by the cold air being dragged in.

There is also a safety factor since the air supply is no longer effected by other influences in the house such as dryers and exhaust fans.

Yes - outdoor air will make the appliance run better - just as a clean air filter will make your car run better

and - since your not aggressively pulling drafts thru your living room window - you will be more comfortable sitting in you evening "jammies"