Most efficient way to control boiler

What is the most efficient way to control the boiler with a primary/secondary loop system. With indirect hot water it would seem quick supply would be important.

OK, I'll bite....Do you mean efficient in dollars or in fuel used? In my opinion the most efficient way would be a cold start oil boiler with a thermostat on the wall along with an outdoor sensor to anticipate heat load. That being said.... no coal boiler is ever a cold start boiler. Oil is efficient with fuel, coal is efficient with dollars. If oil were still $.69 a gallon you wouldn't find a coil boiler in use.

Part of the beauty of an indirect hot water tank is that it doesn't need a terribly quick heat supply to maintain a good amount of hot water.

Freddy, cold start is a novel idea...but with a coal boiler there is always some heat being generated. I guess you could do it if you let the fire go out each day, then the boiler would go cold and you would get to start all over again.

As for the indirect, if it has enough storage the rate of recovery is less important. Generally you want the indirect first in the primary loop, and use the pipe size and circulator recommended in the install manual.

*smile*

Rob, while you were typing I was editing.... I hit "send" before all my thoughts were down & spent 3 or 4 minutes re-writing... you were Johny on the spot!

I want the best way to use the least amount of coal and still have heat on demand. Constant circulation in primary loop or only circulate on demand. Fire boiler independent of zones or only when call for heat. Oil is a dirty word on here supprised you would even mention it.

There is the best way

and there is the best way

you want comfort or economy

pick one

What are the pros and cons. The c70 I have now is primary loop constant circ with boiler temp controlled by aquastat with a high limit dump zone.