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Posted by HeatPro on November 05, 2005 at 23:33:15:
In Reply to: Proper Aquastat setup? posted by Brian on November 05, 2005 at 22:28:40:
The room thermostats or indirect thermostat call for heat to turn the appropriate zone and the burner on through the Argo board to the 8148. The limit on the 8148 is a high limit which pervents the burners from exceeding the high limit; but there is nothing in the 8148 circuit to fire the burner until the water reaches 180F unless one of the zone thermostats (the indirect thermostat is one of them) calls for heat until the boiler does reach 180F (if that is what the high limit is set at.)
There is no need to maintain water temperature for any zone including the indirect. You might add an outdoor reset to limit the water temperature to that needed for the weather. Multiple zones calling for heat create an 'overlapping demand' which makes the water hotter than necessary as one zone calls, then another, then another. Adding an outdoor reset prevents overheating and wasting fuel.
http://illco.com/products/cat.asp?Action=55037
http://www.honeywell.ca/water-controls/products/aq475a.htm
http://customer.honeywell.com/Techlit/Pdf/68-0000s/68-0217.pdf