setting of the thermostat for old bolier

john_181

forgot to mention, the system is ALL cast iron with large pipes

john_181

I have an old gas hot water boiler (430,000 BTU) former gravity system now converted with a circulator from the 1930's. the system has 27 rsadiators. My question is: what is the best setting for my thermostat for maximum heating and least gas used. I installed a digital unit and you can adjust the temp swing from 1 to 4 degrees. Is it better to have it cycle alot or not but run longer when it does?????????

please help - thanks

Mike T., Swampeast MO

"Maximum heating" and "least gas used" are opposing ideas made even moreso by a conventional boiler driving a high volume, high mass system.

Your most economical thermostat setting is--not surprisingly--the lowest you deem acceptable but unfortunately such does not coincide with the most efficient boiler operation. With a conventional boiler that sounds typically oversized, system efficiency drops as you lower the thermostat. If you have reasonable insulation/weatherization I would use no more than 3-4F daily setback during one period (likely at night).

Condensing/modulating boilers thrive driving these systems and you can expect highly significant energy savings.

Thom

I think he is talking about the differential/swing with the Tstat set at a certain temp. Not the setback setting. Some, like mine can be adjusted that way instead of the ma draw. But, I agree with you about limiting the setback to around 4 deg. Thom