Minneapolis-Honeywell

Alan (California Radiant) Forbes

mixing valve installed in 1950 and still going strong. Serving copper tubing in the floor downstairs and copper tubing in the ceiling plaster upstairs.

hot_rod

love that gauge too! Thanks for the trip down memory lane.

Alan (California Radiant) Forbes

After digging around the controls a little bit more, I came to find out that the boiler is controlled by a Honeywell aquastat below the eaves on the east side of the house. The original boiler was probably something with a high water content like one made by American Radiator Co., but it has since been replaced with a Munchkin. The Munchkin complains when the aquastat turns on the boiler, but the thermostat hasn't turned on the circulator. I'm tempted to make it a constant circulation system.

This is the oldest outdoor reset system I've ever seen. Those engineers at Honeywell were mighty smart.

EBEBRATT-Ed

If it's the one I am thinking of they were pretty common. Looked like an aquastat had two bulbs 1 outside air 1 in the boiler. Problem always the capillary length