Adding a thermowell

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velvetfoot

Minister of Fire
Hearth Supporter
Dec 5, 2005
10,203
Sand Lake, NY
I want to get a good measurement of oil boiler water temperature with a Ranco controller. Is it a matter of finding an existing plug high on the boiler and substituting a thermowell? Or is there another way?
 
A surface mount sensor fixed tightly to a surface where hot water readily circulates and then insulated will do a very good job at getting an accurate temperature measurement. Heat transfer paste between the sensor and the surface would be a plus. Fixing the sensor near an elbow rather than on a length of straight pipe also helps, as the elbow mixes the hot water to better insure the hottest water is near the surface being measured. A thermowell can be good, but it too should be in a place where hot water is circulating.