Adding a thermowell

[velvetfoot]

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?

 

[jebatty]

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.

 

[maple1]

I second the external sensor thing.