In short: How does one measure the water temp in a hydronic system -- and don't say "with a thermometer"
Longer version: I'm reviewing my zoning, possible zoning change, and aquastat settings for my heat-only (no domestic hot water) system. Lots of great references about temperature differentials, minimum water temps, "ideal" temp drops across a zone, etc. However, I have no idea how to measure that.
I'd hoped that I could hit the pipes w/a infrared thermometer, at least for a differential reading between supply and return, but no luck. I've got two pipes leading out of my boiler (two zones) and one reads ~190 and the other ~130, and they're both connected to the same boiler, so I know I can't get a good reading that way. Plus the 130 degree one reads about 170 5 feet later on the pipe!
Is there a special thermometer I should have? Something that wraps onto the pipe? Does all pipe conduct at the same rate (assuming it's all 3/4 copper). Lowes/HD/Amazon links appreciated.