best method for temp sensing, 65c - >200c

[RCinFLA]

I used screw in automotive-temp sending thermistors in hot water panel. Sealed, take pressure, and don't have to worry about electrolysis. You can calibrate their resistance with vegetable oil on the stove with a good thermometer.
Ask auto parts store (during low traffic time) to look at a few of their assortment of senders. SAE threads may be difficult to find these days.

 

[tcmtech]

I used screw in automotive-temp sending thermistors in hot water panel. Sealed, take pressure, and don't have to worry about electrolysis. You can calibrate their resistance with vegetable oil on the stove with a good thermometer.
Ask auto parts store (during low traffic time) to look at a few of their assortment of senders. SAE threads may be difficult to find these days.

Mid 80's and earlier American made vehicles are all 3/8" or 1/2" pipe thread. Fords of those era are usually ~10K ohms at ~70 F and follow the typical 10K NTC thermistor temp curves as well.

I use them in my boiler systems too!

 

[large_ghostman]

Now I like that idea! I can goto the scrap yard

 

[dr pepper]

You'd need to thoroughly clean up and re-seat an egr valve, all the used ones I've seen have been covered in burnt black yuccy stuff, you also might need a rust preventative in the water to stop the valve rusting, they are usually cast iron.

Beware american made fords use NPT threads, uk made BSP, if you care they dont fit, if your ham fisted they do.

Boilers tend to have copper and cast in them, both valuable as scrap, leave one by the road and I bet it'd be gone before morning.

 

[debe]

This may be of some help in Solar hot water. Current temp outside is 37 degC average summer day at 3.00PM. This system is Thermal Syphon, the inlet pipe is 48 degC & the outlet pipe is 58 degC. Water out of a hot water tap 55 degC. This system is a mains pressure system & has a pressure relief valve set at 100PSI. At the moment if no taps are turned on the pressure can rise to 100PSI & the valve will start driping water. This solar system works well in the summer, but in the winter it barely takes the chill of the water. So free hot water during summer months. Winter use LPG boosted heater. Hope some of this is some help in your study.