What/where temperature measurements

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tuolumne

Member
Mar 6, 2007
177
Vermont
My system is an EKO 40 with twin 500 gallon propane tanks in a closed, pressurized system. Where to I want to read temperatures. I believe the boiler has an internal reading for water in the boiler. Where on the tanks should I read, and how. Are there surface gages available for the piping?
 
The boiler has a surface-mount temp sensor located at the top under the controller. There's no internal temp sensor that I'm aware of on the EKO.

You can tape meat thermometers to pipes to get an idea of the water temp. It's cheap and reasonably accurate, especially for relative comparisons, say between supply and return lines. For a more accurate reading of the tank, I'd try to sink a well into an existing tapping for an internal thermometer. If you want to check the temps at the bottom and top of the tank(s), you can sink a piece of copper pipe (capped on one end) into the tank and put temp probes at the top, bottom or middle, as you wish. That's one of nofossil's many neat tricks.
 
If you're like me, you want to measure temperatures at the inlet an outlet of every device in the system, and measure tank temps at 3" intervals ;-)

My compromise is top / middle / bottom of my tank, and inlet / outlet of the boiler. I have electronic sensors in those locations. I also put in tee fittings and installed human-readable temp gauges at the boiler inlet / outlet and the tank inlet / outlet. I also have masking tape targets on every copper pipe everywhere so that I can get IR thermometer readings any time.

I also use a magnetic flue temp gauge. It's good for telling when you're ready to kick over to secondary combustion.
 

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This sounds like a good goal, but what do these sensors look like and what fittings do I need to install them? Do temperature gages need special tees to screw into? How can I use the existing holes at the top of my tanks for temperature sensors? If they have threaded bases I could use a bushing in the existing hole. How could I measure temp. at the bottom of the tank through such a hole?
 
The thermometers you buy at heating supply houses fit into brass wells, which screw into standard 1/2- and 3/4-inch tappings--usually black iron tees. With copper fittings, you can make a dip tube that would screw into a standard tapping on your tank and extend down into the tank. If you cap off the end, then you can run wire and sensors from digital thermometers down into the tube to the point where you want to measure the temp. I think that's the way nofossil does it.
 
I have 4 temperature probes that will fit into 1-1/4x1-1/4x1/2" CxCxF tees, and plan to put these at the boiler return, buffer supply/return, and house zones return. I have a temperature/pressure probe that will go at the boiler supply. Any comments on that? If I could be better served by using some in other locations please let me know. These 5 sensors don't satisfy me as an engineer, but are a decent compromise considering the cost. Between the tees and the probes, they are just under $20 apiece. There are also several other spots I will be monitoring that my create redundancy with the above. I have a strap on probe that came with the boiler. I assume this is installed on the return? If I can montior return temps on the digital controller, I won't need a probe there. I haven't read the controller manual in detail yet. I would also like two wells on the buffer tanks to get an idea of stratification. I plan to use a 1-1/2x1/2" bushing in one of the existing holes on each tank, threading a capped pipe to the small hole, and dropping to near the bottom of each tank. Would a temperature probe (the kind that are loose with wires) tell an accurate story at the bottom of that pipe? There was some reference previously to nofossil doing this. Are there any "human readable gages" that would do this job? Thanks.
 
I use the digital dual temperature gauge from www.azeltec.com. Battery or 24V powered and it does some data logging. strap on sensors with insulation over them for accurate reedings. Easier to retrofit compared to a well type, and just as accurate.

I like his setpoint controls also. Nice large display and a very wiiiiide differential range.

hr
 
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