ECN Forum Forums General Topics of the Trade General Discussion Area Digital temp display

I don't think this is necessary unless the temperatures change very quickly. Temperature gradients are linear; if you lag around the probe with enough insulation, it will accurately read the internal water temp even if the probe is outside the pipe.

I'm using a [wired version] barbeque thermometer to measure oil temperatures on my vegetable-oil heating burner; goes up to around 200C / 400F.

Remote wireless versions of these devices are inexpensive, [aimed at a mass market]. Oregon Scientific's AW129, for instance, reads up to 392F at 100 feet range, about $28, on Amazon.

http://www.amazon.com/Oregon-Scientific-AW129-Wireless-Thermometer/dp/B0006G2WYK


I just lightly fix the 'meat' probe to the relevant pipe with a worm-drive stainless hose clip and cover it with a bit of regular split-foam pipe insulation.

The hot water from a wood-fired boiler will fluctuate during the stages of a burn far more than the accuracy of the thermometer. I guess you want this device as a refueliing indicator?

Alan

I just read some of the reviews of the above product. Not looking too good! Ah well, it's the thought that counts!

Alan

I personally would use an LM34CZ from Digi-Key (<$6.00) soldered and shrunk onto a 3 or more conductor cable. DPMs from MPJA range from about $8 to $15. The power supply would depend on the DPM, probably 5 or 9 volts, derived from a used wall wart. Output is 10mV per degree F from -40 to +230 degrees. Set the meter for a 2 volt range and one decimal place and you will read the temperature within a couple of degrees.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=LM34CZ-ND
http://www.mpja.com/products.asp?dept=52

Joe

RTD's and thermocouples come with NPT pipe thread. Male and female. Check http://www.pyromation.com/

All you need is an RTD (so you can extend the conductors) and a temperature controller. Since you only need the display, you will not need to concern yourself with the outputs. But you will have to set/program the sensor type.
The controller will calculate distance and resistance, so you can be accurate with extending the conductors. Use THWN or similar. You also will need a small enclosure for the controller.

Ps.....They can make the RTD cable any length you need. "Special Order"

OK,
Reason I suggested what I did (even though Merlin had the better idea of using a tee), is during my training, I was always told to get the sensor probe as close as possible to the sensed medium,as it makes the readings that more accurate.
Actually in it, is about as close as you can get, however that should not be beyond the expertise of most electricians as far as keeping things from leaking goes.