Temperature sensor in pump line.

[robstar]

Silly question, but why don't people install temperature sensors on the water line going to the pump? (or do they?) That water is coming from the skimmers and main drain and is probably a good representative sample of the temperature.

I ask b/c i've been trying to rig up a system with a floating sensor, but a) it reads too close to the surface, b) it leaks and needs draining, drying, and re-sealing every couple of months, c) it needs batteries.

An electronic temperature probe in a pump line would only have good data while the pump was running, but other than that, can anyone think of downsides? (the pump itself heats the water a little, so you'd probably want the sensor before it.)

As for the mechanical details of what i'm imagining, i'd add a threaded tap to the side of the pipe and construct a modified plug with the sensor to screw into it, making replacement/modification easy.

 

[kadavis]

There is really no reason you can't put the sensor before pump, but it could become a source for a air leak later down the road

 

[JoyfulNoise]

If you found the right kind of adapter, most pumps have two drain plugs - one at the bottom of the basket and one in the volute. You could simply rig your sensor up to a properly sized plug and put it in there.

 

[robstar]

ooh.. good idea on the drain plug!

i think i'll cut down a "tee" with a 1/2" FPT stem and PVC weld it onto the side of my pipe (like an ad-hoc one of these: Saddle tees and Clamp-It saddles ), then drill a 3/8" hole through it into the pipe. the pressure is _negative_, so i expect the weld to work well.

 

[robstar]

Here's the threaded bit (sanded to shape by wrapping sandpaper around a piece of 2" PVC):


And here it is attached:


Tomorrow i'll drill a hole into the pipe. In the meantime, i'm going to see how long a stainless steel machine screw takes to equalize its temperature if one end is in water and the other end is insulated, as that seems like a possible probe design.