Inaccurate water temp reading

Aqualink indoor controller indicates water temp is 82 degrees, but thermometer in pool is reading 65 degrees. Pool was installed 3 years ago. You can only re-calibrate the water temp settings on the indoor controller by approx. 4 degrees so I feel I have a problem, maybe the water temp sensor? Is there a way to test the sensor? Would a faulty sensor give a high temp reading on the indoor controller? Any help would be appreciated. I hate throwing parts at it.

Here is a stupid question: Is the pump running when it is 82 degrees? Unless there is water flow, the temp is inaccurate.

If it is 82 degrees when the pump is running, I would try a new sensor.

I assume that the air temp sensor is also hooked up and giving you an accurate air temp reading - <quick and dirty> - switch the wiring to the two sensors and check what they're saying. You can also go over to the unit and see what it's saying 'in the box', just to be sure it's not a problem with the remote unit.

{edit}You can also remove the sensor and check for deposits, cracks etc. - Easy enough with a flat-head screwdriver, but even easier with a 5/16" nut driver (even easier with a 5/16" bit in a cordless drill - but dial down the clutch when retightening it:) ){edit}

Quote:

---

Originally Posted by mas985

Here is a stupid question: Is the pump running when it is 82 degrees? Unless there is water flow, the temp is inaccurate.

If it is 82 degrees when the pump is running, I would try a new sensor.

---

Yes, the pump is running.

Quote:

---

Originally Posted by waste

I assume that the air temp sensor is also hooked up and giving you an accurate air temp reading - <quick and dirty> - switch the wiring to the two sensors and check what they're saying. You can also go over to the unit and see what it's saying 'in the box', just to be sure it's not a problem with the remote unit.

{edit}You can also remove the sensor and check for deposits, cracks etc. - Easy enough with a flat-head screwdriver, but even easier with a 5/16" nut driver (even easier with a 5/16" bit in a cordless drill - but dial down the clutch when retightening it:) ){edit}

---

Thanks for the response. Good idea about checking the Aquarite display. The Aquarite unit outside is reading the correct water temp,(matches the thermometer in the pool within 1 degree) which indicates to me the sensor is ok. Is there some sort of calibration procedure between the two units?

Sorry about the first question but I had to ask.

The main temperature circuitry is at the main unit outside. The remote display is just that, a display, and does not measure temperature itself. It should have identical readouts to the main unit. It sounds as though the remote unit may have a problem. Try disconnecting it or turning off and then on to see if it can reset itself. You may need to power cycle both units.