SWG Temperature Sensor vs Pool Temperature Sensor

[Tiger56]

I am new to using a SWG. Today I was interested in when my SWG was going to start generating again. The SWG temperature sensor reads 48 degrees F while the pool water temperature sensor reads 52 degrees F.

My question: Is it normal for a 4 degree temperature variance?

My SWG is a T-Cell 15. The pump had been running about 4 hours prior to my temperature observation.

 

[mas985]

Sometimes mine are 1 degree apart or if solar is running, they are further apart since the SWG is post solar while the pool temp is pre-solar. Is one in the sun and the other not? Could be one of the sensors is starting to drift. Shouldn't be a problem unless the SWG sensor gets too far off.

 

[ajw22]

I would not worry about a 4 degree difference. It makes no difference in your pool operations.

The temperature sensor in your SWG is used to calculate the salinity. That is already an estimate. Read...

How Salt Systems Determine Salinity - Further Reading

www.troublefreepool.com

 

[setsailsoon]

Tiger,

I've found temperature variations of 1-2 deg are common even for new sensors. As they fail you will usually see the temperature increase slowly then a short period later the reading will go much higher. Most systems use a standard 10k thermisters which are very reliable but the problem seems to be caused by a failure in the housing. Some are encased n plastic housings others metal. Also they can be embedded in different kinds of materials inside the housing such as epoxy. These differences would contribute to differences. If the difference between the readings remains fairly constant you're probably not near an eminent failure point but if it starts to change you might want to get a sensor on order.

I hope this helps.

Chris

 

[Tiger56]

Sometimes mine are 1 degree apart or if solar is running, they are further apart since the SWG is post solar while the pool temp is pre-solar. Is one in the sun and the other not? Could be one of the sensors is starting to drift. Shouldn't be a problem unless the SWG sensor gets too far off.

Thanks for your response. The pool temperature sensor does receive more direct sunlight than the SWG temperature sensor. The pool temperature sensor is directly on top of the piping prior to my filter.

 

[Tiger56]

Tiger,

I've found temperature variations of 1-2 deg are common even for new sensors. As they fail you will usually see the temperature increase slowly then a short period later the reading will go much higher. Most systems use a standard 10k thermisters which are very reliable but the problem seems to be caused by a failure in the housing. Some are encased n plastic housings others metal. Also they can be embedded in different kinds of materials inside the housing such as epoxy. These differences would contribute to differences. If the difference between the readings remains fairly constant you're probably not near an eminent failure point but if it starts to change you might want to get a sensor on order.

I hope this helps.

Chris

Thank you, Chris.

 

[Tiger56]

I would not worry about a 4 degree difference. It makes no difference in your pool operations.

The temperature sensor in your SWG is used to calculate the salinity. That is already an estimate. Read...

How Salt Systems Determine Salinity - Further Reading

www.troublefreepool.com

Allen, thanks.

 

[mas985]

Thanks for your response. The pool temperature sensor does receive more direct sunlight than the SWG temperature sensor. The pool temperature sensor is directly on top of the piping prior to my filter.

That is probably the reason. Try a measurement at dusk or night.

 

[mguzzy]

I have a temp sensor in my (attached) spa heater, and a temp sensor in my SWG. They are always a little different. When I have the spa running I can see the difference in temp represents the water that is not yet heated and the already heated water going through the SWG.

I have a T-15 too and its the controller temp that will dictate when it starts generating. On mine it will start reducing CL output below 55 and the shuts off below 50, if I recall. Somewhere there is a link that has the specs for that. So I don't really expect my SWG to start kicking in until it gets to about 60F.

 

[Tiger56]

That is probably the reason. Try a measurement at dusk or night.

Will do. I'm a noob at this SWG thing.