Water Temperature Feel vs Actual

[Litespeed]

We use our heater to read the pool water temperature and what's interesting to us, is the same water temperature (reading per the heater screen) can feel so much different. For example, yesterday, it read 83 degrees when we started swimming and it felt perfect and we did not use the heater at all to get it to 83. The morning and early afternoon sun warmed it up (it was at 81 degrees about 9AM). Note that we have an automatic cover and we keep it closed unless we are swimming, of course.

The day before yesterday (Sunday), we used the heater because the temp at about 9 AM was 79 degrees. We heated it to 83 degrees by the time we were swimming, and it felt noticeably cooler when we first got in the water although it felt fine after being in the water for a few minutes.

I'm just wondering if anyone has any thoughts on other factors that may affect the temperature "feel" of the water versus the actual temp as reported by the pool heater.

Our impression is that using the heater to get to a certain temperature just isn't the same as letting the sun warm it to the "same" temperature. Just curious what thoughts TFP user may have on this.

 

[borjis]

I agree! I like it 85. When I'm maintaining that for several days using a bubble cover and nice weather
it sure does seem warmer than using the heater to get it to that degree.

 

[domct203]

Water temp is water temp, the pool doesn't know if it was heated by the sun or a heater.

I believe that what you are noticing is the difference between the air temp and the water temp. In the springtime, the family is fine with a 78-80F pool, when air temps are in the 70'sF. Come summer when air temps are in the 90's, they shiver in an 84F pool.

 

[Perpetual summer]

My filter pad is next to the house on the southwest direction. It gets sun most all day. The temp sensor for pool water is somewhere within this area. Sitting in the sun with reflected heat from house will give me about a 2 degree higher reading than actual water temp. I think on a cloudy day temps from filter pad and actual pool water should be pretty close.

 

[bmoreswim]

And the dewpoint and wind speed play a role. Although you are in the water, part of your wet body is usually exposed. A dewpoint below roughly 65 will cause the evaporation that is always occurring to have a more pronounced "feel", i.e. more evaporation is occurring than is comfortable to your body. It is hard to separate the air conditions from how the water feels. Because the water is always, at least subconsciously, being compared to the air temperature by your brain.

But yes, 83 is 83 for the water portion of the equation.

 

[Litespeed]

Dew point was also my thought. It makes all the difference in the feel of the air and a higher dew point just makes it more comfortable while in the pool, I think. Low dew points - 50's and less, will make the air feel really cool on any wet, exposed skin.

 

[borjis]

Ya dom has a good point! I've definitely noticed it seems less warm, the hotter it outside.