Do pool heaters evaporate water quickly?

[JRzMom]

When I run my pool heater over multiple days, the water level drops significantly. The first time I noticed it was in June when I first installed it and ran it daily to get the water temperature up to 80 degrees. I went so far as to dig up the newly installed piping to inspect for drips but saw nothing. Once the nighttime temps stayed above 70, I stopped using the heater. August has been unseasonably cool for my area, so I've run it a lot more. I noticed the water level dropped over an inch in a week. Is this common?

 

[newdude]

Very much so. If you're paying to heat the pool, a solar cover is a must, or else you are heating the air each night instead. ($$$$). There were days in the extended season that I had horror movie like steam in my yard. The first couple times I thought a neighbors house was on fire. It was real funny until I got the electric bill, then the true horror set in.

But yeah. A solar (bubble) cover will stop evaporation which accounts for about 70% of your heat loss. You'll see it as a 'gain' in temp tomorrow, and the heater will run alot loss saving consoderable money. My cover cut the bill in half. And no more evaporation refilling either.

Get the cheapest thin one (easier to manage) you can find. Consider it disposable as none of them last years and years.

 

[revitup]

The rate of evaporation will increase along with the temp differential between your pool temp and the night air. More evaporation in the spring and fall and less in the middle of the season.

 

[JamesW]

When water evaporates, it requires heat to convert from liquid to vapor.

That heat can come from the water or the sun or the air.

As you put heat into the water, the water evaporates faster.

This is why people sweat.

As the water evaporates, the heat comes from your skin and this causes you to cool off.

The opposite is also true, when a heat pump takes heat from the air, water vapor converts from vapor to liquid and this transfers the heat from the water to the heat exchanger.

This is why heat pumps produce condensation.

 

[JamesW]

The rate of evaporation will increase along with the temp differential between your pool temp and the night air.

Cooler air does not create more evaporation.

Think about a hair dryer.

A hair dryer dries hair faster on high heat vs. medium, low or no heat.

This is because water needs heat to evaporate.

Higher speed fan (air speed) increases evaporation.

Lower humidity also increases evaporation.

 

[JamesW]

Evaporation and Climate

In order to understand why growing food uses so much water, we need to explore the process of evaporation. Evaporation is a hydrologic process that we're all quite familiar with, even if you aren't aware ...

serc.carleton.edu

 

[JamesW]

https://www.acs.org/content/dam/acsorg/education/k-8/inquiry-in-action/fifth-grade/g5-l1.4-bkgd.pdf

 

[JamesW]

There are several factors that determine the evaporation rate of liquid water. This is important to meteorology since the amount of moisture that evaporates into the air leads to changes in the weather. Below are each of these factors and an explanation:

1. Temperature of water: The water molecules move faster as water warms. The faster the molecules move the more easily they can escape the water surface. A warm lake or ocean will evaporate a large amount of moisture. This moisture can be used to generate precipitation.

2. Temperature of air: As the air above the water warms it has the capacity to have a greater amount of moisture evaporated into the air. If the air is cold it is difficult to evaporate a large amount of moisture into the air even when the water is warm. A combination of warm water and warm air will evaporate the most water.

3. Wind speed: A higher wind helps remove moisture that has evaporated from the water. This helps the relative humidity stay unsaturated near the water surface. When the air is saturated the amount of moisture that evaporates into the air is minimized. Higher winds will continue to supply drier air from aloft to the water surface and this allows for a greater amount of evaporation. A higher wind also churns the water (waves, splashing) and this helps lead to a greater surface area in which evaporation can occur from the water surface.

4. Dry air: Dry air will help generate more evaporation especially if the air is warm and dry. There is a higher capacity to evaporate moisture into the air as the air dries. Once the air is saturated then the evaporation rate is minimized. Air with a low relative humidity is optimum for moisture to evaporate into it.

5. Sunlight: Direct sunlight will lead to more evaporation. The direct photons of light increase the motion of the water molecules it strikes giving them a better chance to evaporate.

https://www.theweatherprediction.com/habyhints2/470/

 

[JamesW]

When the air is cool, you see condensation because some of the water vapor is converting back into liquid water.

The same thing happens when you see “Steam” over a boiling pot of water.

The water gas is condensing into liquid.

You cannot see steam.

So, cool air makes the evaporation more visible, but there is more evaporation in hot weather; you just can’t see it.

 

[JRzMom]

Thanks, everyone. I am not imagining it! I don't have to dig up the pipes again! I have a solar cover, and I cover the pool as soon as the sun drops below the treeline. The electric bill motivates me to minimize the hours I run that heater, but I enjoy a nice, warm pool. The weather has been so unpredictable this summer, and having the pool ready when the sun breaks through is vital!

 

[Bill1974]

How much water are you losing when the heater is running? What temp are you keeping the pool at? I would not expect a "significant" water level drop. With your size pool is it being used a lot more when it's heated and water is being lost from people getting in and out and splashing?

I assume the heater is located near the rest of the pool equipment and there isn't any below grade pipes just for the pool heater. Is the heater leaking any water?

 

[JRzMom]

How much water are you losing when the heater is running? What temp are you keeping the pool at? I would not expect a "significant" water level drop. With your size pool is it being used a lot more when it's heated and water is being lost from people getting in and out and splashing?

I assume the heater is located near the rest of the pool equipment and there isn't any below grade pipes just for the pool heater. Is the heater leaking any water?

I apologize for not responding last year. I'm back in pool mode and found your response. We determined it was evaporation (after digging up the return piping) It was a very hot, sunny summer. Thank you for your reply, and again, I apologize for missing a response!