Temperature of water exiting pool heater

[Aquaman7]

Hello,

I know there is a lot of variables like BTU, water temp in/out of heater and ambient temperature but does someone know what the temperature is that exits a gas water heater?

Thanks,
Joe

 

[PoolGate]

Usually this is measured as rise over the input temperature. I think on mine i was getting a good 10 degree rise.

 

[ajw22]

Temperature rise will depend on water flow rate. Slower water flow will have greater outlet temperature since the same BTUs go into less water volume.

Changing my pump speed can vary my return temperature from just warm at high RPM to very hot at minumum flow for the heater.

 

[JamesW]

A 400,000 btu/hr heater with an efficiency of 84% transfers 336,000 btu per hour to the water.

At a minimum required flow of 40 gpm, there will be 2,400 gallons of water (20,000 lbs.) that receives the heat.

Each btu raises the temperature of one pound of water by one degree Fahrenheit.

336,000 btu into 20,000 pounds of water is 16.8 degrees of temperature rise (336,000/20,000).

So, the maximum temperature rise you should ever have is 16.8 degrees Fahrenheit.

Higher flow results in a lower temperature rise.

50 gpm = 13.44 degrees temperature rise.

60 gpm = 11.2 degrees temperature rise.

70 gpm = 9.6 degrees.

80 gpm = 8.4 degrees.

 

[Aquaman7]

Wow. Good info. Thank you everyone.