Hayward H400fdn heater problem

[Bski224]

Hey, my H400FDN Hayward has heater starts, ignites, everything is running fine but now hot water coming from jets. Hot air is blowing out vents from heater , gas valve is on. Any ideas???

 

[ajw22]

If the heater is running and hot air is coming out the exhaust then BTUs (heat) is going into the water. No other place it can go.

What makes you think otherwise?

 

[Bski224]

I stick my hand In front of return and water same temp as pool

 

[Bski224]

There is also a lot of steam coming from vents

 

[ajw22]

I stick my hand In front of return and water same temp as pool

What speed is your pump running at?

Heater Maintenance - Further Reading

www.troublefreepool.com

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

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

For example, 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.

As shown below, higher flow results in a lower temperature rise.

• 40 gpm = 16.8 degrees 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.

 

[ajw22]

There is also a lot of steam coming from vents

What is the water temperature?

That can be from condensation due to the low water temperature and rain.

Heater Condensation - Further Reading

www.troublefreepool.com

Or you have a leak in the heat exchanger.

If the water was boiling in the heater you would hear knocking and the heater would probably shutdown.

 

[Bski224]

I turned up speed and seemed to help. Water temp is a toasty 58. Thank you all!!