Heater Problems


Bronze Supporter
Jun 3, 2016
Austin, TX
I have a Hayward 400k BTU heater that seems to work fine, if i can actually get it to ignite. Sometimes it will fire up right away but it seems most of the time it tried and then i get an IF error and it kicks into service mode. If I press MODE and switch it back to pool, it will try again and eventually it will light and work fine. Does anyone know what I should troubleshoot first? I know nothing about heater internals.



TFP Expert
In The Industry
Jul 6, 2011
Guessing this is an ED2 unit? I would have to guess you have a bad control board. Seeing that if you mess with the mode key it will light off and work. Many times the connection on the board for the ignitor breaks off or becomes unsoldered and thus you get results like you are seeing.


Gold Supporter
Aug 13, 2015
Frisco, Texas
I have a Pentair heater that was starting and then shutting off after 10-30 seconds or so. It turned out to be the water flow sensor tripping the shutdown. I resolved it by speeding my pump up when I ran the heater. Not sure if is even close to your issue, but I though I'd share in case.

Hayward Pool

LifeTime Supporter
In The Industry
Oct 15, 2014
Based on the information provided I would check the gas train first. Could be as easy as removing and cleaning all the orifices. Spiders like to get in there and block the gas flow to the ignitor. When you have an IF code that normally means insufficient fuel. Could be blocked gas line, bad ignitor, or gas valve. As always I recommend this be checked out by a heater technician.


TFP Expert
In The Industry
Jul 6, 2011
Sounds like a possible blower motor issue. Good luck if it is as they are not easy to come by plus consider the age of the unit and putting any $$ into it at this point.
Mar 26, 2017
TexasDeano. I have the problem you are describing on my pentair 400. First it would fire up for about 12 sec. I replaced the stack flue sensor since I received an E05 error. Now it fires up for about 25 sec. And shuts down. Is there a water flow sensor that can be replaced?