Pool heater fires up, then quits

vanellya

Bronze Supporter
Jun 15, 2021
86
toronto
Pool Size
13000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-20
Hello,
I have a 2 year old Mastertemp 300 heater that seems to be malfunctioning. I set it at 86, but the heater fires up, runs for 30 seconds then quits- however, the Pentair app shows that it is heating. The current water temp is 78. Any leads as to why this could be happening?
 
I'm not an expert on heaters but are you getting an error code on the heater display panel? That would narrow it down. I know mine shuts off because of the flow switch every once in awhile.
 
There is no error code and the flow light on the intellichlor is showing as good. The app is showing that it is heating but it is not and the light on the heater is off
 
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I'm not an expert on heaters but are you getting an error code on the heater display panel? That would narrow it down. I know mine shuts off because of the flow switch every once in awhile.
Sorry! I looked now and I see E05! What does that mean?
 
It’s likely the stack flue sensor. Changing It is a 10 minute job. Open the case and you’ll see the sensor in the flue. Look at the connections close to the sensor for worn or missing sheathing. You’ll often find bare wires which is a common problem. Check continuity across the terminals of the sensor for a short. Check resistance across the terminals. It should be 3.5 to 4.0 mega ohms if good. If not replace it and you’ll likely be back in business. If the SFS tests good, there are further items to diagnose.
 
Okay I opened and notbing looked awry and I don’t have a monitor to check the output so I just ordered a replacement off Amazon. Is this normal to happen in a 2 year old heater?
 
Okay I opened and notbing looked awry and I don’t have a monitor to check the output so I just ordered a replacement off Amazon. Is this normal to happen in a 2 year old heater?
Most common failure I see on stack flue sensors for these heaters is frayed sheathing on the pigtail exposing bare wires that short out to the sensor. I would not be surprised to find that on a 2 year old heater. If replacing it doesn't correct your issue then there are more steps we can take to diagnose your issue.
 
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