Mastertemp 400 not firing

Jump to latest Follow Reply
P

pinch52

Active member
Nov 21, 2014
34
Houston, TX
Hi all,
Pentair mastertemp 400, natural gal, model 460736, will initially start up with blower running, when heat is called for. However, it never fires. Eventually after a few minutes the blower will shut down and the service heater light is on. The temperature reads normal, matches the temp of the easy touch controller. I have tryed running the troubleshooting in the owners manual, which led me to believe the control board is not sending 24vac to the gas valve. I tried installing a new control board and with that, the blower wont even turn on, so worse off than with the original board. Anyone ever see anything like this?? Thanks!!
 
Post pics of your old control board and your new control board.

Where did you buy your new control board from?

We have seen people get non-Pentair control boards that do not work properly.

Have you tried putting your old control board back in?

Let's get the heater starting up with the blower.
 
Old board on top, new is below, in pics. The new board is not an oem pentair. Its made by Swimables, bought on amazon. It looks a lot different the my old one. I put the old one back in and the blower turns as previous, but still no heat. This heater was installed in 2010 and the old board in these pics is a replacement, roughly 2013-2014ish. Thanks for the replies!!
 

Attachments

  • IMG_7556.jpg
    IMG_7556.jpg
    74.3 KB · Views: 13
  • IMG_7557.jpg
    IMG_7557.jpg
    56.8 KB · Views: 12
Here is the person who bought the same board on Amazon that did not work...

HELP - Pentair Mastertemp 250 Not connected to EasyTouch and now won't start

Where did you get that new board from? You got the old 42002-0007S board that has been replaced. The old control board is being replaced by the new Connected Heater control board p/n 461105. The new Control Board Kit 461105 comes with "6 button" membrane keypad. When replacing a control board...
www.troublefreepool.com www.troublefreepool.com

Did you look at the diagnostic LEDs on the left hand side of the board when it throws the Service Heater LED?

1681339534127.png
 
You need to test for voltage at the main valve, meter attached when the blower is running. At some point it should read about 24VAC during the ignition try. If it does, the valve is bad. Look at the diagnostic LEDs on the back of the board. If one is lit check that circuit. A bad SFS will not let the heater even try to light and the SFS LED on the back of the board will light almost instantly.
 
None of the diagnostic leds are ever lit, just the service heater light. There doesn’t ever seem to be 24vac going from the control board to the gas valve. The book says wait 24 seconds or so. I backprobed the leads on the board and the gas valve wire leads. No voltage.
As far as the sfs, the diagnostic led will light up if I disconnect the wires to the sfs. (Maybe that’s not a good way to test that system ?). I still need to check the actual resistance of the sfs. Thanks guys, any other ideas much appreciated.🙏
 
It may end up you need a new board. Get a genuine Pentair p/n 461105. The new Control Board Kit 461105 comes with "6 button" membrane keypad. When replacing a control board on an older heater that has a 5 button keypad, you will also need to update the heater to have the 6 button keypad.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com www.troublefreepool.com
 

Enjoying this content?

Support TFP with a donation.

Give Support
1poolman1 said:
A bad SFS will not let the heater even try to light and the SFS LED on the back of the board will light almost instantly.
Click to expand...
For what it's worth, I've seen gobs of SFS's that would let the heater fire and run for a few minutes before erroring out.

If the connection is bad, it'll fire and then error. Can't tell you how many times that dumb spade was crooked from the factory.

If the sensor is failing (the exhaust temp reading jumps all over and then lands on 40 or 80), it'll run for awhile and then error. This is the one I see the most. Especially with the COVID-era OEM.
 
Last edited:
Ok guys, new oem Pentair #461105 board and ribbon cable installed. The heater fires and runs in manual mode(using the keypad and LCD on the heater). However, I run this pool with an Easytouch. As it now stands, the easytouch wont control the heater. The heater is connected with the 2-wire method to the firemans switch. Is there some programming that needs to be done to make this work? Here are some pics.
Also, since there are no longer any error leds on the new board, how does one see error codes now?? LCD screen somehow?

thanks!!
 

Attachments

  • IMG_7570.jpg
    IMG_7570.jpg
    90.8 KB · Views: 6
  • IMG_7571.jpg
    IMG_7571.jpg
    61.8 KB · Views: 37
  • IMG_7572.jpg
    IMG_7572.jpg
    73.5 KB · Views: 6
  • IMG_7573.jpg
    IMG_7573.jpg
    61.3 KB · Views: 5
Error codes are displayed on the LCD screen instead of the LEDs with the new board.

The firemans switch should work the same. Check the connection for the 2 wires at the heater and the ET board.

Those orange wires run to your ET board?
 
Yep. Haven’t touched any of that. On the ET display, it shows “HEATER” and the heater led is on. Previously, with the old heater circuit board, the heater key pad seemed to be disabled. I could ONLY control the heater with the ET. Now, it’s the opposite, can only control from heater keypad
 
pinch52 said:
Now, it’s the opposite, can only control from heater keypad
Click to expand...

Either your ET is calling for heat and has closed the heater relay or the relay is welded shut or the wires are shorted.

Your heater is acting as though the firemans switch is not connected.

You don't want to check voltage.

You want to check continuity on the orange wires. Disconnect them from the heater connections and see if there is no continuity when the ET is NOT calling for heat and contunity when the ET is calling for heat.
 

Enjoying this content?

Support TFP with a donation.

Give Support
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply