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Why doesn't my Pentair Minimax NT heater fire?

I replaced the thermistor probe. Nothing changed. What's the next thing to do on the board? I don't believe the readout E-- is legitimate

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  • Rich Mihalic
    Rich Mihalic Apr 30, 2015

    I replaced this, the name on invoice is"THERMISTOR PROBE MX NT", i also wet finger across terminals and nothing changed, buttons on display dont work with a readout of E--

  • Rich Mihalic
    Rich Mihalic May 06, 2015

    Nothing happens when you push buttons, no fan, the pool or spa bottons don't light up either.

  • Rich Mihalic
    Rich Mihalic May 15, 2015

    it does not try to fire, the blower does not make a sound, everything is silent, it wont move from off, spa, pool and remote wont light

  • Nick Smalling
    Nick Smalling May 15, 2015

    It sounds like you have a remote system controlling the heater. Like a compool, or easytouch, or litetouch, or crestron. Some sort of remote temp control system. The problem might be there, otherwise you have a bad board.

  • Anonymous May 15, 2015

    ok thanks, if I plug the board into another minimax nt heater to test would it be safe no possibilty of causing damage from board

  • Nick Smalling
    Nick Smalling May 18, 2015

    It would be safe to plug in main control board, not the panel in question, it could take out the controller on the other heater. Not likely but possible.

  • Nick Smalling
    Nick Smalling May 18, 2015

    If you have an external control there will be an extra wire coming out of heater, there will be wires connected to the spot on the board that says REMOTE.. hope this helps.

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  • Contributor
  • 21 Answers

Does it try to fire? Do you hear the blower kick on? If it only says E-- you might have a bad control input board. For it to fire the thermostat light, and pressure switch light must be lit up. Also you must push spa or pool mode on right...

Posted on May 06, 2015

  • Nick Smalling
    Nick Smalling May 06, 2015

    The MiniMax NT LN Heater comes from the factory preset with a pool temperature setting of 78° F. and a
    preset spa temperature of 100° F., and in the off mode setting. Once the power is turned on, the DDTC
    board will do a self diagnostic internal check, during this time the display will first read “888”, then the
    display will switch to three dashes “- - -“, this process takes approximately ten (10) seconds. The DDTC
    will then illuminate the “Power” LED and “Off” LED, see Figure 27.
    1. Turn on the power to the heater; the switch is on the bottom of the electrical junction box located internally
    on the right side of the cabinet. The DDTC will now go through the self-diagnostic’s test as stated
    above.
    2. Turn on the circulating system pump and make sure that adequate water is being delivered to the heater,
    The “PRESSURE SW” LED will now illuminate.
    3. If you are using the heater with a remote control system, open the right door of the heater to access the
    rear portion of the DDTC. Locate the three terminals marked “Pool” (J5), “Spa” (J6) and “Com” (J8).
    If the remote system is a three-wire remote unit, connect the pool lead to the “pool” terminal J5, connect
    the spa lead to the “spa” J6 terminal and connect the common wire to the “com” terminal J8. If the
    remote system is a two-wire remote, the remote system will be used to turn the heater on for a selected
    body of water, Pool or Spa, select which application you are working with and connect one wire to the
    common terminal J8 and the other wire to either “Pool J5” or “Spa J6”. Close and latch the door.
    LED INDICATORS
    There are nine lights that can be seen from the front of the control panel, (five are system indicators and four
    are mode indicators), which helps you understand the operation of the heater, see Figure 26. If something
    should go wrong, the lights will aid in troubleshooting the problem. An additional four lights can be seen
    after opening the control panel. These four lights are diagnostic indicators for the service technician to
    troubleshoot the system.
    On the right front of the DDTC board there are four Buttons and corresponding LED lights, see Figure 26.
    Using the buttons allows you to select one of the four modes and the lights indicate which operational mode
    that the heater is in, Off, Spa mode, Pool mode or Remote mode. If the heater is not connected to a remote
    system then the remote mode will not be used.
    The following are descriptions of the five system indicators:
    • POWER
    The light is on at all times, in any switch position, indicating 24 VAC power is being supplied to the control
    circuit. If it fails to light, no other light will be on. Possible causes are:
    1. External power to the heater is disconnected; check service panel circuit breaker or fuses;
    2. Transformer has failed.
    • PRESSURE SW (WATER PRESSURE SWITCH)
    This light is on when Spa/Pool Selector switch is on, indicates the circulating pump is running properly.
    If pressure light fails to light, the pump may have lost its prime or water flow may be restricted by an
    inadvertently closed valve or clogged filter or pump basket. If you have determined that there is no water
    flow restriction to the heater, you should call a qualified technician.
    • THERMOSTAT
    This light is on when the thermostat contacts close, signaled by the water temperature falling below the
    set-point, calling for the heater to fire to maintain the wanted water temperature.
    Section IV. Operation
    Rev. E 4-19-05 P/N 472089
    27
    • HEATING
    The heating light is on any time the thermostat has signaled a call for heat which initializes the ignition
    safety circuit — the light comes on indicating successful firing of the main burners and stays on until the
    pool/spa reach the water temperature setting.
    • SERVICE
    The service light is off during normal operation of heater. The light only comes on if a problem with a
    control has occurred or when the heater is first firing. The problem must be investigated by the technician
    prior to attempts to fire the heater again.
    TEMPERATURE SETTING
    The heater comes factory set at 78° F. for the pool mode and 100° F. for the spa mode, using the up and
    down arrows, you can set the thermostats to a minimum temperature of 65° F., or a maximum of 104° F.
    If you want to heat only one body of water, the thermostat is capable of an off mode. As an example, if you
    only wish to heat the spa and not the pool, simple depress and hold the pool down arrow, and the thermostat
    will lower its setting to 65° F. then go to an off mode. If there is a remote system connected to the heater,
    please see the special thermostat setting features under Heating Mode Selection & Remote mode.
    HEATING MODE SELECTION
    1. Off Mode: The heater will not come on. NOTE: The "Off" display on the Digital Display Temperature
    Controller does not mean that the heater is off. It only states that the pool or spa thermostat has been
    turned off.
    2. Spa Mode: The heater will operate and heat the spa to the wanted temperature.
    3. Pool Mode: The heater will operate and heat the pool to the wanted temperature.
    4. Remote Mode: The DDTC is compatible with two and three wire remote control systems. In order to
    operate by a remote control system, the REMOTE mode must be selected on the front panel. When the
    REMOTE mode is selected, the REMOTE LED will light up.
    REMOTE CONTROL
    THE TWO-WIRE REMOTE CONTROL SYSTEM is typically installed and connected to the heater for spa
    heating. The two-wire remote system is usually provided with a water temperature sensor that monitors the
    system temperature and turns the heater on or off in response to the temperature of the spa. To heat a spa, it
    should be connected to terminals J6 and J8. Pool heating remote control would require connecting to
    terminals J5 and J8. If the REMOTE mode is set at the front panel LED light, the DDTC will respond to a
    contact closure by remote system and heater will operate until the remote system temperature setting is
    satisfied.
    NOTE: With this type of two-wire remote, with its own temperature sensors and system control, using the
    up arrows on the front of the DDTC, hold down the up arrow until you reach the maximum setting of
    104° F., this allows the remote system thermostat to operate the heater at any set-point below 104° F., the
    heater thermostats then act as a secondary controller if water temperature reaches 104° F.
    THE THREE-WIRE REMOTE CONTROL SYSTEM will be connected to terminals J5, J6 & J8. J8 is the
    common terminal. If the heater is in the REMOTE mode, the DDTC will monitor the terminals and respond
    to a contact closure between J5 & J8 or J6 & J8. A contact closure between J5 & J8 will cause the DDTC to
    switch to the POOL setting and control the heater to the DDTC pool set-point temperature. A contact
    closure between J6 & J8 will cause the DDTC to switch to the SPA setting and control the heater to the
    DDTC spa set-point temperature. If only heating the spa, then depress the pool down arrow until the display
    goes to “Off”.

  • Nick Smalling
    Nick Smalling May 06, 2015

    My guess is the control board, since your error code is not listed... But try these steps only if you are mechanically inclined...

×

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Posted on Jan 02, 2017

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SOURCE: Pentair Minimax Nt heater wont turn on and heat, "err" message

temp sensor get the new one with yellow wires.should do the trick.

Posted on Jun 05, 2009

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SOURCE: Pentair Minimax NT 400 heater. fan keeps coming

Sounds like the controller is the problem. This is the circuit board that has the display and controls on it. You can swing that panel open and try tapping on the white plastic cover the controller is under that. This might get the fan relay to release but you will have to replace the controller it will stick again

Posted on Jun 23, 2009

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SOURCE: Pentair Minimax Nt heater wont turn on and heat,

Bad thermistor. The yellow wire that plugs into the control board. Lick finger and touch prongs. Heater should come on

Posted on Aug 30, 2009

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SOURCE: E04 comes on after fan purge cycle-Pentair minimax nt pool heater

This is a fan falure code. It can mean the fan has problems (not likley if the fan goes and isn't labored) You have a sensor in your exaust (probally not this if you don't get a good start) The culperet is probally in the negetive pressure sensor. This is a 2-3 inch disc with wires going to the controls and a rubber tube going to the fan. Pull the tube from the fan and make sure the fan fitting is clear (poke with a tooth pic) Be sure their are no kinks in the hose. If the heater is 4 years old the diaprahm could be bad in the pressure sensor. Check the other things first but this is probally your problem. Good luck, hope this helped.

Posted on Jan 26, 2010

john224
  • 1378 Answers

SOURCE: I have a pentair minimax nt heater. The screen

Thank you for posting your question here on Fixya.com.


Hi means the unit believes the water is 114 degrees or higher. The problem, assuming the water is really not that warm, is the thermistor in the header. You need to replace it with a new one as its function is to read water temp and feed that info back to the control board. It is a part most people can replace on their own.


Your part number should be: 471566


If this answer does not fix your problem, please comment with additional details prior to rating the answer. You may also contact me thru our website at www.arrowpools.net. Positive feedback is appreciated once your problem is solved!


John

Posted on Mar 11, 2011

Testimonial: "John224, Your evaluation was right on target. I purchased the thermister and installed it in 5 minutes. Thanks for the info."

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1 Answer

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Open the service panel and look on the back of the board for 2 white or yellow wires that plug into it... disconnect it from the board, really wet your thumb with saliva, and touch the two connectors where you pulled the wires off of... and try to fire the heater... If it fires then you know that it is the thermistor.... I will show you a link to the thermistor on our site.... Do you have the minimax NT? if so here is your thermistor PENTAIR Thermistor probe complete 472101

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I would say the problem is the thermistor. The board will light up, the SW switch is green, but you get a display that flashes dashed lines and then what looks like 888. That is a start up code. The thermistor is located on the side where the water enters the heater. There are two screws at the top of the side panel. Undo the screws and lift the panel off. The thermistor is a probe with 2 small wires coming out and lead to the control panel. It is a very simple fix and is usually the problem if you have not experienced any other issues. The part runs between 30 and 45 dollars. Most pool stores would carry this.
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Thank you for posting your question here on Fixya.com.


Hi means the unit believes the water is 114 degrees or higher. The problem, assuming the water is really not that warm, is the thermistor in the header. You need to replace it with a new one as its function is to read water temp and feed that info back to the control board. It is a part most people can replace on their own.


Your part number should be: 471566


If this answer does not fix your problem, please comment with additional details prior to rating the answer. You may also contact me thru our website at www.arrowpools.net. Positive feedback is appreciated once your problem is solved!


John

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Bad thermistor. The yellow wire that plugs into the control board. Lick finger and touch prongs. Heater should come on

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temp sensor get the new one with yellow wires.should do the trick.

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