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Thread: Problems with wiring for Heater Fireman's Switch

  1. #1

    Problems with wiring for Heater Fireman's Switch

    Pentair Minimax 250 heater with pump controlled by an external timer. I am trying to figure how to turn off the heater using an external switch to power down the heater 20 mins before the pump shuts off. My problem is that I am looking for a circuit in the heater that could serve this purpose.

    The "professional" that installed the heater used the wiring to the thermal fuse as the circuit to turn off the heater. So when the timer shuts off, the heater "thinks" the thermal fuse is blown and shuts off the gas. Problem is that this triggers one of the safety mechanisms of the heater; it WILL NOT restart the next cycle, displays "ERR" and "call technician". I have to switch the unit off then on again to reset the system. It works fine until this happens again.

    So I call Pentair and they instruct me to use the "Common" and "Pool" terminals on the circuit-board for this purpose. But there was no jumper between these two terminals. When I connect them with alligator clips, it makes no difference how the heater functions, including the fatal error described above.

    Any ideas where to wire this properly?
    35,000 gal pool, Pebble-Tec, Pentair VF pump, DE filter, Aqua Rite SWG, Pentair Minimax Heater in Southern California

  2. #2
    Senior Member In the Industry

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    Re: Problems with wiring for Heater Fireman's Switch

    So what is the controller that you have the unit attached to? Also, do you have the heater on all the time or only when you want it to be on?

    The Pentair folks assumed you had automation such as an Easytouch.
    Paul
    http://www.gastekservices.com

    A word of caution: When working with gas and other things you really might want to consider a licensed contractor. Consider the value of your life and others around you. I recently looked at a burned up heater at a customers house and found out he tried to trouble shoot it. He said he's not sure what he did but the unit caught fire. The unit is now toast and is being replaced. I'm only providing you with help but in many cases you need to hire someone. I realize people are all about saving money but lives are priceless!

  3. #3

    Re: Problems with wiring for Heater Fireman's Switch

    Pump and heater are connected to a digital Intermatic timer. Heater is "on" all the time but of course is controlled by its thermostat.

    I made it clear to Pentair tech support that I was using an external timer. On doing more reading, there is a jumper on the circuit board the needs to be removed to use an external switch.

    Instead I was thinking about using the circuit for the pressure switch for this purpose (I.e. external switching).
    35,000 gal pool, Pebble-Tec, Pentair VF pump, DE filter, Aqua Rite SWG, Pentair Minimax Heater in Southern California

  4. #4
    Senior Member In the Industry

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    Re: Problems with wiring for Heater Fireman's Switch

    What timer model are you using? Does it have an option to turn something off 20 minutes before it shuts off the pump or a heater cool down option? Cutting into any of the safety circuits like the pressure switch isn't the correct way to deal with your issue. Even using the thermal switch option done by the "professional" was not a correct way either. Yes the external switch option on the heater is the way to go but again, the timer has to have the option to turn if off before the pool pump shuts down.

    I'm guessing you have a minimax plus heater?
    Paul
    http://www.gastekservices.com

    A word of caution: When working with gas and other things you really might want to consider a licensed contractor. Consider the value of your life and others around you. I recently looked at a burned up heater at a customers house and found out he tried to trouble shoot it. He said he's not sure what he did but the unit caught fire. The unit is now toast and is being replaced. I'm only providing you with help but in many cases you need to hire someone. I realize people are all about saving money but lives are priceless!

  5. #5

    Re: Problems with wiring for Heater Fireman's Switch

    I am using a popular digital Intermatic model and it does have two dedicated terminals for a fireman's switch. You can program it to shut off up to 20 mins before the pump goes off.

    I have the Minimax NT with the digital control board.

    I am going to call Pentair tomorrow as there is a proper way to do this. I think it involves switching the "com" (for common") and the "pool" terminals on the circuit board. But there is a jumper somewhere on the board you have to remove.

    Both the Pentair installation and service manuals do not explain this in any detail. I guess they wanted it to be a proprietary secret.
    35,000 gal pool, Pebble-Tec, Pentair VF pump, DE filter, Aqua Rite SWG, Pentair Minimax Heater in Southern California

  6. #6
    Senior Member In the Industry

    Join Date
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    Re: Problems with wiring for Heater Fireman's Switch

    Was the heater in remote mode when you tried what Pentair told you?

    I would be interested in a "proprietary secret" that they have. I've worked on these units since they showed up on the market but I've never had a need for using a fireman's switch nor have I seen any that other companies have installed used one. You learn something new every day so I will be waiting to learn.
    Paul
    http://www.gastekservices.com

    A word of caution: When working with gas and other things you really might want to consider a licensed contractor. Consider the value of your life and others around you. I recently looked at a burned up heater at a customers house and found out he tried to trouble shoot it. He said he's not sure what he did but the unit caught fire. The unit is now toast and is being replaced. I'm only providing you with help but in many cases you need to hire someone. I realize people are all about saving money but lives are priceless!

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