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Thread: Replacing Jandy LT Heater with Pentair MasterTemp - Need Advice on the Control

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    Join Date
    Apr 2015

    Replacing Jandy LT Heater with Pentair MasterTemp - Need Advice on the Control

    I am replacing my 10 year old Jandy LT heater with a Pentair Mastertemp. The current setup uses a Intermatic dual mechanical timer with freeze protection (PF1202T). The system also had a boost pump for the pool cleaner, a Jandy Aquapure 1400 SWG system, and a blower for the spa. The main pump is on the first timer, and the second timer handles the boost pump.

    The Jandy LT heater has a small control board (pcb #7530 - assy# 7529), separate from the main control board but connected through a 4 wire cable harness, that controls the Jandy valves for pool or spa mode, and also controls two separate relays/contactors. The relay is wired in series with the power to the boost pump, and presumably interrupts it when the spa is on. The contactor is wired in parallel with the first timer circuit (and the freeze protection) to the main pump - I presume it's purpose it to keep the pump running as long as the spa is on, even if the timer is "off".

    So, it appears that a lot of the responsibility for control of the heater, valves, pump, and boost pump lay within the original Jandy heater and it's controls.

    Upon picking up the new heater, looking through the manual, and removing the covers, the new Pentair does not have this type of control interface. It appears that it only has the ability to interface to a "Fireman's switch" to control it's internal 24Vac supply. While I can buy the added Fireman's switch for the Intermatic timer, this solution does not give the flexibility to keep the spa and pump running if the timer expires.

    I am pretty sure the answer is that this old Jandy control board cannot be retrofitted to the new Pentair heater. Am I correct? I figured I would ask anyway, just in case.

    Otherwise, what are my options for re-establishing these control features? Do I need to upgrade to the newer automatic control system? If so, are there any recommendations?

    Thanks in advance for any help or advise that anyone can give me.


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    ps0303's Avatar
    Join Date
    Jul 2011

    Re: Replacing Jandy LT Heater with Pentair MasterTemp - Need Advice on the Control

    Upgrade to an automation system like a Easytouch. Best way to control all that you have.
    Paul A word of caution: When working with gas and electrical you might want to consider a licensed contractor. Consider the value of your life and others around you. If you would like to provide a review of the help I provided, please use the following link to leave a review. gastek - Google Search,

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