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Thread: Hayward Milivolt heater and Reversing water connections

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    Hayward Milivolt heater and Reversing water connections

    I purchased a used Hayward 350 Millivolt to replace a broken very old heater. I am getting ready to move my pool equipment and install all new valves, pump and the heater. The heater outlets need to be on the other side and the manual states these are reversible. I followed the manual, removed all the upper shielding to get to the Heat Exchanger, the manual says basically to disconnect wires and switches, remove the Front Header and rotate the exchanger 180 degrees (NOT to flip) and then reinstall. This seems to work fine with the front header as all threaded holes will realign with the various switches and the wiring can reroute thru the side panel to the controls. The problem is the rear header, it has a Pressure switch with a tube on one side and there is no corresponding threaded outlet on the opposite side. When I rotate the exchanger, the pressure switch fitting is on the opposite side away from the controls and the switch cannot be reconnected. I see 2 ways to correct this: 1. Flip the exchange over so the fitting will end up on the correct side or 2. remove the rear header and turn it over. Nowhere in the instructions does it mention removing the rear header for any reason and the instructions explicitly state:"CAUTION: Do not flip it (Heat Exchanger) over. The Heat Exchanger will be damaged if installed incorrectly", they only want you to rotate it 180.
    I see there is no physical difference between one side of the heat exchanger to the other, the only difference is in the ports on the headers and as long as they are located properly I don't see how the exchanger would be damaged. So do I do option 1 or 2? Anybody have experience with these?

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    gtemkin's Avatar
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    Re: Hayward Milivolt heater and Reversing water connections

    I have no first hand experience with this model heater but I read in the manual step 15 which says:

    "Move the pressure switch tube over to the left side of the heater and route through hole in intermediate panel. Insert tube in fitting and tighten the ferrule down with the nut."

    Were you able to follow that step?
    21K gal 16' x 40' in-ground pool built 1959, old school with Jacuzzi bronze pump, American Products 24" Sand Filter & Americana Multiport valve, Jandy Lite2 millivolt heater, Coverstar cover, and classic Kreepy Krauly.

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    Re: Hayward Milivolt heater and Reversing water connections

    Thanks for the quick response. Moving the Pressure switch isn't the problem. The switches/wiring can all be moved side to side on the control side to accommodate reversing the exchanger, there are openings in the panel on the control side at each end. As mentioned, the corresponding fitting for the Pressure switch in the rear heading will be on the opposite side (away from the control side where the switch is located) once the exchanger is rotated and there is no place to connect unless I do 1 of the 2 options: Flip the exchanger or remove the rear header and flip it. Either of these 2 options will align the fitting for the pressure switch to an opening on the control side where the switch can be connected.

    Hard to visualize so I photochopped an image. The controls are on the left lower side in picture, 32 is the pressure switch, it can be moved to the other opening as can all wiring/switches to either of the 2 red oval openings. The red arrows indicate the original and rotated position of the pressure switch fitting. If I follow instructions and merely lift the exchanger and rotate it 180, the rear header is now on the right side and the fitting for the switch is now on the opposite side facing away from the controls and the opening in the sheet metal where the controls are.

    I just cant understand why the exchanger cant be flipped as long as all of the fittings, switches , controls are all correctly reconnected. The exchanger itself is nothing more than a radiator, tubes with fins. The exchanger appears to be the same on both sides if you remove the headers.

    [attachment=0:21l63a02]Heater reverse.jpg[/attachment:21l63a02]
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    Re: Hayward Milivolt heater and Reversing water connections

    If you have the space you could have always just run a little extra pipe and left the heat exchanger alone and not reversed the headers.
    Paul
    http://www.gastekservices.com 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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    Re: Hayward Milivolt heater and Reversing water connections

    That would be nice in a perfect world. The layout is based on available space and I would need to run piping all the way around to the other side, makes no sense. Since the selling point of this unit is that the outlets are reversible, they should be!

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    Re: Hayward Milivolt heater and Reversing water connections

    Yes you can do it but it's not always as easy as it seems or is portrayed. If you don't have enough room to run two PVC pipes around to the other side of the unit then you have other issues. There should be plenty of space al the way around that unit for someone to be able to service it.

    Good luck switching the unit around.
    Paul
    http://www.gastekservices.com 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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    gtemkin's Avatar
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    Re: Hayward Milivolt heater and Reversing water connections

    It sounds like a call to Hayward may be in order. They may be able to shed some light on the "do not flip" warning. If you do contact them, I'd be interested hearing their response.
    21K gal 16' x 40' in-ground pool built 1959, old school with Jacuzzi bronze pump, American Products 24" Sand Filter & Americana Multiport valve, Jandy Lite2 millivolt heater, Coverstar cover, and classic Kreepy Krauly.

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    Re: Hayward Milivolt heater and Reversing water connections

    ON all units with a design similar to this unit, the manufacturers say to remove the headers and install them on the opposite side if you need for the entry to be on the left. I'm sure there is some design of how they made the exchanger and even though to the human eye it may look the same on both sides, it isn't. Plus it's easier to just remove the headers and switch them rather than taking the unit apart.
    Paul
    http://www.gastekservices.com 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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