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Thread: Replacing Existing Solar Water Heater

  1. #1
    DIY Junior Member Desert Shower's Avatar
    Join Date
    Dec 2007
    Location
    Phoenix, Arizona
    Posts
    7

    Default Replacing Existing Solar Water Heater

    All...I'm replacing a 19 year old State brand Solar Water Heater that has served me well, but recently died, and replaced with an American Water Heater Brand Model SE62-80H-0455 Solar Storage Tank with a Single Electric Element. I've connected the Hot and Cold sides...for now, so at least I have a functional water heater with limited Hot Water supply. I'm purchasing replacement sensors, Taco Circulating Pump, and other items related to the Solar "Install" side of this installation, but have a few questions. Hope you can help.

    Questions...
    1) The dielectric nipples shipped with this unit seem difficult to remove...prefer to replace with Brass Nipples. Am I not cranking hard enough to remove?

    2) Once removing the "shipped with" dielectric nipples should I "Tape and Dope"?

    3) The American Water Heater Manual is not clear enough...but my plan is to install the "Solar Panel In" line or return to the Top of the Tank mounted position marked "In From Panel". Also to install the "Outgoing" Cold Water to the Solar Panel from a Side "Low Mounted" option on this same tank.

    Direction, corrections welcome.

    Best
    Desert Shower
    My friends call me...Mac

  2. #2
    DIY Junior Member
    Join Date
    Feb 2010
    Location
    Poughquag, New York
    Posts
    2

    Default

    Hey Mac,
    Not sure why you would swap out the dielectric nipples - corrosion over the long haul? I see Tom Lane reccommends against ANY galv fittings, and I guess those dielectric nipps are galvanized...I definately would use tape & dope on the brass nipple threads, IF you're NOT using glycol. If you ARE using glycol, then just use teflon tape. Try to use RED brass nipples as opposed to yellow brass nipples (less zinc). I suppose you just need some oomph to remove the dielectric nipps. Try a larger monkey wrench & pipe extension handle w/ someone to bearhug the tank to keep it from spinnin'.
    Regarding the correct ports to use, this tank has no internal heat exchange coil, if I'm not mistaken. You didn't mention whether your existing solar system is pressurized glycol or water drainback - if you're glycol, then you can't plumb direct without interfacing a heat exchanger between the domestic water supply and your glycol filled collectors. Yes, heated fluid from the solar collector goes into the tank up high - make sure there's no long dip tube to the bottom in this port. You are correct to use the lowest port available for the supply to the collector - the collector wants the lowests temperature water that you can give it for maximum efficiency. Best of luck!

  3. #3

    Default

    I'm going to have to correct a few things aaron.

    1. red brass is worse, not better from a galvanic cell corrosion stand point. Personally, I would leave those dielectric nipples in and just make sure that they are installed correctly and you won't have any problems with corrosion. You have to use a brass FIP adapter and bottom it all the way out on the male threads. The blue plastic that protrudes out of the nipple will seal up against the end (back) of the FIP adaptor and seal the galvanized steel away from the brass. You will be left with an all plastic water way into the tank once you install the extra dip tubes you need.

    2. You want to introduce the solar return water BELOW the upper thermostat. The reason why is that there are going to be times when cold water will be discharged into the tank and if it is discharged into the top it can cause all kinds of problems like: breaking up the thermo cline, being sucked into the hot water out let during times when the there is demand for heat and the pump is running, cooling the upper backup thermostat as it sinks to the bottom causing unnecessary electrical consumption.

    I recommend picking up 3 addition dip tubes for the heater and arrange/modify them in the following ways.

    Hot outlet: cut a dip tub down to 4" long and insert it into the hot outlet port.

    Solar outlet: Install the dip tub unmodified into the solar "out" port.

    Solar inlet port: Plug the dip tube and drill baffle holes. When not using factory made tubes you can make one by drilling a hole thru the tube about 1" from the end. Make up some epoxy putty and push it up into the bottom of the tube while someone pushes a rod down the top of the tube. This will form a slug of epoxy and cause some to shoot sideways out of the hole you drilled. Trim the excess epoxy that comes out of the 2 side holes flush with the tubes outer diameter. Now drill 4 - 1/4" holes about spaced equally in 3 intervals along the last 6" of the tube before the plug. This allows the heated water to flow slowly out of the baffle holes and allows it to stratify to the top of the heater. If this is not done, a good portion of the heated water is sucked right back into the "solar out" tube instead of fresh cold water. This boost efficiency considerably.

    Good luck

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