Solar water heater plumbing .... can this be right?

Discussion in 'Solar and Geothermal Water Heating Forum' started by Gary2, May 28, 2013.

  1. Gary2

    Gary2 New Member

    Messages:
    6
    Location:
    Hawaii
    I've been assuming that the increase in my power bills was due to increases in oil prices. But upon turning off the the power to the hot water heater in order to rely solely on solar, and running out of hot water seemingly way too soon especially given the sun this time of year is nearly straight up at noon here in Hawaii, I took a closer look at the installation that was done on my system a couple years ago.

    I noticed one thing in particular that did not seem right to me. There is a check valve mounted just above the 'out' connection (back to the solar panels, right?) that appears to me to have been put in backward. The arrow is pointing opposite the direction of (assumed) flow, is it not? I've attached a couple pictures:

    solar installation.jpg arrow close-up.jpg

    Thanks to anyone who might be able to offer some advice on this! I'm trying to gather information before calling back the contractor in order to hopefully be in an informed position.

    Gary
  2. Dana

    Dana In the trades

    Messages:
    3,029
    Location:
    01609
    What is the flow direction indicated on the pump?
  3. Gary2

    Gary2 New Member

    Messages:
    6
    Location:
    Hawaii
    I looked for that, but there doesn't seem to be any indication of flow direction on the pump.
  4. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

    Messages:
    1,143
    Location:
    South*East
    There should be an arrow on the back of the housing.

    John
  5. Gary2

    Gary2 New Member

    Messages:
    6
    Location:
    Hawaii
    Thanks John, I'll take another look after work today.
  6. leejosepho

    leejosepho DIY scratch-pad engineer

    It looks to me like the pump and check valve are in correct orientation with each other (or you would be getting no solar heat at all), but that the contractor has the flow running backwards through the heat exchanger and has thereby caused it to be less effective than it should be. In a regular electric water heater, that would be like the upper element being energized first and the water in the lower portion of the tank never being heated. Knowing the internal structure of your water heater could be helpful here.
    Last edited: May 29, 2013
  7. Gary2

    Gary2 New Member

    Messages:
    6
    Location:
    Hawaii
    Thanks Dana, John and Lee,

    Typical me I missed the arrow indeed on the back of the housing, which is pointing UP away from the tank -- 'out' of the 'in' connection. I had taken a couple pictures of the back parts but for some reason the arrow didn't show up, but a mirror and flashlight did the trick.

    So apparently there is flow going on, but as Lee surmised the thing's maybe just plumbed wrong as to be inefficient. This is an 'American Electric Water Heater Co.' 80 gal tank, model # SE62-80H-045S. Manual doesn't have any internal plumbing diagrams and I can't seem to find any on the Internet. Do solar water heaters have an actual heat exchanger design? I guess I just assumed all this time the water from the panels mixed directly with the water in the tank.

    This is actually a replacement installation after 15 years on the original system (panels started leaking) which seemed to work pretty well even with the power turned off, which really should be the goal especially for this latitude. It's just that since the new install we've always had the electric back-up on, and until recently turning the power off, I had no idea as to the possible deficiencies of this install.

    I guess I'm ready to call the guy and quiz him as to just why they would install it this way. Thanks to all for your help in clearing things up for me as to flow direction and efficiency.
  8. leejosepho

    leejosepho DIY scratch-pad engineer

    It appears you also have solar connections at the bottom...
    SE62-80H-045S.png
    ...and I would assume your top connections are teed to those on the inside, and all of that would indicate a heat exchanger in the lower portion of the tank and cause me to doubt my theory that a reverse flow would greatly affect its effectiveness. So, try checking the in and out temperatures of your solar connections at the top and see how much heat you are actually bringing down and how much of it is being consumed.

    PS Edit: I just found this saying "This storage tank DOES NOT INCLUDE A HEAT EXCHANGER."
    http://www.altestore.com/store/Sola...olar-Storage-Tank-with-Electric-Element/p198/

    So, what you have going on is that your solar panel is being fed the tank's hottest water from the short "In/Down" connection (that is actually similar to the regular internal short tube supplying hot water to your house), and then the water coming down from your solar panel is presently being sent down the long tube to the bottom of your heater where it immediately begins losing its heat on its way back to the top. Switch your "In/Down" and "Out/Up" lines to where they should be and your system should work just fine.

    Note: I would guess the "Solar In/Down" connection on the side of your tank has at least a short tube going up internally. But either way, you want to put water from your solar heater into the top of your tank (either from the top connection or at the side) and not send it to the bottom.
    Last edited: May 30, 2013
  9. Gary2

    Gary2 New Member

    Messages:
    6
    Location:
    Hawaii
    Wow Lee, thanks so much for all your thoughts and research. Yes indeed, there are connections on the side; that's my heater alright. From your last couple paragraphs I think I have an excellent case to be made to this contractor that he needs to correct this, although it's been 2-3 years so who knows what he'll say. I wish I had more plumbing experience and I'd probably just do it myself. I may have wasted a lot of money on power bills as we pay over 40 cents / KWH -- I've heard the highest in the nation!

    Thanks again,

    Gary
  10. leejosepho

    leejosepho DIY scratch-pad engineer

    Your situation *might* be an honest error in sorting all the inlets and outlets, or maybe the contractor had a helper who did not understand them do the actual connections and that is just where the lines happened to be pointed at the time. Three years ago I called a contractor who had done some work for my in-laws seven years prior to that and convinced him to at least come make some corrections of what I called "shoddy work" at half-price! So, let us know how you make out here.
  11. protech

    protech Master plumber

    Messages:
    53
    Location:
    Central Fl
    Is that an open loop tank? It looks like an american water heater co. open loop solar tank. If that is the case, the stickers on the tank mean nothing as the tanks come with the dip tubes taped to the side of the tank and you have to field install them. Since what ever port you install each type of dip tube determines where your connections go, there is no reason to think that systems solar loop is piped in backwards. Most open loop systems around here (Lakeland Florida) have the pump hooked up on the right because you want it as close to the cold water inlet dip tube as possible.






    http://lakelandplumbers.co
  12. Gary2

    Gary2 New Member

    Messages:
    6
    Location:
    Hawaii

    Thanks protech,

    Indeed that is correct in my case, as I learned from the installer who came out to fix my problem just a few days ago after asking him about the conflict between the arrows and the stickers.

    Sorry for abandoning this discussion for so long, but I had family priorities that put this on the back burner for the last month or more. After a day with straight up sun at noon and starting with the hot water depleted down to about 90 degrees and the power to the tank off, there was no solar heating whatsoever that had taken place during this very sunny day. So I called the installer who came out a week or so later. He simply replaced the sensors at the panels and at the tank, and now we seem to be back to getting 140-150 degree water for free again. The agonizing part is wondering just how long this has been the case since we've had the power on for back-up, so the whole thing was disguised. My fault for not being more curious and vigilent, I suppose.

    Thanks to all who took the time to comment on my little problem. I guess the one thing someone reading this might take away is that these sensors apparently can go out, even though on our previous system they didn't for like 15 years. And also if you have your power on for back-up, turn it off once in a while on a sunny day to make sure you're getting your fair share of free hot water! (Well, after the panels etc. have paid for themselves anyway.)
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