My solar geyser setup.





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  1. #1
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    Default My solar geyser setup.

    I am starting a new thread on a solar setup at my house.I am doing this because as a plumber it is important I understand and do it correctly.I have done a few solar geysers and worked on a few but those are just simply burst replacements.

    I am hoping to present some of the problems I am having so that the clever guys on this site can steer me in the right direction.

    I believe many home owners are oblivious to their systems not actually performing properly.
    I have a 150l solartherm system in my house .It is a split thermosyphon system. The Geyser is in the roof ,A 30 year old flat panel is what is feeding energy into this geyser.
    It is controlled by a geyserwize max. I like these controllers alot.It is set to boost the element from 5 to 6 AM and from 4 to 5 PM. It is set to heat up to 55 c.
    This has been in for about five years or more.
    In summer it gets to about 65c but in winter it gets into the low fiftys,but remember its boosted in the morning so starts from about 36c .

    I decided to install a extra geyser to my house to improve my electrical savings but to also learn how to do it and teach my guys at the same time.
    I am using all second hand stuff.
    I have a 100 liter conventional kwikot pressure geyser and I have a 24 tube evacuated tube system.

    I decided to do a split pumped system and the 100 l geyser will simply pre feed my existing system.There will be no power to this system.

    It is controlled by its own controller (src868 solar controller).

    RESULTS
    The first day was 22c at noon. The water in the geyser only got to 37c.I was dissapointed. The second day was cloudy and would only get to 29c
    The third day I installed in total 16 tubes . But it didnt get much better .
    Today I installed twenty two tubes (i only have twenty two, two have lost their vacuum). But my wife and I showered at lunch time so I cant get a proper result.

    I dont have any lagging. Could this make such a difference and what kind of temp should I be getting .
    Another thing of concern is how much heat it loses at night.At night the panel gets to 14c .The water at the top of the geyser is 22c and the temp at the bottom of the geyser is 24c. I am confused as to how this happens .?Surely hot water rises, not sinks. Shouldnt the water be hotter at the top of the geyser, not the bottom.

    Could my installation be wrong.

  2. #2
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    Default Re: My solar geyser setup.

    Sounds like your thermosyphon goes into reverse as soon as the panel drops to lower temp than the geyser. Thats why your temp is lower on top than bottom. Do you have a non return valve that only allows thermosyphon in one direction?
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  3. #3
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    Default Re: My solar geyser setup.

    I may not use the right technology but on the solar panel I have used a t to branch off on the cold to feed the panel. I have a shut off valve and then the pump and then the non return valve.Are you saying at night the heat from the geyser is travelling up to the panel due to the fact that hot water rises. ?If I did some form of trap like maybe some elbows to form a trap would that help. I would think the non return valve would stop water travelling through because its spring loaded and I would think the natural force of hot water rising would not be sufficient to to bypass the nrv.Unless its doing so by convection passed the nrv ?

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    Default Re: My solar geyser setup.

    Quote Originally Posted by plunger View Post
    I may not use the right technology but on the solar panel I have used a t to branch off on the cold to feed the panel. I have a shut off valve and then the pump and then the non return valve.Are you saying at night the heat from the geyser is travelling up to the panel due to the fact that hot water rises. ?If I did some form of trap like maybe some elbows to form a trap would that help. I would think the non return valve would stop water travelling through because its spring loaded and I would think the natural force of hot water rising would not be sufficient to to bypass the nrv.Unless its doing so by convection passed the nrv ?
    I had difficulty maintaining temperature overnight until I put U bends in at both ends of the pipe run to/from the panels. This stops the heat from thermosiphoning up to the highest point. I used short lengths with elbows to make the U bends.
    Lagging makes a huge difference, too.
    I don't think the non return plays a part in water flowing up to the highest point, the fact that it is a conductive medium allows heat transfer though it, even with no water flow.
    Cheers,
    John

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    Default Re: My solar geyser setup.

    Following

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    Default Re: My solar geyser setup.

    Duplicated post..
    Last edited by JohnnoK; 2019/07/14 at 08:25 PM.
    Cheers,
    John

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  7. #7
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    Default Re: My solar geyser setup.

    My "feeling" is just my understanding from what I have heard the guys talking about offgrid systems on youtube. I have heard it mentioned a few times that systems would go in reverse if you dont have a check valve. Could be a non return valve, or a solinoid that shuts down below a certain temp.

    I mention it as this is something I have been trying to figure out on a system I would love to build for myself at some stage. I don't like electronics, and would like to have some comparator system that can check the difference in temp between panel and tank, and shut off as soon as panel temp drop below tank temp. Nogood heating water to 55, but when the sun starts dipping, I cool the tank down by a few degrees again. But I want to do it the mechanical way. Maybe with a few temp switches in various configurations to always maintain a few deg higher panel than tank situation. Dont know if its even possible.

    Anyhow, I'm going off topic again, sorry... just check though, I'm sure NRTV just have a flap (not spring loaded) that shuts close as soon as there is no flow, or flow goes negative. Sure there are spring types, but I have seen flap types at builders and hardware's as well.
    David/Hillbilly - 1997 SFA Nissan Sani 2,7 TD - 5" lift on 33" tires - Dual Transfer with 4.1 gears

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  8. #8
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    Default Re: My solar geyser setup.

    Quote Originally Posted by JohnnoK View Post
    I had difficulty maintaining temperature overnight until I put U bends in at both ends of the pipe run to/from the panels. This stops the heat from thermosiphoning up to the highest point. I used short lengths with elbows to make the U bends.
    Lagging makes a huge difference, too.
    I don't think the non return plays a part in water flowing up to the highest point, the fact that it is a conductive medium allows heat transfer though it, even with no water flow.
    Any chance of getting pics of your bends please.

    Thermosyphon can be fairly strong. I have seen systems that can "pump" into an underfloor grid to do underfloor heating during the day. Simply due to the return water being so much cooler, it moves up through the panel, makes a 180 back down to floor level, and moves through the floor.
    David/Hillbilly - 1997 SFA Nissan Sani 2,7 TD - 5" lift on 33" tires - Dual Transfer with 4.1 gears

    http://www.youtube.com/user/davidabcab



  9. #9
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    Default Re: My solar geyser setup.

    They are covered with lagging, but all I did was to cut off the installed pipe running up to the panels, add a 90 facing down with a length of pipe for the vertical, another 90 with a short pipe to a 3rd 90 turning back upwards to the original pipe run to the roof panels.
    Cheers,
    John

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  10. #10
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    Default Re: My solar geyser setup.

    Please draw a sketch of your setup, which system is on its own controller, which is on geyserwise, where are the tubes / panels connected.

    FYI, 22 tubes to a 100l tank is plenty, that water shoud be 70C in summer. I. Have 20 tubes, heating 150l,the temp gets to 65C - 70 in summer from a low if 15C in the morning. That's in JHB though.

    I threw my panel out, it was not effective at all, water only reached 45C in summer,replaced with the tubes.

    Geyserwise "heats" the panel/tubes at night if the temp in the panel/tubes drops to 5C (this can be set on the newer geyserwise).
    Last edited by NewLandy; 2019/07/15 at 05:27 PM.

  11. #11
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    Default Re: My solar geyser setup.

    I think I may have figured out the problem. It is not a solar geyser so I have made my own extra ports. From the cold pumped feed to the evacuated tubes I have taken a compression tee and teed off to the solar pump. I think what is happening is that it is pumping water from the bottom of the geyser as well as from the mains.Is this possible?

    I have also put a trap on the hot return pipe from the ev manifold. Hopefully this will prevent some heat loss at night.Anyone in solar who I can talk to.?

  12. #12
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    Default Re: My solar geyser setup.

    I am going to machine a nipple and weld or braze it into the flange plate so it is not connected to the cold inlet.

  13. #13
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    Default Re: My solar geyser setup.

    My setup feeds the hot panel water into the geyser outlet to the house and draws from the cold side to the panels, so it is a reverse circulation, giving the hottest water from the panels immediate accessibility for use.
    Cheers,
    John

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