Trying to understand my solar water heating system...

ReinierReinier Registered Users Posts: 13
The house I bought came with a solar water heating system. Its collectors are on the roof and the tank is in the basement.
I have figured out somewhat by now how it is supposed to work, but it seems to be broken. It is supposed to feed warm water into the "regular" system, which is heated by an oil furnace -- except that it doesn't seem to do that.
I would like to repair the system, but I do not know where to start. I can not even figure out the make and/or model. Would this be a good place to ask for advice?
I think the system was installed in the mid-80's. I have attached a picture to give an impression. I understand this does not say much, but maybe someone recognizes it.

Attachment not found.

Thank you in advance,
Reinier

Comments

  • icarusicarus Solar Expert Posts: 5,233 ✭✭✭✭
    Re: Trying to understand my solar water heating system...

    Welcome to the forum.

    Does it circulate domestic water, and co-mingle water, or does it use a glycol loop wi th a heat exchanger in the tank? Do the collectors have water in them?

    Find out as much info as you can and report back. In short, a solar system like this probably circs water, controlled with diffential controller to turn the pump on when there is a diffence in temp. I would first try to pressurize the system, hot wire the pump and see if water circulates. Work through all the potential failure points and test them individually.

    Good luck and keep in touch,

    Tony
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Trying to understand my solar water heating system...
    icarus wrote: »

    Find out as much info as you can and report back. In short, a solar system like this probably circs water, controlled with diffential controller to turn the pump on when there is a diffence in temp. I would first try to pressurize the system, hot wire the pump and see if water circulates. Work through all the potential failure points and test them individually.

    Good luck and keep in touch,

    Tony

    It goes without saying that there must be fluid in that circuit so that you do not operate the pump dry. So I will say it anyway. :-)

    A look at what the collector(s) on your roof are like will tell us a lot too.
    SMA SB 3000, old BP panels.
  • fix_it_guyfix_it_guy Solar Expert Posts: 26
    Re: Trying to understand my solar water heating system...

    One thing I would do is make a drawing of where all the pies and components are. That's just how I am. If I look at a drawing, whether it's a new idea or existing system somehow it helps me figure it out.
  • BB.BB. Super Moderators, Administrators Posts: 29,489 admin
    Re: Trying to understand my solar water heating system...

    Look at www.solarroofs.com

    They have some very clear drawings about the basic systems.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ReinierReinier Registered Users Posts: 13
    Re: Trying to understand my solar water heating system...
    icarus wrote: »
    Welcome to the forum.

    Does it circulate domestic water, and co-mingle water, or does it use a glycol loop wi th a heat exchanger in the tank? Do the collectors have water in them?

    Find out as much info as you can and report back. In short, a solar system like this probably circs water, controlled with diffential controller to turn the pump on when there is a diffence in temp. I would first try to pressurize the system, hot wire the pump and see if water circulates. Work through all the potential failure points and test them individually.

    Good luck and keep in touch,

    Tony

    Hello Tony,

    I think it uses a glycol loop with a heat exchanger in the tank, but I am not sure how to come to a definite conclusion on that. All pipes disappear into this big orange tank and there is no way for me to look inside of course.
    It does have a meter which I suppose is to indicate the circulation speed of the fluid, but I have never seen any fluid in there. It looks like this:

    Attachment not found.

    As you can see on my original picture, there is a thermometer (the circle-shaped sensor). I have seen it indicate 60C/140F at one time, but it is typically stuck at 21C/70F.

    It is hard to inspect the collectors closely because they are high up on a 45 degree slanted roof. I went up there but was not able to open the lid or look through it, so I do not know if there is anything inside the collectors. However, from the fact that I have seen warm water in the tank, I conclude that fluid sometimes does flow from the collector to the tank. This contradicts the fact that I have not seen anything in that fluid meter I just showed.

    Some more information: Indeed I see a differential temperature thermostat which is connected to the pump. I have never seen or heard that pump run though. But then again, I do not know how often it is supposed to run and maybe I just did not sit down there long enough. Again, from the fact that I have seen warm water in the tank, I would say that the pump must have run at least somewhat to transport the heat from the collector to the tank.

    You should know I am really inexperienced. I do not know hot to pressurize the system (don't even know what it means) or hot-wire the pump. I guess the latter means I should work around the differential controller, but I am hesitant to do anything that I do not fully understand... If the advice is that I should get someone to look at it, then I am fine with that as well, but I would like to figure this out as far as I can by myself (with the help of some friendly people on the Internet ;-) )

    Hope this gives you a better idea and thanks for your response,
    Reinier
  • ReinierReinier Registered Users Posts: 13
    Re: Trying to understand my solar water heating system...
    inetdog wrote: »
    It goes without saying that there must be fluid in that circuit so that you do not operate the pump dry. So I will say it anyway. :-)

    A look at what the collector(s) on your roof are like will tell us a lot too.

    Thanks for the warning -- should I switch off the system if I do not know whether there is any fluid in the circuit?
    I could go up the roof tomorrow and make a picture of the collector. But previously, I was not able to open the lid; does a picture from the outside only have any value?

    Best regards,
    Reinier
  • ReinierReinier Registered Users Posts: 13
    Re: Trying to understand my solar water heating system...
    fix_it_guy wrote: »
    One thing I would do is make a drawing of where all the pies and components are. That's just how I am. If I look at a drawing, whether it's a new idea or existing system somehow it helps me figure it out.

    Well, the problem I have is that all pipes run into / out of this orange tank and some pipes are interconnected, and there are several valves, some of them are open and others are closed. The design is not as simple as I would expect.
    So far, I have not been able to grasp the purpose of all pipes. But it is a good idea to make a drawing and see how it improves my understanding. Always good to keep around as a reference as well.

    Here is a picture of (the majority of) the pipes:

    Attachment not found.

    Thanks,
    Reinier
  • ReinierReinier Registered Users Posts: 13
    Re: Trying to understand my solar water heating system...
    BB. wrote: »
    Look at www.solarroofs.com

    They have some very clear drawings about the basic systems.

    -Bill

    Thanks, the installation manuals already teach me a lot. It shows an expansion tank, which I have not seen anywhere. Does every system have that? Also, the manuals distinguish between models in tropical climate and freeze climate. I am in Nova Scotia, Canada, so my system (hopefully) belongs in the second category. That was a reason why I thought it was more likely that the system uses something like glycol for heat transmission. Is that a correct assumption?

    Reinier
  • icarusicarus Solar Expert Posts: 5,233 ✭✭✭✭
    Re: Trying to understand my solar water heating system...

    i would cast a net in your area (Wayne,, are you busy?) to find someone who can give you a heads up. What I mean by pressurize, is to put water in the collectors, by figuring out the valveing to see if it holds water. By hot wiring the pump, you are right, dictly bypassing the controller and t-stats to see if it circs. Given your neophyte status, finding a good plumber, and ideally one who knows about solr hot water. It may be working fine! Do this simple test. Go to Canadian tire, buy a $$20 infrared thermometer. Point it at various components when the sun is out, and see what temp things read.

    Good luck, be careful and keep in touch,

    Tony

    Ps, from a safety point of view, a couple of things to keep in mind,,don't allow any glycol mixture to have a way into potable water. If. You don't know what a valve does, don't mess with it. Second, hot water systems can get very hot,, be ware of scalding, and more importantly, make sure that there is proper pressure/temperature relief valves, and that they work. Finally, don't run pumps dry for more than an instant or you will damage it. (a quick start stop dry probably won't hurt it.

    T
  • BB.BB. Super Moderators, Administrators Posts: 29,489 admin
    Re: Trying to understand my solar water heating system...

    There is a very good chance that your best bet will be to rip the whole thing out and start over (either with an installer, or on your own).

    Hot Water Tanks generally last 15-20 years (at best). You can pull the collectors apart, clean/flush the pipes, look for leaks, etc... They might be worth salvaging.

    The controller--probably not. The pump--May be rebuild-able if there is a bad seal.

    This guy did a barn heating system (office in his barn). Lots of good information--including mistakes and how he fixed them:

    www.arttec.net/Solar/BarnHeat.html

    If this was a system with anti-freeze--I would expect an expansion tank.

    If this was a system that simply circulated domestic water through the panels--it may not. If you have a check valve or well--Then if you don't have a expansion tank, it can over pressure you water system (tanks, etc.) and/or cause the Temperature/Pressure valve (typically set at 150 PSI and 210F), to vent a bit of water (around a 1/2 gallon per 40 gallons of hot water from cold to hot).

    Solar Hot Water is probably the best bang for the buck in the alternative fuel world. However, it can be a plumbing nightmare and many systems probably have a fair mix of home-brewed design/parts (and solar hot water does lend itself well to do it yourself projects, with lots of study before hand).

    -Bill

    PS: It may be a simple drain back system (close the domestic water valves and open drain(s) for winter prep).
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Trying to understand my solar water heating system...

    I agree with Icarus and BB in their posts. Trying to resurrect an old, possibly warn out system could well be a huge waste of time, money and energy.
    My personal way of thinking, for my situation is to KISS. (Keep It Simple Stupid) I'm lucky, was able to build and install my own flat plate solar water heater and position it on the South facing wall, (outside of course) below the 60 gal storage tank (located inside of course and extremely well insulated), and this allows direct heating of the potable water, no pumps, no heat exchangers etc. The down side? I do have to baby-sit the outside panel during the colder seasons and drain it if necessary, but that's not a problem all Summer long, and in Wnter, it stays drained and the water is heated from the wood stove instead of the sun. BTW, the storage tank temperature last evening was 160F at the top and 150 F at the bottom, so scalding is something we must be aware of. This morning, before the sun hits the panel, the temps are 155F top and 145 bottom. I don't waste hot water, but use what I need and have not been without hot water for the last year. There is an electric heating element in the tank, near the top, but I've never used it. Never.
    It truly boggles my mind when I look around at my neighbors and how they have no idea the energy waste they live with. On the other hand I'm sure many of them think I'm weird.
  • RybrenRybren Solar Expert Posts: 348
    Re: Trying to understand my solar water heating system...

    Wayne:

    Not to hijack this thread, but do you have a build page or thread for your hot water heater? Sounds like something that might be useful for my 3-season off-grid camp.

    Thanks, Jerry
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Trying to understand my solar water heating system...
    Rybren wrote: »
    Wayne:

    Not to hijack this thread, but do you have a build page or thread for your hot water heater? Sounds like something that might be useful for my 3-season off-grid camp.

    Thanks, Jerry
    No Rybren, I don't, but if you PM you're email address, I could email a couple of photos.
  • ReinierReinier Registered Users Posts: 13
    Re: Trying to understand my solar water heating system...

    Thanks to all for the answers so far, I appreciate it.
    I climbed up the roof today to inspect the collectors a bit better, hoping to find out about the amount of fluid in them. Having those collectors up so high (8m/26ft, 45 degrees slanted roof...) is definitely impractical, I would much rather have them placed somewhere near to the ground so I can actually move around without fear. For now, I decided not to do much more than taking two pictures.
    Even if it eventually turns out to be too expensive to repair, I still would like to figure out how the thing is supposed to work exactly and what is wrong currently with it. I will follow some of your tips and let you know the progress, or any new questions.

    Reinier
  • ReinierReinier Registered Users Posts: 13
    Re: Trying to understand my solar water heating system...

    Bill,
    BB. wrote: »
    If you have a check valve or well--Then if you don't have a expansion tank, it can over pressure you water system (tanks, etc.) and/or cause the Temperature/Pressure valve (typically set at 150 PSI and 210F), to vent a bit of water (around a 1/2 gallon per 40 gallons of hot water from cold to hot).

    I took a picture which shows the bottom of the tank. Does this horizontal outlet look it is supposed to vent water if needed?

    Attachment not found.

    Thanks,
    Reinier
  • BB.BB. Super Moderators, Administrators Posts: 29,489 admin
    Re: Trying to understand my solar water heating system...

    I cannot tell if the riser on the right to the top/side of the tank is a T&P Vent or something plumbed into a T&P vent on the side of the tank.

    Is the pipe open or capped on the right? If Capped, that could be your tank drain with the blue valve the drain valve. The valve under the pump does not make a lot of sense--There should be a valve isolating the tank so you can drain the solar panels...

    But, the two capped pipes above/below the pump almost look like where you could introduce anti-freeze into the panel loop. But I cannot tell if the loop is really a secondary fluid path separate from the domestic hot water tank (I assume this is a domestic "fresh" water heating system and not a "hydronic" recirculating boiler for home heating.

    It appears the pump pulls "cool" water from the base of the tank and pumps it up to the solar panels on the top of the roof (the direction for your flow gauge appears to be "up").

    You might try cracking open any plugged lines or unions to see if there is fresh water or anti-freeze in the loop (without an expansion tank somewhere would be useless--It would over pressure and vent anti-freeze without such a expansion tank).

    Be careful--The system might be shut down--or else with your hard freezes (I assume), you will end up with broken and leaking pipes/collectors).

    If you do go with solar hot water--You might think about mounting vertical on a south facing wall. Many systems tend to overheat in summer, so having the panel raised (more towards vertical) tends to reduce the amount of heat collected in summer and biased towards fall/spring (and winter if you go with anti-freeze and keep the panels above the snow line).

    Using PV Watts for Sidney NS, first at 46 degrees, second at 90 degrees:
    Month      Solar Radiation (kWh/m2/day)
    1      2.93     
    2      3.52     
    3      4.33     
    4      4.38     
    5      4.80     
    6      5.35     
    7      4.60     
    8      4.89     
    9      4.43     
    10      3.32     
    11      2.00     
    12      2.32     
    Year      3.91
    

    And 90 Degrees (vertical)
    Month       Solar Radiation (kWh/m2/day)
    1      2.86     
    2      3.05     
    3      3.23     
    4      2.65     
    5      2.54     
    6      2.52     
    7      2.31     
    8      2.83     
    9      3.10     
    10      2.80     
    11      1.86     
    12      2.34     
    Year      2.67
    

    Hmm... Does not do much for "winter months" to be vertical. Does cut down the summer collection. I guess it depends if you ~double the size of the array and run anti-freeze for winter collection (if it is even worth it)...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • RybrenRybren Solar Expert Posts: 348
    Re: Trying to understand my solar water heating system...
    No Rybren, I don't, but if you PM you're email address, I could email a couple of photos.

    PM has been sent.
  • ReinierReinier Registered Users Posts: 13
    Re: Trying to understand my solar water heating system...

    Today I made progress: the differential controller seems to be broken. Like Tony suggested earlier, I bypassed the controller and then the pump started running -- sounded like music to me ;-) The pipes and tank started gurgling and the flow meter I posted earlier was completely full. I have not yet waited to see any rise of temperature in the tank, because it was night already when I did this. Tomorrow is supposed to be sunny...

    The broken controller is a Delta-T Heliotrope DTT-84 (http://www.aurorapower.net/pdf_reference/Solar_Hot_Water/delta-t-install-manual.pdf). Would it be worth the effort to try and repair it, or have it repaired? Anybody have any experience with that? If not, any suggestions for a good replacement? I need one that has anti-freeze protection. With Bill's remarks, and after closer inspection, I have drawn the new conclusion that the system is directly connected to my home water supply.

    Bill: thanks for the numbers and suggestions. Once I have this up and running, I will have a more close look at them again.

    Reinier
  • solar_davesolar_dave Solar Expert Posts: 2,343 ✭✭✭✭
    Re: Trying to understand my solar water heating system...

    My system uses a goldline GL 30 and is has the capabilities you,are looking for about $150 or better if you shop it a bit.
  • icarusicarus Solar Expert Posts: 5,233 ✭✭✭✭
    Re: Trying to understand my solar water heating system...

    Azel (http://www.azeltec.com/catalog.0.html.0.html) makes a nice differential controller, with a freeze prevention mode,, for under $$100 if memory serves,, probably higher now.


    I have used goldline as well, but I'm not sure they are still around?


    Tony
  • solar_davesolar_dave Solar Expert Posts: 2,343 ✭✭✭✭
    Re: Trying to understand my solar water heating system...
    icarus wrote: »
    Azel (http://www.azeltec.com/catalog.0.html.0.html) makes a nice differential controller, with a freeze prevention mode,, for under $$100 if memory serves,, probably higher now.


    I have used goldline as well, but I'm not sure they are still around?




    Tony
    Source for Goldline, YMMV
    http://shop.solardirect.com/product_info.php?products_id=151
  • ReinierReinier Registered Users Posts: 13
    Re: Trying to understand my solar water heating system...

    An update if anybody is still interested in this thread: today I finally figured out that my system is actually a drain back system, filled with regular water. With that conclusion, a lot of pieces of the puzzle come together. Not knowing anything about solar heating previously, the idea of continuously pumping water through the collectors (as opposed to the water mostly sitting still) seemed so silly and inefficient to me that I did not give it a serious thought...

    One remaining thing I am not sure about is how to determine the water level in the tank. There is no glass tube or anything like that. I think I figured out which valves to open to add water to the tank, but how do I know when to stop? There is a spill tube, is it safe to fill up the tank until it spills?

    Thanks,
    Reinier
  • BB.BB. Super Moderators, Administrators Posts: 29,489 admin
    Re: Trying to understand my solar water heating system...

    Your tank should be simply like an electric water heater. Full city (or well) pressure when "active". And the solar thermal array will also be at city water pressure. The pump moves water (hopefully cooler water) from the tank to the thermal array to get heated and returned to the tank.

    Drain back, depending on your system/climate, the drain back can be just from the solar panels and their plumbing... Or you could drain out the whole water storage tank too.

    Guessing (I don't have solar hot water and don't live in a freezing climate)... You can have solar panel drain back at night (below ~40F temperatures) as a daily event in late fall/early spring... Or you could drain the whole system (including storage tank) for winter shutdown (if you get freezing temps where the tank is located).

    The solar panel drain back may be automatic or manual. The whole tank drain would (guessing again) be manual (you don't want to dump 50-80 gallons of water every night it goes below 40F).

    There is also the possibility that the solar thermal panels may have a thermal relief (turn on a small valve to pull water from the tank through the array/plumbing) during soft freezes. As well as an over temperature/overpressure relief too (safety).

    And, possibly an air vent at the top of the array to prevent "air lock" when refilling the thermal array.

    And/or the pump turns on (again in sub 40F weather) to circulate tank water through the solar thermal array/plumbing (again, during soft freezes) which wastes a bit of the stored heat.

    You may have one or a combination of several in your system.

    Solarroofs.com has some nice diagrams of the various systems:

    http://www.solarroofs.com/tanks.html

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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