Trying to understand my solar water heating system...

[BB.]

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).

[waynefromnscanada]

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.

[Rybren]

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

[waynefromnscanada]

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.

[Reinier]

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

[Reinier]

Bill,

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?



Thanks,
Reinier

[BB.]

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

[Rybren]

No Rybren, I don't, but if you PM you're email address, I could email a couple of photos.

PM has been sent.

[Reinier]

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_refer...all-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_dave]

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.