Solar hot water - Poly pipe collector

It was a chilly and windy day in the hills today. But the sun was out for a while in the morning.

The ambient temperature was around 11°C as I added the rest of the T junctions to my new poly pipe collector, and I was almost confident that I'd sooner or later, be making some solar hot water. 

The water temperatere was around 10°C from my rainwater tank.

It was interesting to note the temperature of the collector was very close to the temperature of the storage tank, and the air temperature in the collector stayed low. (digital thermometer is testing water temperature and the glass one is testing air temp in the collector) 
No doubt this means that the heat exchange area of the black poly pipe is sufficient. This came as a bit of a surprise to me, although in hindsight it would appear that the transfer rate is self governing to some degree. The hotter the water gets, the faster it will flow and thus the more heat exchange will occur.




Final temp before it started raining and I went inside was only 22°C, and it didn't get any higher in the overcast, windy and rainy conditions, even when I went outside hours later. But, I think it was actually a success. I doubled the temperature of the water and it only took an hour and a half. 


Given I only used two sheets of corflute for insulation, and the insulation for the top, bottom, and sides was just tape, which isn't really insulation it's really just tape, It did about as well as I hoped.


The experiment served its purpose in that I learnt a few things and didn't cost anything as I'll be pulling it apart and using all the bits in the real thing.


Lessons learnt ...

• Air bubbles are not your friend. Don't let them collect.
• You don't need a lot of tubing to shift a lot of heat from a collector.
• Insulation is amazingly important. (tape leaks heat so that you can feel it leaking)
• A tube based solar siphon regulates itself, so there wont be any issues with the collector overheating.
• Even at the rate this poorly constructed solar collector collected heat, it would still be worth using it as a bathroom heater or something*. On a bigger scale without changing anything except scale I could heat my house by building a wall out of water tank and simply circulating the water to my collector.
• Collecting free energy is a worthwhile pastime.
• I'm not very skilled at gluing.
• there was a reason I collected all that 19mm poly pipe for all those years, even though it had holes in it every few metres, and kinks in the sections between the holes.

*Hmmm towel heater...

Aquaponics - Water testing

Its extremely important to make sure your water quality is within a desirable range. Aquaponics is remarkably stable and robust, but, for the first few weeks of setting up a new system it can require a little extra care. The best way to avoid any problems is to test your water every day until your system is mature and in balance or "cycled". (pictured here taking 30 days or so)

An aquaponics system is said to be cycled when it can process approximately 1 ppm of ammonia into nitrites and then process those nitrites into nitrates within 24 hours.

A decent freshwater test kit will enable you to get accurate test results for pH, ammonia, nitrites, and nitrates. It will set you back around 50 Australian dollars. They are widely available online or any good aquarium shop should sell them.

If you try aquaponics without water testing you will lose fish unless you are very lucky.

Add ammonia until you see a reading of 2ppm, then wait until your tests show ammonia is 0. Then add more and continue until your system can process 1ppm of ammonia and nitrites in 24 hours. Once you see readings of 0 ammonia and 0 nitrites you are cycled and can add fish.

Plants can be added on the day you first build your system but there wont be much for them to live on for a few days. My house water supply is rainwater and has some nitrates in it from normal environmental nutrient. Even normal tap water will have some nitrates in it so there will actually be something for small seedlings to live on.

Be careful to wash the soil from any store bought seedlings you transplant as they may have any number of additives that may be toxic to an aquaponics system. Growing directly in the grow beds from seeds is safest (and often quicker!)

Conduct water testing every day until you are cycled and then test every week or so or if ever anything strange occurs. Plants yellowing or dying can be a sign of something being wrong with your water chemistry and you might need to intervene in the early stages of your aquaponics system setup. More on correcting water problems later.

Always keep a record of your tests so that you can see emerging trends before they become an issue.