Any how my wife has been wanting to move in a greener direction and has been rather matter a fact about it as well. We now compost our organic waste and recycle that in to our garden. Her new kick was "How can we heat the spa without using the electronic heater?" She got up on the roof with 50ft of black hose and ran it back and forth a few times, hooked it to a pump and came up with the proof of concept. Yay! [The original idea was sourced from my coworker Gary which has a similar setup for his pool]
Today we decided to move from conceptual proof to full on production. This instructable will walk you through the process that we went through and try to help you avoid some of the gotchas that we found along the way. Hope you enjoy reading this as much as we enjoyed building/documenting this project.
Step 1: Parts list
20ft of 1/2in diameter PVC pipe
1 x 1/2in 4-way Cross PVC Fitting
PVC cement for gluing PVC sections to 4 way fitting
500ft 1/2in diameter black drip irrigation hose
2 x drip irrigation to standard garden hose coupling
Around 200 outdoor 8in zip ties
2 x 25ft or so normal garden hoses to use as water feed and return (Not included in $60 est as we had 2 on hand)
1 water pump to push water up to the roof and through the solar coil for heating. (Also not included in $60 est as we had one on hand)
Step 2: Frame Setup
Step 3: Work area setup
The spool unwinding was managed by my wife for the most part and my son helped guide the hose while I walked in circles like a carnival mule.
Step 4: Spiral construction at a snails pace.
The hose was spun on to the frame starting at the middle and working outwards. We took a lead of around 6ft and attached to one leg of the frame, then we guided it in to the middle to begin the spiral. There were issues with kinks and worked out that at around 5in from the lip of the fitting the curve was easy enough that we could form the shape without kinking the hose. I marked out this 5 in using a marker and fastened the hose to the frame to begin the spiral. Working in chunks of around 4 to 5 rotations seems to work well until the later stages of construction. After each set of rotations you loosely fasten the hose using zip ties. Working from the last tightened point you guide the coil so that the hose sits evenly next to the previous loop. Too tight and it will overlap, too loose and it will cause grief on the next loop.
Step 5: Completion of the spiral
Step 6: Spiral deployment and finishing touches
I will update this instructable with thermal findings once we get a full day to test the system.
Step 7: Full Integration
Step 8: Results
Time - Spa - Water from Solar coil
09:32am - 82.2 - 93.9
11:11am - 85.8 - 93.9
01:03pm - 91.0 - 101.1
01:57pm - 93.9 - 104.3 * Peak reading
03:37pm - 96.8 - 106.8
04:18pm - 98.6 - 103.8
Total increase over the time we monitored: 16.4 degrees fahrenheit