Step 17: Other options
- I have also added a solar boost loop to this by attaching a T-junction to the hot water inlet for a garden hose attachment.
- I have 30m of black polytube that I attach to the bottom outlet and hot water inlet. Use a one way valve on the cold water outlet pipe at the bottom of the tank to stop the tub from reverse thermo-siphoning at night. String the tubing out on the lawn in full sun. I don't know how effective this is yet - I'll keep you posted - but it should add a couple of degrees at least and reduce the burn time.
Either I haven't had this connected long enough in hot enough conditions or my loop is too short, but this technique's a non-starter :(
On the up side the new house I'm building has a 30 evacuated tube solar hot water heater and a wood fired wetback so hot water should be in plentiful supply in summer!
- I am toying with adding a 12v pump to the cold inlet to scoot the water through a bit faster. The thermosiphon works but 4 hrs is a long time to wait.
I recently bought a 2nd hand intex inflatable pool pump and set this up to pump water from the bottom outlet of the tub to the cold inlet of the heating coil. You need to buy a few doohickeys to connect everything up properly but it's very straightforward. The results are interesting. The heat up times are not dramatically affected by active pumping (it may give you a 1/2 hour on the thermosiphon method), but it totally eliminates the flash boiling of the water in the heating coil. This is great because I've been poached a few times by the hot water inlet!
BTW - Thanks everyone for your comments and support!