solar water heat

ws9876 · January 2018

if you were doing a solar hot water drainback setup would you use this to turn on your circulator pump??
https://www.amazon.com/Inkbird-All-Purpose-Temperature-Controller-Fahrenheit/dp/B00OXPE8U6
or is there a cheaper way???

westbranch · January 2018

I am not following your logic for draining the system daily. Are you just heating water without antifreeze?

ws9876 · January 2018

yes but I would drainback no matter ...why leave fluid out in the cold??

westbranch · January 2018

what happens when those evacuated tubes are in the direct morning sunshine and there is no fluid to transfer the energy (Heat) to? I can understand not circulating the fluid....
plus the fact that you will have introduced air into the fluid and have tp get it out again

ws9876 · January 2018

drainback systems are common. They wouldnt be if they didnt work. Maybe you have to use a specific kind of panel.Vents in the panels let out pressure. I am wanting to find out who makes the diff controllers that are cheap and work with SHW systems. I assume they need 2 probes ,one on each end.?? And how much is a decent Grundfos or Taco pump..maybe DC is better run on a solar panel.

BB. · January 2018

This guy wrote some nice articles about his solar heating system (and mistakes along the way):

http://www.arttec.net/Solar/BarnHeat.html

He even ended up designing and marketing his own controller (I guess he is still selling them, he started almost 20 years ago):

http://arttecsolar.com/

Anyway, some information.

Regarding your drain back system... Most people design them for drain back once at the beginning of winter and charge them backup after freezes are over in the early spring. Your system you plan to drainback every operational cycle (every evening)?

-Bill

Dave Angelini · January 2018

BB. said:

Regarding your drain back system... Most people design them for drain back once at the beginning of winter and charge them backup after freezes are over in the early spring. Your system you plan to drainback every operational cycle (every evening)?

-Bill

I think you are mixing this up Bill

Most people use drainback all year long and in very cold places! I do and have for many years for clients all over the place, Many!

To the OP, it can be as simple as a thermo switches to power the pump and shut off by a thermo switch at desired temp, or a full blown controller.

ws9876 · January 2018

btw I need to run 100 ft of pipe for this panel. I cant afford copper. What do you think about Pex AL Pex..I will need to build the panel of PEX too.
.I have the tools for it.
Copper is such a hassle to solder. what do you think??

Estragon · January 2018

I used pex for both potable and infloor heating, and it has worked well in both cases. Just need to be careful with fitting locations, and UV exposure. The pipe itself can generally handle freezing with some water left in it, but fittings don't.

If buried or otherwise covered, it should be ok to use instead of copper for the home run. Heating applications can run hotter than normal potable, so you'll want the pipe and insulation made for heating. Some pex may have some UV protection, but I doubt even that would last long if used in the collector panel. The pex I've used is rated for 30 days max exposure to sunlight.

My black poly water line pipe from the lake OTOH, has been lying in the sun for decades and is fine.

ws9876 · January 2018

the most expensive thing is a heat exchange 30 ga water tank with 2 coils. One coil for solar and one for wood stove.I saw on the net some lady built a square box with a rubber lining as an exchange tank. The new factory ones cost WAY too much. I was thinking a plastic tank.
running 2 coils of PEX thru that would be do able. It would have to be thick walled and sturdy.

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