Noodle Check - Solar Heating while away?

[Rednecktek]

So inspired by another thread, and honestly a little rum, I had a noodle to bounce off everyone.

My boss has a couple of the coil-of-tubing-in-a-box solar water heaters for his pool in Cali and I'm wondering if something similar couldn't be set up to keep a place warm-ish when unattended without having to spend $$UberMoney on batteries and system to support a mini-split or the like. Here's my thought with a krappy MSPaint sketch of what I'm thinking:

A small 12v or 24v system, doesn't need to be much...
A couple of the tube-in-a-box solar water heaters...
A coil in a box or repurposed radiator from a car would be better...
A DC fan, maybe from a small car that uses electric fans anyways...
A DC water pump...
A few gallons of antifreeze mix...
A DC thermostat...
A photocell so it only pumps water when the sun is out warming up the antifreeze...

Put the heaters outside in the sun, pipe them to the pump, pump goes inside to the radiator, out of the radiator and back to the boxes outside. Fill the whole thing with antifreeze mix so it'll stay liquid even at $StupidCold temps. Set up the DC thermostat to turn on the pump AND the fan at say 50F and shut off at 75F. When it gets cold inside the pump and fan kick on pumping the sun heated antifreeze through the radiator and into the house. When it gets warm inside the fan and pump shut off so you don't cook yourself in summer. The photocell would only allow the pump to run when the sun is out and warming up the antifreeze so it's not blowing cold air around inside all night.

Thoughts?

 

[Frank in Thailand]

Good idea!

Personally I would not use a photocell to start/ stop the pump, but temperature sensor.
inside / outside (tubing temp) difference 5 degrees before starting the pump and fans.
There probably are some (cheap) standard switches that do this, or easy with arduino.
Last one will also alow you to set a maximum temperature

 

[Rednecktek]

Personally I would not use a photocell to start/ stop the pump, but temperature sensor.

My idea was based on a temp sensor to control the pump & fan, the photocell would just prevent it from coming on at night when the coils were full of cold water to prevent blowing cold air around at night.

An arduino would give you lots of options, but I can't make "Hello World" work so I pretty much never go there.

 

[Daddy Tanuki]

An arduino would give you lots of options, but I can't make "Hello World" work so I pretty much never go there.

me too! I am hopelessly analog... but its hard to hack a thermo switch that's not connected to the IOT.

 

[efficientPV]

These home made systems aren't as efficient as the evacuated tube systems and when you add everything up they aren't cheap. I think the answer to everything is electricity. Odd that everyone on a solar forum ahs a dire fear of it. Here is my little heater. Thee oil finned heaters can be found curbside when their cheap controls fail. This one operates at only 60V and frankly that is all I would put into it. At 400W it is no longer touch safe.

 

[Crowz]

So inspired by another thread, and honestly a little rum, I had a noodle to bounce off everyone.

My boss has a couple of the coil-of-tubing-in-a-box solar water heaters for his pool in Cali and I'm wondering if something similar couldn't be set up to keep a place warm-ish when unattended without having to spend $$UberMoney on batteries and system to support a mini-split or the like. Here's my thought with a krappy MSPaint sketch of what I'm thinking:

A small 12v or 24v system, doesn't need to be much...
A couple of the tube-in-a-box solar water heaters...
A coil in a box or repurposed radiator from a car would be better...
A DC fan, maybe from a small car that uses electric fans anyways...
A DC water pump...
A few gallons of antifreeze mix...
A DC thermostat...
A photocell so it only pumps water when the sun is out warming up the antifreeze...

Put the heaters outside in the sun, pipe them to the pump, pump goes inside to the radiator, out of the radiator and back to the boxes outside. Fill the whole thing with antifreeze mix so it'll stay liquid even at $StupidCold temps. Set up the DC thermostat to turn on the pump AND the fan at say 50F and shut off at 75F. When it gets cold inside the pump and fan kick on pumping the sun heated antifreeze through the radiator and into the house. When it gets warm inside the fan and pump shut off so you don't cook yourself in summer. The photocell would only allow the pump to run when the sun is out and warming up the antifreeze so it's not blowing cold air around inside all night.

Thoughts?

Old thread but I just ran across it. I did this at my old home kinda.

You don't need radiators or anything more than some black paint, plexiglass or another clear firm covering and some dc fans.

You build a few enclosures on the sun facing walls of the house. My first test of doing this was boards turned on edge attached to the outer wall.

The house outer wall is painted black between the boards and clear plexiglass placed across the boards and screwed to them. Then you cut a slot at the top and the bottom of the painted area into the house. A fan blows air from inside of the house into the bottom slot and it returns via the top slot into the house. Heated very nicely. How large an area you want to cover this way will determine how much heat you get of course. The only running cost is the fans.

On a 28F degree day at lunchtime the living floor air temp was 60F and ceiling return was 73F best I remember.

 

[Crowz]

I did some googling just now and found a diagram that matches what I did.