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buffalobillpatrick · 06-30-14, 11:08 AM

I'm leaning toward using NG boiler along with HP DSH to heat DHW.
COP balance point looks to be about 3.0

If I use HP to only heat the radiant floors via ST120 buffer tank, (ODR controlled temp).

I would use my 360ft2 solar array to heat the 1,000 gal. solar storage tank, insulate top.

Tank has surface area of sides + bottom = 120ft2
500' 3/4 pipe has surface area = 115ft2
So about 580ft2 total in direct contact with my crappy heat transfer gravel soil type GP.

I expect to have an abundance of solar heat even in winter.

Heat from this solar storage tank would be pumped out through the 4 x 500' slinky loops, I read that I need about 6gpm for my 2T HP. That would be 1.5 gpm through each loop, about 10' head loss. A Taco brass 008 should work fine here.

The question is: must I use antifreeze in loops?

Cold water from HP would 1st go through the solar storage tank, pick up heat & then distribute it in slinky loops. water back from slinky loops source HP.

My choice would be PG or Etheyl alcohol in loops (I don't want to accidently poison my water well.)

If antifreeze isn't required in my abundant solar situation, then I would not need the HX in solar tank. Water only needs about 1 GPM to start turbulent flow in 3/4 pipe , but glycol or alcohol needs about 3.5 GPM.

5 Tips on Designing Vertical or Slinky Geothermal Loop Fields | HeatSpring Magazine

06-30-14, 11:08 AM	#9
buffalobillpatrick Master EcoRenovator Join Date: Mar 2014 Location: Florissant, Colorado Posts: 599 Thanks: 814 Thanked 59 Times in 55 Posts	I'm leaning toward using NG boiler along with HP DSH to heat DHW. COP balance point looks to be about 3.0 If I use HP to only heat the radiant floors via ST120 buffer tank, (ODR controlled temp). I would use my 360ft2 solar array to heat the 1,000 gal. solar storage tank, insulate top. Tank has surface area of sides + bottom = 120ft2 500' 3/4 pipe has surface area = 115ft2 So about 580ft2 total in direct contact with my crappy heat transfer gravel soil type GP. I expect to have an abundance of solar heat even in winter. Heat from this solar storage tank would be pumped out through the 4 x 500' slinky loops, I read that I need about 6gpm for my 2T HP. That would be 1.5 gpm through each loop, about 10' head loss. A Taco brass 008 should work fine here. The question is: must I use antifreeze in loops? Cold water from HP would 1st go through the solar storage tank, pick up heat & then distribute it in slinky loops. water back from slinky loops source HP. My choice would be PG or Etheyl alcohol in loops (I don't want to accidently poison my water well.) If antifreeze isn't required in my abundant solar situation, then I would not need the HX in solar tank. Water only needs about 1 GPM to start turbulent flow in 3/4 pipe , but glycol or alcohol needs about 3.5 GPM. 5 Tips on Designing Vertical or Slinky Geothermal Loop Fields \| HeatSpring Magazine Last edited by buffalobillpatrick; 06-30-14 at 11:43 AM..