Hi
 Just joined and am looking for some advice on a radiant floor I am setting up.  The foot print of my radiant floor is 28x 80 ft basement. I used 2"of pink board under a 5" cement slab with 1"around the perimeter. I laid 1/2 pex in 9 zones, each zone is 275' before the pour on top of the pink board.  I found 5 flat plate solar collectors for a price I couldn't refuse. Each panel s 40 sq ft for a total of 200 sq ft of panel with an over all southern view. Panels will be run in parallel, and have 3/4 inch copper inlet and outlets. This will be a closed loop system using gycol.
  My question is what size pump to run? I am a full believer in the kiss principle (keep it simple stupid) so have been thinking of using a pv powered pump. When the sun is out the panels heat, the pump runs. No sensors used. I looked at an el-sid pump that is a 20 watt pushing 5-6 gal/min.  Is that enough pump?
 Any thoughts, ideas help or suggesgtions would be welcomed.

Are you talking 9 loops of half inch PEX plumbed in parallel, 275' each? ("Zone" means something else in the heating trades)

At what head/pressure does that 20watt pump move 5-6gpm? (I'd be surprised if it's enough pump, but we don't know enough to say with absolute certainty.) How much head are the panels? The head of the PEX can be calculated, once we know for sure the configuration.

I'm thinking 200' of hydronic solar panel isn't a whole lot to be the primary heating of 2240' of living space in many climates unless it's well insulated and super tight, but it'll likely be enough to create serious overheating issues in the warmer shoulder-months. Hopefully you've designed in some means of heat dumping. Using a PID-algorithm thermostat for controlling the room temp would be a good idea too. A "look ma, no controls" KISS approach just won't work 365 days out of the year, if you care what temp the room hits. (I'm assuming 90-100F room temps might be bit much if humans are supposed to live there.)

The best systems start with a real design. Study up on solar & hydronic design before committing to an approach here (or hire somebody to design it for you.) There are many places where you can shoot yourself in the foot. KISS can work for domestic hot water pre-heat, provided it's somewhat under-sized. Space heating loads are much more variable, and the solar output peaks during seasons of less (or no) load. But even during the deepest part of the heating season you may need more than just a 5" slab to buffer the output.

Hi
Thanks for the reply. Your right my term of zone was off base. This is for a basement so it is going to be 1 zone of 9 parallel loops. The head of the pump isn't much from what I can find from their homepage,ie el-sid pumps. Looks like about 3-4 gpm at 36" head and 5gpm at 30". The panels, no idea as I cannot find any manufacture on them. So it would be a guess from other panels online the same size and tube dia.Ie, 4x10 panel 3/4" supply and discharge .
Since this is an unheated walkout basement with r19 walls, I am not looking for greatness just help taking the chill off as I work down there, and free heat is my kind of ok! The home is in the mountains of N.C. so climate is moderate. The home upstairs is SIP's and pretty tight. I use a heat pump as backup and high efec. fireplace for main heat. Last year I used around 1 1/2- 2 cords of hardwood for 3000 sq ft of home.
The panels will be ground level almost vertical, so they can catch winter sun, and I plan on covering them in the summer when not needed. I did this to some air collectors in Colo and it worked pretty well.
I do like the thought of having minimal control to run the system. Again when in colo I had a solar domestic hot water system and the only problems I had were from the control box. On the other hand my air system had just a temp sense snap disk to turn on the fan and never gave me a prob in ten years of using it. Both systems were home built.
Being hard headed and set in my old and maybe not so smart ways I stilll feel like going down the "kiss" road right now. If it ends up giving me to hot of a basement I can always setup a control panel next year. Maybe run a heat exchanger to storage for a hot water preheat or the such. Or just move a ball valve a bit to slow down volume if the basement gets a bit warm in march. You know simple ways for a simple, well never mind....
But for the moment, what would you guess for gal flow rate I would need. And any recomends of a pv powered pump to give me that needed flow.

You might consider a drain back, still use your glycol if you are in an upper latitude, but now you do not have to worry about a heat dump.
just a thought.
Dan

Dan
Thanks for the thought, I hadn't really concidered that and it might just work. I will need to run a couple of elavations but it should work. I would need to locate the pump/storage tank at a different location but not a big problem. If I go that route I would need a pump that has more head than the ones I have been looking at. Do you know of any pv pumps that can give me 10 ft of head while giving enough gpm? Still not sure what a proper gpm would be. From what I have been reading I would need at least a bit over 1 gpm per panel or around 6gpm, and not sure yet about the needed gpm for the floor run. Again the floor is 9 275 ft runs of 1/2 inch pex run parallel.