Control System and Circulation Pump for Solar Collectors

[NMTrains]

Hello there,

So my experiments are producing fruit, now to refine it's operation. Currently I am running it manually.

I am now looking for two things.

1) a 120v pump, that can move 50 to 100 GPH, 50 ideal, the that can handle a head of 12'

2) a simple programmable control system that can detect input and output water temps and decide if it should turn on the pump or not

As for #2, someone must make something like this, so I shouldn't have to reinvent the wheel. I found this but I am leary http://www.amazon.com/TK-SC6-Electro.../dp/B003SVLPZ2

[skeeter_ca]

I assume you mean 50 - 100 gallons per minute?

The controller does have some decent reviews with really the only red flag being it says 110v but actually uses 220v. That would warrant a little investigation if I were buying it.

skeeter

[J.P.M.]

Solar differential controllers are readily available. Again, Google is your friend.

[NMTrains]

I assume you mean 50 - 100 gallons per minute?

skeeter

No 50 -100 GPH

If we need to talk GPM, then .84 - 1.68 GPM, leaning to the .84 side of things.

[J.P.M.]

No 50 -100 GPH If we need to talk GPM, then .84 - 1.68 GPM, leaning to the .84 side of things.

Get a pump that will handle a somewhat, but not grotesquely larger flow than you think you need and throttle the pump outlet with a ball valve. That's probably what you'll wind up with anyway. Some oversizing is to be expected. Also, some flexibility is always nice.

[NMTrains]

Get a pump that will handle a somewhat, but not grotesquely larger flow than you think you need and throttle the pump outlet with a ball valve. That's probably what you'll wind up with anyway. Some oversizing is to be expected. Also, some flexibility is always nice.

I have already realized that, so I have ordered a "Little Giant" 2E-38N. It should do about 70 GPH at 10' head, and will tolerate a restrictor (if I want to try throttling it back).

The idea of getting the pump sized correctly is first most minimizing power consumption.

As to the differential controller, for now I have it being run manually. If I can find a canned one fairly priced, I'll go that route. Heck, I'll make my own, but why reinvent the wheel.

I saw the 240v requirement, and there is some confusion on if it can be used on 120v. In my case, it wouldn't matter because I have a couple of 240v-120v converters in my inventory.

[J.P.M.]

I have already realized that, so I have ordered a "Little Giant" 2E-38N. It should do about 70 GPH at 10' head, and will tolerate a restrictor (if I want to try throttling it back). The idea of getting the pump sized correctly is first most minimizing power consumption. As to the differential controller, for now I have it being run manually. If I can find a canned one fairly priced, I'll go that route. Heck, I'll make my own, but why reinvent the wheel. I saw the 240v requirement, and there is some confusion on if it can be used on 120v. In my case, it wouldn't matter because I have a couple of 240v-120v converters in my inventory.

Understood and generally agreed. I'd only respectfully offer that minimizing power consumption at the expense of other helpful and convenient considerations for the operation, maint. and testing of the system, and for future considerations may be worth thinking about. FWIW, I've found that the best all round selection for an application usually is the result of consideration of more than one criterion. Hence, a slight oversize - again, which will probably happen as a result of availability of pumps.

[skeeter_ca]

What size pool and what kind of solar panel are you using?

skeeter

[NMTrains]

200 gal 3 person spa.

Solar collector is 360' 1/2" polyethylene distribution tubing on the patio canopy roof. 3 120' parallel circuits.

[skeeter_ca]

Ahh, I see......tiny volume needs tiny pump.

skeeter

[NMTrains]

Yep,

So as you can see my requirements fit my application.

So my $140 investment in tubing, (and my time, but I'm retired so that isn't worth anything) looks to be producing about 9000 BTU's/hr.

My purpose in this exercise is to play with it, reuse material that I have and save a tree.

It's fun and I'm not hurting anyone.

I picked up a broken hot tub and my total investment so far is $570 for EVERYTHING! And I and my spouse of 41 years sat in 100 degree water right after I filled it yesterday. Of course I ran the fill water through the collector.

I am getting ready to soak with a Miller in a bit, so I guess we're pleased. Overnight, ambient air got down to 63, and the tub lost 8 degrees. I've got a 12v transfer pump that I won't be using it as soon as the Little Giant comes, and in an hour I have it back to 100 degrees in about an hour and a half.

I am actually going to go farther and put a retrofit kit in it. Our first idea was to use it only as a dip pool during the summer, I may go farther and try to at least extend the season if not year round.