Anthony-Sylvan by any chance? (The hose bibb and 'main drain return' are two things they do that most do not.)
To turn off both skimmers, the handle on the left most valve should point to the left. For both on, it points to the right. Select either one by having it point front or rear. You can also turn off both skimmers by turning the center handle to the right.
The way the Jandy valves work is the closing gate is opposite the handle. So if the nose (my word for the pointer opposite the handle) points at a pipe, that pipe is closed. If the nose points to the side of the valve with no pipe, then flow is unrestricted among all the pipes going to the valve.
The Main Drain Return is a trick A-S builds into their systems that allows the return to flow through the main drain instead of the wall returns. In theory, you can use it in the spring to accelerate warm-up by pulling water off the top and returning it at the bottom. It seems to work. Obviously, the main drain return valve and the main drain valve cannot be open at the same time, or you will be just recirculating water in a very short loop that does not reach the pool.
It also makes blowing out your lines a little tricky. Getting the order right is key. The way I do mine is:
Blow skimmers first. Open each skimmer in sequence (forward first, and then back on left valve, middle one with handle to the left, closing off main drain. MP at closed. I inject air from my compressor at the handy-dandy hose bibb. I apply 15 psi air, and use the hose valve to cycle it in bursts through each skimmer until no more water is blown out the pipe.Then plug skimmers at pool and leave left valve handle pointing to left closing both skimmers.
Then blow main drain from suction side. Center valve handle to the right. Right valve handle to the right. Open hose bibb and you should see a lot of air coming out the drain. Move center valve handle to left and quickly close down air. This locks air into main drain. Do not touch valves again. They should be with handles left-left-right.
Now the return side. Set MP to Recirc. Apply air which should now blow out returns. If below water line plug returns. You will want to cut air to maybe 6 Psi. I prefer to drop the water below returns and use the full 15psi. I plug all but the one return farthest from the filter and then blow it. Plug that and unplug second furthest. And so on. Then I blow the first one again and replug. Again, use the hose bibb to cycle air in bursts until no water comes out pool end of returns. Finally, set MP to Winter or halfway between any two settings if no Winter position.
You're done. Now open and drain filter, heater, etc.
