The Hydrostatic valve is usually on the lowest part of the pools floor. The hydrostatic valve is there to protect the pool from being lifted by ground water in the event that it is empty. it allows the ground water under the pool to get into the pool thereby stopping it from floating out of the ground on top of the ground water.
Any pool can have a hydrostatic valve and nothing has been made that cannot be broken eventually.
Yes just be careful that the hydrostatic valve works in case of ground water causing the pool to start floating.
If it still works, it will open before the pool is completely empty. But are you sure the valve is hydrostatic? If it is not, then you will need to shop-vac the water remaining over the bottom drain, remove the drain cover, shop-vac the water under the cover, and then remove the lug nut and slide out the (manual) relief valve.
Perhaps it is not a drain but a hydrostatic valve. These are fitted at the bottoms of pools to let ground water that has built up under an empty pool into the pool in order to stop it from floating out of the ground.
If there is no drain valve at the radiator you can drain the system at the drain valve on the boiler
I don't know about your pool I do know however that most pool don't have a way out for the water other then through the static skimmer. and people often mistake the hydrostatic valve at the bottom of the pool as the pool drain
the hydrostatic valve is only to equalize pressure of ground water to that of the pool the only time it does anything is when the water table becomes higher in the ground water than in the swimming pool . it doesn't connect to anything. it is simply to keep the pool shell from floating out of the ground
There should be a drain valve where you can hook up a hose and then open the valve to drain.
For as long as you like just make sure that the pool has a hydrostatic valve or some other means to stop it from floating out of the ground if it starts raining or the water table underneath it rises. In gunite and concrete pools, the hydrostatic relief valve is located in the bottom drain. Sump or ShopVac the remaining water covering the drain, take out the screws, and remove the cover. Again, using a ShopVac, remove the water just beneath the cover and look inside the drain. There are two possibilities: 1) a relief valve that can be unscrewed and removed, or 2) a second pipe that doesn't point toward your pump and filter. Inside this pipe is a hydrostatic relief valve that probably won't open because of sand or dirt clogging it. Using the handle of a short screwdriver, tap the valve inside the pipe (you may not see it, but it is there) several times until water comes into the pool. There may also be hydrostatic relief valves near the bottom of the steep slope that can be removed. Good luck. -Bill
If you don't have a hydrostatic valve on the bottom I would suggest at least a third. otherwise it may start floating in ground water if it is present.
A lot of people confuse the hydrostatic valve at the bottom of the pool for a main drain. this is in fact not a drain but is there to allow water into the pool from outside if the pool is empty or partially empty to stop it from floating in ground water. Since hydrostatic valves are positioned in the sump next to the main drain pipe, unless you remove the drain grate you won't even see the hydrostatic valve. I have never heard of anyone mistaking one for the other as one looks kind of like a plug and the other is obviously a pipe. I have had to correct many of the answers from the original answerer of this and many other questions and would not follow any of his advice. I speak from 34 years of pool building and remodeling experience and am considered by my peers an expert in this field. I have drained about 20,000 pools and except for a handful of times have always used a submersible pump.