My pool is situated on a hill. I have two returns and one skimmer. No main drain. The pool is painted concrete and was probably built in the 1940s or 1950s. My pump is located about 10 feet below the waterline of the pool, down the hill. My filter is in the basement of a little pool hut and is another 10 feet down (20 feet below the surface water of the pool). This means that all of my lines have a straight vertical run from the pump, down 10 feet into the hut, across the floor of the hut about 10 feet and then back up and out of the hut to my heater. The pressure gauge on my filter registers 10 PSI even when it is off, because of this.
I've had a pool company blow out the lines -- sometimes with a air compressor and sometimes with a Cyclone. Each time they have been able to get the lines to blow and have gotten the anti-freeze to spray all the way through the pipes. When I talked with the guys who closed last year, they did say that it was hard to move the water through my lines.
This year, I set the multiport to recirculate, blew the water with my shop vac from the farthest return to the pipes in the basement (hoping to work with gravity), opened the cap on the pipe and let the water out. Then, I blew the water from the skimmer to the floor and let the water out an opening in that line at floor level. Then, from the skimmer, I blew out each outlet and the heater with only one of these open at a time, This seemed to get rid of the water. However, there was never any really strong "spray," maybe because a lot of the pressure was already gone with the water I let out at the pool hut basement level???
How do I know if I got all the water out of the lines?
I put antifreeze into the skimmer and blew it down toward the pump and the pool hut, hoping that it would continue to go past the pump, through the basement, up through the heater and into the returns. However, it seems like the stuff gets to the bottom of the hut and sits there. I get air from the returns, but no antifreeze. I borrowed a Makita Mac 2300 and used that to blow from the pump at about 10-20 psi, with the same results: tons of air from the last outlet (all others were plugged), but no antifreeze. We added more antifreeze, with the same results. It sounds sort of like the antifreeze starts to go up the 10 feet of vertical pipe and then just stops. I went a little higher in pressure for a few minutes, but stopped, because I was afraid I'd cause damage to the pipes.
What am I doing wrong??? Should I have a valve closed that isn't? Do I not have enough pressure? Not enough antifreeze? Something else? I have seen this work (but, to be fair, they did it and got a spray without having drained the lines first, so maybe there was more pressure in the lines from the water?)! Am I ok?
We did manage to pour two gallons of antifreeze into the outlets, blow with the vacuum back towards the pool hut and cap the returns. But for all I know, most of it is sitting on the floor of the pool hut.
We also put a little antifreeze into the place where the plug comes off of the heater. Not much, because it came flowing back at us. Will this work? If not, how do i add antifreeze to the heater without having wash back down into the pool hut? (As far as I know there is no check valve. Should there be?)
The following should be a drawing of my pool set up. Arrows show the flow of the water, dotted line shows where the pipes are moving vertically into the basement of the pool hut.
I'd appreciate any advice you have.