Sunday, April 26, 2009

Ready for gunite


We passed our plumbing inspection, so we're ready for gunite. This has been the eighth weekend in a row that I've worked both days on the pool plumbing. Virtually all of that work has been on the hot tub. (Earlier I was working on plumbing too, but I was machining bits and it didn't feel as much like plumbing.)

Picture right is David Kanter, by the way, who was generous enough to come down last weekend and sweat in the 100 degree noontime sun to lay gravel in the trenches around the pool. This is us right before cutting those 3" pipes to make the main drains. Thanks, Dave!

I like this picture because it gives a sense of the scale of this thing. Granted, it will be a smaller hole once 6 to 15 inches of gunite have gone into the sides, and 10 inches has gone into the bottom. But it will still be big enough that, standing on the bottom with no water to buoy you, you will not be able to jump up and touch a string suspended across the waterline. It's significantly deeper than most rooms are tall.

After looking at this thing, the inspector asked me to double the rebar in the hot tub because of all the plumbing. Done in two hours, and the pic is below. [Update, years later: damn good thing the inspector caught this.  The spa dam wall has developed a small circumferential crack. Because the inner layer of gunite has it's own reinforcing, this is not a big problem, but in retrospect I should have inserted rebar that stitched the inside curtain to the outside curtain.]


We tested a fair bit of this hot tub plumbing to 30 psi, and I was amazed that it held. Most of my flexPVC is tested now, and not a single leak.

Unfortunately, the Valterra 4 inch gate valve on the suction side of the fountain pumps leaks. This is an expensive part, and after talking with the manufacturer it seems that it was never going to work right. Finding an alternative is going to be very expensive. If any reader happens to know of a 4 inch valve made of something compatible with ozone (stainless steel, especially 316, and PVC are the big ones) which won't rust and leave stains on my plaster, and which doesn't have a huge flange... please pass along the info. Oh, and it should take 30 psi of internal pressure without leaking. It doesn't have to take 30 psi across the ports when closed, but 3 would be good.

[Update: I've ordered a 4 inch Spears PVC ball valve. It's a very nice valve, very, very easy to turn, but it was crazy expensive: $670. Including the cost of the built-to-fail Valterra gate valve and installation and rip-out of that, this one item has cost $1000. This could have been done more cost-effectively.]

It is now conceivable that we could have the pool open by June 5 (Anya's birthday), but I don't think it's going to happen. Every other aspect of this pool has taken much longer than expected, so I assume that it will be hard to just finish the plumbing over the next four weekends, let alone get the tile, plaster, cover, coping, electrical, solar panels, diving board, rock facing, patio, drainage, lighting, planting, and sprinklers done.