I'm looking at installing a Hayward CL-100 in-line chlorinator in my AGP plumbing system, and am trying to decide whether to install it at the same level as the filter return port (as was recommended to me by the pool store) or to drop it down to near ground level.
I posted a couple of photos of the set-up in another thread (that was going off topic):
abs-fittings-t42537.html (pics are in the 7th post down)
I'm trying to understand the implications of installing below the water level. Although the CL-100 has an integral check-valve in the feedline (to prevent back-flow in to the chamber) the recommendation is to install ball stop valves on either side of the chlorinator so that it can be isolated when recharging. I'm fine with that, although I would have thought that closing the filter multi-port valve would serve the same function as a stop-valve on the inlet side of the chlorinator.
My question is, during operation, does the chlorinator chamber completely fill with water or is it normal and possibly necessary for an air pocket to persist in the chamber head-space? For 'bottom feed' chlorinators, at least, I would have thought that a head-space helps to ensure that the lower pucks in the stack are eroded first, provided of course that the air pressure is not so great as to prevent water from entering the chamber through the inlet control valve.
The reason I ask, is that when the lid is opened for re-charging (after switching off the pump, closing control valve and stop valves) will the chamber be filled to the brim or will the water be held in check at a low level so that fresh pucks can be added safely without risk of overflowing.
In the Rainbow 320 in-line chlorinator user guide it specifies "If installed below water level, a drain valve must be installed (literally hole drilled and tapped) to prevent spillage and dangerous splash back of high chlorinated water during recharging". It is not clear whether that applies to both "top feed" and "bottom feed" modes, but I can see no equivalent drainage requirement in the Hayward CL-100/200 instructions. All it says is:
1. Shut off all pumps and pump timers.
2. Turn chlorine feeder flow control valve to “OFF"
3. Verify chlorine feeder return line to pool is unrestricted.
4. Wait one minute to relieve system pressure before attempting to remove cover.
5. If installed in a flooded system (i.e. below water line) shut off valves to isolate chlorinator.
6. Remove cover.
Edit: Just spoke to Hayward technical support here in Canada, and they told me it is normal for the chamber to fill up when running and that if installed below water level, yes, it can be expected that the chamber will be full of water. I wondered whether running the pump with the inlet control valve closed, prior switching off and closing the stop valves, might help to drain some water from the chamber, and they said maybe a little, but not enough to evacuate it.
I guess, after loosening the lid, one could evacuate through the bottom drain, but I suspect the plug and seal would not last too long if that were done on every recharge. Maybe, like the Rainbow, install a drain valve in that hole????