Chlorinator
Pulsar System
Accu-Tab System
Prior to 2024, a PowerBase Model 3150 chlorinator (that utilized the "Accu-Tab" system) was responsible for chlorination. This system was removed prior to the 2024 swim season.
Retrospective
Upon installing the new chlorinator prior to the 2024 swim season, we learned that the prior system should never have been sourced from "Unfiltered Water". This was likely a carry-over from an earlier system that passively relied upon a pressure differential to feed chlorine into the system. Many of our issues (that were addressed via the modifications described below) could have likely been avoided had the system been re-plumbed to tap into "Filtered Water".
The inline Y-strainer was regularly bypassed, as once it captured debris, flow was reduced to the point that the chlorinator was starved of incoming water. This would often lead to malfunction as contamination would clog up the solenoid when large debris was present in the incoming water.
Theory of Operation
Process Flow
Water flows to the chlorinator from a tap on the outlet side of the main pump, i.e., "Unfiltered Water". An inline strainer provides a limited amount of filtration (i.e., ASTM 30, 600 µm), preventing harmful particulates from entering the chlorinator. Evidence has shown that the chlorinator solenoid is subject to malfunction without sufficient inline filtering.
A bypass valve, whose exact purpose is not presently well understood, allows some amount of water flow to return to the pool essentially bypassing all mechanical filtration and chemical treatment. Further investigation of use of this valve is needed.
From this point, there are two paths for water to flow:
- Into the tablet (upper) tank when the solenoid is active. The solenoid is actuated (along with the pump) when there is a demand for adding chlorine. Water flow in the tablet tank dissolves chlorine tabs and adds highly chlorinated water into the solution tank (pumped out to the pool).
- Into the solution (lower) tank when the float valve is open. The float valve provides make-up water to maintain the solution tank level during operation (ideally 50 to 75 percent full).
Water is pumped from the solution tank to the pool via a check valve, preventing pressure on the pool return line from forcing water back into the solution tank.
Programmable Logic Controller
In June 2021, a programmable logic controller (PLC) was added to the chlorinator power cabinet to mitigate air lock (loss of prime) conditions. The PLC implementation was done solely in-house.
A call for chlorination provides power to the PLC. When the PLC is powered up, it automatically engages the pump and solenoid (per the high-level cut-off/float switch) by default. If the float switch fails to engage after 10 seconds (indicating a drop in solution tank water level), the chlorinator pump motor is stopped for 10 seconds. During this period, air bleeds from the pump. After the 10 second period has elapsed, the pump is restarted. Testing has shown this to be a highly effective method for restoring pump functionality.
Subsequent checks of switch function occur every 60 seconds (rather than 10 to prevent frequent cycling).
It should be noted that the float switch always controls the solenoid (via the PLC). If the water level is high, the solenoid is disabled to prevent overflow of the solution tank. Lacking a low-level switch, there is no means to prevent the pump from running dry. Outside controls (such as verification of bypass line flow in the chemical controller) are used to ensure sufficient water is supplied to the chlorinator to prevent this from happening.
Maintenance
At some point, flow into the chlorinator is restricted by scale build-up on the sieve plate in the solid tablet tank. This may result in prolonged operation upon a call for chlorine, as the water flow rate through the tabs is reduced. When this occurs, cleaning is necessary. It is assumed that cleaning should be performed at least once per season.
To clean the tank, the following procedure is recommended (based on the manufacturer's procedure):
- Open all doors in the pump house. Proper ventilation is a must.
- Remove all solid tabs from the tank.
- Remove chlorine from the tank as much as possible by flushing it out with (pool) water. This may be done by engaging the chlorinator manually via the Chemtrol unit. A hose may be used to help loosen the scale.
- Once the excess water has drained (if a hose was used), stop the chlorinator pump.
- Remove the chlorinator from the loop by closing the isolation valves (near the boiler).
- Open the bypass valve.
- Carefully mix a diluted acid solution and pour it into the tank. The manufacturer recommends 1 qt of muriatic acid to 2 gallons of water (remember to add acid to the water, not the other way around). Extreme care must be taken to remove the chlorine prior (to prevent the generation of toxic chlorine gas). Appropriate PPE must be worn. The acid will produce carbon dioxide as it reacts with the scale. Some chlorine gas may be produced - hence the absolute need for ventilation and PPE.
- Allow soaking for 30 minutes.
- Operate the chlorinator for 10 minutes.
- Open the isolation valves to begin flushing out acid.
- Use of a hose (again) may be required to fully wash out the acid.
- Return the chlorinator to automatic (or off) mode and re-fill with chlorine tabs.
Troubleshooting
Overflow
Overflow in the reservoir (mixing basin) is likely due to the failure of one of two valves:
- A PurAqua PASV150B solenoid valve controls water fill via the solid tablet tank. This valve is electrically actuated by a small float switch. Verify that the solenoid opens/closes (listen for an audible click) when the float switch is operated. The valve's purpose is to stop water flow to the solid tablet tank (and ultimately the reservoir) when the water level has reached the upper threshold. The build-up of contamination on the rubber diaphragm or debris in the housing may prevent the valve from fully closing, allowing water to flow uncontrolled. To clean, remove the 1/2" bolts and separate the two metal parts carefully not to damage the rubber diaphragm. Remove the diaphragm and clean surface contamination with fresh water. Inspect for cracks, tears, or other signs of deterioration. If all is in good working order, re-assemble (careful not to over-tighten the bolts). Verify that the strainer (before the chlorinator) is installed and functioning properly.
- Make-up water into the mixing basin is controlled by a mechanically-operated plunger valve, opened and closed by a float ball. This valve is a 1-inch Kerick PT100SS. This valve appears to make up the difference between outflow (via the chlorinator pump) and inflow that would otherwise only pass through the solid tablet tank. The valve may, over time, become damaged or blocked by debris. Inspect and clean as needed. The valve can be purchased individually from various sources. Alternatively, a rebuild kit (p/n 9500200) or the whole assembly (p/n 9501056) may be purchased from Aquatic Source or PurAqua Products. Assuming the rod and float ball are in good condition, replacing only the valve (re-using the rod and float ball) is a good balance of cost and ease of repair.
Pump Leakage
The pump shaft seal may have failed.
Drawings
Chlorinator wiring, including the PLC, is shown in the drawing below.
