Short answer: Dosing pump repair means finding and fixing the cause of faults such as the pump not delivering, a drop in flow rate, leaks, alarms or the pump not switching on at all. Common causes include air entering the suction line, sodium hypochlorite crystals building up in the check valves, and worn hoses or seals; these can usually be fixed by cleaning or replacing parts. For AnTech dosing pump repair, send us the pump model, the symptoms and a short video through our contact page or on +9+90 216 606 44 72 / WhatsApp +9+90 532 542 81 24.
When a chlorine dosing pump develops a fault, the first step is to identify the symptom correctly. “Not working” and “working but not delivering” point to entirely different causes. This page describes the repair work covered by our chlorine dosing pump service: a table of symptoms and possible causes, the decision between repair and replacement, and the information we need with a repair request.
Which Symptom Points to Which Cause?
The symptom shows where to look for the fault. The table below summarises common symptoms, their possible causes and the first points to check. The causes in the table are possibilities; the actual cause is confirmed by checking.
| Symptom | Possible causes | First check |
|---|---|---|
| Pump is stroking but not delivering chemical (air lock) | Air in the suction line, loose suction connection, empty tank, clogged foot filter, crystals in the check valve, hypochlorite gas trapped in the head | Tank level, suction connections, priming |
| Flow rate has dropped | Crystals or wear on the check valve balls, partly clogged foot filter, increased line pressure, worn diaphragm, calibration drift | Clean the foot filter and check valves, check line pressure, measure flow |
| Leak | Loose fitting or hose end, worn O-ring or one not compatible with the chemical, cracked hose or head, loose head screws | Location of the leak, tightness of the connections |
| Level alarm | Empty tank, dirty or faulty level sensor, loose sensor cable | Tank, cleanliness of the sensor, cable connection |
| Flow alarm (on systems with a flow sensor) | The pump is not delivering, or the flow sensor is not sending a signal | First the causes of non-delivery, then the sensor |
| Measurement alarm or inconsistent pH, ORP or chlorine value | Dirty or expired electrode, calibration drift, clogged housing filter, air bubbles in the housing, cable | Comparison with a test kit, cleaning, calibration |
| Display is on but the pump is not stroking | Pump stopped, no signal from the water meter in proportional mode, waiting for an external trigger, on hold due to a level alarm | Operating mode, meter and signal connection |
| Pump will not switch on at all | No power (plug, fuse, residual current device), loose power cable, unsuitable supply voltage, electronic fault | Socket, fuse, cable connection, voltage on the label |
A frequently overlooked cause of air locking is hypochlorite gas. Sodium hypochlorite releases gas as it decomposes; the gas can get trapped in small heads and check valves and cause the pump to stroke without delivering. The catalogue lists a head assembly with automatic air bleed as an option for the 3.5 and 10 L/h models in the Nova series. On models without a level input, such as the AnTech Lara A 5 L/h 7 Bar Analogue Dosing Pump, the pump carries on running without warning when the tank runs empty, and the suction line fills with air. If the tank level needs to be monitored, level-controlled models are chosen.
When the flow rate drops, the line pressure also needs to be checked. According to catalogue values, the AnTech Nova D 10 L/h 10 Bar Digital Dosing Pump delivers 20 L/h at 2 bar and 10 L/h at 10 bar; when line pressure rises, the pump delivers less even without a fault. On pumps with a leak, the seal material must be compatible with the chemical: the AnTech Optima A 5 L/h 10 Bar Analogue Dosing Pump has Viton O-rings as standard, and there are also models in the series with Teflon O-rings.
Repair or Replace? How to Decide
The decision depends on the type of faulty part, the cost of repair relative to a new pump, and whether the pump is still suitable for the application.
- Wear parts: For faults caused by air locks, crystal blockages, or a worn check valve, hose, seal or suction and discharge assembly, repair is usually the right choice. These parts are available as separate spare parts in the catalogue.
- Head damage: If the head is cracked or has a damaged thread, the head assembly is replaced; if the housing and electronics are sound, the pump can stay in service.
- Electronic fault: If the cost of repairing a board or coil fault approaches the price of a new pump, replacement may be the better option. You can see current pump prices on our chlorine dosing pump prices page.
- The application has changed: If the line pressure or required flow rate has moved outside the pump’s limits, moving to a suitable capacity is better than repeated repairs. For example, on a line above 10 bar, the Nova 3.5 L/h model, which operates up to 20 bar, could be considered. You can compare the options on our chlorine dosing pump models page.
We share the information you need to decide which route makes sense; the decision is yours. For the parts that need replacing and model compatibility, see our dosing pump part replacement page.
What Information Is Needed for a Repair Request?
A repair request should include the pump model, the chemical, the symptoms and photos of the installation; this information often reveals the cause of the fault in advance.
- Label photo: With the model name and code legible.
- Chemical: Its type and, if known, its concentration.
- Symptoms: When they started, whether they are constant or intermittent, and any alarm or message on the display.
- Video: A short video taken while the pump is running, showing the stroke sound, bubbles in the suction hose and the leak point.
- Installation photo: Tank, suction assembly, discharge line and injection point.
- Line pressure and setting: The pressure at the injection point, the pump setting and the operating mode.
- History: Work done so far and parts replaced.
Before working on the pump, disconnect its power, relieve the pressure in the discharge line, and wear gloves and safety goggles. If the pump has to be dismantled, first flush the chemical out of the head and hoses by running clean water through them. After repair, the pump’s actual flow rate should be measured; on digital Nova models, capacity calibration is renewed. Details are on our AnTech dosing pump calibration page.
Some faults can be prevented with regular maintenance; crystal build-up and hose ageing are caught during maintenance before dosing drops. See our dosing pump maintenance service page on this. All AnTech pumps are listed in the dosing pumps category, and by series on the AnTech Nova and AnTech Lara pages.
Sources
- AnTech 2025 Product Catalogue (KT_25 R02): flow–pressure values for the Nova and Optima, series feature lists and accessory lists (head assembly with automatic air bleed).
- Blue-White Industries, “Causes and Solutions for Vapor Locking in Chemical Metering Pumps”: blue-white.com
Frequently Asked Questions
My dosing pump is running but not delivering. What could be the cause?
The most common causes are air entering the suction line, an empty tank, a clogged foot filter and crystals building up in the check valves. On pumps running on sodium hypochlorite, gas trapped in the head produces the same symptom. First check the tank and suction connections and bleed the air; if the problem persists, write to us with a short video.
Should the pump be repaired or replaced?
For faults caused by wear parts such as hoses, check valves, seals, and suction and discharge assemblies, repair is usually the right choice. For an electronic fault, replacement may be the better option if the repair cost approaches that of a new pump, or if the application's flow rate and pressure have moved outside the pump's limits.
Do I need to dismantle the pump before repair?
First send us the information and photos, and we will decide together whether dismantling is necessary. If you do need to dismantle it, disconnect the power, relieve the pressure in the discharge line and flush the chemical out of the head by running clean water through it.
The pump is showing an alarm. What should I do?
Identify the type of alarm. For a level alarm, check the tank and level sensor; for a flow alarm, check whether the pump is delivering; for a measurement alarm, check the electrode and calibration. If you send us a photo of the message on the display, we can narrow down the cause together.
Do you also repair pumps of other brands?
The information on this page is for AnTech pumps. If you have a pump of a different brand, send us its brand and model, and we will tell you whether we can help.