Tenselo has separate softener workflows for a house or tank supply and for larger process duties. Both calculations use the water hardness load and the hydraulic service-flow requirement because either one can control the final resin and vessel size.
Inputs that control softener size
- Total hardness with its stated basis, normally mg/L as CaCO3 in Australia
- Iron concentration and any upstream iron-removal requirement
- Peak and continuous service flow through the resin bed
- Average daily treated-water volume and target run between regenerations
- Salt dose and simplex or duplex operating requirement
A small resin charge can have enough chemical capacity for the daily hardness load but still fail the required peak flow. Tenselo checks both constraints.
Domestic worked example
This DOM-004 example uses 1,000 L/day, hardness of 250 mg/L as CaCO3, no iron, a five-day design run, a salt dose of 150 g/L resin and a household duty of 30 L/min average with 45 L/min peak.
The hardness load alone needs about 23 L of resin. The peak-flow check increases the resin charge to 68 L in a generic 1465 composite vessel.
| Output | Calculated value |
|---|---|
| Resin charge | 68 L, or 2.38 ft³ |
| Service-flow check | About 25 L/min continuous and 45 L/min peak |
| Backwash flow | About 20 L/min |
| Throughput between regenerations | 14,850 L |
| Estimated interval | About 14.8 days at 1,000 L/day |
| Salt use | 10.1 kg per regeneration and about 249 kg/year |
Industrial worked example
WTR-018 sizes a commercial duty at 120 L/min, 200 mg/L hardness and 30 kL/day. The static result uses a single 42 × 72 inch vessel with 850 L of resin. The calculated cycle treats about 204,000 L, giving about 6.8 days between regenerations and estimated salt consumption of 102 kg per regeneration, or about 5.5 tonnes per year.
A duplex arrangement may be required where the downstream process cannot accept hard-water breakthrough during regeneration.
Checks before choosing the valve and vessel
Confirm the water analysis, peak flow, bed-depth and vessel freeboard, continuous and intermittent resin loading, backwash supply and drainage, salt storage and the control-valve operating range. Treat significant iron upstream because iron can foul softening resin and reduce capacity.
Start with water analysis interpretation when the incoming chemistry is uncertain. Continue to iron-removal sizing when iron or manganese is present.
Questions
What information is needed to size a water softener?
Use total hardness with its stated basis, iron concentration, peak and continuous flow, daily water demand, target regeneration interval and the selected salt dose.
Does hardness load or flow determine the softener size?
Either can control. The resin needs enough capacity for the hardness load and enough bed area and volume for the required service flow.
Should iron be removed before a water softener?
Significant iron can foul ion-exchange resin. Review the full analysis and assess upstream iron removal before relying on the softener as the complete treatment.
What is the difference between simplex and duplex softeners?
A simplex unit goes offline during regeneration. A duplex system alternates vessels so treated water remains available for processes that cannot accept an interruption or hardness breakthrough.