Instructions for Using Sodium Silicate and Sodium Sulfite in Thermal Stores

Purpose

---

Sodium Silicate (Corrosion Inhibitor)

• Function: Forms a thin, protective silica film on metal surfaces (such as copper, brass, and steel), preventing corrosion.
• Dosage: 400 grams of sodium silicate solution per 1 cubic meter of water.
• (Dosage Calculation of Sodium Silicate (SiO₂.) 100 to 200 mg/L per liter (mg/L) of water.
• Benefits:
  • Prolongs the lifespan of your heating system.
  • Reduces maintenance costs by minimizing corrosion-related damage.

Sodium Sulfite (Oxygen Scavenger)

• Function: Chemically reacts with dissolved oxygen in the water, eliminating it and thus reducing corrosion risk.
• Dosage: 30 grams of sodium sulfite per 1 cubic meter of water.
• Dosage calculation of sodium sulfite (Na₂SO₃) 20 to 50 milligrams per liter (mg/L) of water.
• Benefits:
  • Essential in systems where air ingress occurs, as it continuously removes oxygen entering the system.
  • Enhances the effectiveness of sodium silicate by maintaining a low-oxygen environment.

---

How to Add and Maintain the Chemicals

Step 1: Preparation

• Safety First:
  • Wear protective gloves and safety goggles when handling chemicals.
  • Ensure the area is well-ventilated.

Step 2: Adding the Chemicals

A. Sodium Sulfite

1. Dissolve the Sodium Sulfite:
   • Measure 30 grams of sodium sulfite per cubic meter of water.
   • Dissolve it in a clean container with warm water until fully dissolved.
2. Add to Thermal Store:
   • Pour the solution into the thermal store, preferably near the circulation pump inlet for thorough mixing.

B. Sodium Silicate

1. Dilute the Sodium Silicate:
   • Measure 400 grams of sodium silicate solution per cubic meter of water.
   • If using a concentrated solution, dilute it with water to make handling easier.
2. Add to Thermal Store:
   • Slowly pour the diluted sodium silicate into the thermal store, ensuring even distribution.

Step 3: Circulation

• Run the Circulation Pump:
  • Operate the pump for at least 1 hour per m3 to mix the chemicals thoroughly throughout the system.
  • Be aware of operating the pumps on a freezing day when there is no sun!

Step 4: Monitoring and Maintenance

A. Regular Testing (Every 3 Months)

1. pH Level:
   • Optimal Range: 9.0 to 10.5
   • Testing: Use pH test strips or a digital pH meter.
   • Adjustment: If pH drops below 9.0, add a small amount of sodium silicate to raise it.
2. Sodium Sulfite Levels:
   • Residual Sulfite Concentration: Aim for 20–40 mg/L.
   • Testing: Use a sulfite test kit to measure the concentration.
   • Adjustment: If levels fall below 20 mg/L, add more sodium sulfite proportionally.

B. Visual Inspection

• Check for Signs of Corrosion:
  • Inspect accessible metal components for rust or discoloration.
• Monitor Water Clarity:
  • The water should remain clear; cloudiness may indicate scaling or contamination.
• Corrosion indicator:
  • It might be worthwhile to place a sacrificial piece of steel in the thermal store as a corrosion indicator.

Step 5: Topping Up Chemicals

When to Top Up

• After Adding or Replacing Water:
  • Recalculate and add chemicals based on the volume of new water added.
• If Test Results Indicate Low Levels:
  • Top up chemicals according to the original dosage per cubic meter.

How to Top Up

1. Calculate the Required Amount:
   • Use the per-cubic-meter dosages to determine how much to add.
2. Add Chemicals:
   • Follow the same procedure as in Step 2 for dissolving and adding the chemicals.

---

Additional Tips

Addressing Air Ingress

• Minimize Air Entry:
  • Ensure all seals, gaskets, and fittings on your thermal store are airtight.
• Regular Maintenance:
  • Periodically check and maintain the integrity of the thermal store’s lid and connections.

Water Quality Management

• Use Softened or Demineralized Water:
  • Helps prevent scaling and enhances the effectiveness of the chemicals.
• Avoid Contaminants:
  • Ensure that any water added is clean and free of impurities.

Safety Precautions

• Chemical Storage:
  • Store chemicals in labeled, sealed containers away from children and pets.
  • Keep in a cool, dry place.
• Disposal:
  • Dispose of any waste chemicals according to local regulations.

Professional Consultation

• Seek Expert Advice:
  • Consult a water treatment specialist or heating engineer to ensure compatibility with your specific system and compliance with local regulations.

---

By following these guidelines, we expect to effectively protect the thermal store from corrosion, ensuring efficient operation and extending the life of the heating system.

Both chemicals are registered under the REACH Regulation (EC) No 1907/2006, which means they have been evaluated for safe use in the EU.