Welcome back to our #TechFriday series! In last week’s article, we covered the essentials of water circuit installation for Tongyi heat pumps, including water pressure management, air venting, and corrosion prevention. This week, we dive deeper into critical components such as the expansion vessel pressure, water volume management, and charging the water system. Proper attention to these factors ensures smooth, long-term operation and helps prevent costly malfunctions.
1. Expansion Vessel Pressure
Tongyi heat pumps come with a 5-liter expansion vessel, pre-set at 1 bar. This vessel is crucial for absorbing pressure changes due to temperature fluctuations in the system.
If the pre-pressure needs to be adjusted, it should only be done by a licensed installer using dry nitrogen. Moisture can damage the system, so using air or inappropriate methods may lead to corrosion or malfunction. The pre-pressure must be set correctly to ensure the system performs efficiently.
2. Handling Water Circuit Pressure Drop
Excessive pressure drop in the water circuit could limit the heating or cooling capacity, or even freeze the heat exchanger. If the pressure drop is too high, an auxiliary pump should be installed to maintain proper water flow. Failure to address this can cause system damage over time.
Additionally, if the unit hasn’t been running for over 24 hours, both the primary pump and any auxiliary pump installed will automatically turn on for 3 minutes. This routine operation prevents the pumps from getting blocked and ensures smooth functioning when the system resumes.
3. Connecting the Water Circuit
When connecting the water circuit, proper care must be taken to avoid issues like air, dust, or moisture entering the system. Key steps include:
- Use clean pipes to prevent contaminants.
- Hold the pipe end downwards while removing burrs, and cover pipe ends to prevent dirt from entering.
- Use a reliable thread sealant that can withstand the system’s pressures and temperatures.
Ensure that all components are connected properly, avoiding damage to pipes. Use the correct tooling and be careful when working with brass piping—it’s important to insulate brass from other metals to prevent galvanic corrosion.
4. Charging the Water Circuit
Once the water circuit is installed, it’s time to fill the system. Here’s how:
- Connect the water supply to a drain and fill valve.
- Open the automatic air purge valve (at least 2 turns).
- Fill with water until the manometer shows 1.0 to 2.0 bar.
- Purge air manually using the air purge valves.
After the system is filled, check that the backup heater vessel is also full by opening the pressure relief valve and allowing water to flow out.
In the first few hours of operation, any remaining air will be removed by the automatic air purge valve, and you may need to top up the water. It’s important to keep the water pressure above 0.3 bar to prevent air from entering the system. Any excess water will be expelled through the pressure relief valve, so ensure proper drainage is in place.
5. Water Quality
For optimal performance, the water quality must comply with EN Directive 98/83 EC. Using water that doesn’t meet these standards can result in scaling, corrosion, and reduced system efficiency. Regular checks on water quality will help prevent these issues and extend the lifespan of your heat pump.
Stay tuned for more #TechFriday tips to keep your heat pump running at its best!
