Circulation pump and how to damage it
Hello and welcome to the new edition of the HVAC Education Hub newsletter. This week I want to share a few photos of a broken circulation pump from one heat pump.
There could be different causes of damage but number 1 is the cheapest part of the system: WATER!
I am not a chemical engineer but as we are dealing with water (as a main fuel) and different materials in the heating system (copper, plastic, steel etc.) it is clear that we need to take care of proper water quality and materials used.
You can see useful comments and explanations in one of my previous posts about water quality HERE.
The main guideline for heating water treatment is VDI 2035 and, from my experience, very few people take care of that. Here is a very long and useful read on Heat Geek's website: Heating Water Treatment Explained.
Water quality
Water quality plays a crucial role in the longevity and efficiency of a heat pump system. Water with high levels of impurities, such as minerals, oxygen, and even certain chemicals, can lead to various issues:
- Corrosion: High levels of dissolved oxygen or improper pH levels can lead to corrosion of metallic components within the system. Over time, this corrosion can compromise the integrity of the pipes, heat exchangers, and pumps.
- Scale Formation: Hard water (high in calcium and magnesium), can cause scale deposits to form inside the system. These deposits can restrict water flow, reduce heat transfer efficiency, and increase the workload on the pump, leading to premature failure.
- Debris and Contaminants: Inadequate filtration can allow debris to circulate within the system. This can lead to blockages and damage to moving parts within the circulation pump, as seen in the images:
The impact on circulation pumps
The circulation pump is the heart of a heat pump system, responsible for moving water through the system. When the water quality is poor, the pump is one of the first components to suffer. The images provided show clear signs of damage:
- Impeller Wear: The impeller inside the pump, which is responsible for moving water, can become eroded or clogged due to contaminants in the water.
- Seal Degradation: Poor water quality can lead to the degradation of seals within the pump, causing leaks and further mechanical failures.
- Internal Corrosion: internal surfaces that appear corroded, likely due to improper water chemistry. This corrosion not only affects the pump's efficiency but can also lead to complete system failure.
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Different materials
In addition to maintaining water quality, selecting the right pipe materials is equally important. Pipes made from inappropriate materials, such as certain metals that react adversely to the water's pH or mineral content, can contribute to the degradation of the system. For example:
- Copper Pipes: While commonly used, copper can suffer from pitting corrosion if the water is too acidic.
- Galvanized Steel Pipes: These can corrode over time, particularly in systems with poor water quality, leading to rust that can clog and damage pumps and other components. Actually, it is not recommended to use in heating systems (especially in combination with glycol).
- Plastic Pipes: Materials like PEX or CPVC are often preferred in systems with water quality issues, as they are more resistant to corrosion and scaling.
Conclusion
Maintaining proper water quality in your heat pump system is not just about ensuring efficient operation; it's about protecting your investment. Poor water quality and the wrong choice of piping materials can significantly damage the circulation pump and other vital components, resulting in costly repairs or replacements.
Regular water testing, the use of appropriate filtration systems, and choosing the right materials for your pipes are all steps that can help you avoid these issues. By taking proactive measures, you can extend the life of your heat pump system and ensure it operates at peak efficiency.
Remember, a small investment in water quality maintenance can save you from the large costs of system failure down the line.
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Thank you for reading and see you next Wednesday! ?
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Foarte informativ
Head of Heat Pump System Design & MCS Compliance at British Gas. Co-author of ‘Heat Pumps Unlocked’ ?? HeatPumpsUnlocked.com
7 个月This is a very timely article as Dominic Eves podcast covered this same topic yesterday with Ricky Prescott . Great post as usual Mario Dodi? . I was advising Vaillant installers to look into VDI2035 over 3 years ago and it seems only recently that it has started to be understood by the wider community in heat pumps.
Healthy and efficient systems heating & ceiling cooling unique radiant for buildings
7 个月VDI 2035 is a German guideline that sets recommendations and requirements for water treatment in heating systems. It emphasizes the prevention of harmful substances such as scale and corrosion, which can impede heat transfer and reduce system performance
HVAC & Building Services Engineer
7 个月Great Wednesday post Mario. Water quality is everything in hydronic heating & cooling circuits. Another cause of pump failure is cavitation. Cavitation occurs when the inlet suction pressure on the pump is too low, causing the water pressure to briefly drop below the fluid vapour pressure. The fluid literally boils to create small bubbles of steam. These almost immediately implode as they move to higher pressure in the pump casing. This causes noise, vibration and erosion of the pump impeller and casing. The gas bubbles form preferentially on tiny surface imperfections. Pumps are specified with a minimum net positive suction head requirement NPSHr The best way to avoid cavitation is to ensure the head pressure at the suction port of the pump is > NPSHr + 1m margin. On a well-maintained hydronic system problems are unlikely. But poorly maintained systems that have lost pressure, have blocked filters and strainers, etc., risk cavitation. A secondary pump located upstairs or in an attic space may have little static head on the suction side, perhaps almost no pipework above it to meet minimum NPSHr by gravity. It may rely on system pressure for NPSH. 1 barg system pressure = 10.2m head.