Low Loss Header Sizing Calculator
Getting the right size for your low loss header is key to getting the most out of your system. You should size it based on the system’s top flow rate. This includes looking at the boiler’s output, the system’s load, and the design. The goal is to make sure the pumped pressure through the header is as low as possible at full flow.
It’s also vital to make sure the water flowing through the boiler loop matches the boiler’s minimum flow rates and design temperature differences. This ensures the boiler works well, especially with modern, efficient boilers that use less water.
Key Takeaways
- Low loss headers are sized based on the maximum flow rate of the system, considering factors like boiler output and system load.
- The header size should minimize pumped pressure resistance at full flow to maximize efficiency.
- Correct water volume in the boiler loop is crucial for proper boiler control, especially with high-efficiency, low-water-content boilers.
- Low loss header diameter and length are determined by the boiler output and system requirements.
- Maintaining water quality is essential for the long-term performance of the low loss header and the overall heating system.
What is a Low Loss Header?
A low loss header (LLH) is key in heating systems, especially in big homes or businesses with boilers that have low water content. It helps separate the primary and secondary circuits, making sure pumps work on their own. This setup is vital for keeping the system running smoothly and reliably.
Definition and Purpose
A low loss header mixes primary and secondary flows while keeping pressure loss low. This lets the primary and secondary pumps work independently, avoiding problems that could slow down the system. Its main goal is to manage flow rates in systems with more than one boiler, making the heating system more efficient.
Getting the low loss header’s size right is important. It depends on the water flow, system Delta T, and the boilers’ minimum flow rates. This ensures the system works at its best, making boilers last longer and improving heating performance.
Installing a low loss header lets different secondary circuits run on their own without changing the primary circuit’s flow. This is especially useful in big systems, keeping heating steady and reliable across the building.
Some low loss headers also act as air and dirt separators, cutting down on the need for extra devices and saving space and money. Vertical ones are preferred because they help collect sludge, keeping systems clean and extending boiler life. Horizontal ones don’t do this as well.
Principles of Low Loss Header Sizing
When sizing low loss headers, a few key principles are important. The rule is, the more powerful the boiler, the bigger the header needs to be. On the other hand, if the system loses more heat and flows less, the header can be smaller. This is because low loss headers help keep pressure balanced and flow steady, especially in big heating systems.
To figure out the minimum diameter of your low loss header, look at your boiler’s max output and the system’s temperature drop. Then, calculate the header length by multiplying the diameter by 4. This is the minimum space needed between the flow and return lines.
Low loss headers can connect to heating circuits, heated circuits, and sometimes even more circuits together. Most use horizontal couplings, but vertical ones are becoming more popular for better air flow. Steel low loss headers are known for lasting a long time and are a smart choice.
Insulating low loss headers is key to keeping heat in and saving energy. This is especially true for big systems, where running cooler can cut energy use a lot. A metal mesh inside the header helps balance flows when outlets face each other.
Remember, low loss headers are different from plate heat exchangers, which keep separate systems and don’t mix fluids. By applying these guidelines, you can make sure your low loss header works well and saves energy.
Calculation of Parasitic Flow
Calculating parasitic flow in an offline load circuit is complex. It involves looking at several important factors. The pressure drop on the header between the secondary ports is a key factor. This pressure drop acts as a force that pushes flow through the offline load circuit.
Also, the dynamic pressure from the primary flow entering the secondary port is crucial for type 1 headers. This pressure adds to the overall flow calculation.
To cut down on parasitic flow, it’s vital to size the primary and secondary flow ports right. Making these ports too big can slow down the injection velocity into the header. This helps reduce the parasitic flow.
| Parameter | Value |
|---|---|
| Primary Flow Port Size | Oversized to reduce injection velocity |
| Secondary Flow Port Size | Oversized to reduce injection velocity |
| Pressure Drop Across Header | Considered as a pressure source for parasitic flow calculation |
By focusing on these factors and optimizing port sizes, we can accurately calculate and minimize parasitic flow. This ensures the system works more efficiently and performs better.
Low Loss Header Sizing
Designing efficient heating systems means getting the low loss header (LLH) size right. The flow velocity and pressure drop should stay under 0.3m/s and 5Pa/m, respectively, for boilers up to 3MW. For a 3MW boiler, the LLH diameter should be at least twice the size of the main pipes. At 50kW, it can be up to three times bigger. The distance between secondary ports doesn’t matter much if the design follows the rules.
The LLH’s size depends on the boiler output, system load, design, and temperature difference. Getting the size right means small pressure loss and the right temperature for secondary circuits. Also, the right water circulation volume is key for good boiler control, especially with efficient, low-water boilers.
The LLH is made from 4mm steel with insulation inside a mild steel casing. Its size changes with the number of boilers and their output. For example, it’s 26mm for two 52kW boilers, and 100mm for two 200kW boilers. The number of pumps also changes, from 6 to 8 for bigger setups.
Knowing how to size a low loss header helps designers make systems work better. This means longer boiler life and better efficiency.
Design Considerations
Header Configuration
To make sure the low loss header works well and lasts long, it should be mounted upright. This setup helps trap sludge at the bottom and lets air out at the top. The header should work at neutral pressure. All pump suction sides connect to the header, and the system’s pressure goes right to the header.
Velocity and Pressure Drop
Keeping the water clean is key to keeping the low loss header working right over time. There are two sizes of low loss header kits: DN50 (UIN 219476) and DN80 (UIN 219477). Different Evo S models offer options for 1, 2, 3, or 4 boilers. Each has its own flow and return header specs.
| Boiler Model | Boiler Output Range | Header Size | Pump Size | Flow Rate |
|---|---|---|---|---|
| Evo S 50 | 20-26 kW | DN50 | 6 | 65 ltr/min |
| Evo S 70 | 26-35 kW | DN50 | 6 | 65 ltr/min |
| Evo S 95 | 40-47 kW | DN80 | 8 | 100 ltr/min |
| Evo S 115 | 54-60 kW | DN80 | 8 | 100 ltr/min |
| Evo S 135 | 60-73 kW | DN80 | 8 | 100 ltr/min |
The low loss header must be attached to a solid wall or object upright. It needs specific space for pipe fittings and for servicing. Following safety standards and building codes (like BS EN 14336:2004, BS EN 12828:2003, BS EN 12831:2003) is crucial for the system to work right.
System Integration
Getting the pump placement and design right is key to a system’s performance. It’s best when the main flow equals the secondary flow for top hydraulic separation. If the secondary flow is more, it can dilute the temperature, affecting equipment like air handling units. On the other hand, if the main flow is higher, it can cause a temperature rise, stopping boilers from condensing if the design calls for cooler return temperatures.
Pump Placement and Configuration
A low-loss header needs two pumps: one from the boiler to it and another from it to the heating system. Where and how these pumps are set up is crucial for efficiency. This setup ensures a steady flow, making boilers last longer and boosting efficiency.
Secondary Circuit Considerations
The size of a low-loss header depends on the water flow in the building. It boosts the flow in the second circuit and mixes water from the primary boiler circuit. With multiple boilers, a low-loss header helps control the flow, saving costs. It also keeps the system clean by removing dirt and debris.
Installing a low-loss header vertically helps collect sludge, keeping the system clean. This setup makes air venting easy, allowing for automatic air venting.
| Low Loss Header Specifications | Value |
|---|---|
| Nominal Capacity | 11.5 litres |
| Weight (Empty) | 18.5 kg |
| Weight (Full) | 30.0 kg |
| Immersion Heater Output | 3 kW |
| Electrical Supply | 230V 50Hz 1ph |
| Connections | 1″ BSP inlet/outlet, ½” BSP drain cock, ⅜” BSP manual air vent |
| Construction Materials | Mild steel shell, galvanized mild steel with polyester powder coating for outer casing, mineral wool insulation |
| Electrical Wiring | Control: 3x 0.75mm², Power: 3x 1.5mm² |
| Relevant Standards | Building Regulations, Local Bylaws, Water Supply Regulations, MCS Installer Standards, MIS3005 Requirements |
“A low-loss header increases the water flow passing through the second heating circuit and adds water from the primary boiler circuit.”
Maintenance and Water Quality
Keeping the header in good shape and ensuring the water is clean are key to keeping your heating system efficient. New steel pipes lose pressure slowly, but corroded ones lose more, up to 11.78Pa/m. Regular maintenance and clean water are crucial to avoid expensive problems later.
Regular cleaning and checking the header are important. Debris and corrosion can make the system less efficient. Using water treatment, like inhibitors and filters, helps prevent these issues and makes your system last longer.
- Regular cleaning and inspection of the header to remove debris and scale buildup
- Use of water treatment inhibitors to prevent corrosion and scale formation
- Installation of filters to remove impurities and suspended solids from the system
Investing in good maintenance and clean water saves money in the long run. It keeps your heating system running well and avoids expensive fixes or replacements. Simple steps can help your header work efficiently for a long time.
| Header Type | Pressure Loss (Pa/m) |
|---|---|
| New Steel Pipe | 3.65 |
| Corroded Pipe | 5.26 |
| Badly Corroded Pipe | 11.78 |
For homes, low loss headers cost about 90-100 €. For bigger buildings, they start at 250 € and can connect many heating circuits. Quality parts like Nordic Tec hydraulic couplings made from solid steel ensure your system works well for years.
By focusing on header maintenance and clean water, you keep your heating system efficient and performing well for a long time.
Conclusion
Getting the size and setup of a low loss header right is key for top efficiency and performance. This guide shows how to make sure your low loss header works well. It helps cut down on pressure losses, stop unwanted flows, and make your system work better. A well-made low loss header means big cost savings, better system efficiency, and a more dependable heating system.
The benefits of low loss headers are many. They fix issues like temperature swings, poor circulation, and remove impurities. They also keep the flow steady, making your boiler last longer and boosting system efficiency. Even with some design considerations like space, cost, and heat loss, the good points of a well-sized low loss header usually win out.
By using best practices for designing and adding a low loss header, you get the most out of your heating system. This means picking the best header type, placing and sizing the pump right, and thinking about the secondary circuits to cut down on pressure losses and boost efficiency. With the right steps, a low loss header can change the game for your heating system. It brings steady comfort, saves energy, and cuts costs over time.
FAQ
What is the purpose of a low loss header?
A low loss header helps separate the primary and secondary circuits. This lets the pumps work independently of each other.
How is a low loss header sized based on boiler output?
The size of the low loss header depends on the boiler’s max output and the system’s temperature drop. Bigger boilers need bigger headers. Lower flow rates and bigger temperature drops mean smaller headers.
How is parasitic flow in an offline load circuit calculated?
To find parasitic flow, look at the pressure drop on the header and the dynamic pressure from the primary flow. Making the flow ports bigger reduces the parasitic flow by slowing down the injection.
What are the recommended design guidelines for low loss headers?
Keep the flow in the low loss header slow and the pressure drop small, especially for boilers up to 3MW. The header should be at least twice as wide as the main pipes for a 3MW boiler. It should be mounted upright to catch sludge and remove air.
How does the placement and configuration of pumps impact low loss header performance?
Where pumps are placed and how they’re set up affects the low loss header’s performance. The primary and secondary flows should match for the best results. If not, it can cause temperature problems.
Why is water quality important for maintaining low loss header performance?
Keeping the water clean is key to keeping the low loss header working well. Corrosion can make pipe pressure losses much higher, from 3.65Pa/m in new pipes to 11.78Pa/m in old ones.
Source Links
- https://hamworthy-heating.com/Knowledge-portal/Article-library/How-to-size-a-low-loss-header – How to size a low loss header
- https://hamworthy-heating.com/Knowledge-portal/Article-library/What-is-a-low-loss-header-And-when-to-use-one – What is a low loss header? And when to use one.
- https://www.viessmann.co.uk/en/heating-advice/boilers/what-is-a-low-loss-header.html – What is a low loss header? | Viessmann UK
- https://nordictec-store.com/gb/blog/post/hydraulic-clutch-in-the-central-heating-system – Low Loss Header in Central Heating Systems – What is it and How Does it Work? | Nordictec-store.com
- https://nordictec-store.com/gb/blog/post/hydraulic-clutches-structure-principles-of-operation-application – Hydraulic coupling for central heating systems – application | Nordictec-store.com
- https://renewableheatinghub.co.uk/avoid-the-heat-pump-villain-why-low-loss-headers-and-buffers-can-sabotage-your-heat-pumps-efficiency – Avoid the Heat Pump Villain: Why Low-Loss Headers and Buffers Can Sabotage Your Heat Pump’s Efficiency – Renewable Heating Hub
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- https://www.boilercentral.com/boiler-advice/what-is-a-low-loss-header/ – What Is A Low Loss Header, How Does It Work & Do You Need It?
- https://www.grantuk.com/media/5367/grant-combined-volumiser-low-loss-header-installer-uk-doc-0184-rev-1-1-april-2023.pdf – PDF
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