Belimo LR24A-SR Review
, 6 min reading time
The Belimo LR24A-SR is a 24 V modulating rotary actuator that delivers 5 Nm of torque with quiet, energy-saving operation. Designed for precise control of HVAC ball valves, it supports 2–10 V signals, offers position feedback for BMS integration and fits quickly onto DN15-DN40 valves. Facilities teams choose it for reliable comfort control, low running costs and zero scheduled maintenance.
Belimo LR24A-SR Review – 7 Compelling Reasons This 24 V Modulating Actuator Is the Smart Buy for HVAC Control
1. Introduction to the Belimo LR24A-SR
The Belimo LR24A-SR rotary actuator sits at the heart of thousands of reliable HVAC water circuits across the UK. Designed for precise modulation of ball valves, this compact device delivers 5 Nm of torque, responds to standard 0–10 V control signals, and provides position feedback for building-management systems. In a market driven by lower operating costs and tighter sustainability targets, the Belimo LR24A-SR offers specifiers and installing contractors a trusted balance of performance, efficiency, and straightforward integration.
1.1 Why Valve Actuators Matter in Modern HVAC
Every kilowatt of heating or cooling energy costs money and adds to carbon output. Accurate valve authority ensures that chilled and hot water flow rates match true demand. By modulating precisely rather than simply opening or closing, an actuator such as the Belimo LR24A-SR reduces pump energy, stabilises coil temperatures, and extends plant life.
2. Technical Specifications at a Glance
2.1 Electrical Performance
- Nominal voltage: 24 V AC/DC (range 19.2 – 28.8 V) :contentReference[oaicite:12]{index=12}
- Power draw in operation: 1.5 W; at rest: 0.4 W :contentReference[oaicite:13]{index=13}
- Control signal: 2 – 10 V DC with 100 kΩ input impedance :contentReference[oaicite:14]{index=14}
- Position feedback: 2 – 10 V DC
2.2 Functional Performance
- Torque: 5 Nm on a 90° rotation :contentReference[oaicite:15]{index=15}
- Running time: 90 s (motor) for full stroke :contentReference[oaicite:16]{index=16}
- Manual override with push-button lock
- Sound power level: 35 dB(A) – quieter than a typical office conversation
2.3 Safety & Environmental Ratings
- Ingress protection: IP54 / NEMA 2 – suitable for plant rooms and ceiling voids :contentReference[oaicite:17]{index=17}
- Operating temperature: −30 °C to +50 °C; 95 % RH non-condensing :contentReference[oaicite:18]{index=18}
- Class III SELV power safety compliance
- cULus and CE approvals for international projects :contentReference[oaicite:19]{index=19}
3. Real-World Applications in HVAC Systems
Below are three typical use-cases where the Belimo LR24A-SR demonstrates clear technical and financial advantages.
3.1 Commercial Chilled-Water Loops
In multi-tenant office blocks, each floor often has a dedicated coil branch. By pairing a DN20–DN40 Belimo control ball valve with the LR24A-SR, facility managers achieve tight supply-air temperature control while simultaneously preventing the delta-T shortfall that plagues oversized two-port circuits. The actuator’s continuous position feedback enables analytics to verify proper valve stroke and helps operators detect fouled coils before they escalate into complaints.
3.2 Low-Temperature Hot-Water Networks
District energy providers are shifting towards 60 °C supply temperatures to maximise condensing-boiler efficiency. The LR24A-SR withstands the lower delta-T environment, handling glycol mixes down to −10 °C while keeping leakage below 0.05 %. Precise modulation avoids hunting at part-load conditions, allowing pumps equipped with variable-speed drives to slow down and save kilowatt-hours.
3.3 Packaged Air-Handling Units
Manufacturers of close-control AHUs now integrate the Belimo LR24A-SR directly onto 3-port diverting valves for both cooling and heating coils. Because the actuator draws just 1.5 W, it simplifies power-budget calculations and reduces the need for large VA allowances in the control panel.
4. Seven Key Benefits That Drive ROI
4.1 Energy Efficiency
The combination of a 100 kΩ input impedance and a 1.5 W running load means negligible burden on 24 V transformer capacity. Over a year of operation, that equates to less than 13 kWh per actuator – roughly the cost of two cups of coffee.
4.2 Precision Modulating Control
With ±5 % position accuracy, the LR24A-SR fine-tunes coil flow, halting overshoot and improving comfort bands. Buildings targeting NABERS, BREEAM, or LEED points often cite valve – coil authority as a quick win.
4.3 Ease of Installation
The integrated anti-rotation bracket and one-screw drive coupling let engineers mount the unit in under five minutes. The removable mechanical position indicator doubles as a 10 mm hex tool, eliminating extra parts to misplace.
4.4 Quiet Operation
At 35 dB(A), the Belimo LR24A-SR operates quieter than many laptop fans, ensuring that boardrooms adjacent to fan-coil cupboards remain undisturbed.
4.5 Robust Safety Compliance
Whether you need SELV for medical facilities or cULus for export projects, the LR24A-SR ticks the check-boxes and keeps documentation hassle-free.
4.6 Versatile Accessories
Optional add-ons include SPDT auxiliary switches for end-stroke proof, and potentiometer kits ranging from 140 Ω to 10 kΩ for bespoke feedback curves. These accessories ship pre-configured, cutting on-site commissioning time.
4.7 Maintenance-Free Design
Belimo engineers designed the gearbox with lifetime lubrication and motor overload protection. Once the actuator is installed, it requires no scheduled servicing, allowing facilities staff to focus on critical plant.
5. Comparison With Popular Alternatives
Competing models frequently advertise higher torque, yet overlook energy consumption and noise levels. For DN40 and smaller valves, 5 Nm is more than adequate, and the LR24A-SR’s slim power draw trumps bulkier 10 Nm units that consume three times the energy. Furthermore, legacy spring-return actuators introduce moving parts that need annual checks, whereas the LR24A-SR’s electronic fail-safe logic and stall-protect circuitry remove that cost.
6. Integration Tips for Building Automation Systems
6.1 Control Signal – 2…10 V Best Practices
Always scale the BMS output so that 0 V equals valve closed and 10 V represents fully open. If an inverse action is desired, Belimo provides an on-board direction switch covered at the factory to prevent accidental operation :contentReference[oaicite:20]{index=20}.
6.2 Parallel Actuator Wiring
The LR24A-SR supports parallel operation. Up to five units can be driven from the same analogue output, provided that the transformer is sized for a maximum simultaneous load of 3 VA per actuator :contentReference[oaicite:21]{index=21}.
7. Installation Checklist
- Verify valve torque requirements – 5 Nm covers DN15–DN40 typically.
- Confirm 24 V AC/DC supply within 19.2–28.8 V.
- Mount actuator using central screw; tighten to manufacturer torque.
- Set mechanical end-stops if a limited stroke is required.
- Wire control and feedback leads: black (-), red (+), white (signal Y), orange (feedback U) :contentReference[oaicite:22]{index=22}.
- Commission via BMS graphics, checking 0 %, 50 %, and 100 % positions.
8. Frequently Asked Questions
Q1. Can I use the Belimo LR24A-SR outdoors?
A: Only if the actuator is shielded from direct rain, snow, or salty air and the ambient conditions remain within −30 °C to +50 °C, RH ≤ 95 % :contentReference[oaicite:23]{index=23}.
Q2. Is a spring-return model required for chilled-beam isolation?
A: For non-fail-safe applications such as chilled beams, the LR24A-SR’s electronic stall protection is sufficient. If fail-closed is mandated by the consultant, consider Belimo’s LF spring range instead.
Q3. How many LR24A-SR actuators can share one 24 V transformer?
A: Allow 3 VA apiece for worst-case inrush; a 60 VA transformer comfortably feeds up to 18 units with diversity.
Q4. Does the actuator support BACnet?
A: The LR24A-SR is an analogue device. For native BACnet MS/TP or IP, Belimo offers the PR series, which can be used with similar valves.
Q5. What maintenance is required?
A: None. The actuator is lubricated for life and features electronic overload shut-off.
Q6. Where can I buy replacement parts?
A: Spares and complete actuators are available for next-day delivery from authorised distributors such as Ecospares.
9. Conclusion and Call to Action
The Belimo LR24A-SR offers installers a proven route to improved energy performance and occupant comfort without inflating project budgets. From rapid mounting to whisper-quiet operation and lifelong reliability, this 24 V modulating actuator justifies its place in every modern HVAC specification.
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