910064CC Electronic Thermostatic Mixing Valve
The Legom 910054NT MULTI-Thermostatic Circulation Valve is a dual-cartridge thermostatic balancing valve for hot water circulation systems, combining a thermostatic control function (35–60°C, factory preset 55°C) and a built-in thermal sterilization bypass function (preset 70°C, shutdown 75°C) in a single compact valve body. Unlike standard thermostatic mixing valves, the 910054NT is installed on hot water circulation return branches to automatically balance flow across multiple branches, maintain minimum return temperatures above the Legionella growth threshold, and enable full-system thermal sterilization without interrupting normal hot water operation.
Manufactured from lead-free brass rated to PN16 nominal pressure, the 910054NT is designed for DN20 pipework with G3/4″ female inlet and G3/4″ male outlet connections. Maximum inlet temperature is 90°C, maximum pressure drop across the valve is 1 bar, and full open flow coefficient Kvmax is 1.6 m³/h. The valve ships with a prefabricated thermal insulation shell as standard, and accepts an optional 10 mm thermometer interface for direct temperature monitoring at the valve body.
Key Benefits
- Dual-cartridge design: thermostatic control and thermal sterilization in one valve – The 910054NT contains two independent valve cores in a single body. The control valve core (preset 55°C) manages daily circulation balancing; the sterilization valve core (preset 70°C) activates the mechanical bypass circuit during thermal disinfection cycles. This eliminates the need for separate bypass valves or motorized actuators to run periodic Legionella sterilization procedures
- Automatic branch flow balancing to prevent Legionella growth – When return water temperature in a circulation branch falls below the 55°C preset, the control valve core increases its opening to raise circulation flow through that branch until temperature recovers. When the preset is reached, flow is reduced to minimum to allow other branches to balance. This continuously maintains return temperatures above the Legionella proliferation threshold (35–46°C) across all branches simultaneously
- Mechanical bypass thermal sterilization without system shutdown – When hot water supply temperature exceeds 65°C during a thermal disinfection cycle, the sterilization valve core opens a dedicated bypass circuit, routing high-temperature water through the branch independently of the control cartridge. The system reaches 70°C for sterilization. Above 75°C, bypass flow reduces to minimum to protect downstream equipment. No electrical actuator or controller is required for this function
- Wide temperature control range 35–60°C with field-adjustable set point – The outlet temperature set point can be adjusted across the full 35–60°C range by rotating the handle, covering both lower comfort temperatures and the higher return temperatures required by German (55°C minimum) and UK (50°C minimum) Legionella control guidelines
- Temperature locking mechanism to prevent unauthorized adjustment – After commissioning, the handle can be locked to the set point using the integrated base locking feature, preventing unauthorized temperature changes by building occupants. Unlocking requires deliberate reversal of the locking procedure, suitable for commercial, institutional, and multi-occupancy residential installations
- Lead-free brass body with PN16 pressure rating – The lead-free brass construction complies with drinking water material requirements and is rated to PN16 (1600 kPa), covering the full range of building hot water system operating pressures in residential and commercial applications
- Vertical and horizontal installation flexibility – The 910054NT can be installed in any orientation — vertical or horizontal — according to the flow direction arrow on the valve body, without affecting thermostatic performance. This simplifies installation in tight riser shafts and ceiling-mounted pipework runs
- Prefabricated insulation shell included as standard – The factory-supplied thermal insulation shell is fitted over the valve body after installation, reducing heat loss from the valve body itself and preventing the valve from acting as a heat sink in the circulation loop
Technical Specifications
| Parameter | Specification |
|---|---|
| Model | 910054NT |
| Identification Number | CBTCV02001 |
| Main Material | Lead-free brass |
| Medium | Hot water |
| Nominal Pressure | PN16 |
| Maximum Pressure Drop | 1 bar |
| Maximum Inlet Temperature | 90°C |
| Temperature Control Range | 35–60°C |
| Control Valve Core Preset Temperature | 55°C (factory set) |
| Sterilization Valve Core Preset Temperature | 70°C (factory set) |
| Shutdown Temperature | 75°C |
| Full Open Flow Kvmax | 1.6 m³/h |
| Sterilization Flow Kvdis | 0.6 m³/h |
| Minimum Flow at 55°C Kvmin | 0.15 ± 20% m³/h |
| Connection Size | DN20 — G3/4″ female inlet x G3/4″ male outlet |
| Thermometer Interface | 10 mm |
| Dimensions (L x H1 x H2) | 112 x 74 x 17.5 mm |
Application & Use Cases
- Multi-riser hot water circulation systems in apartment buildings and commercial facilities – In buildings with multiple vertical hot water risers, each riser return branch is fitted with a 910054NT. The valve automatically adjusts circulation flow in each branch to maintain return temperatures at or above 55°C across all risers simultaneously, eliminating the cold branch and hot branch imbalance common in traditionally balanced systems
- Layered hot water circulation in large villas and multi-storey residential buildings – In floor-by-floor circulation layouts, the 910054NT is installed at each floor return connection, ensuring that each floor maintains adequate return temperature without manual hydraulic balancing. This is particularly relevant in large villas and multi-storey residences where upper floors often receive lower circulation temperatures than lower floors
- Legionella control in hotels, hospitals, aged care, and student accommodation – Buildings with large hot water distribution systems and high Legionella risk are required in many jurisdictions to maintain hot water circulation return temperatures above 50–55°C throughout the system. The 910054NT provides the per-branch thermostatic control required to maintain these temperatures across complex distribution networks with multiple circulation loops
- Thermal disinfection systems requiring periodic high-temperature flushing – The built-in sterilization bypass allows full-system thermal disinfection cycles to be run without replacing or bypassing individual branch valves. When supply temperature is raised above 65°C for disinfection, the sterilization valve core opens automatically on every installed branch, distributing high-temperature water throughout the entire circulation system
- Energy-efficient hot water circulation optimization – In traditional circulation systems, all branches circulate at full flow continuously regardless of return temperature, resulting in excessive heat loss and pump energy consumption. The 910054NT’s minimum flow function (Kvmin 0.15 m³/h at 55°C) throttles branches that have reached their set point temperature, directing available circulation flow to branches still below temperature — reducing overall pump load and heat loss compared to unbalanced systems
Installation Notes
- Thoroughly flush the entire hot water distribution pipework before installing the 910054NT. Pipe debris, flux residue, and installation contaminants entering the valve body can impair thermostatic element performance and damage the valve seat sealing surfaces. Install a suitable strainer upstream at the system inlet if not already present
- Install the valve according to the flow direction arrow marked on the valve body. The 910054NT can be installed vertically or horizontally without affecting thermostatic performance. Position the valve to allow clear access to the handle for temperature adjustment and periodic maintenance
- To set the outlet temperature: rotate the handle clockwise to decrease temperature, counterclockwise to increase. Confirm the return branch temperature using a calibrated thermometer at the 10 mm thermometer interface on the valve body or at a nearby measurement point. Allow sufficient time for the branch to reach steady-state temperature before confirming the set point
- To lock the temperature set point after commissioning: remove the nameplate from the handle, unscrew the fixing screw at the top of the handle, remove the handle, lift the handle groove section to the base position, and reinstall the screw. Note: after locking, the temperature scale markings on the handle are no longer visible. Retain a record of the set point value for future reference
- Fit the supplied prefabricated insulation shell over the valve body after installation is complete and the temperature set point is confirmed. The insulation shell reduces heat loss from the valve body and should remain in place during normal system operation
- Do not expose the valve to inlet temperatures above 90°C. If the hot water system is capable of producing supply temperatures above 90°C — for example during extended thermal disinfection cycles or boiler malfunction — install a temperature limiting device upstream to protect the 910054NT thermostatic cartridges
- For thermal sterilization cycles: raise the hot water supply temperature above 65°C. The sterilization valve core will open automatically on each installed 910054NT branch. The system will reach 70°C for effective Legionella thermal kill. Above 75°C, the sterilization bypass reduces to minimum flow automatically. No manual intervention at individual valves is required during the disinfection cycle
Frequently Asked Questions
How is the 910054NT different from a standard thermostatic mixing valve like the 910034NT?
A standard thermostatic mixing valve blends hot and cold water to deliver a safe mixed outlet temperature at a fixture supply point. It is installed at the end of a distribution branch, between the hot supply and the user outlet. The 910054NT is a completely different device serving a completely different function: it is installed on the return line of a hot water circulation branch, and it does not mix hot and cold water at all. Its job is to control how much hot water circulates through each return branch to maintain the return temperature above the Legionella threshold, and to allow the entire circulation system to undergo thermal disinfection without any valve being manually bypassed. The two products address different problems in different positions within the system.
Why is the control valve core factory preset to 55°C specifically?
55°C is the minimum hot water circulation return temperature recommended by German DVGW W 551 guidelines for Legionella control in large hot water systems. At this return temperature, Legionella bacteria cannot establish and multiply in the circulation pipework. The 55°C preset means the valve begins throttling circulation flow only once the branch return temperature has reached this safe minimum — if temperature falls below 55°C, the valve opens wider to increase circulation and restore temperature. The set point can be adjusted down to 50°C (the UK requirement under ACOP L8) or held at 55°C depending on the applicable regulatory standard for the installation country.
How does the thermal sterilization function work without shutting down the system?
The 910054NT contains a second independent valve core — the sterilization cartridge — preset to 70°C. During normal operation (supply temperature below 65°C), this cartridge remains closed and has no effect on system behavior. When the hot water supply temperature is raised above 65°C for a scheduled thermal disinfection cycle, the sterilization cartridge opens a dedicated mechanical bypass circuit within the valve body. High-temperature water flows through this bypass independently of the control cartridge, reaching all points of the circulation branch at sterilization temperature. When supply temperature exceeds 75°C, the bypass throttles to minimum to protect downstream equipment. The control cartridge resumes normal function once the supply temperature returns to the normal operating range. No electrical signal, controller, or manual intervention is required at any individual valve during the cycle.
What does Kvmin 0.15 m³/h mean in practice?
Kvmin is the minimum flow coefficient through the valve when the control cartridge is at its most closed position — that is, when the branch return temperature has reached the 55°C set point. At Kvmin 0.15 m³/h (±20%), a small but continuous circulation flow is maintained through the branch even at set point temperature, preventing dead zones and ensuring the branch remains thermally active. This minimum flow prevents stagnation and biofilm formation in the branch pipework while keeping energy consumption low. Branches that have reached temperature circulate at this minimum rate; circulation flow is automatically directed toward branches still below temperature.
How many 910054NT valves are needed for a building installation?
One 910054NT is installed per hot water circulation return branch. In a multi-riser system, one valve is installed at the return connection of each riser. In a layered (floor-by-floor) system, one valve is installed at each floor return connection. The number of valves required equals the number of independently controlled circulation branches in the building’s hot water system. For most residential apartment buildings, this is one valve per riser or one per floor zone. For complex commercial systems with sub-branches, a valve may be required at each sub-branch return as well. Refer to the piping schematic in the user manual for the recommended configurations for multi-riser and layered system layouts.
OEM & ODM Customization
Legom supports OEM and ODM services for the 910054NT MULTI-Thermostatic Circulation Valve. Customization options include temperature control range, connection size, pressure rating, and body configuration. Custom preset temperatures for both control and sterilization cartridges are available to meet specific regional Legionella control standards. All customization projects are developed with the Legom engineering team to confirm suitability for the intended application. Contact us via WhatsApp or info@legomsmart.com.
User Manual
Product information last reviewed by the Legom Technical Team. For the most current specifications, refer to the official datasheet or contact our sales team.
Custom OEM & ODM Solutions
Legom is a direct manufacturer offering end-to-end OEM and ODM services. With our in-house engineering and production capabilities, we work closely with distributors and system integrators to deliver fully customized solutions under strict NDA.
