The Belimo ZONE325S-80+ZONE120NC is a zone valve assembly: the ZONE325S-80, a forged brass, 3-way on/off diverting zone valve with 1" sweat ends: Cv 8, 20 psi close-off, 300 psi body pressure rating and ANSI Class III 0.1% leakage, for chilled or hot water up to 50% glycol, fitted with the ZONE120NC spring return fail-safe actuator for 2-wire on/off control at AC 120 V.
Typically used on fan coil units, baseboards and other hydronic applications where fail-safe operation on 2-wire control is required, in systems with variable or constant flow. The compact body and actuator fit tight spaces where on/off control is needed.
Specifications per Belimo ZONE325S-80 technical data sheet 2023-01-10; ZONE325S-80+ZONE120NC assembly data sheet (ZONE325S-80 and ZONE120NC pages, 2022-01-12). Reviewed 2026-10-09.
Best For
- Fan coil units, baseboards and other hydronic terminal units
- On/off diverting duty in hydronic systems with variable or constant flow
- Soldered piping with 1" sweat ends
- Line-voltage thermostat circuits at AC 120 V
Warranty
Belimo covers the ZONE325S-80 valve and the ZONE120NC actuator each with a 2-year warranty.
Key Features
3-way on/off diverting
Flow pattern 3-way, on/off diverting flow characteristic, ANSI Class III 0.1% leakage, Cv 8.
20 psi close-off
Close-off pressure 20 psi with a 300 psi body pressure rating.
Spring return fail-safe
Spring return actuator for fail-safe operation on 2-wire on/off control.
AC 120 V supply
AC 120 V, 50/60 Hz; 6.5 W in operation, transformer sizing 7 VA.
1" Sweat connection
1" sweat ends; actuator connects by 6 in. wire leads.
Manual override
Hand lever manual override, 90° rotation, integrated mechanical position indication.
ZOT Supply is an authorized distributor of Belimo products.
Technical Specifications
Valve: Belimo ZONE325S-80
| Valve model | Belimo ZONE325S-80 |
| Valve size | 1 in. [DN 25] |
| Flow pattern | 3-way |
| Flow characteristic | on/off, diverting |
| Cv | 8 |
| Close-off pressure | 20 psi |
| Body pressure rating | 300 psi |
| Leakage rate | ANSI Class III 0.1% |
| Fluid | chilled or hot water, up to 50% glycol |
| Fluid temperature range (water) | 32...212°F [0...100°C] |
| Pipe connection | sweat |
| Valve body | forged brass |
| Housing seal | EPDM |
| Stem | stainless steel |
| Seat | EPDM |
| Suitable actuators | ZONE (spring) |
| Dimensions A / B / C / D / E / F | 4.0 in. [102 mm] / 3.4 in. [86 mm] / 3.7 in. [93 mm] / 5.5 in. [140 mm] / 1.2 in. [30 mm] / 1.2 in. [31 mm] |
Actuator: Belimo ZONE120NC
| Actuator model | Belimo ZONE120NC |
| Nominal voltage | AC 120 V |
| Nominal voltage frequency | 50/60 Hz |
| Power consumption in operation | 6.5 W |
| Transformer sizing | 7 VA |
| Electrical connection | 6 in. wire leads |
| Manual override | hand lever |
| Angle of rotation | 90° |
| Noise level, motor | 35 dB(A) |
| Noise level, fail-safe | 35 dB(A) |
| Position indication | Mechanically (integrated) |
| Degree of protection IEC/EN | IP20 |
| Degree of protection NEMA/UL | NEMA 1 |
| Enclosure | UL Enclosure Type 1 |
| Agency listing | CE, cULus |
| Quality standard | ISO 9001 |
| Ambient temperature | 32...104°F [0...40°C] |
| Storage temperature | -40...176°F [-40...80°C] |
| Ambient humidity | Max. 95% RH, non-condensing |
| Servicing | maintenance-free |
| Housing material | galvanized steel |
| Grounding | Meets cULus requirements without the need of an electrical ground connection |
Documentation
FAQ
What is the Cv and close-off pressure of the Belimo ZONE325S-80+ZONE120NC?
Cv 8 with a 20 psi close-off pressure and a 300 psi body pressure rating.
Is the ZONE325S-80+ZONE120NC a 2-way or 3-way valve?
3-way. The flow characteristic is on/off, diverting, with ANSI Class III 0.1% leakage.
How is the ZONE325S-80+ZONE120NC wired?
Two wires: the thermostat switches L1 (hot) to one black actuator lead and L2 connects to the other.
What power supply does the ZONE325S-80+ZONE120NC need?
AC 120 V, 50/60 Hz. Power consumption is 6.5 W in operation and transformer sizing is 7 VA.
What fluids can the ZONE325S-80+ZONE120NC control?
Chilled or hot water, up to 50% glycol, at fluid temperatures of 32...212°F [0...100°C].
- Valve Pattern:
- 3-Way
- Valve Size:
- 1 Inch
- Connection Type:
- Sweat
- CV Rating:
- 8
- Actuator Type:
- Fail-Safe
- Voltage:
- 120VAC
- Control Signal:
- On/Off
- Auxillary Switch:
- None
