The Belimo ZONE320S-50 is a forged brass, 3-way on/off diverting zone valve with 3/4" sweat ends: Cv 5, 25 psi close-off, 300 psi body pressure rating and ANSI Class III 0.1% leakage, for chilled or hot water up to 50% glycol. It takes a ZONE spring return actuator, sold separately.
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 ZONE320S-50 technical data sheet 2023-01-10; ZONE320S-50 valve page of the ZONE320S-50 assembly data sheets 2022-01-12 (pipe connection). 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 3/4" sweat ends
- Pairing with a Belimo ZONE spring return actuator chosen for the control voltage
Warranty
Belimo covers the ZONE320S-50 valve 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 5.
25 psi close-off
Close-off pressure 25 psi with a 300 psi body pressure rating.
Forged brass body
Forged brass valve body, EPDM seat and housing seal, stainless steel stem.
3/4" Sweat connection
3/4" sweat ends.
Water and glycol
Chilled or hot water up to 50% glycol, fluid temperature 32...212°F [0...100°C].
ZONE spring actuators
Belimo lists ZONE spring return actuators as suitable for this valve.
ZOT Supply is an authorized distributor of Belimo products.
Technical Specifications
Valve: Belimo ZONE320S-50
| Valve model | Belimo ZONE320S-50 |
| Valve size | 0.75 in. [DN 20] |
| Flow pattern | 3-way |
| Flow characteristic | on/off, diverting |
| Cv | 5 |
| Close-off pressure | 25 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] / 2.8 in. [70 mm] / 3.5 in. [89 mm] / 5.0 in. [127 mm] / 1.2 in. [30 mm] / 1.2 in. [31 mm] |
| Weight | 0.88 lb [0.40 kg] |
Documentation
FAQ
What is the Cv and close-off pressure of the Belimo ZONE320S-50?
Cv 5 with a 25 psi close-off pressure and a 300 psi body pressure rating.
Is the ZONE320S-50 a 2-way or 3-way valve?
3-way. The flow characteristic is on/off, diverting, with ANSI Class III 0.1% leakage.
Which actuators fit the Belimo ZONE320S-50?
Belimo lists ZONE spring return actuators as suitable for this valve. The actuator is sold separately.
What pipe connection does the ZONE320S-50 have?
3/4" sweat ends.
What fluids can the ZONE320S-50 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:
- 3/4 Inch
- Connection Type:
- Sweat
- CV Rating:
- 5.0
- Max Close-Off Pressure:
- 25 psi
- Max Operating Pressure:
- 300 psi
- Medium Temperature Range:
- 32-212 °F
- Body Material:
- Forged Brass
- Actuator Type:
- Valve Only
