The Belimo ZONE315S-35 is a 1/2 in. sweat, 3-way diverting zone valve body: forged brass with an EPDM seat and stainless steel stem, Cv 3.5, 30 psi close-off, ANSI Class III leakage and a 300 psi body pressure rating, for chilled or hot water up to 50% glycol. It takes a ZONE spring return actuator, sold separately.
Built for 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 assembly fits tight spaces where on/off control is needed.
Specifications per Belimo ZONE315S-35 technical data sheet rev 2023-01-10. Reviewed 2026-10-09.
Best For
- Fan coil units and baseboard heating
- Hydronic systems with variable or constant flow
- Sweat (solder) 1/2 in. pipe connections
- Pairing with a ZONE spring return actuator chosen for the control voltage
Warranty
Belimo covers the valve with a 2-year warranty.
Key Features
3-way diverting body
Forged brass body, EPDM seat and housing seal, stainless steel stem; 300 psi body pressure rating.
Cv 3.5, 30 psi close-off
On/off diverting flow with ANSI Class III 0.1% leakage.
1/2 in. sweat ends
Sweat (solder) connection for 1/2 in. pipe; DN 15 valve size.
Wide fluid range
Chilled or hot water up to 50% glycol, 32 to 212°F [0 to 100°C].
ZONE actuator fit
Takes a ZONE spring return actuator for fail-safe operation on 2-wire control.
ZOT Supply is an authorized distributor of Belimo products.
Technical Specifications
Valve: Belimo ZONE315S-35
| Valve size | 0.5 in. [DN 15] |
| Flow pattern | 3-way |
| Flow characteristic | On/off, diverting |
| Cv | 3.5 |
| Close-off pressure | 30 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 to 212°F [0 to 100°C] |
| Pipe connection | Sweat |
| Valve body | Forged brass |
| Housing seal | EPDM |
| Stem | Stainless steel |
| Seat | EPDM |
| Suitable actuators | ZONE spring return |
| Valve weight | 0.88 lb [0.40 kg] |
Assembled dimensions
| A: actuator length | 4.0 in. [102 mm] |
| B: valve body length, port to port | 2.8 in. [70 mm] |
| C: pipe centerline to top of actuator | 3.5 in. [89 mm] |
| D: overall height | 4.8 in. [122 mm] |
| E / F: pipe centerline to side | 1.2 in. [30 mm] / 1.2 in. [31 mm] |
FAQ
What is the Cv and close-off pressure of the Belimo ZONE315S-35?
Cv 3.5 with a 30 psi close-off pressure. The body pressure rating is 300 psi and the leakage rate is ANSI Class III 0.1%.
What pipe connection does the ZONE315S-35 have?
1/2 in. sweat (solder) ends (DN 15).
Which actuator fits the Belimo ZONE315S-35?
A ZONE spring return actuator. The valve is sold without an actuator.
How much does the ZONE315S-35 valve weigh?
The valve weighs 0.88 lb [0.40 kg].
What fluids can the ZONE315S-35 control?
Chilled or hot water, up to 50% glycol, from 32 to 212°F [0 to 100°C].
- Valve Pattern:
- 3-Way
- Valve Size:
- 1/2 Inch
- Connection Type:
- Sweat
- CV Rating:
- 3.5
- Max Close-Off Pressure:
- 30 psi
- Max Operating Pressure:
- 300 psi
- Medium Temperature Range:
- 32-212 °F
- Body Material:
- Forged Brass
- Actuator Type:
- Valve Only
