The Caleffi 644256A is a 2-Way motorized ball zone valve with 3/4" Press connections.
Best for zones needing low pressure drop and positive shutoff, including larger branches and snowmelt loops.
Specifications transcribed from Caleffi technical brochure 01131/23 NA. Last verified August 2026.
Warranty
Key Features
Full-Port Ball Design
A ball closure gives a full-port, low-pressure-drop design when open and tight shutoff when closed, unlike a characterized globe seat.
Motorized Actuation
A synchronous motor drives the ball open and closed on a thermostat signal, with an auxiliary end switch available for pump or boiler interlock.
Auxiliary End Switch
An auxiliary microswitch rated 5 A at 24 V confirms valve position for pump or boiler interlock.
Technical Specifications
| Product Type | Motorized Ball Zone Valve |
| Connection Size | 3/4" |
| Connection Type | Press |
| Configuration | 2-Way |
| Flow coefficient (Cv) | 13.0 Cv |
| Medium temperature range | 20-230 °F |
| Electric supply | 24 V AC |
| Power consumption at full capacity | 4 VA |
| Auxiliary microswitch contact rating (24 V) | 5 A |
| closing delta p max. | 150 psi |
| Series | 2-Way |
| Published weight (Caleffi "Wt.") | 2.4 lb |
Documentation
Related Products
- Caleffi 644250A : Motorized Ball Valve 2-Way 3/4" Male NPT
- Caleffi 644259A : Motorized Ball Valve 2-Way 3/4" Sweat
- Caleffi 644260A : Motorized Ball Valve 2-Way 1" Male NPT
- Caleffi 644266A : Motorized Ball Valve 2-Way 1" Press
Frequently Asked Questions
What does Caleffi 644256A do?
It is a motorized ball zone valve. A motor drives a full-port ball open and closed on a thermostat call, giving very low pressure drop when open and tight shutoff when closed.
How is Caleffi 644256A different from a thermo-electric zone valve?
A ball valve gives a full-port, low-pressure-drop path and positive shutoff, and suits larger zones. A thermo-electric valve is smaller and silent but has a characterized seat with higher pressure drop.
What connection does Caleffi 644256A use?
It is supplied with 3/4" Press connections. Other sizes and connection styles in the range are listed under Related Products.
What supply voltage does Caleffi 644256A require?
Electric supply is 24 V AC, drawing 4 VA at full capacity.
- Product Type:
- Motorized Ball Zone Valve
- Product Family:
- Motorized Ball Zone Valves
- Series:
- 2-Way
- Connection Type:
- Press
- Connection Size:
- 3/4 inch
- Configuration:
- 2-Way
- Electric Supply:
- 24 V AC
- Medium Temperature Range:
- 20-230 deg F
- Flow Coefficient:
- 13.0 Cv