The Caleffi 221500A is a straight thermostatic radiator valve body with a 3/4 in NPT female pipe connection and a 3/4 in NPT male radiator union with tailpiece. It is the valve body only. Fit a Caleffi thermostatic control head, a 6564 series 24V actuator or the 449010 manual knob, ordered separately.
Best for NPT-threaded cast iron and steel radiators fed in line with the valve connection.
Specifications from Caleffi datasheet 01034/23 NA (replaces 01034/19 NA). Assembly Cv from 01198/23 NA. Reviewed August 2026.
Key Features
NPT Threaded Throughout
3/4 in NPT female to the system and 3/4 in NPT male union to the radiator, so it lands directly on standard North American radiator piping with no metric or conical adapters.
Accepts Head, Actuator or Manual Knob
The M30 x 1.5 stem takes a Caleffi 200, 201, 203 or 472 series control head, a 6564 series 24V thermo-electric actuator, or the 449010 manual knob. Install the body first and fit the control at commissioning.
Straight Body
In-line body for radiators fed along the same axis as the valve connection.
Strong Return Spring
Because the Caleffi head uses an incompressible liquid-filled element, the 220 and 221 bodies carry a heavy return spring. After a long off-season the spring reliably lifts the plug seal off the seat without sticking.
Also Isolates and Balances
With the standard cap or the optional 449010 manual knob the valve can be shut off for isolation or throttled for balancing, with no second valve required.
EN 215 Certified Assembly
Combined with the 200000 or 201000 control head the 220 and 221 series in 1/2 in and 3/4 in are certified to UNI EN 215.
Technical Specifications
| Product Type | Radiator Valve Body |
| Series | 221 Series |
| Body Style | Straight |
| Connection type | NPT |
| Pipe connection | 3/4 in NPT female |
| Radiator connection | 3/4 in NPT male union with tailpiece |
| Head connection | M30 x 1.5 |
| Body material | Brass, chrome plated |
| Valve control stem | Stainless steel |
| Seals | Peroxide-cured EPDM |
| Control knob and cap | ABS, white RAL 9010 |
| Suitable fluids | Water, glycol solutions (30% max.) |
| Maximum working pressure | 150 psi (10 bar) |
| Max. differential pressure with control head | 15 psi (1 bar) |
| Temperature range | 40 to 212°F (5 to 100°C) |
| Cv, valve fully open | 2.6 |
| Cv at 2°F proportional band | 0.50 |
| Cv at 4°F proportional band | 0.76 |
| Max. Cv with 6564 series actuator | 2.3 |
| Approval | UNI EN 215 with 200000 or 201000 control head |
| Body length | 2 in |
| Radiator centerline | 2-1/2 in |
| Height to stem | 1-3/8 in |
| Overall height with 200000 head | 4-1/2 in |
Documentation
Related Products
- Caleffi 221400A : Straight TRV Body 1/2" NPT
- Caleffi 220500A : Angled TRV Body 3/4" NPT
- Caleffi 200000 : Control Head, Built-in Sensor
- Caleffi 449010 : Manual Knob
- Caleffi 656404 : Thermoelectric Actuator 24V
Frequently Asked Questions
What does the Caleffi 221500A do?
It is the straight valve body of a two-part thermostatic radiator valve. It fits between the 3/4 in NPT pipe and the radiator, and a separately ordered control head or actuator regulates flow through it to hold the room at setpoint.
Does the Caleffi 221500A include a control head?
No. The body ships with a cap only. Add a Caleffi 200, 201, 203 or 472 series thermostatic control head, a 6564 series 24V thermo-electric actuator, or the 449010 manual knob.
What size and thread is the Caleffi 221500A?
3/4 in NPT female on the pipe side and 3/4 in NPT male union with tailpiece on the radiator side.
What is the difference between the 220 and 221 series?
The 220 series is angled and the 221 series is straight. Both are NPT threaded and take the same control heads. Choose angled where the pipe arrives from the wall or floor, straight where the pipe runs in line with the radiator connection. The equivalent in the other style is the 220500A.
Can the Caleffi 221500A be used for balancing?
Yes. With the standard cap or the optional 449010 manual knob the valve can be shut off for isolation or throttled to preset flow for balancing.
What are the pressure and temperature limits of the Caleffi 221500A?
Maximum working pressure is 150 psi (10 bar) over a temperature range of 40 to 212°F (5 to 100°C). Maximum differential pressure with a control head fitted is 15 psi (1 bar).
- Product Type:
- Radiator Valve Body
- Product Family:
- Radiator Valve Bodies
- Series:
- 221 Series
- Body Style:
- Straight
- Connection Type:
- NPT
- Connection Size:
- 3/4 in
- Body Material:
- Brass, Chrome Plated
- Max Operating Pressure:
- 150 psi (10 bar)
- Max Medium Temperature:
- 212 deg F (100 deg C)
- Approval:
- EN 215
