The Caleffi F29635 is a replacement thermostatic sensor cartridge with a 140 F (60 C) set point for Caleffi 280 series ThermoProtec boiler protection mixing valves and 281 series ThermoBloc recirculation and distribution units. It is a service part fitted into an existing valve body, not a complete valve.
Specifications sourced from Caleffi technical brochure 01223/23 NA and ThermoBloc instructions NA10294.03. Last reviewed August 2026.
Key Features
Factory Calibrated to 140 F
The wax sensor is calibrated to 140 F (60 C) with an accuracy of +/- 4 deg F (+/- 2 deg C). Fitting it sets the valve to hold boiler return at that temperature.
Service Part, Not a Complete Valve
Supplied as a replacement thermostatic sensor cartridge. It installs into a Caleffi 280 or 281 series body that is already in the piping, and does not include a valve body.
Changes Set Point Without Repiping
On a ThermoProtec valve the cartridge comes out through the lower body plug, so the return temperature can be changed without removing the valve body from the pipe.
Fits Every 280 and 281 Configuration
Common to all 280 series ThermoProtec valves and 281 series ThermoBloc units, in NPT and sweat union styles across the 1 in. and 1-1/4 in. sizes.
Technical Specifications
| Product Type | Replacement thermostatic sensor cartridge |
| Application | Boiler protection - non-condensing boilers |
| Series | ThermoProtec 280 / ThermoBloc 281 |
| Set point temperature | 140 F (60 C) |
| Sensor cartridge accuracy | +/- 4 deg F (+/- 2 deg C) |
| Sensor type | wax thermostatic element |
| Compatibility | Caleffi 280 series ThermoProtec valves, Caleffi 281 series ThermoBloc units |
| Available set points in range | 115 F (45 C), 130 F (55 C), 140 F (60 C), 160 F (70 C) |
| Supplied as | replacement thermostatic sensor cartridge |
Documentation
Related Products
- Caleffi F29633 : ThermoProtec Thermostatic Cartridge 115 F
- Caleffi F29634 : ThermoProtec Thermostatic Cartridge 130 F
- Caleffi F29636 : ThermoProtec Thermostatic Cartridge 160 F
- Caleffi 280165A : ThermoProtec Boiler Protection Mixing Valve 130 F 1" NPT
Frequently Asked Questions
What is Caleffi F29635?
A replacement thermostatic sensor cartridge calibrated to 140 F (60 C) for Caleffi 280 series ThermoProtec boiler protection mixing valves and 281 series ThermoBloc units. It is a service part, not a complete valve.
Which valves does Caleffi F29635 fit?
All Caleffi 280 series ThermoProtec boiler protection valves and 281 series ThermoBloc units, in both NPT male union and sweat union styles, across the 1 in. and 1-1/4 in. sizes.
How is Caleffi F29635 installed?
On a ThermoProtec valve, isolate the valve, unscrew the lower body plug and withdraw the existing cartridge, then fit the replacement in the same position and reassemble. Apply the supplied set point label to the lower body plug. On a ThermoBloc the shutter locking nut is removed with a 17 mm hex key to access the assembly.
Can Caleffi F29635 change my valve's set point?
Yes. Fitting this cartridge sets the valve to 140 F (60 C). Caleffi supplies cartridges at 115, 130, 140 and 160 deg F, so an installed valve can be re-rated to suit a different boiler requirement.
What is the warranty on Caleffi F29635?
Caleffi North America covers this product under its two-year limited warranty against defects in material and workmanship from the date of shipment. ZOT Supply is an authorized Caleffi distributor.
- Product Type:
- Replacement Thermostatic Cartridge
- Application:
- Boiler Protection
- Series:
- ThermoProtec
- Set Point Temperature:
- 140 F (60 C)
- Compatibility:
- Caleffi 280 and 281 Series
