The Caleffi 280175A is a ThermoProtec thermostatic anticondensing valve with 1-1/4" NPT connections, holding boiler return temperature at 130 F. It protects biomass and solid-fuel boilers from flue gas condensation and the corrosion that follows.
Best for wood, pellet and other solid-fuel boiler returns where sustained low return temperature would corrode the heat exchanger.
Specifications sourced from Caleffi North America technical literature. Last reviewed July 2026.
Key Features
Protects the Boiler From Flue Gas Condensation
Holds the return temperature to the appliance at 130 F, keeping the heat exchanger above the flue gas dew point where corrosive condensate forms.
Thermostatic, No Power Required
A wax-actuated element modulates the bypass automatically as return temperature changes, with no controller, wiring or power supply.
Field-Replaceable Cartridge
The thermostatic element is supplied as a serviceable cartridge, so the set point can be changed or the element renewed without replacing the valve body.
Brass Body Construction
Body material: brass, selected for durability at solar loop operating temperatures.
Technical Specifications
| Product Type | Anticondensing Mixing Valve |
| Application | Biomass |
| Series | ThermoProtec |
| Connection Size | 1-1/4" |
| Connection Type | NPT |
| Set Point Temperature | 130 F |
| Maximum operating pressure | 150 psi |
| Medium temperature range | 40 to 212 deg F (5 to 100 deg C) |
| Material | brass |
Documentation
Design Resources
Related Products
- Caleffi 280165A : ThermoProtec Anticondensing Valve 130 F 1" NPT
- Caleffi 280166A : ThermoProtec Anticondensing Valve 140 F 1" NPT
- Caleffi 280176A : ThermoProtec Anticondensing Valve 140 F 1-1/4" NPT
- Caleffi 280965A : ThermoProtec Anticondensing Valve 130 F 1" Sweat
Frequently Asked Questions
What does Caleffi 280175A do?
Caleffi 280175A is a thermostatic anticondensing valve. It blends hot supply into the return so the temperature entering a biomass or solid-fuel boiler stays at 130 F, keeping the heat exchanger above the flue gas dew point where corrosive condensate forms.
Does Caleffi 280175A need power or a controller?
No. A wax-actuated thermostatic element modulates the bypass mechanically as return temperature changes. There is no wiring, controller or power supply.
Can the set point on Caleffi 280175A be changed?
Yes. The thermostatic element is a replaceable cartridge. Caleffi supplies cartridges rated 115, 130, 140 and 160 F, so the return temperature can be changed without replacing the valve body.
What is the temperature rating of Caleffi 280175A?
The medium temperature range is 40 to 212 deg F (5 to 100 deg C), with a maximum operating pressure of 150 psi.
What is the warranty on Caleffi 280175A?
Caleffi covers this product under its standard two-year limited warranty against defects in material and workmanship from the date of shipment. ZOT Supply is an authorized Caleffi distributor.
- Application:
- Biomass
- Product Type:
- Anticondensing Mixing Valve
- Series:
- ThermoProtec
- Connection Type:
- NPT
- Connection Size:
- 1-1/4 inch
- Set Point Temperature:
- 130 F
- Max Operating Pressure:
- 150 psi
- Medium Temperature Range:
- 40 to 212 deg F (5 to 100 deg C)
- Body Material:
- brass