The Caleffi 253046 is a solar safety relief valve preset to 90 psi (6 bar), with a 1/2 inch female straight-thread inlet and 3/4 inch female straight-thread outlet. It protects a solar thermal collector loop by discharging before system pressure exceeds the design limit.
Best for glycol-filled solar collector arrays where stagnation can drive loop pressure toward the system limit.
Specifications sourced from Caleffi North America technical literature. Last reviewed July 2026.
Key Features
Rated for Solar Thermal Service
Sized and set for the stagnation pressures a glycol-filled solar collector loop can reach, discharging before system pressure exceeds the design limit.
171,000 BTU Discharge Capacity
Published discharge capacity of 171,000 BTU (50 kW) with a 10% opening overpressure and 20% closing differential.
Glycol Compatible
Rated for glycol solutions to 50 %, the antifreeze concentration typical of a freeze-protected solar collector array.
Brass Body Construction
Body material: brass, nickel plated finish, selected for durability at solar loop operating temperatures.
Technical Specifications
| Product Type | Solar Safety Relief Valve |
| Application | Solar Thermal |
| Connections | 1/2" female straight thread inlet x 3/4" female straight thread outlet |
| Connection Type | Straight Thread |
| Relief Pressure Setting | 90 psi (6 bar) |
| Medium temperature range | -22 to 320 deg F (-30 to 160 deg C) |
| Nominal Pressure | PN 10 |
| Finish | nickel plated |
| Maximum glycol % | 50 % |
| Medium | glycol solutions, water |
| Material | brass |
| Shipping Weight | 0.3 lb |
Documentation
Related Products
- Caleffi 253040 : Solar Safety Relief Valve 150 psi
- Caleffi 253042 : Solar Safety Relief Valve 36 psi
- Caleffi 253043 : Solar Safety Relief Valve 45 psi
- Caleffi 253044 : Solar Safety Relief Valve 60 psi
Frequently Asked Questions
What pressure does Caleffi 253046 relieve at?
Caleffi 253046 is preset to 90 psi (6 bar). It opens at that pressure with a 10% opening overpressure and reseats with a 20% closing differential, and has a published discharge capacity of 171,000 BTU (50 kW).
Can Caleffi 253046 be used with glycol?
Yes. It is rated for water and glycol solutions to 50% concentration, which covers the antifreeze mixes used in freeze-protected solar collector loops.
What is the temperature rating of Caleffi 253046?
The medium temperature range is -22 to 320 deg F (-30 to 160 deg C).
What is the warranty on Caleffi 253046?
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:
- Solar Thermal
- Product Type:
- Solar Safety Relief Valve
- Connection Type:
- Straight Thread
- Connections:
- 1/2 inch female straight thread inlet x 3/4 inch female straight thread outlet
- Relief Pressure Setting:
- 90 psi (6 bar)
- Max Operating Pressure:
- PN 10
- Medium Temperature Range:
- -22 to 320 deg F (-30 to 160 deg C)
- Max Glycol Concentration:
- 50 %
- Body Material:
- brass