The Caleffi 521509AC is a MixCal thermostatic mixing valve with 3/4" Sweat connections, listed to ASSE 1017. It is used for point of distribution temperature control in domestic hot water and hydronic systems.
Best for water heater and storage tank outlets where a single valve sets the distribution temperature for an entire building, zone or riser.
Specifications sourced from Caleffi NA technical literature, 2025 revisions.
Key Features
ASSE 1017 Listed
Certified for point-of-distribution service, controlling water heater outlet temperature for an entire building or zone.
Thermostatic Element Control
A wax-actuated element responds to outlet temperature changes and repositions the shuttle continuously, holding setpoint without power or controls.
Integral Check Valves
Inlet port check valves are built in, preventing crossflow between hot and cold supplies without additional fittings.
Low-Lead Brass Construction
Wetted surfaces carry a weighted average lead content below 0.25%, meeting Section 1417 of the Safe Drinking Water Act.
Technical Specifications
| Connection Size | 3/4" |
| Connection Type | Sweat |
| Configuration | 3-Way |
| Maximum operating pressure | 200 psi |
| Adjustment temperature range | 85 - 150 deg F |
| Maximum inlet temperature | 200 deg F |
| Flow rate working range | 1.0 - 14 gpm |
| Material | DZR low lead brass |
| Certification | ASSE 1017 |
| Series | MixCal |
| Valve Technology | Thermostatic |
| Shipping Weight | 2.4 lb |
Documentation
Related Products
- Caleffi 521500A : MixCal 3-Way Thermostatic Mixing Valve 3/4" NPT
- Caleffi 521500AC : MixCal 3-Way Thermostatic Mixing Valve 3/4" NPT
- Caleffi 521506A : MixCal 3-Way Thermostatic Mixing Valve 3/4" Press
- Caleffi 521506AC : MixCal 3-Way Thermostatic Mixing Valve 3/4" Press
Frequently Asked Questions
Is Caleffi 521509AC approved for point-of-distribution service?
Yes. Caleffi 521509AC is listed to ASSE 1017, the standard covering temperature-actuated mixing valves used to control hot water distribution from a water heater or storage tank. ASSE 1017 valves regulate system supply temperature; they are not a substitute for ASSE 1070 point-of-use scald protection at individual fixtures.
What is the temperature adjustment range of Caleffi 521509AC?
The adjustment temperature range is 85 - 150 deg F. Maximum inlet temperature is 200 deg F. Confirm the setpoint against the applicable plumbing code for the installation.
What connection does Caleffi 521509AC use?
Caleffi 521509AC is supplied with 3/4" Sweat connections. Other connection styles in the MixCal family are listed under Related Products.
Does Caleffi 521509AC include check valves?
Yes. This model includes integral inlet port check valves, which prevent crossflow between the hot and cold supplies. The C in the product code identifies models supplied with integral check valves.
What is the warranty on Caleffi 521509AC?
Caleffi covers this product under its standard two-year limited warranty against defects in material and workmanship from the date of purchase. ZOT Supply is an authorized Caleffi distributor.
- Product Series:
- MixCal
- Valve Technology:
- Thermostatic
- Application:
- Point of Distribution
- Connection Type:
- Sweat
- Connection Size:
- 3/4 inch
- ASSE Listing:
- ASSE 1017
- Integral Check Valves:
- Yes
- Temperature Gauge:
- No
- Adjustment Temperature Range:
- 85 - 150 deg F
- Body Material:
- DZR low lead brass