The Caleffi 574151A is an AutoFill Combo with a 3/4 in NPT inlet x 3/4 in NPT outlet connection with integral pressure gauge, pre-assembling an automatic filling valve with a testable ASSE 1013 RPZ backflow preventer to feed and protect a hydronic system in one code-compliant unit.
Product data compiled from Caleffi North America technical documentation. Last reviewed July 2026.
Key Features
Fill Valve + Testable RPZ
Pre-assembled 553-series AutoFill filling valve with a 574-series testable reduced-pressure-zone backflow preventer.
ASSE 1013 High-Hazard Rated
Meets high-hazard cross-connection requirements for boiler feed with chemical treatment or glycol.
Pre-Adjustable Fill Pressure
Set the target system fill pressure; the valve reduces and holds it automatically.
Integral Pressure Gauge
A built-in gauge shows system fill pressure at a glance.
Lead-Free Construction
Suitable for connection to the potable water supply.
Technical Data
| Function | Combination automatic filling valve and backflow preventer |
| ASSE listing | ASSE 1013 |
| Certifications | ASSE 1013, CSA B64.4; NSF/ANSI 372 (ICC-ES PMG-1360) |
| Connection | 3/4 in NPT female inlet x 3/4 in NPT male union outlet |
| Pressure gauge | Included |
| Adjustment pressure range | 6-90 psi |
| Factory pressure setting | 15 psi |
| Maximum operating pressure | 150 psi |
| Maximum working temperature | 140 °F |
| Pressure gauge scale | 0-100 psi |
Documentation
Technical brochureRelated Products
- Caleffi 574156A 3/4 in ASSE 1013 Fill + Backflow Combo
- Caleffi 574157A 3/4 in ASSE 1013 Fill + Backflow Combo
- Caleffi 573002A 1/2 in ASSE 1012 Fill + Backflow Combo
- Caleffi 535051A 3/4 in Auto Fill Valve
Frequently Asked Questions
What is the Caleffi 574151A?
It is an AutoFill Combo: an automatic filling valve pre-assembled with a backflow preventer, feeding a hydronic system while protecting the potable supply.
Which backflow preventer is included?
A testable ASSE 1013 reduced-pressure-zone (RPZ) preventer, rated for high-hazard applications such as glycol or chemical treatment.
When do I need ASSE 1013 instead of ASSE 1012?
Most codes require an ASSE 1013 RPZ when the system contains glycol or chemical treatment (high hazard); ASSE 1012 covers typical low/intermediate-hazard residential boiler feed. Confirm with your local authority.
- Type:
- Filling Valve & Backflow Combo
- ASSE Standard:
- ASSE 1013
- Series:
- AutoFill Combo
- Pressure Gauge:
- Included
- Connection Type:
- NPT Threaded
- Connection Size:
- 3/4 in
