The Caleffi 166612A is a HydroMixer 166-series thermostatic mixing unit with a Grundfos Alpha high-efficiency pump mounted on the left, providing fixed-point temperature mixing and circulation for a low-temperature radiant zone, with an integral stainless supply temperature gauge.
Product data compiled from Caleffi North America technical documentation (01170 NA, 01155 NA). Last reviewed July 2026.
Key Features
Fixed-Point Thermostatic Mixing
A thermostatic valve holds the zone supply at a constant low temperature for radiant panels - fully mechanical, no controls wiring.
Grundfos Alpha High-Efficiency Pump
Integral Grundfos Alpha ECM high-efficiency circulator mounted on the left.
Stainless Supply Temperature Gauge
Integral Caleffi stainless temperature gauge shows the mixed supply at a glance.
Compact Zone Add-On
A complete drop-in unit for adding a mixed low-temperature zone to an existing boiler system.
Technical Data
| Function | Thermostatic mixing unit (166 series) |
|---|---|
| Circulator | Grundfos Alpha high-efficiency |
| Pump orientation | Pump Left |
| Temperature gauge | Caleffi stainless steel |
| Maximum operating pressure | 145 psi |
| Adjustment temperature range | 80-125 °F |
| Electric supply | 115 V (AC) (AC) |
Documentation
Technical brochureRelated Products
Frequently Asked Questions
A HydroMixer 166-series thermostatic mixing unit: a fixed-point mixing valve with integral circulator and stainless supply temperature gauge, for adding a low-temperature radiant zone.
A Grundfos Alpha high-efficiency pump, mounted pump left.
No. Mixing is fully thermostatic; only the circulator needs 115 V power.
- Type:
- Mixing Unit
- Series:
- HydroMixer
- Pump Type:
- Alpha High-Efficiency Pump
- Configuration:
- Pump Left