The Caleffi NA573100 is the filter housing assembly for the NA573 replenishment water treatment filling unit, complete with a color-changing resin demineralization cartridge and 1/2 in NPT female inlet and outlet, producing demineralized make-up water on the fill line of a sealed hydronic system.
Product data compiled from Caleffi North America technical documentation. Last reviewed July 2026.
Key Features
Complete Housing + Cartridge
Filter housing supplied with a color-changing demineralization cartridge, ready to install on the fill line.
Color-Change Exhaustion Indicator
The resin changes color as capacity depletes - replace the cartridge on sight, no test kit needed.
1/2 in NPT Female Connections
Installs in-line on the make-up water piping of a sealed hydronic system.
Pairs with AutoFill
Designed for the NA573 replenishment filling unit alongside the AutoFill valve and backflow preventer.
Technical Data
| Function | Filling unit service part |
| Assembly | Filter housing with color-changing demineralization cartridge |
| Connections | 1/2 in NPT female inlet and outlet |
| Application | NA573 replenishment water treatment filling unit |
Documentation
Technical brochureRelated Products
- Caleffi F59650 Service Part
- Caleffi NA10197 Service Part
- Caleffi NA570971 Service Part
- Caleffi 535051A 3/4 in Auto Fill Valve
Frequently Asked Questions
What does the NA573100 include?
The complete filter housing with a color-changing demineralization cartridge installed, with 1/2 in NPT female inlet and outlet.
How do I know when to change the cartridge?
The resin changes color as it exhausts - replacement is judged visually, no water testing required.
Where does it install?
In-line on the make-up water piping of a sealed hydronic system, typically alongside an AutoFill filling valve and backflow preventer (as in the NA573022 unit).
- Type:
- Accessory
- Series:
- AutoFill
