Shower stems are a fundamental component found primarily in two-handle shower and faucet systems. They act as valves that control the flow of water for a specific temperature.
In these systems, each handle is dedicated to controlling one water temperature. As the reference states, "one handle is responsible for cold water and the other is responsible for hot water." The stem is the part located behind each of these handles that performs this function.
The Function of a Shower Stem
A shower stem's main job is to regulate the flow of water from the pipes into the showerhead or faucet spout. Here's a breakdown of how they generally work:
- Connection to the Handle: The stem is directly connected to the shower handle you turn.
- Valve Control: Inside the faucet body, the stem interacts with a valve seat. When you turn the handle, it moves the stem. This movement either lifts the stem away from the seat (opening the valve and allowing water to flow) or presses it down onto the seat (closing the valve and stopping water flow).
- Temperature Specificity: Because there is one stem for hot water and one stem for cold water in a two-handle system, turning only the hot water handle's stem controls only the flow of hot water. Similarly, the cold water handle's stem controls only the flow of cold water. You mix the desired temperature by adjusting the flow from both handles.
Practical Insight: If you have a leaky two-handle shower that drips water from only the hot side (even when turned off), the issue is often with the hot water stem or its associated washer/seal not properly closing against the valve seat.
Stems vs. Cartridges
The reference highlights the distinction between stems and cartridges:
- Stems: Typically used in two-handle faucets, controlling hot or cold water flow individually via separate handles.
- Cartridges: Used in single-handle faucets and showers, allowing control over both hot and cold water temperature and flow with just one handle's movement (usually up/down for flow, side-to-side for temperature).
Here's a simple comparison based on the reference:
| Feature | Stem Systems | Cartridge Systems |
|---|---|---|
| Number of Handles | Two (Hot & Cold) | One |
| Water Control | Separate control for hot and cold flow | Combined control for temperature & flow |
| Typical Use | Older style showers/faucets | Newer style showers/faucets |
In essence, shower stems are the internal valving mechanism in two-handle systems that allows you to precisely control the amount of either hot or cold water flowing into your shower by turning their respective handles.
