---
title: "PID Cascade Regulation"
description: "Cascade PID for underfloor heating: a zone PID sets the floor thermostat, a floor PID drives a TapHome Bus output in PWM mode; smoother than hysteresis, floor max 28 °C."
url: "https://taphome.com/en/docs/functional-areas/heating-cooling/pid-cascade/"
language: en
lastmod: 2026-11-09
generator: hugo
ai:
  topics: ["pid-cascade","underfloor-heating","heating-control","temperature-regulation","smart-rules"]
  questions: ["What is PID cascade regulation and how does it work in underfloor heating?","What is the difference between cascade PID control and hysteresis control?","What is the maximum floor temperature allowed in underfloor heating systems?","How do the Zonal PID and Floor PID Smart rules work together?","What is the 15-minute switching period in cascade PID control?","What temperature range should I set for the zone thermostat?"]
---

# PID Cascade Regulation

Increasing heating system stability using two interconnected PID Smart rules for underfloor heating control.

Last updated: 2026-11-09

If the temperature of the heating element is measured, it is possible to increase the stability of the heating system using two interconnected **PID Smart rules** (so-called cascade PID control).

## Comparison with simple hysteresis control:
| **Cascade PID control** | **Hysteresis** |
|-----------------------------|--------------|
| ✅ smooth continuous control | ✅ fast start |
| ❌ slow start | ❌ oscillating control |

An example of using cascade PID control in underfloor heating, where the **temperature under the floor** and the **temperature in the room** are measured.
![cascade.webp](https://taphome.com/documentation/functional-areas/cascade.webp)

| **Parameter**                  | **Zonal PID Smart rule**            | **Floor PID Smart rule**          |
|---------------------------------|-------------------------------------|-----------------------------------|
| **Output actuator**             | Thermostat for the heating element 0% ... 19 ºC <br> 100% ... 28 ºC | TapHome Bus module output in **Pulse-width modulation** mode (an analog output of the PID), **15-minute switching period** |
| **Limit temperature**             | Optional: 10 ºC - 30 ºC (default), adjustable in the zone thermostat service settings | Optional: Floor temperature sensor, max. temperature **28 ºC** |

> [!NOTE]
> The maximum floor temperature allowed by hygienic standards is **28 ºC**. However, for heating purposes it is possible to use a few degrees more (e.g. **36 ºC**), because the sensor measures the temperature beneath the floor surface.

**See also** — [Boiler Cascade](https://taphome.com/en/docs/functional-areas/heating-cooling/boiler-cascade/), [Equithermic regulation](https://taphome.com/en/docs/functional-areas/heating-cooling/equithermic-regulation/).