---
title: "Equithermic regulation"
description: "Set up weather-compensated heating control. Configure equithermic curve angle, parallel shift, and dew point protection in TapHome."
url: "https://taphome.com/en/docs/functional-areas/heating-cooling/equithermic-regulation/"
language: en
lastmod: 2026-11-06
generator: hugo
ai:
  topics: ["equithermic-regulation","heating-curve","cooling-control","primary-circuit-temperature","zone-thermostats","dew-point-protection","condensation-prevention"]
  questions: ["What is equithermic regulation and how does it work?","What equithermic curve angle should I use for underfloor heating?","What does parallel shift do in equithermic regulation?","How does dew point protection work when using equithermic regulation for cooling?","What is dew point protection in TapHome?","What options are available for cooling to configure dew point protection?","How do I configure dew point protection for hydronic cooling?","Why is dew point protection important when cooling with TapHome?","How do zone thermostat setpoints affect the equithermic curve calculation?","What is the reference temperature 22°C used for in equithermic regulation?","What are the drawbacks of equithermic regulation?"]
---

# Equithermic regulation

Equithermic regulation is a simple method for calculating the temperature of the heating or cooling medium in the primary circuit based on the outdoor temperature.

Last updated: 2026-11-06

Equithermic regulation is a smart rule that calculates the temperature of the heating or cooling medium in the primary circuit from the outdoor temperature. It works with the outdoor temperature and the zone thermostats connected to the rule; in cooling mode it also uses zone humidity for dew point protection. You need zone thermostats connected to the rule and, for dew point protection in cooling, also a source of relative humidity in each cooled zone. The result is the setpoint of the virtual thermostat for the primary circuit, shaped by the curve angle, parallel shift and temperature limits.

## **Equithermic regulation**
Equithermic regulation is a simple method for calculating the temperature of the heating or cooling medium in the primary circuit based on the outdoor temperature. In most cases, this function is controlled by the boiler or heat pump.

If the curve is configured correctly, it should be possible to achieve the desired temperature in zones with the lowest possible medium temperature (in heating mode) or the highest possible medium temperature (in cooling mode).

A drawback of this method is that it does not have a built-in automatic correction mechanism. If the equithermic curve is not set correctly, it can lead to insufficient or excessively intensive heating/cooling in the zones.
Equithermic regulation in principle: the Equithermic regulation smart rule calculates the set point of the heating medium from the outdoor temperature (8 °C), and a PID smart rule reaches it.


### Heating and cooling control
| **Aspect**        | **Heating**                                     | **Cooling**                                       |
|------------------|--------------------------------------------------|--------------------------------------------------|
| **Inputs**       | - **Outdoor temperature** <br> - Zone temperatures | - **Outdoor temperature** <br> - Zone temperatures <br> - Zone **Humidity** |
| **Output**       | - Setpoint of the virtual thermostat for the primary circuit | - Setpoint of the virtual thermostat for the primary circuit |
| **Limits**       | - Minimum / maximum configured value                      | - Minimum / maximum configured value <br> - **Dew point (early warning)** <br> - Calculation of the minimum setpoint based on the highest relative humidity from all connected zone thermostats |
| **PID correction** | ❌ | ❌ |

[More information about heating/cooling modes](https://taphome.com/en/docs/functional-areas/heating-cooling/heating-cooling-mode/)

## How the final setpoint is calculated
The equithermic curve returns the temperature of the circulating water based on the outdoor temperature. The curve angle, parallel shift, temperature limits, and adjustments based on thermostat data influence the final result.


### **Angle**
For underfloor heating systems, values between 0.2 and 0.8 are commonly used. Lower values are more suitable for buildings with high-quality insulation.
The following table shows the resulting setpoint based on outdoor temperature and the curve angle:

**Outdoor temperature**
| **Angle**  | -20°C | -15°C | -10°C | -5°C | 0°C  | 5°C  | 10°C | 15°C | 20°C |
|:------:|:-----:|:-----:|:-----:|:----:|:----:|:----:|:----:|:----:|:----:|
| **0.2**  |  33  |  32  |  32  |  30  |  29  |  27  |  24  |  22  |  20  |
| **0.4**  |  42  |  40  |  38  |  36  |  33  |  30  |  27  |  24  |  20  |
| **0.6**  |  50  |  48  |  45  |  41  |  37  |  33  |  29  |  25  |  20  |
| **0.8**  |  59  |  56  |  52  |  47  |  42  |  37  |  31  |  26  |  20  |

Example: If the outdoor temperature is 0°C and the equithermic curve angle is 0.6, the resulting setpoint is 37°C.


### **Parallel shift**
Increases or decreases the curve by a defined value.

Example: If the temperature set based on the curve angle is 37°C and the parallel shift is set to 4°C, the resulting setpoint is 41°C.


### **Adjustments based on data from thermostats**
All zone thermostats that are connected to the equithermic **Smart Rule** affect the final result.

|                      | **Heating**                                                                 | **Cooling**                                                                 |
|----------------------|------------------------------------------------------------------------------|------------------------------------------------------------------------------|
| **Setpoint from zones** | The equithermic curve shifts upward if the highest setpoint of zone thermostats is greater than 22°C | The equithermic curve shifts downward if the lowest setpoint of zone thermostats is less than 22°C |
| **Result**               | Resulting setpoint = Setpoint based on angle and parallel shift + Proportional value * (highest thermostat setpoint - 22) | Resulting setpoint = Setpoint based on angle and parallel shift + Proportional value * (lowest thermostat setpoint - 22) |


### Example scenario for zoned hydronic heating with equithermic regulation
Zoned hydronic heating: each zone thermostat opens its valve through a Hysteresis smart rule, an Equation smart rule runs the pump while any valve is open, the Equithermic regulation smart rule sets the set point of the heating circuit thermostat, and a PID smart rule drives the mix valve to it.


## Dew point protection in cooling

When the equithermic Smart Rule runs in **cooling** mode, it actively protects connected zones from **condensation** by dynamically clamping how cold the primary-circuit setpoint is allowed to go. This safety mechanism is called **dew point protection** and is one of the limits shown in the heating/cooling control table above.

### Why dew point protection matters for hydronic cooling

Chilled water that is colder than the **dew point** of the surrounding air causes moisture to condense on pipes, manifolds, fan-coils and radiant ceiling panels. Visible results are dripping surfaces, puddles on the floor and long-term damage to plaster. Preventing condensation is the single most important safety feature of any hydronic cooling installation — and equithermic regulation configures it in one place, at the primary-circuit level, for all downstream zones.

### How dew point protection works

1. Each zone thermostat (or a dedicated air humidity sensor) reports **relative humidity** and temperature for its zone.
2. The equithermic controller picks the **highest relative humidity** across all connected zones and uses it together with the zone temperature to compute the current **dew point** of that zone's air.
3. The primary-circuit setpoint is clamped **above the dew point** plus a configurable safety offset. If the equithermic curve would otherwise demand a colder chilled-water temperature, the controller overrides the curve and holds the setpoint at the dew point + offset instead. This is the *early warning* behaviour listed in the cooling limits table.

### Configuring dew point protection

In the **Dew point** group of the equithermic Smart Rule you configure:

- **Dew point adjustment (%)** — how far above the calculated dew point the minimum setpoint sits. Higher values mean a larger safety margin against condensation, but reduce peak cooling performance.
- **Humidity source** — relative humidity can be read from the connected **zone thermostats** or from **additional air humidity sensors**. When multiple sources are present, the *highest* relative humidity value is used for the dew point calculation.

### What you need to enable dew point protection

- At least one source of **relative humidity** per cooled zone: either a zone thermostat with an integrated RH sensor, or the [Air Humidity and Temperature Sensor](https://hardware.taphome.com/en/air-humidity-and-temperature-sensor/) connected to the EXT terminal of a 2UI / 6UI / 6UI6OC / 4UI2DO bus module.
- A zone temperature reading from the same zone (typically the same thermostat).
- The equithermic Smart Rule configured in **cooling** mode with zone thermostats linked to it.

### When to enable dew point protection

Always enable dew point protection for **hydronic cooling** — chilled water distributed through underfloor loops, fan-coils or ceiling cooling panels. The only scenario where it is not needed is purely *air-based* cooling (e.g. split A/C units controlled over IR), where there is no cold water surface to condense on.

### Example scenario for zoned hydronic cooling with equithermic regulation
Zoned hydronic cooling: each zone thermostat opens its valve through a Hysteresis smart rule, an Equation smart rule runs the pump while any valve is open, a PID smart rule drives the mix valve to a set point limited by a Formula smart rule, and the Equithermic regulation smart rule keeps the flow temperature above the dew point.