Why Your Smart Boiler Stays On When VTherms Are Idle

Unraveling the Mystery: When Your Central Boiler Refuses to Rest

It's a common scenario in smart homes, isn't it? You've invested time and effort into setting up a sophisticated heating system with individual zone control, perhaps using something as versatile and powerful as the versatile_thermostat custom component in Home Assistant. The idea is simple: each room or zone, managed by its own virtual thermostat (or vtherm), signals the central boiler when heat is needed. But then, you wake up to an unexpected problem: your central boiler keeps running, humming along merrily, even though all your vtherms are reporting a happy idle state. This isn't just a minor annoyance; it leads to overheated rooms, wasted energy, and a significant dent in your comfort and wallet. We're talking about areas like bathrooms becoming saunas overnight, all because your smart heating system isn't quite as smart as it should be.

The core of the issue, as many users of jmcollin78's excellent versatile_thermostat component have sometimes experienced, is a disconnect between the desired idle status of individual zones and the actual on state of the main heating appliance. You expect the system to be intelligent enough to shut down the boiler when no heat demand exists, ensuring efficiency and preventing discomfort. However, when the boiler persists in running despite all indicators pointing to idle, it signals a deeper configuration challenge or perhaps an intricate interaction that needs careful investigation. This article aims to dive deep into these scenarios, exploring the common reasons behind such behavior and providing a comprehensive guide to troubleshoot and resolve this persistent problem. We'll look at how your specific versatile thermostat configuration might be contributing to the issue, what to check within Home Assistant, and how to reclaim complete control over your smart heating system to ensure it operates exactly as intended – providing warmth when needed and resting when it's not.

Understanding the intricacies of the versatile_thermostat and its interaction with your central heating system is paramount. This robust custom component offers a wealth of features, from Time Proportional Integral (TPI) control to various safety mechanisms and preset modes. But with great power comes great responsibility in configuration. A single overlooked setting or a misunderstanding of how specific parameters interact can lead to unexpected behavior. For instance, the is_used_by_central_boiler: true setting is crucial, indicating that this particular vtherm should influence the central heating source. When multiple vtherms share this responsibility, their collective on_percent values are aggregated to determine the central boiler's state. If even one vtherm is misbehaving or reporting an on_percent value greater than zero, even if its hvac_action is idle, it could potentially keep the central boiler active. The goal here is to ensure a harmonious symphony where every vtherm plays its part correctly, allowing the central boiler to rest when the entire house has reached its desired temperature, thereby optimizing energy consumption and maximizing home comfort.

Diving Deeper: Understanding Your Versatile Thermostat Configuration

When your central boiler keeps running even when all your vtherms are reporting idle, the first place to truly scrutinize is your versatile_thermostat configuration. This isn't just about glancing at the settings; it's about understanding the implications of each parameter and how they contribute to the overall behavior of your smart heating system. A vtherm, or virtual thermostat, is designed to give you precise control over individual heating zones, aggregating demand to a central heating source. The provided configuration snippet offers a fantastic starting point for our investigation, highlighting several key areas that could be at play.

Let's break down some of the most critical parts. Firstly, observe the hvac_action: idle and is_device_active: false attributes. These are strong indicators that the individual vtherm itself believes it has no active heating demand. However, the is_used_by_central_boiler: true setting is equally important, as it designates this vtherm as a contributor to the overall central heating demand. When multiple vtherms are configured this way, the versatile_thermostat component orchestrates their requests to control a single, central heating switch, typically for a boiler or a circulation pump, like your switch.underfloor_heating_pump.

The vtherm_over_switch section of your configuration is particularly vital. This is where the magic, or sometimes the mystery, happens regarding how the vtherm interacts with the actual hardware switch. The function: tpi indicates that the vtherm is using a Time Proportional Integral (TPI) control algorithm. TPI is a sophisticated method that calculates the on_percent (the percentage of time the heating device should be active within a given cycle) based on the difference between the current and target temperatures, considering factors like external temperature and temperature slope. If the TPI coefficients (tpi_coef_int, tpi_coef_ext) or thresholds (tpi_threshold_low, tpi_threshold_high) are not optimally tuned, the calculated_on_percent might never truly reach zero, even when the hvac_action is idle. A non-zero on_percent value, however small, can be enough to signal the central boiler to remain active, causing it to overstay its welcome.

Furthermore, the minimal_activation_delay_sec and minimal_deactivation_delay_sec parameters are crucial for preventing rapid cycling of your heating equipment, which can reduce its lifespan. While these delays are generally beneficial, a long minimal deactivation delay could potentially keep the boiler switch engaged for an extended period even after the heating demand has theoretically ceased. For instance, a minimal_deactivation_delay_sec of 900 seconds (15 minutes) means that once the boiler has been activated, it will remain on for at least that duration, regardless of immediate changes in demand. If multiple vtherms have staggered delays or if one vtherm's delay overlaps with another's, it can create a scenario where the central boiler is perpetually kept active without a clear, unified off signal from all zones. Thoroughly reviewing these smart thermostat settings and their potential cumulative effects is a crucial step in diagnosing and resolving the persistent problem of your boiler staying on.

Common Culprits: Why Your Smart Boiler Might Be Overstaying Its Welcome

It’s incredibly frustrating when your central boiler keeps running and refuses to shut off, leaving parts of your home overheated and your energy bills soaring. While the versatile_thermostat component is designed for precise control, several common culprits can lead to this unwelcome behavior. Understanding these potential issues is key to effective troubleshooting. One of the primary suspects is related to timing and delays. Your configuration includes minimal_deactivation_delay_sec: 900 (15 minutes). This setting dictates that once the heating switch (in your case, switch.underfloor_heating_pump) is turned on, it must remain on for at least 15 minutes. While this prevents rapid cycling and protects your equipment, if multiple vtherms are calling for heat at different times, or if a vtherm just barely meets its target temperature and then goes idle but hasn't completed its deactivation delay, the central boiler could be kept active by this persistent delay. Imagine a scenario where one vtherm fulfills its heating demand, but its deactivation delay keeps the central switch on, and during this delay, another vtherm briefly calls for heat, effectively resetting the cycle for the central boiler switch.

Another significant factor, especially with the function: tpi setting, is the TPI (Time Proportional Integral) Algorithm itself. TPI works by calculating an on_percent, representing how long the heating element should be active within a given cycle. Even when a vtherm reports hvac_action: idle, if its internal calculated_on_percent isn't exactly zero, it might still issue a minor demand to the central boiler. This can happen if the tpi_threshold_low or tpi_threshold_high values are not perfectly calibrated for your specific system's thermal characteristics, or if there's a slight temperature oscillation around the target. A non-zero on_percent from even one contributing vtherm, however small, is often enough to keep the central boiler switch on because the aggregation logic prioritizes any active demand. This is why a deeper look into the power_percent and on_percent values of all your vtherms is critical when the smart boiler stays on.

Beyond delays and TPI intricacies, we must consider the central boiler logic itself. The versatile_thermostat component, particularly when used with multiple vtherms controlling a single switch, relies on an aggregation mechanism. It sums up the on_percent from all vtherms that have is_used_by_central_boiler: true. If this aggregated value is above zero, the central switch is typically commanded to be on. The bug you're observing suggests this aggregation or the final command isn't working as expected to turn off the switch when all vtherms are genuinely idle. This points to potential Home Assistant troubleshooting within the custom component's logic or its interaction with the underlying switch entity. Could the switch.underfloor_heating_pump itself be glitching or failing to respond consistently to off commands? It’s important to rule out the basic hardware functionality. Furthermore, while you mentioned