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Rectifying a Poorly Installed Heatmiser Underfloor Heating System


We’re excited to share a recent project where our expertise in Heatmiser underfloor heating and electrical problem-solving proved instrumental in fixing underfloor heating problems. The client reached out to us after watching one of our informative YouTube videos, seeking assistance with their problematic Heatmiser underfloor heating setup.


Property Overview & Initial Assessment

The property featured a substantial ground floor with underfloor heating loops connected to two manifolds in a designated cupboard. Each manifold was controlled by a Heatmiser uh8 hub. The challenge was apparent from the beginning; the initial installation lacked the necessary understanding of Heatmiser equipment. The underfloor heating system required meticulous setup and proper labelling, which the original installer failed to execute.

Identifying fixing underfloor heating issues

Our first task involved deciphering the unlabelled loops on the manifolds, as the plumber hadn’t provided adequate information. Once identified, we addressed the wireless Neostat Heatmiser room thermostats that were incorrectly paired with the uh8 rf wiring centre. The plumber’s assumption that a single thermostat could control multiple loops was a critical oversight, leading to uneven heating in adjacent rooms. We strategically added thermostats to separate and optimize control for each heating loop.

Paul, our skilled technician, demonstrated the disarray in the heating cupboard. The electric 12-kilowatt water heaters, meant to control the underfloor heating, were poorly connected. Cables were too short, nothing was labelled correctly, and the thermostats were insufficient for the setup. Our intervention aimed to bring order to this chaos.

Progress and Corrections

Our team diligently organized the cables, ensuring they followed the correct order from the manifold. We labelled each loop for clear identification, preventing any confusion in the future. The addition of thermostats to distinct zones enhanced the system’s efficiency, preventing discrepancies in room temperatures.

Paul showcased the progression in the heating cupboard, emphasizing the stark difference from the initial messy setup to the neatly organized and labelled system. The importance of precise installation was evident in every step we took.

Uncovering Additional Issues

During our diagnostic work, we discovered more significant problems beyond the underfloor heating system. The previous attempts to make the system operational had resulted in severe damage. One of the critical findings was the connection of a 230-volt output from the uh8 wiring center to the electric boiler’s programmer controls. This error not only damaged the uh8 but also fried one of the boilers, necessitating replacements.

Addressing Electrical System Flaws

Our expertise extended beyond the underfloor heating system. We identified loose breakers on the three-phase board, a deviation from the manufacturer’s instructions. The lack of blank spaces beside the RCBO supplying the boiler posed a risk due to the high load device. The wiring was untidy, with cables unsupported and lacking proper glandings.

Further inspection of the isolators revealed underrated components for the boiler’s load. Inconsistencies with the flex connecting the isolator to the boiler and poor mounting of the boilers on the wall added to the list of issues.

Comprehensive Resolution

Our comprehensive approach involved addressing every identified issue methodically. We replaced damaged components, corrected the wiring, and ensured compliance with manufacturer instructions. The isolators were upgraded to handle the load appropriately, and proper flex was used between the isolator and the boiler.

The final result showcased a well-organized and fully functional underfloor heating system. All identified issues were resolved, and the client was provided with a system that not only worked efficiently but adhered to safety and compliance standards.


This case highlights our commitment to fixing underfloor heating issues. We are often called to rectify poorly executed installations and our expertise in handling complex electrical issues proves that we’re experts at Heatmiser systems. If you’re experiencing challenges with your heating or any electrical installation, Heritage Electrical is here to provide reliable solutions. Contact us or book an appointment below and let us bring order and efficiency to your electrical systems.

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