There are many reasons why your underfloor heating could be malfunctioning, from blockages and leaks to trapped air and problems with the pipework. The fault will also depend on what type of underfloor heating you have. Homes boasting large expanses of underfloor heating (living and kitchen areas), as well as new build properties, will typically opt for a water underfloor heating system (wet system) rather than an electric (dry) system. These systems are made up of a series of pipes that are laid underneath the floor and connected to the boiler. Wet systems work like your central heating system, although the temperatures needed are far lower than when relying on a radiator. In this article, we will be concentrating on faults common to wet underfloor heating systems to help you determine why your underfloor heating is not working efficiently.
Common underfloor heating problems
in wet systems
Faulty motorhead valve
One of the most common faults tends to be with the motorheads. When underfloor heating (UFH) covers a wide area such as the lower floor of your home, the area will likely be divided into zones that correlate with the layout of the rooms on that level. Each zone will have its own thermostat. For example, let’s say on the ground floor of your home you want underfloor heating in the kitchen, living room, and in the dining room. That means you’ll likely have three zones with three thermostats, enabling you to control the temperature in each room separately.
Each of those thermostats react with a motorised valve head. Motorised valves open and close to control the flow of water from the heating boiler to the individual underfloor heating zones. These valve heads can sometimes jam closed, resulting in a faulty system. When this happens, the valve will require maintenance and adjustment.
Damaged mixing valve on the manifold
A broken mixing valve on the system manifold is a common cause of underfloor heating problems. The manifold is a vital component of any underfloor heating system, allowing you to maintain temperature and water flow. The manifold is the system that distributes warm water to each UFH zone. It works by connecting the underfloor heating pipework to the heat source, feeding water at the correct temperature from either the boiler or heat pump, and directing it to each UFH tube at the correct flow rate. Manifolds can control multiple zones at once, allowing each zone to be warmed to a different temperature depending on the needs or requirements of the homeowner.
The mixing valve is the component that mixes the flow from the boiler or heat pump with the return from the underfloor heating system, to provide the correctly mixed temperature for the heating pipes beneath your floor. Essentially, the mixing valve reduces the temperature of the water going through the pipes under the floor. When the valve is faulty, the pipework could become damaged by the excessive temperature flowing through it. The pipework is predominantly plastic, so it is a particularly important component to look after.
Defective heating pump
Because the underfloor heating manifold is hidden away, it can often be overlooked and faults can develop. The heating pump can also be affected. The pump ensures that the demand of the underfloor heating is met when the system is running, as the underfloor heating pipe covers a large area with a high capacity. If the heating pump isn’t working efficiently your UFH will stop working.