An electric heater in a heat-recovery ventilation unit may raise questions: does it run continuously, does it heat the whole house and should it be switched off to save energy? The answers depend on the particular model and function. Preheating may be associated with frost protection, while additional heating may control the supply-air temperature. These tasks should not be confused. The first requirements are an exact schematic, settings and information on actual operating time.
The same name can conceal different positions
A heating element before the heat exchanger and one after it may perform different tasks. Other configurations are also used, depending on the model. The Komfovent installation manual provides schematics for specific units. Establish what is installed in your own system rather than drawing conclusions from the general word “heating” in an offer.
If an additional element is installed in a duct, its controls, sensors and safety requirements also matter. It is not an independent domestic heater that can be connected anywhere. Installation must comply with the component's documents and those for the overall system. The owner must understand what function the element performs and under which conditions it may switch on.
Rated power is not continuous energy use
The maximum power on the label does not tell you how many kilowatt-hours are consumed per day. Energy depends on actual operating time and control. For example, in an illustrative calculation, a one-kilowatt element fully switched on for half an hour would consume half a kilowatt-hour. This is arithmetic only, not a forecast for a particular house.
If the element is modulated or cycles on and off, suitable data is needed. A controller status of “heating enabled” may not mean the same as continuously using full power. The Komfovent C6M user manual illustrates the capabilities of a particular control system, but you must check the meaning of readings against your own model.
What outdoor conditions change
Colder outdoor air and indoor humidity can change the operation of protection and heating functions. However, outdoor temperature alone does not explain every difference. Airflows, heat exchanger, settings and equipment configuration matter too. Two neighbouring houses may therefore use different amounts of heating energy even on the same day. Comparing bills without context is misleading.
It also matters whether the unit is used in a completed, occupied house or on a still-damp construction site. These conditions are not equivalent. If rooms are not heated to the intended regime or wet building work is still under way, a separate appropriate operating plan is needed. A domestic unit's protective functions must not be bypassed to dry materials more quickly.
A heat-recovery ventilation unit does not replace whole-house heating
The DOE ventilation-system overview helps distinguish air exchange from heat recovery. Neither automatically covers the entire building's heating load. Additional air heating may have an intended purpose in a particular system, but that purpose must not be extended without a design. “Warm supply air” and “sufficient house-heating capacity” are not the same thing.
If the owner wants to heat rooms through the ventilation system, that is a separate design task. The building load, airflows, temperatures and all related requirements need assessment. A domestic unit's catalogue rating does not in itself confirm that solution. Do not arbitrarily raise temperatures in the hope of replacing non-functioning primary heating.
Illustrative example: an unexpected rise in electricity use
Suppose the owner notices higher total unit energy use after changing settings. Compare the selected supply temperature, operating modes and outdoor conditions, and establish whether the display shows measured or calculated energy. One higher bill is not enough to conclude that the heat exchanger or fan has failed.
A specialist checks the actual configuration, settings, sensor condition and airflows. If incorrect control is found, it is adjusted according to the documents. If operation is normal, the specialist explains which function consumed the energy. In either case, the owner should receive a clear record, not just advice to “turn the number down” without considering protection and comfort.
Why simply disconnecting it is not the answer
If the heater forms part of the protection system, switching it off may change airflows or increase the risk of damage. The precise consequences depend on the model. There can be no universal recommendation that owners disconnect a wire, fuse or controller function. Qualified specialists carry out electrical work and technical configuration changes.
Even settings that users are allowed to change require an understanding of their purpose. Record the initial condition before making a change. If an error occurs, save the code and time. Repeated factory resets can conceal information needed for diagnosis. Address energy-saving questions by analysing the cause, not by removing a safety function.
How to assess consumption on a sound basis
Separate fan and heating energy as far as actual measurements allow. If you have only a total meter reading, describe it as such. Use your own current tariff, not a universal advertised figure in cents. This article gives no monetary prices because they depend on the date, contract and usage.
For comparison, collect a history of operating modes and temperatures, filter maintenance information and dates of changes. If there is too little data, describe the result as indicative. It is worth asking the contractor for a clear explanation of winter operation before purchase, including the configuration and planned protection. This reduces surprises after moving in.
The offer must include the winter configuration
Before comparing two prices, check that both options include all necessary winter protection. In one offer, it may be factory-fitted; another may require a separate duct element and its connection. This is not just the cost of an extra part: space, wiring and adjustment may be needed. Ask to see the specific schematic and identify who will implement it.
If some functions have not yet been installed, the system must not be treated as the fully operational package promised. Interim use must have clear conditions permitted by the manufacturer. These help prevent damage while the house is unfinished and distinguish a temporary mode from intended everyday operation.
What to provide for a discussion
State the full model, set temperature, operating mode and period over which energy was measured. Add controller messages. Read about the overall system in the heat-recovery article, and submit the information in an enquiry. A good answer must distinguish function, power and actual energy, without making the same promise to everyone of either almost-free operation or continuously running at full power.
Information sources
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