In a ventilation estimate, the heat-recovery unit model often receives most of the attention. However, the overall result also includes ducts, connections, insulation, air distribution, controls and commissioning. An offer with an attractive appliance price may cover only some of the work. It is therefore worth establishing the scope first and comparing the final amount only afterwards. A clear estimate should show what will be installed, what will be left to another contractor and how operation will be checked.
The equipment line needs an exact model
A series name does not always identify the heat exchanger, controller or supplied configuration. Ask for the full model designation and technical documents. It should be clear what is included at the factory and what is provided separately. If an additional preheater or another component is needed, it must not be concealed behind a general promise that the unit is suitable for the house.
The Komfovent installation manual illustrates that different designs have their own connection and environmental requirements. The estimate must match the selected model and its operating conditions. The price of another, similar appliance is not equivalent if the necessary accessories or installation arrangement differ.
Assess ducts and fittings against the layout
A total length in metres does not describe branches, distribution boxes, bends, sealing and fixings. Ask for a duct layout or a clear basis for the quantities. If the design has not yet been prepared, the offer must state which quantities are indicative. Uncertainty is not necessarily a problem in itself, but it must not be presented as a finally confirmed total for all the work.
The specific duct types and their purposes must also be clear. One metre of different systems does not necessarily include the same set of components. Connections, boxes and the installation method may differ. You need to understand whether the offer covers complete installation of the planned air path or merely supply of the main materials without some installation components.
Do not take insulation for granted
The estimate must state which duct runs are insulated and what solution will be used. Requirements may differ between cold and warm sections. The word “insulation” alone does not describe the extent, airtightness or treatment of joints. If some of the work is left to the builders, this must be explicitly stated so that no unfinished gap remains in the completed assembly.
Apply the same approach to penetrations through walls and floors. Who drills, seals and restores the required layers and finishes? Different people may do these tasks, but the owner must know where responsibility begins and ends. An apparently cheaper offer without this work is not directly comparable with an estimate covering the entire assembly.
Acoustic components must be specified
Silencers and vibration-control arrangements are selected for the system, not as decorative accessories. The Lindab sound-theory document discusses why sound sources and transmission paths matter. The estimate should make clear which components are provided and where they will be installed. A promise that the system will “run quietly” does not define a technical solution.
If acoustics are not included, ask for the reasoning behind the selected option. Not every property needs the same set of components, but the decision must be based on the design. Components added later may not fit in the space allocated. The estimate and the plant-room layout should therefore be assessed together.
Electricity, controls and condensate
A clearly identified contractor must be responsible for the unit's power supply, sensors, controller and communications work. The simple word “connection” can describe very different scopes. Check whether the required cables, protection and qualified connection are included or will be handled by another contractor. Setting up an account or app should not be left unclear either.
If the model needs condensate drainage, the estimate must include the complete, appropriate assembly. A short hose from the casing alone is not necessarily a finished solution. It must be clear where and how the water drains, what maintenance is needed and who is responsible for the final connection. This detail often creates additional work on another system.
Commissioning and balancing
Switching on the power is not the same as checking the intended airflow. The DOE system overview helps explain the general principles of supply and extract ventilation. The offer should make clear whether measurement of actual airflows, adjustment and a report are included. If this is a separate service, include it in the comparison.
Also discuss when the work will be done. If the final doors or finishes are not yet in place, the checks may have limitations. It is worth specifying in the estimate how the final condition will be assessed. Otherwise, the owner may receive a document reflecting an earlier stage of the unfinished house rather than normal occupied operation.
Illustrative example: a smaller total also means less work
Suppose two contractors offer the same heat-recovery unit. One includes insulation, silencers and balancing; the other lists the appliance and main ducts. The lower total in the second offer does not prove that the first is unjustifiably expensive. First, make the scopes equivalent and establish the cost of the missing parts.
The owner prepares a simple scope table and asks for written explanations of missing items. At the same time, they check that final prices include the same taxes and scope of work. This article does not give market rates: these depend on the date and property. The aim is comparable terms, not an invented total price for a house.
Define the procedure for additional work in advance
If some structures in a renovation project have not been opened up, discuss possible changes before work begins. The estimate can clearly state which conditions still need clarification and how the owner will approve additional work. This is better than a vague note that everything else will be priced later. Ask for genuinely unknown conditions to be distinguished from items that can already be calculated from the available plan. This makes it easier for both parties to maintain the agreed result and deal with changes at the property.
If the estimate is presented in stages, clearly separate materials being purchased now from work to be done later. Acceptance of a stage should not mean confirmation that the entire system works. This is particularly important when ducts are installed first and the unit and final air terminals are fitted several months later.
What the owner should receive
On completion, hand over the equipment documents, as-built layout, settings and test data. It must be clear who handles warranty and maintenance matters. In your enquiry, provide a plan and the desired scope; read about the basis for establishing demand in the selection article. A good estimate clearly defines the result, not just the equipment name.
Information sources
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