Two heat-recovery ventilation estimates may have similar final totals but very different contents. One may cover a complete working system; the other, a better appliance and only some of the work. Comparing euros alone or a manufacturer's name alone is not enough. First make the task equivalent and clearly mark what is included, excluded or still unknown. The price difference then becomes understandable and a sound decision is possible.
Start the comparison with the same plan
Give both contractors the same room plan, number of occupants and intended use. If one uses a different ceiling height or misses an additional room, the offers are already not equivalent. The DOE system overview helps explain the overall task, but airflows for the particular property must be justified by its needs.
If there is no design yet, ask for the sizing assumptions. This distinguishes an honest indicative offer from a supposedly final amount with no clear quantities. Show unknown items separately. Otherwise, it will be difficult later to understand whether additional work is genuinely new or was simply omitted from the first price.
Compare units at the same operating point
You need the exact model, heat exchanger and configuration. Maximum capacity under free-air conditions does not describe operation with your ducts. Ask for the required airflow and resistance data. If an additional component is necessary in one offer but factory-included in another, the full scope must reflect the difference.
The Komfovent installation document illustrates the requirements of different designs. You cannot compare casing prices alone without considering condensate, the environment and connections. Also check that both options actually fit in the intended location with a servicing area. Poor access may create future costs that do not appear in the purchase table.
Prepare an equivalent work-scope table
List design, equipment, ducts, insulation, air terminals, external openings and controls separately. Add drilling, sealing, electrical work, condensate connection and restoration of finishes where required. Mark each item as included, excluded or awaiting clarification. Such a table is simpler than trying to remember promises made in several conversations.
Also state the basis of quantities and the procedure for possible changes. If one contractor measured the property while another received only its floor area, their accuracy may differ. A lower total does not necessarily mean poorer work, but you must understand what it is based on. Comparable data is needed, not automatic trust or distrust.
Keep acoustics and maintenance visible
Lindab sound theory discusses the different sources and paths of sound. The offer needs a clear solution, not merely the word “quiet”. Check the silencers, mounting and other selected components. If they are absent, the basis for the choice must be explained.
Maintenance scope matters too. Will you receive filter codes, an accessible servicing location and instructions? Who performs warranty diagnosis, and where are parts available? Do not treat these as minor questions for after purchase. The system will be used for a long time, and convenient maintenance depends on the initial installation arrangement and clearly assigned responsibility.
Commissioning scopes must match
One offer may include only start-up; another, airflow measurements and a report. These are different jobs. Ask for a clear statement of what will be checked and at what stage of house completion. If doors are fitted or finishes changed later, another check may be needed. The estimate must make clear how this is handled.
Handing over documents is not merely a formality either. The as-built layout, settings and airflows will help maintain the system in future. If one offer does not provide for this, add it to the comparison or clearly identify the omission. Results with different checking scopes cannot be called equivalent.
Illustrative example: one appliance, two packages
Suppose both offers specify the same heat-recovery unit. The first includes external openings, insulation and balancing; the second leaves these to the owner. Matching the appliance alone does not create an equivalent scope. Obtain an offer for the missing work and understand who is responsible for the final interaction of all the parts.
The owner asks for clarification and compares complete options using the same tax treatment. It then becomes clear whether the difference comes from different materials, work, warranty or actual pricing. This text gives no market totals because they depend on the date and property. The comparison method remains useful even when prices change.
The procedure for additional work and deadlines
Before choosing, agree how changes are approved and what happens if an unforeseen obstacle is discovered. A clear decision procedure protects both parties. In renovation, not everything can be known before opening up structures, but known uncertainty must be shown. There should be no vague general right to change the entire total at any time without justification.
Also coordinate when other contractors' work must be ready. If the electricity or drainage connection is not prepared, completion of ventilation may be delayed. The schedule must make this dependency clear. A promised installation date alone does not prove that full operational acceptance will be possible that day.
Review the final version of the offer
After several conversations, an old document and new verbal agreements may coexist. Before ordering, ask for one clear updated version showing all approved changes. The model, quantities and work by other contractors are particularly important. Do not rely on remembering separate messages when installation or acceptance time arrives. A well-organised document helps both owner and contractor work to the same task, not two different interpretations of it.
Keep running-cost assumptions separate
If the offer promises lower future costs, ask to see the basis for their calculation. An installation estimate and an annual forecast are not the same document: the first defines the work, while the second depends on use and prices. Clearly separated assumptions help avoid confusing a guaranteed work scope with an indicative energy estimate.
How to make the decision
Assess the complete result, its justification and clear boundaries of responsibility. The cheapest or most expensive option is not automatically the best. Read more about airflow selection in this article. In your enquiry, you can provide two estimates after removing unnecessary personal information. A good comparison ends not only with a chosen total but with an understanding of exactly what you will receive for it.
Information sources
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