Ducted vs. Ductless Fume Hoods — Which Do You Need?
Complete comparison of ducted vs ductless fume hoods. Cost, safety, chemical compatibility, installation, and operating costs. Free evaluation.
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Ducted vs. Ductless Fume Hoods — Complete Comparison
| Factor | Ducted | Ductless |
|---|---|---|
| Chemical Range | All chemicals | Filter-specific only |
| Installation | Ductwork + HVAC modification | Plug in and use |
| Initial Cost | $7,000–$25,000 installed | $2,500–$6,000 |
| Operating Cost | $3,000–$6,000/yr (energy) | $300–$800/yr (filters) |
| Portability | Fixed | Moveable |
| Best For | Full chemistry labs | Specific, known chemicals |
Deciding Between Them: Five Questions
The comparison table above covers the differences. In practice the decision is settled by five questions, in this order.
1. Do you know the full chemical list, and will it change?
Ductless filtration is chemistry specific. A defined, stable list of compounds can be matched to a filter with confidence. A research lab whose chemistry changes every project cannot, and that alone usually decides for ducted.
2. Is there an exhaust path at all?
This is the constraint that drives most ductless enquiries: leased buildings, interior rooms, renovations where the roof and shafts are out of scope. Where there is genuinely no path, the options are ductless, a portable filtered unit, or relocating the work.
3. What quantities, and for how long at a time?
Small quantities and short duration work suit filtration. Sustained work, heating, or open quantities generate a loading rate that shortens filter life and pushes the economics and the safety case back towards ducted.
4. Who owns the filter routine?
A ductless hood is only as safe as its filter management. There has to be a named owner, a monitoring method, and a spare set. Where nobody owns it, the hood quietly stops protecting anyone long before it stops running.
Cost of Ownership and Scope Split
Comparing a ducted and a ductless quote fairly means comparing the same scope. The hood is only part of a ducted installation.
| Line | Ducted | Ductless |
|---|---|---|
| Hood | Supplied by us | Supplied by us |
| Blower and exhaust fan | Required; sometimes packaged with the hood, often the mechanical contractor’s scope | Not required |
| Ductwork and roof or wall penetration | Mechanical contractor scope; varies most between buildings | Not required |
| HVAC make-up air impact | Real and sometimes significant on smaller buildings | None |
| Airflow monitor and alarm | Recommended, and required in many specifications | Filter monitoring instead |
| Recurring cost | Conditioned air exhausted to atmosphere | Filter sets plus the labour to change them |
| Certification and testing | Face velocity verification at commissioning and periodically | Filter integrity and breakthrough monitoring |
Ask for both quotes structured the same way if you are choosing between approaches. Where the building side is out of our scope, we will say so explicitly rather than leaving it implied.
Sizing, sash types and utilities are covered on the fume hoods hub. For acid and digestion work see perchloric acid hoods, and for bench top options see benchtop fume hoods.
Frequently Asked Questions
We have no exhaust path to the roof. Is ductless acceptable?
Sometimes, and it is the most common reason people ask. Ductless is acceptable when the chemicals in use are on the filter manufacturer’s compatibility list, the quantities are small, the work is intermittent, and someone owns the filter change routine. It is not acceptable for unknown or mixed chemistry, for perchloric acid or radioisotope work, or where a risk assessment requires containment independent of a filter’s remaining life.
What do ductless filters actually cost to run?
Budget for the filter set plus the labour to change it, at an interval driven by use rather than by the calendar. The cost is modest against ductwork and fan installation, but it is recurring and it is easy to under-plan. Keep a spare set on the shelf and log change dates from day one.
Can a ducted hood be replaced with a ductless one in the same footprint?
Often physically yes, and it is a real option in leased buildings where a roof penetration is not possible. The decision is chemical, not dimensional: the filter has to suit everything that will be used in the hood, and the existing duct penetration then needs capping properly.
Who provides the blower, the ductwork and the roof penetration?
Usually the site’s mechanical contractor, not the hood supplier, and that split should be explicit on the quote. We quote the hood, the blower where it is part of the package, and the monitor; the building side is separate scope. If you want one number, say so and we will note what is excluded.
Which is safer — ducted or ductless?
Ducted hoods provide broader protection because they remove all vapors from the building. Ductless hoods are safe for their rated chemicals when filters are properly maintained. The ‘safer’ choice depends on your chemical list. If you use a wide variety of chemicals or work with unknowns, ducted is the safer choice.
Can I replace a ducted hood with a ductless one?
In some cases, yes — if the chemicals you use are compatible with available filters. This can save significantly on HVAC costs. Labs USA evaluates your chemical inventory to determine if ductless is appropriate before making a recommendation.
Related Pages
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