Can I vent a tumble dryer into a room?
No — a vented dryer's exhaust is the load's entire water content plus fine lint, and putting that into a room causes damp in the short term and mould in the medium term.
- Difficulty
- beginner
- Time
- 25 min
- Read
- 5 min
- Safety
- warning
Short answer
A vented dryer must go outside, through a wall vent or a properly sealed window kit. It cannot be vented into a room, a cupboard, a loft or a cavity. If you have nowhere to vent to, the answer is a condenser or heat pump dryer, which collect the water in a tank instead — not a vented machine with the hose left loose.
The question comes up because a vented dryer is the cheapest type to buy, and the hose looks like it could go anywhere. It cannot. Understanding why takes one number: a normal wash load carries roughly two litres of water, and a vented dryer's entire job is to put all of it into the air leaving the hose. Indoors, that is two litres of water added to the room, every load.
Safety
What you'll need
- An external wall or a window that can take a vent kit, for a vented dryer
- A vent kit or wall vent with a flap (optional)
- A condensing box, only as a stopgap (optional)
Step by step
- Understand what is coming out of the hose.Hot air carrying the whole water content of the load — around two litres for a typical wash — plus fine lint that got past the filter. That is the design output, not a leak.
- Work out what two litres of water does to a room.It condenses on the coldest surfaces: window reveals, external wall corners, behind furniture. Repeated several times a week it produces black mould, peeling paint and, in a poorly ventilated house, damage to plaster and joinery.
- Rule out the places it must never go.Not into a loft, where it rots the roof structure. Not into a wall cavity or a void. Not into a cupboard, a garage without ventilation, or through an open window with the hose simply resting on the sill so it blows back in.
- Vent it through a wall properly if you can.A fitted wall vent with an external flap and a short, straight, well-supported hose run. Keep the hose as short and as straight as possible; every bend and every extra metre reduces airflow and lengthens the cycle.
- Use a proper window kit if a wall vent is not possible.A panel that fills the opening and seals around the hose, rather than a hose poked through a gap. An open window with a hose in it lets the moist air straight back in and lets cold air and rain out of the equation entirely.
- Keep the run supported and free of low points.A sagging hose collects condensate, which restricts the flow and eventually drips. Support it so it runs level or slightly downhill to the outlet.
- Check the external flap actually opens and closes.It opens under the airflow and closes when the machine stops, keeping out weather, draughts and wildlife. A flap stuck shut chokes the machine; a flap stuck open lets cold air and smells in.
- Treat a condensing box as a stopgap at best.The plastic boxes sold to catch dryer exhaust condense some of the water and release the rest into the room, and they need emptying constantly. They are better than a bare hose and much worse than a condenser dryer.
- If you cannot vent, buy the right type of machine.A condenser or heat pump dryer collects the water in a tank you empty, or can be plumbed to a waste. This is the correct answer to having no external wall, and heat pump machines cost far less to run as well.
- Remember that closed types still put heat into the room.Condenser and heat pump dryers release their heat indoors rather than their moisture. That is pleasant in a cold utility room and unpleasant in a small kitchen in summer, and it needs ventilation either way.
- Never restrict the outlet to make it fit.Reducing the hose diameter, coiling excess hose behind the machine or partly blocking the vent all cut airflow. The machine then runs hotter and longer, which is the condition that makes lint dangerous.
Tips
- If a room the dryer is in gets a lot of condensation, check the machine type first. A vented machine that has been discharging indoors is often the entire explanation for the damp somebody has been treating as a building fault.
- Vent hoses are consumable. A crushed, split or lint-caked hose is cheap to replace and immediately improves drying times.
- Some vented machines can be converted to condensing with a manufacturer kit, and some cannot. Check the model rather than assuming either way.
- A tumble dryer venting outside is also exporting heat you have paid for in winter. It is a fair trade for keeping the moisture out, but it is worth knowing.
Common mistakes
- Letting the hose blow into the room 'just for now' — Two litres of water per load into a house, several times a week, is one of the largest sources of household moisture there is. Mould on cold walls follows within a season.
- Venting into a loft or a cavity — It puts warm moist air into an unventilated, cold, timber-framed space. It rots roof timbers and saturates insulation, and it is invisible until it is expensive.
- Using a long coiled hose to reach a distant vent — Every bend and every metre reduces airflow. The machine runs hotter and longer, cycles lengthen, and lint accumulates faster along the length of the hose.
If it doesn't work
Windows streaming and mould appearing since the dryer arrived
Cause: A vented dryer discharging indoors — Fix: Vent it outside through a wall or a sealed window kit, or replace it with a condenser or heat pump machine.
Drying times much longer than they should be on a vented machine
Cause: Long, kinked or lint-caked hose, or a blocked external flap — Fix: Shorten and straighten the run, clear the hose, and check the outside flap opens freely.
Water dripping from the vent hose
Cause: Condensate collecting in a sag in the run — Fix: Support the hose so it runs level or falls towards the outlet, with no low points.
Questions people ask
Can you vent a tumble dryer into a room?
No. The exhaust contains the whole water content of the load — around two litres — plus fine lint. Indoors that causes condensation, mould and damp, and hot lint-laden air blown into an enclosed space is also a fire risk. If you have no external route, buy a condenser or heat pump dryer instead.
Can I vent a tumble dryer out of a window?
Yes, with a proper window vent kit that fills and seals the opening around the hose. Simply resting the hose in a partly open window does not work — the moist air comes straight back in, and the machine loses airflow.
Do condensing boxes work?
Partly, and only as a stopgap. They condense some of the water into a container you empty and release the rest into the room. They are better than an unvented hose and considerably worse than a machine designed to condense.