I'm installing a shower/WC in a ground floor flat. Unfortunately it is not adjacent to the edge of the building, so I can't have the extractor fan blowing through a wall to the open air outside.. Will it be OK to have it blowing down throught the floor to the well-ventilated space underneath? I could easily mount the fan in a hole in the floor... (I cant see anywhere else I can extract to.)
Anyone seen that done.. or done it? Any problems?
Thanks
Dave
No - you'll rot the floor joists. You can still put the fan as you say if you can get underneath the floor but you then need to run flexible ducting from the fan to a new airbrick to the outside.
"Dave£" wrote | I'm installing a shower/WC in a ground floor flat. Unfortunately | it is not adjacent to the edge of the building, so I can't have | the extractor fan blowing through a wall to the open air outside | .. Will it be OK to have it blowing down throught the floor to | the well-ventilated space underneath? I could easily mount the | fan in a hole in the floor... (I cant see anywhere else I can | extract to.) | Anyone seen that done.. or done it? Any problems?
It is not a good idea to extract moist steam-laden air into the floor void. It may cause moulds and rot.
The usual thing is to take up to the ceiling and out through an adjacent room at ceiling level, in a rectangular duct, concealed by a false coving. The fan has to be powerful enough to work with the length of duct; try and get the duct to go up to the ceiling and then have a slight fall to the exterior so condensation can drain out.
As it's a GF flat you might be able to drop down to the floor and run along at about joist level to a new outlet grille at airbrick level. But do not discharge into the floor void.
Owain
If you do this be careful as the warm air will condense inside the = ducting as it passes to the cooler air space under the floor and collect = at the lowest point, it will then start to smell and eventually it will = probably 'rot' the ducting. =20 You will be better to use rigid ducting if you can and ensure there is a = fall to enable the collected condensation to drain out of the ducting.
We had a builder who tried to vent our tumble dryer using a similar = arrangement,
1st attempt was up then through an unheated roof space, Asked him to = redo it, 2nd attempt was under the floor through flexible ducting and then join = up to the everso handy 10 foot length of 4" soil pipe that was connected = to an air brick that he had fitted to supply the air route under the = extension to vent under the suspended floor !!!Eventually me repositioned the tumble dryer on to an external wall.=20
With all that trouble it may be cheapr to install a dehumidifier. Certainly much cheaper to run.
NT
A dehumidifier would solve the moisture in the air - but I think building regs require an extractor fan rather than a dehumidifier, yes? And how do you come to the conclusion that a dehumidifier would be cheaper to run than an extractor fan?
RR
Since the power consumption of a dehumidifier is a few hundred watts and the extractor a few tens. I must be missing an aspect of your thinking?
BR requires ventilation. If its permitted, a door grille could provide that. If not, some of the airstream out of the dehumid can be safely vented through the floor, without causing any problems, and avoiding the difficulty, expense and ugliness of running ducting through the house.
A small fan might eat 20w, a dehumidifier 200w, a larger fan maybe
80w. Fans chuck warm air out continuously, adding to the heating burden. Dehumidifiers throw away nothing. Dehumids typically eat 200w for a small percentage of the time, all of which is dissipated into the interior air.In this case installation costs are also significant to the overall calculation, and a dehumidifer is quite likely to win there as well.
NT
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.