Bathroom extractor fan

The ease with which a *professional* diamond core drill will go through a wall is surprising. And with wetting and suction built in there is surprisingly little mess.

Don't know how much they cost, but most boiler fitters seem to outsource this part of the job to a man with a suitable machine.

Alternatively soffit venting is easy, but you might need a condensation trap at the fan end if the loft is cold.

Owain

Going thru the wall is the 100% reliable method with the best result: more air moved, no chace of drip-back. It's straightforward with an sds drill, albeit not fast drilling 100 holes. A thermal outlet saves money versus a gravity flap.

Control is another subject to consider.

When we had a bathroom vent fitted, it seemed to take them no tine at all to drill a 150mm hole through the 22 inch thick[1] stone wall.

Yes, thinking a bit more on it, agreed.

I think I'd look for a decent diamond core bit rather than the 100 hole route. Trying to stop the cavity filling pouring out is a concern though.

Heat recovery types are £300+. Not sure I could stretch to that - and not seen a thermal outlet type

Yes, think I'd go for a simple timer.

What I did was as follows, not for an extractor fan,but soil stack ventilation, and that was to run a a pipe to theh soffit then a 90 degree bend and then a simple grille. I did have to modify it as the pipe sagged in the middle, collected a pool off condensation and that leaked out of a joint into an upstairs room. Making it a peak instead of a valley worked fine. That bathroom has a fan straight through a wall.

Another upstairs bathroom has an extractor fan in the ceiling that goes via a short pipe run of flexi conduit to the soffit and an identical grille. That works fine too. Teh fan and a lot of the pipe is loft mounted and accessible.

I have two more bathroom fans on the ground floor. Both have fans IN the ceiling and SHORT pipe runs to grilles in the walls. One has failed twice and requires the ceiling to be mostly dismantled to fix it, so its stayed broken this time.

What is easiest to maintain and install is a straight through the wall (or window) fan

Mounting fans with long pipe runs is a nono and mounting fans in ceilings is something that really needs an access panel..

If you are under a cold roof, consider venting into the roof space if it has soffit and or ridge vents.

I think in your case IF there are no floors above, Id go into the loft space with a solid pipe, grille in the bathroom., mount a fan there and construct as short a run to a soffit vent as possible.

Again just a grille to connect some pipe to. Put insulation round it although nearly all fans represent a f****ng great cold bridge.

If there are floors above you will have no option BUT to go through a wall - the longer pipe runs to get to the roof will ruin fan efficiency

- or get a window cut for a fan if there is such.

In the case of a wall *hire the biggest fuckoff SDS* you can find and a

The answer is "it depends". In our bathroom we have a ceiling vent directly over the bath, which then goes to a stand alone fan unit in the loft, which then vents through more ducting to a soffit vent (which is very easy to fit).

This is an expensive option, but allegedly gives more suction power than most integrated units.

We also have a complex control system, again independent of the fan body.

There is a run on timer, and a humidistat, and a pull switch. So you can switch it on and it will run for a while after you switch off using the timer. Or the humidistat can cut in and keep the fan running until the humidity drops + the timer delay.

This avoids the issue of linking to the bathroom light and switching the fan on if you just nip in for a wee in the middle of the nigh, amongst other things.

But I digress.

Cheers

Dave R

If someone who uses that bathroom has a penchant for curried eggs then yes, get an extractor in there PDQ but what's the problem and how old is the bathroom design?

We have a flat in Buenos Aires which was built in the middle of the last century with a bathroom which has no windows and no ventilation beyond opening the bathroom door. It wouldn't be allowed today, even out there. It's about 18m^3 and we have found that a small dehumidifier with a 500ml tank keeps the place dry and free of mould. It won't solve the problem of the curried eggs, though.

Nick

On behalf of curried eggs I find this a completely vile hate speech and rant against eggs and curries in general, and those who identify as them.

Just because I dance round my bedroom wearing nothing but a poppadom, flexing my yolks on the mirror, I do not see why I have to be subjected to eggophobic 'fans' in the bathroom

I have done that in the past - easy enough, and has some advantages.

Can't see any benefit to this route if the other options are open.

Again easy enough if you have a suitable core bit, and a drill man enough to spin it. (easy to hire the bit and drill together)

The soffit vent option is well suited to a ducted fan. So you can place a large quiet fan in the roof space, and use flexible ducting in and out. If the fan is at a high point, then you don't need to worry about condensation particularly. It also makes for less fan noise in the room, and no need to chase power runs into the fan. It is also the most discrete option since the only visible intrusion into the room is the inlet vent (or vents) for the fan.

The direct through the wall approach is probably the simplest to do. IME a 750W SDS drill will just about cope with a 107m diamond core and take it carefully. (drilling straight helps prevent the core from snagging)

If the filling is loose beads, then it will likely POUR out, so maybe use a core drill that is at least close to being as long as the wall is thick and have someone push a vent pipe in from a ladder on the outside, as you pull the drill back in.

If it is blown fibre, then not much seems to fall out.

When I had a fan installed in the bathroom, the only place for it took a small chunk out of the lintel. The guy doing it wore out his old diamond core drill bit, and had to use a new one to complete the job. Are diamond cores known to not like rebars when they meet them?

They are not optimised for metal, no.

Traditional diamond abrasives are generally no keen on steel. While there are some new diamond cut of discs that will cut steel, I have not see the same touted for core drills.

I'm sure I have successfully cut lintels with reinforcement with diamond discs?

There is an issue with carbon and steel. Steel will absorb diamond and my understanding the ideal material to cut steel is a nitride.

Easier & quicker but £££ for one hole.

Most cwi types don't, but unglued beads get everywhere. Do you know what type you have? Unglued beads need glue injected around the hole before drilling, though that's not the only way to do it.

DMEV fans are available for 60, with far better energy efficiency than olde squirrel motor ones. Also much quieter. Last one rated just 2.5 watts.

If you want hrv, diy it.

The advantage of a thermally actuated outlet flap over gravity is the latter flaps open when windy. Thermals don't.

Bathroom extractor fans have more potential. Run them overnight in summer to cool the bathroom through the day. Let them switch on when RH gets high & heating isn't in use. A dmev fan plus 2 switches can do that.

Small beads - blessed with a few on the kitchen counter every time it's windy day ;-)

Collected about 2 buckets full on the outside toilet floor after I moved in. I'd be surprised if there's much left.

Ta, I'll look into that. I'm now coming round to the soffit/inline option.

Ah good point.

Ah, you got unglued beads.