Condensation in the bathroom

Window and door open whilst showering, even though the extractor sits right over the showerhead. Its the only way here, as we also have a small bathroom. No self-conscious kids though, there's just the two of us.

Worth having a dehumidifier in a room nearby (like on landing).  Do you have the showers really hot ?. The only time our bathroom got drippy was when my son would have the shower on hot.

We generally just have the window on vent. Never use the extractor.

Is the bathroom heated and warm before you shower? I find if my small bathroom is cold it creates much more steam and condensation.

Thanks all.  The shower is generally hot yes and the window is always open.  I worry about opening the door as the condensation will just spread around the house making the whole house damp.

I do use dehumidifiers but id rather solve the cause of the issue if possible (I know turn the shower temperature down).

Good point about the bathroom temperature, it is much colder than the rest of the house and only heated by a towel rail.  So that's likely to be the main issue to think about.

Thanks

I installed a huge inline fan for our tiny bathroom last year. We still get condensation if we don't pre-heat the room beforehand. The new fan does a better job than the old one, but doesn't cure the problem.

We now just run a dehumidifier in there once everyones done using it, which seems to be the best solution so far.

Obviously during the summer we'll have the windows open, which will negate all the issues.

By the sounds of your layout, the way your extractor is positioned it is removing mainly air from the window rather than humid air from the shower area. You might do better to open the window as you leave the bathroom. Inline fan will help, and yes, if you can position the vent so it grabs mainly shower air, that will do a much better job.

But condensation is about the temperature of the surfaces the air meets. It's relatively easy to swap a towel rail for something that actually puts out some warmth, and pre-heating the bathroom will help.

We have a similar issue as the walls are cold in winter (Victorian house). In summer it is fine as the window is open.

Our fan is above the shower but it makes little difference, you'd need something much larger and more powerful to shift the volume of air required. I tend to leave the door open after the shower with the light and fan on. I'm assuming this will pull the warmer dry air from the house.

I looked at dehumidifiers but never got round to buying one. It wouldn't solve the immediate problem in the bathroom but it would keep it under control and prevent damp in nearby rooms.

When I replaced the fan there were various different quality options that had the same size but pulled more air through. It might be worth upgrading the fan. Don't know enough about ducting but flexible is standard (and used industrially when mobility is required). Condensation can occur in ducting so look at how that is set up. Our fan died because it was at a low spot and it got damp over the years and corroded.

Inline fans have the ability to move more air than a surface mounted and if installed correctly are almost silent so can be run for longer without bothering people. Solid duct is always better than flexi due to the baffle effect of the air passing by the ridges but a short run of flexi pulled as tight as possible probably won’t make much difference. You could leave the original fan as is and put the inline one over the shower and use a pull switch to activate it when the showers in use and leave it on as long as necessary instead of the timer. Also cut a vent in the bottom of the door or a decent sized gap at the bottom so you pull air up and through the bathroom rather than from the window to the fan

New towel rail 100%. If you warm the room up, you will get much less condensation. 

I insulated our bathroom on the inside with polyurethane boards under water resistant plasterboard. A bit of a faff to retile etc but condensation is much reduced and soon evaporates. The air is still humid after a shower so ventillation still needed.

Our bathroom has a radiator so is as warm as the rest of the house. Maybe that's part of the issue ?

We leave the window fully open for about 5-10 minutes after showering with the door closed. Dries out perfectly even in the current monsoon season. 

Personally I wouldn’t leave the door open as it will just increase humidity in the rest of the house. However, ensuring there is sufficient gap at the bottom of the door is beneficial in terms of general airflow around the house, mine were all very close to the floor so I ended up taking them all off and slicing 10mm off the bottoms!

I have an axial fan through about 6 meters of flexible duct to the soffit, it works well enough see the vapour get pulled through out, but it’s only enough to clear the room once the shower is off, if you want more power you will need a centrifugal fan, and perhaps a humidistat to lengthen the overrun.

My fan vent is over the shower cubical.  We also squeegee the shower walls afterwards and we added an electric timer element to the towel rail, so it’s now dual fuel and you can turn on the electric control either timed or permanent to help dry the room and towels.  The room is normally dry within 15 minutes.

What made a big difference for us is fitting a fan that runs full time on trickle so that theres always air movement. So is has three states - an alway-on trickle flow, a humidistat-triggered boost that increased ventilation if the room is humid (so through the night after a shower if required) and also runs faster again if the light is on. The air flow rates for each function are adjustable too.

Its no more efficient than any other kind of fan while you're showering but you're starting with a room with drier air and doing more to dry the room in the period after a shower.

To pull air out of the room efficiently there also needs to be a way in for air, all the time, not just when you're in the shower. So our bathroom door is ventilated so that theres always airflow, which means the trickle fan/humidistat is actually managing moisture/airflow for the whole house (well half managing it because we've got the same fan in the kitchen too)

Our room seems to clear better with the window closed than open as the fan is above the window, so I presume the fan is just pulling air from the window opening up and out through the ceiling while the air in the rest of the room is fairly still. With the window closed its pulling air from the door, across the room and out

In a similar vein. I replaced one of our double glazed units. 
It gets more condensation than the old units. Does this mean it’s more or less efficient?

In a similar vein. I replaced one of our double glazed units. 
It gets more condensation than the old units. Does this mean it’s more or less efficient?

Condensation forms on the coldest surface in the room. So you'd maybe presume that it's less efficient if everything else is equal.

Buy 'unit' do you mean you replaced a window? Or replaced part of a window?

If the new window gets more condensation than other windows in the house either that window is less effective than the others or the room is more humid than the others.

Its less ambiguous is the unit is part of a window

What was happening before you made the replacement?

The glass must be colder so your new double glazing is worse all other things being equal.

A new build has a fan that is a trickle but has a movement detector that increases the speed for abou five minutes when we step in the shower. The buildiing is insulated to the latest standards and condensation negligible.

As maccruiskeen said, you want a fan that runs constantly at a low level then boosts. I've put them in 1930's houses with corner bathrooms so two external walls and they've always solved the problem of condensation on the walls even with teenagers 20minute showers. Worked with both ceiling mounted ducted and through external wall.

I'd start by just replacing the existing fan and see how that goes before installing an additional one.

Fit the inline fan. Relocate the intake to above the shower. (Use the cut out to patch the old hole). Use Flexi duct, but as tight as possible. Use insulated Flexi duct. Make sure there is a downward slope from the inline fan to your external exhaust point - you don't want condensation building up in the pipe, and eventually causing a sag and a water trap. My tip is to use 100mm diameter jubilee clips to hold to he ducts on. They are more secure than tape.

I would keep the window closed. Hot steam meets cold air means more condensation. When condensation droplets form they will then accumulate on any surface. Air from the rest of your house will be warmer and drier than external air. Draw that through the bathroom to dry it out.

If you have a modern 100mm inline fan, it will probably draw over 200m3 an hour, more than enough to clear the room and dry it out.

If you can add additional insulation above the ceiling in the loft, this will help too. The top of the external wall is usually the worst point for this.

I did all of this when we refitted our bathroom, including a humidistat to trigger the fan. The fan only comes on when the shower is running, and then clears the room no problem. Humidistat to trigger the fan, then run-on timer to ensure humidity drops to background levels.

I found rigid duct more noisy, even when I insulated it.

The previous window unit had steamed up between the panes so I replaced the double glazed unit.

Posted by: markspark

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Inline fans have the ability to move more air than a surface mounted and if installed correctly are almost silent so can be run for longer without bothering people.

Would you (/anyone) have any recommendations for such a thing please?

My partner keeps turning ours off because it's "too noisy" and I can't afford a new bathroom, so "almost silent" appeals greatly.

I turned the HW temp on my boiler down to 50c.

Figured I was mixing cold water with the hot at the tap, so in my mind I was paying to heat water up just to cool it down again.

Less steam too.

So if you have any scope to dial it down a bit, you're preventing a lot of the issue at source.

https://www.hse.gov.uk/healthservices/legionella.htm

Just be mindful of legionella. Water should be heated to 60c to ensure any bacteria is killed off.

@Cougar the standard will be something like the Manrose MF100, or something similar from Ventaxia. 

The Manrose MF100T has a run on timer. If you search for 100mm inline extractor there will be loads. There are some that are cheaper. Most will quote dB, usually at 3m. If you want to get really picky, you could mount it on a vibration isolating mount. The length of the run and the "straightness" of the run will also have an effect.

I now dismantle any new fan and reassemble it, sealing all the joints so there can be no "drippage" of condensation. If you get the overrun and insulation right, there should be no moisture left in the pipe when it shuts down, but once I saw a damp spot on the chipboard floor in the attic and thought "Right!".

If you can add additional insulation above the ceiling in the loft, this will help too. The top of the external wall is usually the worst point for this.

Although be careful stuffing insulation under the narrowest part of the eaves on a pitched roof, you need airflow under the roof or different problems will happen. We have a very tight gap right at the corner of our bathroom which is on an external corner. Even with good ventilation it got mouldy up in that corner. 

Eventually I gave up and boxed in the ceiling edge at that end of the room with insulation inside that.

Posted by: bruneep

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https://www.hse.gov.uk/healthservices/legionella.htm

 

Just be mindful of legionella. Water should be heated to 60c to ensure any bacteria is killed off.

 

Yeh I think that's more if you have a tank.

@TroutWrestler thankyou

Inline fan should help as they usually have a higher air flow rate so should be able to extract air quicker.  

Think about where the replacement air is coming from.  Keep the window cracked a bit or make sure your bathroom door has enough gap at the bottom to allow air into the room to break the vacuum and keep air flowing.

Think about the duct positioning, you want it as close to the shower as possible to draw in the moisture air quickly and stop it dissipating into the room.  You also don't want it in a position where it's just drawing in fresh air from the house or window and not drawing the air from the shower.   Ideally you want fresh air -> shower -> duct, so the duct is taking the damp air out the room which is replaced by fresh air coming into the room, its not always possible to get the ideal set up so try to figure out the best comprise that works for you.

Lots of guides on YouTube that will go into more detail so have a search and watch a couple vids to understand the concepts better.

All that will help to expel the damp air but if your bathroom is not warm and not insulated well it will always have condensation.  To reduce that you need heat and ventilation, heat to encourage the water off the surfaces and into the air and ventilation to take that damp air out of the room ready to take up more damp from surfaces.  So look to see if you can do changes to heat the room effectively  and keep a fan on a long overrun or constant trickle.

A recent cheap and easy addition we made was a window vac and it's been a game changer.  All four wall of our bath room are tiled and left damp after a shower, we go round quickly with the window vac and it takes up most of the moisture from the walls, they are still a bit damp, it doesn't get them bone dry but gets rid of the majority of the dampness.  It means the remaining damp is much easier to dry out by keeping the window open for a bit or just running the dehumidifier for a short while.  The bathroom used to stay damp of a couple hours before now its dry within 15-30mins depending if the heating is on or not.

similar issue here. 

Solution is ditch the towel rail and install a large radiator to keep the room warm. if its cold then the water will condensate on the walls / glass regardless. Youll not shift enough air to take out all the moisture in the air with a fan. 

ive used constant running fans as well. Then once you are out the room is well ventilated. But its useless if its cold. 

Towel rail also means that your warming up wet towels into the room so your just increasing the moisture content. All hooks for the towels and a big rad. and turn the heating on. Most issues are with the house being <16degC

We had similar here too - old house with cold stone walls and a bathroom that just had a towel rail in it. 

- we fitted a decent sized radiator (back where the previous owners had taken it out from, FFS).

- we're diligent about squeegying the sides and floor of the shower cubicle after every shower to get as much water down the drain as quickly as possible rather than sitting and evaporating.

- we leave the light one for ages to keep the fan running. I keep meaning to get into the lift to up the timer on the fan, but the access is an absolute PITA (to the point that I've never actually been up the loft at all)

cold shower?

Posted by: nwgiles

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cold shower?

You are Bear Grills and I claim my £5!

But seriously, if you don't run the water steaming hot in the first place... You've already solved half of the problem. And you'll save on gas/electric at the same time. Tripple win!

I dunno about anyone else but I don't like to get my skin burned either.

Thanks for the ideas everyone.

Looks like I'll be moving the inline fan directly over the shower and swapping the towel rail for a proper rad.

And turning the boiler down a bit.

Cheers all

When our bathroom was redone last year I got the shower built in totally with the extractor inside the shower cubicle. Apart from preventing condensation in the rest of the bathroom it also means it stays nice and warm in there when drying yourself.

Probably to late to the party and some points repeated from above, but gives the OP an alternative if they are interested.

Due to condensation issues I installed 20ish years ago ceiling mounted:

• Icon Airflow 15 (shutters [ceiling monuted so really helps retain heat], timer and humidity detectors) in our relatively small ensuite which has a small outside wall and window
• Icon Airflow 30 (shutters, timer and humidity detectors) in a decent sized bathroom with 2 outside walls and a large window.
  Both rooms have a radiator and a towel rail (to avoid blanketing the radiator).
• Both fans 
  • are above the shower, which due to the dampness there, does result in a slow build up of dirt on the fan blades which I clean off, say, every 5(?) years
  • discharge through 4" flexible ducting and a roof tile due to access issues (bathroom duct route is twisty but vertical)
  • air make up is not restricted by tight fitting doors.
  • will hold a credit card against the grill
    The original fans held a piece of toilet paper (I didnt think much of a test) but were ineffective
  • have independant power supplies and pull cord switches from the lights.

They have proven very effective and, I think, are quiet. Setting the humidity detectors was the fiddliest bit. 

I did wonder if the biggest downside to the OPs idea of installing a second fan was the likelihood of the more powerful fan simply reducing/negating the performance of the weaker fan, especially if the air make up route is restricted.

It is obviously more of an issue the further north you live, my eldest lives in south London and has no issues just using a cheap wall mounted extract fan the other side of the room from his walk in shower.

Ooops double post.