Condensation & dehumidifier questions

SecondStar

We have an 80’s chalet bungalow, with bedroom and home studio in the eaves, 2 reception rooms, kitchen, and bathroom downstairs. All rooms are in use by 2 people, and 3 pets.

We’re trying to save on gas and electric costs by only running the heating sporadically, maybe 30 mins a day in all rooms, primarily to dry towels and bath mats on the bathroom radiator, and knock some of the ‘cold damp’ feeling off the air.

The house has an average temp of around 17 degrees during the day. The heating will go on if that drops to 15/16, and will heat until it reaches 18 degrees.

We keep the kitchen window cracked on the vent, the bedroom and bathroom windows are always ajar, and the bathroom window is kept wide open with the door closed during showers.

Unfortunately the bathroom has no extractor fan. A 15 minute shower with the door closed and window open will leave the room dripping wet on every surface.

We use the smallest room upstairs for the bedroom, and keep the door open all the time. Even with the window ajar there is still a build up of condensation on the window overnight, the top of the duvet and our clothes in the drawers often feel slightly cold or damp. The air in there always feels too damp.

I acquired a secondhand dehumidifier yesterday, and I’m wondering what the best use of it might be for our situation? I’ve never had one before, but I’m keen to keep the house damp-free, without burning through the gas.

It’s quite a noisy unit - would we need to run it in the bedroom overnight to get the most benefit, or would turning it on in the morning and running it during the day be as useful?

Likewise for the bathroom, I assumed we’d wipe down the worst of the water from the walls and surfaces, and then close the window and run the dehumidifier with the door closed for…an amount of time? Not sure how long?

I’ve also read that we can use it to help dry clothes on a clothes horse, if we use a suitable room and run it for…an amount of time? Also don’t know how long?

I’m just not sure what expectations to have of this unit, whether they’re the sort of thing you run for 1 hour, or for 10 hours?

Any light shed would be useful, it’s this unit for reference - https://www.manualslib.com/manual/857242/Argos-Mdt-10dmn3.html

powercharge

Depending on the temperature on the house and if you have the beed door open or not, you will still get condensation on the bedroom windows overnight even with a dehumifier.  I tried running one on in the bedroom over night, it did help, but it didn't completely eliminate condensation on the windows.  It might be different for you, just my experience.
I don't use mine anymore as it uses a lot of electricity.  Now I use a window vac to suck up all the condensation off on the windows in the mornings and after a shower, rather than it evaporating into the air and absoring into the walls etc.

SecondStar

powercharge said:

Depending on the temperature on the house and if you have the beed door open or not, you will still get condensation on the bedroom windows overnight even with a dehumifier.  I tried running one on in the bedroom over night, it did help, but it didn't completely eliminate condensation on the windows.  It might be different for you, just my experience.
I don't use mine anymore as it uses a lot of electricity.  Now I use a window vac to suck up all the condensation off on the windows in the mornings and after a shower, rather than it evaporating into the air and absoring into the walls etc.

I’ve edified the post with the house temps, thank you!

It usually averages 17 degrees indoors during the day. It can be 15/16 first thing in the morning, in which case the heating will go on for a while until it’s back to 17/18 again.

BUFF

SecondStar said:

I’m just not sure what expectations to have of this unit, whether they’re the sort of thing you run for 1 hour, or for 10 hours?

Any light shed would be useful, it’s this unit for reference - https://www.manualslib.com/manual/857242/Argos-Mdt-10dmn3.html

It is a small unit - depending upon how humid the air is to start with I would suggest that you are looking at the 10 hours+ rather than 1. Over time this would hopefully reduce though.

SecondStar

BUFF said:

SecondStar said:

I’m just not sure what expectations to have of this unit, whether they’re the sort of thing you run for 1 hour, or for 10 hours?

Any light shed would be useful, it’s this unit for reference - https://www.manualslib.com/manual/857242/Argos-Mdt-10dmn3.html

It is a small unit - depending upon how humid the air is to start with I would suggest that you are looking at the 10 hours+ rather than 1. Over time this would hopefully reduce though.

Sorry for the silly question, but would that be 10 hours positioned centrally in the house (top of stairs, in centre of house), to try and take the edge off the whole house? Or 10 hours in each room, over several days? 

powercharge

With temperature around 18 you would need it running all the time I think. You will definitely still get condensation on the windows in the mornings

smellymel74

from expert from personal experience I think you’d need to place a small dehumidifier line you seem to have as close as possible to where you want to dehumidify - and within a closed space if possible - for it to be effective. Best bet then would be to test it - run it for 1. 5, 10 hours etc and see how long it takes to get rid of the condensation. 

For bigger spaces (or equally more condensation), you’d probably be better off with a bigger and more powerful unit. The back of my house, anlarve open plan kitchen-diner, is in constant shade (shadowed by neighbouring wall) so I get pretty bad condensation on two large back (new) windows when it’s been a chilly night. I have a large dehumidifier, stick it in for 1-2 hours when I get up in the morning and close the doors while it does its noisy thing. That’s long enough for my unit to dry out the windows completely.

you also don’t have to empty larger units as often which is handy. 

aoleks

Open the bathroom window and the windows in the room opposite the bathroom to create a flow that removes all steam when you shower. Leave the doors open.

also 15-17 degrees is too cold, if you ask me.

FreeBear

Last winter, I had the heating set for 16-18°C and only really had a bit of condensation on a few of the windows. Even in the bathroom, condensation wasn't a huge problem - Yes, a mirror, window, and tiled walls got a bit of mist on them, but never "dripping wet". Unlike other posters, I keep windows closed and don't have an extractor in the bathroom. Nor do I have trickle vents...

This winter, the temperature has not fallen below ~18°C internally, so heating hasn't kicked in yet. Have had the fire lit in the lounge a few nights which has seen the whole house temperature climb to ~20°C.

Devongardener

I use a Karcher window vac for condensation on windows, much quicker and cheaper than waiting for a dehumidifier to do the job.  I also use it in the shower cubicle, including the surrounding tiles and base, and as much of the rest of the bathroom surfaces I can reach.   

I’d say try to spend less time showering, 15 minutes is a lot!

jennifernil

We have extractor fans in all bathrooms and the kitchen.  After 2 consecutive showers, it takes 15-20 minutes to clear any condensation on bathroom mirrors or windows.

Windows are rarely opened in the  bathrooms, and certainly not while showering or in winter, we like a reasonably warm bathroom!  We have trickle vents, but close them up in winter.  We rarely get condensation on bedroom windows.

In the lounge we keep around 21 degrees, less in the kitchen and hallway,  main bathroom TRV is set to 19, but it feels warmer than that in there.  Bedrooms are not usually heated directly at all, but all doors are left open to allow heat from the hallway to circulate.
Heating is presently on 2 hours in the morning and 5 hours in the evening, we are at home all day.    

The house is from 1988, timber frame, and well insulated.  We have had a new boiler installed this year so hope to use a bit less gas this winter.  We have large south facing windows , so if there is any sun, the house warms up nicely.  I would call it a "dry" house.

I could not stand having only 18 degrees when sitting reading, or watching TV!   We will just have to dip into our savings to pay the bills.

Our daughter has an older house (1920s, 1970s and 2010s) and runs a few dehumidifiers to combat condensation on windows, even though they are double glazed, and to stop the internal doors swelling so much they cannot be closed.  She has extractors in the bathrooms, but it still takes a long time to clear the condensation after baths/showers.