[wizzo227]

A dehumidifier has helped to decrease my heating bills this winter. A thermoelectric device traps condensation in a drip tray of about 600 cc. It uses about 0.024 kW and collects typically 1 ounce (30 grams) of water overnight. The drip tray is a safer place for that damp to go to than the walls carpet and wardrobe. At a cost of about 0.2 kWh per night, that saves needing to open a window so much, and has saved several kWh of heating per night to get the same drying effect.

[DebF_EONNext]

This is a fantastic idea @wizzo227, I thought about trying this but I worried about the noise are they loud?

[wizzo227]

@DebF_EONNext
Not at all loud. I sleep in the same room as mine. You can set a scrap PC fan at 9 Volts to test listening to exactly what these things do. The thermoelectric part is solid state and silent. This week grams water collected overnight has been 31, 44, 48, 41, 28 somewhat weather dependent. I do still open the window in the daytimes, but not for so long, so letting in less cold.

[wizzo227]

The BBC report one of the most reputable brands of house sized dehumidifer; things which run at 0.1 to 0.2 kW to pull perhaps a pint of water out of the air overnight. https://www.bbc.co.uk/news/business-67623256
With just me damply exhaling into the small bedroom, the smaller thermoelectric dehumidifier reported last year suits me better. This week with warm damp weather outside for January, mine has been collecting around 2 ounces of water overnight while running at 0.02 kW; less than having a TV on.
The week before, while it got to freezing outside, I didn't bother with the dehumidifier as the cold window glass was collecting far more condensation than a cold-box dehumidifier would, so I'd open the windows briefly and wipe down condensation to drip to outside as my main way to get rid of surplus damp. I have also used it near to a clothes drying rack which had not finished off drying outdoors before we ran out of daylight, again collecting a few ounces of water in a few hours.

It is also possible to get "zeolite disc" type dehumidifiers which use typically 0.6 kW, which is enough to be useful heating byproduct, and might suit a bigger house with more occupants and laundry, and who want anyway to burn 0.6kW of electric heating at times. Has anybody tried various types who could comment ?

[meldrewreborn]

@wizzo227

Others have mentioned the Aero 360. I've looked at these and came to the conclusion that the cartridge inside is just common salt. (I may be wrong) Living in London our water is quite hard so we have a water softener that means the vast majority of our supply is softened (all bar kitchen sink). The water softener uses pebble salt in an ion exchange process to soften the water. Inevitably I spill some of the salt when filling the softener (its in the garage) and I've noticed how the spilled salt attracts condensation. An old technique for keeping salt dry in a condiment set was to put rice in it. I shall have to construct a device using salt or salt and rice to see if its effective in absorbing condensation.

To remove overnight condensation from our bedroom window we use a J cloth slightly damp to remove most of the excess water and then a chamois pad from Lidl to dry completely.. Works a treat and is sometimes my morning exercise. However I've only had to do it once so far this week the problem is quite variable in nature.

[retrotecchie]

@meldrewreborn

I have double glazing and haven't experienced condensation on the inside of a window since the late 70s!

My house, being of stone construction and not having any DPC can be a bit prone to higher humidities, but keeping it at a fairly constant 16C and using non-electric dehimidifiers in strategic locations and using the trickle vents on the windows means it's never a real problem.

The cheap half-litre dehumidifiers costing a few tens of pence each are all that is needed in bedrooms and the living areas, but the Aero 360 has proven it's worth in my unheated barn/office.

[wizzo227]

Originally Posted by retrotecchie

never a real problem.

It sounds like you don't have much exhaled dampness. Unplanned draughts are improbable given your history of considerable energy saving. Does your success mean that you've worked out how to not breathe at night time ? Asking fuel-poverty households to not exhale at night time seems to me to be rather an unfair way to save their heating cost of opening windows enough to dry the room, which is why I still prefer my small thermoelectric dehumidifier.

[retrotecchie]

@wizzo227

Unwanted draughts are all eradicated. But the window trickle vents are more than adequate to mitigate exhaled moisture and even in winter I tend to leave one of the windows open just an inch or two at night. I don't heat the bedroom as I find the heat coming from downstairs is more than enough to maintain a comfortable sleeping temperature of around 14°C.