my house smells of damp

[gee]

Hi
My house smells of damp!!
We moved in about 18months ago to a cold damp detached bungalow which had been empty for 3 months. It smelt. On putting the heating back on, condensation started running down windows by the bowl full. The old owner had left us a de-humidifier. (Wish I’d seen that on the viewing) we obviously started using it.
We've since changed most of the carpets etc and thought we'd cured the smell. How wrong I was.
We did find that the extraction in the en-suite was blocked so changed it. Again this helped reduce the amount of condensation on the bedroom window in the mornings.
The de- humidifier now spends most of it time in the back bedroom were it currently take out 3 litres of water every 24 hrs!! give or take a few hrs weather dependant. I occasionally move it round the house and it takes out about a little less but it is working hard.
We do have a few black spots on walls in the house.
We don't have any obvious signs of damp on the walls and our loft is well ventilated
If any one has any ideas to help us understand the problem would be great.
Thanks all.

[Perry525]

If it smells of damp, then it is damp!
Very often a home is damp because of the way the people who live there use it.
Breathing, sweating, cooking, washing, drying things indoors, all these things put water vapour into a home.
Opening windows, using extractor fans in kitchen and bathroom, not drying things indoors will all reduce water vapour and therefore condensation and damp.

The appearance of damp is most often due to turning off the central heating.

Warm air at 30 degrees centigrade can hold 30 grams of water vapour per cubic metre.
That's about enough water to cover the bottom of a whiskey glass to a depth of half an inch - not much but, work out the number of cubic metres in your home and it soon mounts up.
At 20 degrees air can only hold 18 grams of water.
At 10 degrees its down to 8 grams.

From the above you can see that holding the indoor temperature steady 24/7 will stop most condensation and damp.

Do not turn off your heating at night, perhaps turn it down a degree or four, ditto during the day.

Use the dehumidifier to control the amount of water vapour in the air, aim at an average of 65%. Don't worry that on a hot summers day the humidity goes down to 15% nor that on a cold wet day it goes up to 70%

Just concentrate on sorting the home out.
By the end of summer you may well be down to one litre a day.