dehumidifier/damp readings

I moved into a new house a few months back and the survey indicated some positive damp readings in some of the rooms. Its an old house (3 stories/ solid brick walls throughout) so I was not overly worried about this. There was of course no very obvious damp problems (sign of mould/smell etc).

I got the sense that the house was not heated much or ventilated so I left windows open as much as I could and heated all the rooms for a few months. I get no overt signs of any damp.

Someone lent me 2 large dehumidifers. I ran them in all rooms. The readings is the same in most places - but I don't know how to interpret them much. On turning on they read early to mid 60's and comes down within the hour to mid/high 50's. Some water is being extracted. The light stays green throughout (it can turn red with higher levels detected he told me but it has never turnt red) I do intend to run them for longer over the next few weeks.

What is the normal range expected with dehumidifiers? - never owned or had the need to run one before

I appreciate any time taken to respond, thanks!!

Probably cowboy with a damp meter , you don’t need the dehumidifiers.

Thanks, I did ignore a lot of the survey stuff on damp, given it was an old solid brick house and I read a bit around damp and old houses. Nothing has materialised that concerns me since I have been living here.

I was just wondering about the readings and what they mean/indicate - what is the 'normal' range of such properities

Many factors affect humidity, whatever you have is normal for your property.

Just to give a comparison.

I run a dehumidifier in my up stairs bedroom when I hang clothes on the clothes horse. When they are fresh out of the washing machine and still damp the dehumidifier reads normally 60+ after a few hours it’s into the 50s by the time it is dry mid to low 40s.

The AC does dehumidify and removes more than 2 litres a day, however rarely used, and this house is sitting at 55% at moment at 20°C. That is rather low, last house was around the 65% this time of year, and father-in-laws house was hitting the 80%, in the main high reading down to very well sealed doors, no vents, and gas cooking.

But run an open fire and it draws air from the room, forcing ventilation. And old house were designed with open fires, single glazing, poorly fitting doors, so moisture was removed. Central heating means reduced ventilation, double glazing means water not removed, old single glazed windows use to get condensate forming on them collecting in a tray at bottom which directed it to a hole so it could drain outside, as least it did with dads steel framed windows.

In out first house we would fill trays with water and place in central heating intake as house so dry, plants everywhere, still got shocks as so dry, all because using hot air central heating.

I know for every gallon of petrol burnt we get 1.5 gallons of water from the exhaust, I suspect something similar for gas, we know with modern gas boiler we get condensate from the gas, so the amount of water put into a room using a gas stove is likely more due to burning gas than from steam from food, so with an electric cooker no real need for cooker hood vented to outside, but with gas there is, if you do a lot of cooking.

Solid fuel was main way to cook when we had solid walls, and I know with my mothers solid fuel cooker the kitchen was really hot, so had louvred windows for cooling the room.

I know there are many variables and its good to hear some of those factors and comparisons. As I said earlier most of my rooms are now low 50's and tend to stay there with the odd one hitting high 40's. I understand this is normal for my house - with no experience of dehumidifiers I wondered what is 'normal' for other homes and situations. Thanks all for the comments