To think that my house should get warmer quicker?

[Axlcat]

it takes about 2 hours to move 2 degrees and won’t go above 18.4. I can’t afford to have it on constantly! Surely 1 degree an hour is slow? And to not go above 18.4? It’s been on 4 hours now.

I don’t know what is going on. It wasn’t like this last year. The house feels so cold - it’s even colder upstairs. Boiler is not old and is set to 70 and radiators all feel hot.

Is there something that I am missing? Why won’t it go up and stay warm?

Yes, outside air at the moment is often very high humidity often high 80's and 90's when damp, but it's high humidity at a low temperature e.g. at 8 degrees.- but when that air is heated up the humidity % drops significantly.

It's beneficial, in terms of humidity, to air your house with cold air and then heat that air to room temperature to reduce the relative humidity.

However, in real life it's difficult to constantly do this, it is cold and damp air coming in so the house is uncomfortable and then it's expensive to heat it up.

The reason I'm a fan of dehumidifiers is you don't need to do any of this; you keep the windows shut, extract the moisture from the already warm air, and the dehumidifier expels slightly warmer air which can keep the house from getting cold while it works - usually overnight in my case.

Depending on your house design, you could consider 2 dehumidifiers (say 15litre size) for upstairs and downstairs, or 1 bigger one say 25l for a central area if you have an open style of rooms / stairway.

Assuming that is there aren't water ingress issues to sort first - plus all the other good practices about laundry and bathroom ventilation.

I'd also add (cos I'm a big fan of dehumidifiers!) that I've noticed that using a dehumidifier over a period of weeks (for about 6 hours each night) seems to have reduced the overall underlying humidity of the house - I'm assuming it's drying out any residual dampness that may have accumulated over the years in the walls, ceilings, corners etc.