In message , John Doe
writes
Bought a cheap humidity meter, really enjoying it. Its main purpose
combined with a dehumidifier is to help keep the humidity under 50%.

The inside humidity seemed to follow the outside humidity until about a
week ago. It was dry. But then very humid. Ninety-six percent outside for
the last several days and yet the humidity inside has remained less than
45%. Today it was up to 45% but now it's down to 40% even though it's 80%
outside.

We use a gas heater. Is that the cause?

Thanks.

Any heating of the air indoors that raises its temperature above what it
is outdoors is going to lower the relative humidity, because warm air
can hold more water vapour than cold air. The relative humidity value is
the percentage of the maximum amount of water that the air could hold at
that temperature.
--
John Hall "Never play cards with a man called Doc.
Never eat at a place called Mom's.
Never sleep with a woman whose troubles
are worse than your own." Nelson Algren