During the winter, I regulate the temperature in my apartment at 18 Celsius (64 Fahrenheit) for most of the day and 21 Celsius (70 Fahrenheit) for 5-6 hours when I'm home in the afternoon/evening and on weekends.

(Heating system is electric, far away from the piano)

I'm guessing this isn't helping the piano hold the tuning. But is this short-term regular cycling of temperature actually bad for the piano in the long term?

The piano is a nice English upright Knight from the 50s, in good condition.

No. Humidity cycling is worse. Make sure the tuner tunes it at the temperature it is played at. Don't use the setback that day.

That's not a big temperature change at all; don't worry about it. As Keith says, it's better to measure humidity.

--Cy--

No, not measure humidity but keep it even by letting the temperature go up and down. Keeping the temperature even drives the humidity up and down according to Ron Nossaman.

Ron is giving what sounds to be a detailed soundboard class in Salt Lake at the PNW convention. Anybody going?? Cy? you're near there.

Can't make it this year; I'm planning for the National in June. Ron N has built some awesome tools, like his pinblock drilling rig that floats on compressed air for positioning (just like air hockey!).

--Cy--

I'll be there. Looking forward to meet you, Keith. Check your PM