Church organs are particular beasts – they don’t like it too dry because it spoils their leather bellows. One of our hosts, the Methodists, have requested we monitor their organ because their organ humidifier is on the blink. As always, if you’re on site and you see anything you don’t recognize with our logo on it, well, that’s us at work! Our battery operated sensor location, running with a DHT22 temperature and relative humidity sensor, is the little white box with the aerial, at arm’s length just inside the organ chamber. The Raspberry Pi feeding the readings to the web is in the room just outside the organ – you’ll find it if you look for electric sockets!
Here are the feeds, starting 26 Nov 2015. Straight lines are time periods of missing readings. If you can’t see anything, mouse over the graph and try pressing D for day or M, for month. If you still can’t see anything, our equipment has been down for a month (!) and you may need to tweet us. You can mouse areas of the graph to see more detail. For historical readings, scroll way down.
The first graph is relative humidity (%RH), nominally to within 2% with a maximum error of 5%. We think the error is broader than this, up to 10% . That’s still a normal error range for this kind of measurement (relative humidity is hard!), but enough that we intend to check against other instruments when we can.
Relative Humidity (%RH)
Here’s temperature, in degrees C.
Temperature (degrees C)
Experimental: Dream Factory
And while we’re here, we’ve also put a temperature sensor in the Dream Factory, the social enterprise space the Methodist Church very graciously lets us use in their basement. They don’t even mind us doing things with soldering irons and hot glue guns there! It’s blocky because we’re at the extreme edge of the radio range, I think; but it does serve to show that it’s actually pretty warm down there.
Spot readings (to check instrumentation):
- 26 November: DHT22 51%, CMM80 55%, whirling hygrometer 60%.
- 27 November: DHT22 50%, CMM80 50%, whirling hygrometer 61%.
- Apr-May 2014 (png picture format) – sanctuary temperature and RH. This was after the new boilers and pipework were in, but is believed to be before the controls were properly configured. They were taken with Tinytags gratefully received on loan from the Edinburgh School of Architecture and Landscape Architecture. That makes the readings “as good as they get”.
- Jan-Feb 2015 – organ temperature and RH, with a caveat. These may have used a box lid that only had air holes above the sensor, not a full cut out with the sensor poking out. We aren’t sure whether that would have made them slow to respond to change or artificially low.
- Aug-Oct 2015 – organ temperature and RH. According to our tests, these are within 5-10% of the “ground truth”.