Monitoring beyond servers. Watching plaster dry.

By Chris Hannam, Product Engineer at Server Density.
Published on the 6th February, 2014.

A while ago I wrote about monitoring our office chilli plant. It’s really interesting how many things in every day life we can monitor to make our lives easier, so over the last week I took what I’ve learnt and applied it to monitoring the environment of my living room – for a good reason.

The reason

So, last week we finally decided to sort of our living room. It’s quite a large room and was in dire need of the walls being fixed ready to paint. We hired a plasterer to come in and “skim” the walls, which involves putting a thin layer of new plaster over the existing damaged walls to give a smooth finish suitable for painting. The whole process took 4 days.

Obviously, the new plaster needed to dry out before we could paint the walls or reuse the room, and as part of the drying process, the plaster gives off a lot of moisture. This can cause issues with condensation and slow down the drying time to a week… we couldn’t be without our living room for that long. Enter one Arduino Nano and a DHT 22 sensor.

The tech

Watching plaster dry is only slightly less dull than watching paint, so as with all things of this nature – it’s always best to get a computer to take care of the boring bits, here’s what I used:

  • An old laptop I had lying around.
  • An Arduino Nano.
  • DHT 22 sensor
  • BMP 085 sensor
  • Server Density free trial for 15 days (if your plaster takes any longer than that to dry, you’ve got bigger problems)

I had all of these things from previous projects and hobbies, but to buy they cost me no more than £10.

The setup

With an old laptop running the Server Density agent, and a humidity and temperature sensor, I wrote a simple plugin to read from the Nano and report back the environment inside of the room.

I then setup an alert to monitor the humidity and email me when it exceeded 80%. To complete the process in a Walace and Gromit esq fashion, this alert would have triggered a dehumidifier – but as I don’t have one, it meant me nipping downstairs to open doors and windows and airing out the room.

Below is the Arduino Nano and the attached sensor, the dark patches are the damp patches waiting to dry.

Environment Monitor

The following graph shows the humidity (in purple) almost mirroring the temperature (in pink) of the room.

Monitoring the home environment

In the graph above the big dips around 08:15 were caused by the plasterer arriving and opening the patio doors. The dips continue as he nips outside to mix up more plaster and leaves the doors open.

Monitoring the humidity level in the room like this allowed me to react to changes in the environment and reduce the overall drying time of the room, without having the doors and windows open all of the time. It’s interesting how simple the sensors and alert was to setup, and how much time it could have saved; I wasn’t constantly going in the room to check everything or worrying about the humidity.

In the real world.

Server Density already do a lot of basic server room environment monitoring, because it can help to diagnose issues and provide important warning signs of potential problems. I know from my experience in a previous job for example, when an air conditioner in a server room develops a leak over the weekend, getting alerted about the change in environment would have saved a lot clearing up on the Monday morning.

I’m a big fan of monitoring my home environment, I’m not sure I would have seen a return on my £10 in this instance, but I find it fun to play around with these technologies. The point of this post was more to highlight how these basic techniques can map into the server room; I’m of the opinion that the basic humidity and temperature monitoring of a server room should be as standard as monitoring the servers themselves.

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