Wednesday 11 November 2020

Am I freezing in the cottage?

 The time has come for the annual renewal of insurance for our holiday home. One of the conditions raised by the insurer is that when the property is not occupied, we should maintain a minimum temperature of 15 degrees celsius. Presumably the logic behind this is to  prevent water pipes freezing in the winter and causing water damage when it thaws.

As a matter of course, we leave the gas central heating running on a low setting when there are low temperatures around. We've also insulated the condensate pipe from the gas central heating boiler and installed an electric thermostatic heating wire under the length of the external condensate pipe. This heater is triggered if the temperature drops below 5 celsius, preventing a build up of ice in the condensate pipe.  If the pipe becomes blocked with ice at the drain outlet, water can back up the pipe causing the central heating boiler to turn itself off.

Generally the insurers insist the property is inspected once a week during periods of low occupancy. One of the companies was looking to have daily inspections, which in our case is not feasible. There's a risk that a fault develops in the central heating leading to a loss of heating while the building is not attended. This would lead to the temperature dropping below the 15 degree threshold. 

We decided we needed to find a solution to this risk. After some research we found a temperature monitor/sensor which can provide alerts via the cottage broadband internet. The result is fairly low cost and we can check the health of our premises via a web browser or on a smartphone App. It also  can raise automatic SMS/Email alerts if a threshold is crossed.

The details shown in the graphic are: 
  • Temperature (Celsius.  Fahrenheit is possible), 
  • humidity (percentage), 
  • Light level (lux), 
  • supply battery voltage, 
  • WiFi signal strength. 

The sensor we are using can also monitor vibration affecting the device, so it can detect people causing vibration. These readings are monitored every 15 minutes (variable) and we can produce analyses over a time period. This data is held in a central database and can be interrogated via a web browser or smartphone app. If necessary we can prove to the insurance company that remote checks are performed.

We can also advise guests on the actual temperature/humidity during their stay at our cottage.

We now offer this as a rental service, to ourselves and others, at a modest cost of £10/month. It is a fraction of the cost of a single visit from our home to the holiday cottage. Alternatively people can buy the sensors, and register/sign on to the Internet of Things (IoT) to monitor their properties. There are more expensive versions which can report via GSM service. If you to buy one here's a link to an Amazon page, we have no financial interest in this link.

Edit 14th Nov 20

After a couple of days trial, the results are looking good. No cabling is necessary to install as it can be battery powered and connects via WiFi. It was just a matter of downloading a phone App and setting up the WiFi Router password on the sensor. The following images give a snapshot of some of the data available remotely via a web browser.

The monitor is sensitive to fractions of a degree. In this case I can spot when a door adjacent to the sensor is opened letting in cooler air from an unheated room.

In this example you see the relative humidity around the sensor. On the web browser you can move the crosshair cursor to check information at any time.

The sensor contains a light meter (Lux) and you can detect the amount of light falling on it at any time. I was able to detect when people come into the room at night and switch on the lights. I also ran a test to automatically send an SMS text message to my cell phone (mobile) when a light level threshold had been crossed.

It is possible to see the strength of the WiFi signal in the room. In our case we get occasional interference from vehicle mounted WiFi servers on the nearby roadside (A6 main road), which cause momentary dips in signal. Studying other monitors I can see it is the sensor losing contact momentarily with the network access point, not a genuine dip in available WiFi.  They look worse on the graph than reality because of the plotting method.

It is also possible to share a "view" of the device with other people. So one person can operate as an administrator, perhaps settings up and maintaining such devices whilst others (clients) can freely check the temperature, etc. of installed devices. The clients have the capability to set their own alert thresholds and create warning messages via email (free) or SMS texts ($0.18 in UK). Clients cannot configure the device parameters settings from their account.

Edit 16th Nov 2020
Today I decided to end the bench testing and to deploy the sensor out in the field for testing. I had to do a little work to have it recognise the WiFi  at our holiday cottage. I re-read the instruction leaflet, but had it operational within less than 10 minutes. I noticed that the cottage was a bit cold and discovered that despite us leaving the central heating running, the previous guests had turned off the radiators at the thermostatic valves. Visiting each radiator soon had them warm and toasty.  I also turned on the boiler condensate pipe heater. Someone had unplugged the trace heater..

This configuration certainly gives me an increased level of comfort that I'll be able to spot any heating problems remotely when the property is unoccupied, particularly during winter weather.  A spin-off is I'll also get a feel for how the guests use the heating in the cottage.

I also discovered today that the sensor monitor can be powered by a main USB power source while the internal batteries are also in place. If the main power goes out, the sensor will continue to record, using the internal batteries, and then when the power and Internet is restored, it will be able to automatically upload the backlog readings to the central database in the "Cloud".  Incidentally, the monitor device (set at 15 minute sample reporting intervals) seems to transmit about 2 Mbytes/day of sensor readings to the central database. The "free" allowance for data is 1 Gb/month per monitor.


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